Micro inertial measurement unit

• US 6,456,939 B1
• Filed: 01/04/2000
• Issued: 09/24/2002
• Est. Priority Date: 01/04/2000
• Status: Expired due to Term

• Current Assignee: American GNC Corporation
• Original Assignee: American GNC Corporation
• Inventors: Lin, Ching-Fang, McCall, Hiram
• Primary Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US09/477,151
• Time in Patent Office: 994 Days
• Field of Search: 701/220, 701/221, 701/225, 735/140.1, 735/140.2, 735/140.4, 356/462
• US Class Current: 701/220
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis

Abstract

A micro inertial measurement unit, which is adapted to apply to output signals proportional to rotation and translational motion of a carrier, respectively from angular rate sensors and acceleration sensors, is employed with MEMS rate and acceleration sensors. Compared with a conventional IMU, the processing method utilizes a feedforward open-loop signal processing scheme to obtain highly accurate motion measurements by means of signal digitizing, temperature control and compensation, sensor error and misalignment calibrations, attitude updating, and damping control loops, and dramatically shrinks the size of mechanical and electronic hardware and power consumption, meanwhile, obtains highly accurate motion measurements.

Claims

1. A micro inertial measurement unit, comprising:

an angular rate producer for producing X axis, Y axis and Z axis angular rate electrical signals;

an acceleration producer for producing X axis, Y axis and Z axis acceleration electrical signals;

an angular increment and velocity increment producer for converting said X axis, Y axis and Z axis angular rate electrical signals into digital angular increments and converting said input X axis, Y axis and Z axis acceleration electrical signals into digital velocity increments; and

a thermal controlling means comprising a thermal sensing producer device, a heater device and a thermal processor for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer, wherein said thermal sensing producer device, which produces temperature signals, is processed in parallel with said angular rate producer and said acceleration producer for maintaining a predetermined operating temperature of said angular rate producer and said acceleration producer and angular increment and velocity increment producer, wherein said predetermined operating temperature is a constant designated temperature selected between 150°

F. and 185°

F., wherein said temperature signals produced from said thermal sensing producer device are input to said thermal processor for computing temperature control commands using said temperature signals, a temperature scale factor, and a predetermined operating temperature of said angular rate producer and said acceleration producer, and produce driving signals to said heater device using said temperature control commands for controlling said heater device to provide adequate heat for maintaining said predetermined operating temperature in said micro inertial measurement unit.

2. A micro inertial measurement unit, as recited in claim 1, wherein said X axis, Y axis and Z axis angular rate electrical signals produced from said angular producer are analog angular rate voltage signals directly proportional to angular rates of a carrier carrying said micro inertial measurement unit, and said X axis, Y axis and Z axis acceleration electrical signals produced from said acceleration producer are analog acceleration voltage signals directly proportional to accelerations of said vehicle.

3. A micro inertial measurement unit, as recited in claim 2, wherein said angular increment and velocity increment producer comprises:

an angular integrating means and an acceleration integrating means, which are adapted for respectively integrating said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals for a predetermined time interval to accumulate said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals as a raw X axis, Y axis and Z axis angular increment and a raw X axis, Y axis and Z axis velocity increment for a predetermined time interval to achieve accumulated angular increments and accumulated velocity increments, wherein said integration is performed to remove noise signals that are non-directly proportional to said carrier angular rate and acceleration within said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals, to improve signal-to-noise ratio, and to remove said high frequency signals in said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals;

a resetting means which forms an angular reset voltage pulse and a velocity reset voltage pulse as an angular scale and a velocity scale which are input into said angular integrating means and said acceleration integrating means respectively; and

an angular increment and velocity increment measurement means which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular increments and said X axis, Y axis and Z axis accumulated velocity increments with said angular reset voltage pulse and said velocity reset voltage pulse respectively to acquire angular increment counts and velocity increment counts as a digital form of angular increment and velocity increment measurements respectively.

4. A micro inertial measurement unit, as recited in claim 3, wherein said angular increment and velocity increment measurement means also scales said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments into real X axis, Y axis and Z axis angular and velocity increment voltage values, wherein in said angular integrating means and said accelerating integrating means, said X axis, Y axis and Z axis analog angular voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals are each reset to accumulate from a zero value at an initial point of every said predetermined time interval.

5. A micro inertial measurement unit, as recited in claim 4, wherein said resetting means comprises an oscillator, wherein said angular reset voltage pulse and said velocity reset voltage pulse are implemented by producing a timing pulse by said oscillator.

6. A micro inertial measurement unit, as recited in claim 5, wherein said angular increment and velocity increment measurement means, which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments, comprises an analog/digital converter to substantially digitize said raw X axis, Y axis and Z axis angular increment and velocity increment voltage values into digital X axis, Y axis and Z axis angular increment and velocity increments.

7. A micro inertial measurement unit, as recited in one of claims 3 to 5, said angular increment and velocity increment producer further comprises an angular amplifying circuit for amplifying said X axis, Y axis and Z axis analog angular rate voltage signals to form amplified X axis, Y axis and Z axis analog angular rate signals and an acceleration amplifying circuit for amplifying said X axis, Y axis and Z axis analog acceleration voltage signals to form amplified X axis, Y axis and Z axis analog acceleration signals.

8. A micro inertial measurement unit, as recited in claim 7, wherein said angular integrating means of said angular increment and velocity increment producer comprises an angular integrator circuit for receiving said amplified X axis, Y axis and Z axis analog angular rate signals from said angular amplifier circuit and integrating to form said accumulated angular increments, and said acceleration integrating means of said angular increment and velocity increment producer comprises an acceleration integrator circuit for receiving said amplified X axis, Y axis and Z axis analog acceleration signals from said acceleration amplifier circuit and integrating to form said accumulated velocity increments.

9. A micro inertial measurement unit, as recited in claim 3, wherein said resetting means comprises an oscillator, wherein said angular reset voltage pulse and said velocity reset voltage pulse are implemented by producing a timing pulse by said oscillator.

10. A micro inertial measurement unit, as recited in claim 9, wherein said angular increment and velocity increment measurement means, which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments, comprises an analog/digital converter to substantially digitize said raw X axis, Y axis and Z axis angular increment and velocity increment voltage values into digital X axis, Y axis and Z axis angular increment and velocity increments.

11. A micro inertial measurement unit, as recited in claim 10 or 6, said angular increment and velocity increment producer further comprises an angular amplifying circuit for amplifying said X axis, Y axis and Z axis analog angular rate voltage signals to form amplified X axis, Y axis and Z axis analog angular rate signals and an acceleration amplifying circuit for amplifying said X axis, Y axis and Z axis analog acceleration voltage signals to form amplified X axis, Y axis and Z axis analog acceleration signals.

12. A micro inertial measurement unit, as recited in claim 11, wherein said angular integrating means of said angular increment and velocity increment producer comprises an angular integrator circuit for receiving said amplified X axis, Y axis and Z axis analog angular rate signals from said angular amplifier circuit and integrating to form said accumulated angular increments, and said acceleration integrating means of said angular increment and velocity increment producer comprises an acceleration integrator circuit for receiving said amplified X axis, Y axis and Z axis analog acceleration signals from said acceleration amplifier circuit and integrating to form said accumulated velocity increments.

13. A micro inertial measurement unit, as recited in claim 12, wherein said analog/digital converter of said angular increment and velocity increment producer further includes an angular analog/digital converter, a velocity analog/digital converter and an input/output interface circuit, wherein said accumulated angular increments output from said angular integrator circuit and said accumulated velocity increments output from said acceleration integrator circuit are input into said angular analog/digital converter and said velocity analog/digital converter respectively, wherein said accumulated angular increments is digitized by said angular analog/digital converter by measuring said accumulated angular increments with said angular reset voltage pulse to form a digital angular measurements of voltage in terms of said angular increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis angular increment voltage values, wherein said accumulated velocity increments are digitized by said velocity analog/digital converter by measuring said accumulated velocity increments with said velocity reset voltage pulse to form digital velocity measurements of voltage in terms of said velocity increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis velocity increment voltage values.

14. A micro inertial measurement unit, as recited in one of claims 1 to 6, wherein said thermal processor comprises an analog/digital converter connected to said thermal sensing producer device, a digital/analog converter connected to said heater device, and a temperature controller connected with both said analog/digital converter and said digital/analog converter, wherein said analog/digital converter inputs said temperature voltage signals produced by said thermal sensing producer device, wherein said temperature voltage signals are sampled in said analog/digital converter to sampled temperature voltage signals which are further digitized to digital signals and output to said temperature controller which computes digital temperature commands using said input digital signals from said analog/digital converter, a temperature sensor scale factor, and a pre-determined operating temperature of said angular rate producer and acceleration producer, wherein said digital temperature commands are fed back to said digital/analog converter, wherein said digital/analog converter converts said digital temperature commands input from said temperature controller into analog signals which are output to said heater device to provide adequate heat for maintaining said predetermined operating temperature of said micro inertial measurement unit.

15. A micro inertial measurement unit, as recited in claim 14, wherein said thermal processor further comprises:

a first amplifier circuit between said thermal sensing producer device and said digital/analog converter, wherein said voltage signals from said thermal sensing producer device is first input into said first amplifier circuit for amplifying said signals and suppressing said noise residing in said voltage signals and improving said signal-to-noise ratio, wherein said amplified voltage signals are then output to said analog/digital converter; and

a second amplifier circuit between said digital/analog converter and heater device for amplifying said input analog signals from said digital/analog converter for driving said heater device.

16. A micro inertial measurement unit, as recited in claim 15, said thermal processor further comprises an input/output interface circuit connected said analog/digital converter and digital/analog converter with said temperature controller, wherein said voltage signals are sampled in said analog/digital converter to form sampled voltage signals that are digitized into digital signals, and said digital signals are output to said input/output interface circuit, wherein said temperature controller is adapted to compute said digital temperature commands using said input digital temperature voltage signals from said input/output interface circuit, said temperature sensor scale factor, and said pre-determined operating temperature of said angular rate producer and acceleration producer, wherein said digital temperature commands are fed back to said input/output interface circuit, moreover said digital/analog converter further converts said digital temperature commands input from said input/output interface circuit into analog signals which are output to said heater device to provide adequate heat for maintaining said predetermined operating temperature of said micro inertial measurement unit.

17. A micro inertial measurement unit, comprising:

an angular rate producer for producing X axis, Y axis and Z axis angular rate electrical signals, wherein said X axis, Y axis and Z axis angular rate electrical signals produced from said angular producer are analog angular rate voltage signals directly proportional to angular rates of a carrier carrying said micro inertial measurement unit;

an acceleration producer for producing X axis, Y axis and Z axis acceleration electrical signals, wherein said X axis, Y axis and Z axis acceleration electrical signals produced from said acceleration producer are analog acceleration voltage signals directly proportional to accelerations of said vehicle; and

an angular increment and velocity increment producer for converting said X axis, Y axis and Z axis angular rate electrical signals into digital angular increments and converting said input X axis, Y axis and Z axis acceleration electrical signals into digital velocity increments, wherein said angular increment and velocity increment producer comprises;

an angular integrating means and an acceleration integrating means, which are adapted for respectively integrating said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals for a predetermined time interval to accumulate said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals as a raw X axis, Y axis and Z axis angular increment and a raw X axis, Y axis and Z axis velocity increment for a predetermined time interval to achieve accumulated angular increments and accumulated velocity increments, wherein said integration is performed to remove noise signals that are non-directly proportional to said carrier angular rate and acceleration within said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals, to improve signal-to-noise ratio, and to remove said high frequency signals in said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals;

a resetting means which forms an angular reset voltage pulse and a velocity reset voltage pulse as an angular scale and a velocity scale which are input into said angular integrating means and said acceleration integrating means respectively; and

an angular increment and velocity increment measurement means which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular increments and said X axis, Y axis and Z axis accumulated velocity increments with said angular reset voltage pulse and said velocity reset voltage pulse respectively to acquire angular increment counts and velocity increment counts as a digital form of angular increment and velocity increment measurements respectively.

18. A micro inertial measurement unit, as recited in claim 17, wherein said angular increment and velocity increment measurement means also scales said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments into real X axis, Y axis and Z axis angular and velocity increment voltage values, wherein in said angular integrating means and said accelerating integrating means, said X axis, Y axis and Z axis analog angular voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals are each reset to accumulate from a zero value at an initial point of every said predetermined time interval.

19. A micro inertial measurement unit, as recited in claim 18, wherein said resetting means comprises an oscillator, wherein said angular reset voltage pulse and said velocity reset voltage pulse are implemented by producing a timing pulse by said oscillator.

20. A micro inertial measurement unit, as recited in claim 19, wherein said angular increment and velocity increment measurement means, which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments, comprises an analog/digital converter to substantially digitize said raw X axis, Y axis and Z axis angular increment and velocity increment voltage values into digital X axis, Y axis and Z axis angular increment and velocity increments.

21. A micro inertial measurement unit, as recited in claim 17, wherein said resetting means comprises an oscillator, wherein said angular reset voltage pulse and said velocity reset voltage pulse are implemented by producing a timing pulse by said oscillator.

22. A micro inertial measurement unit, as recited in claim 21, wherein said angular increment and velocity increment measurement means, which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments, comprises an analog/digital converter to substantially digitize said raw X axis, Y axis and Z axis angular increment and velocity increment voltage values into digital X axis, Y axis and Z axis angular increment and velocity increments.

23. A micro inertial measurement unit, as recited in claim 22 or 20, said angular increment and velocity increment producer further comprises an angular amplifying circuit for amplifying said X axis, Y axis and Z axis analog angular rate voltage signals to form amplified X axis, Y axis and Z axis analog angular rate signals and an acceleration amplifying circuit for amplifying said X axis, Y axis and Z axis analog acceleration voltage signals to form amplified X axis, Y axis and Z axis analog acceleration signals.

24. A micro inertial measurement unit, as recited in claim 23, wherein said angular integrating means of said angular increment and velocity increment producer comprises an angular integrator circuit for receiving said amplified X axis, Y axis and Z axis analog angular rate signals from said angular amplifier circuit and integrating to form said accumulated angular increments, and said acceleration integrating means of said angular increment and velocity increment producer comprises an acceleration integrator circuit for receiving said amplified X axis, Y axis and Z axis analog acceleration signals from said acceleration amplifier circuit and integrating to form said accumulated velocity increments.

25. A micro inertial measurement unit, as recited in claim 24, wherein said analog/digital converter of said angular increment and velocity increment producer further includes an angular analog/digital converter, a velocity analog/digital converter and an input/output interface circuit, wherein said accumulated angular increments output from said angular integrator circuit and said accumulated velocity increments output from said acceleration integrator circuit are input into said angular analog/digital converter and said velocity analog/digital converter respectively, wherein said accumulated angular increments is digitized by said angular analog/digital converter by measuring said accumulated angular increments with said angular reset voltage pulse to form a digital angular measurements of voltage in terms of said angular increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis angular increment voltage values, wherein said accumulated velocity increments are digitized by said velocity analog/digital converter by measuring said accumulated velocity increments with said velocity reset voltage pulse to form digital velocity measurements of voltage in terms of said velocity increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis velocity increment voltage values.

26. A micro inertial measurement unit, as recited in one of claims 17 to 19, said angular increment and velocity increment producer further comprises an angular amplifying circuit for amplifying said X axis, Y axis and Z axis analog angular rate voltage signals to form amplified X axis, Y axis and Z axis analog angular rate signals and an acceleration amplifying circuit for amplifying said X axis, Y axis and Z axis analog acceleration voltage signals to form amplified X axis, Y axis and Z axis analog acceleration signals.

27. A micro inertial measurement unit, as recited in claim 26, wherein said angular integrating means of said angular increment and velocity increment producer comprises an angular integrator circuit for receiving said amplified X axis, Y axis and Z axis analog angular rate signals from said angular amplifier circuit and integrating to form said accumulated angular increments, and said acceleration integrating means of said angular increment and velocity increment producer comprises an acceleration integrator circuit for receiving said amplified X axis, Y axis and Z axis analog acceleration signals from said acceleration amplifier circuit and integrating to form said accumulated velocity increments.

28. A micro inertial measurement unit, comprising:

an angular rate producer for producing X axis, Y axis and Z axis angular rate electrical signals, wherein said X axis, Y axis and Z axis angular rate electrical signals produced from said angular producer are analog angular rate voltage signals directly proportional to angular rates of a carrier carrying said micro inertial measurement unit;

an acceleration producer for producing X axis, Y axis and Z axis acceleration electrical signals, wherein said X axis, Y axis and Z axis acceleration electrical signals produced from said acceleration producer are analog acceleration voltage signals directly proportional to accelerations of said vehicle;

an angular increment and velocity increment producer for converting said X axis, Y axis and Z axis angular rate electrical signals into digital angular increments and converting said input X axis, Y axis and Z axis acceleration electrical signals into digital velocity increments, wherein said angular increment and velocity increment producer comprises;

an angular integrating means and an acceleration integrating means, which are adapted for respectively integrating said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals for a predetermined time interval to accumulate said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals as a raw X axis, Y axis and Z axis angular increment and a raw X axis, Y axis and Z axis velocity increment for a predetermined time interval to achieve accumulated angular increments and accumulated velocity increments, wherein said integration is performed to remove noise signals that are non-directly proportional to said carrier angular rate and acceleration within said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals, to improve signal-to-noise ratio, and to remove said high frequency signals in said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals;

a resetting means which forms an angular reset voltage pulse and a velocity reset voltage pulse as an angular scale and a velocity scale which are input into said angular integrating means and said acceleration integrating means respectively; and

an angular increment and velocity increment measurement means which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular increments and said X axis, Y axis and Z axis accumulated velocity increments with said angular reset voltage pulse and said velocity reset voltage pulse respectively to acquire angular increment counts and velocity increment counts as a digital form of angular increment and velocity increment measurements respectively; and

a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer.

29. A micro inertial measurement unit, as recited in claim 28, wherein said angular increment and velocity increment measurement means also scales said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments into real X axis, Y axis and Z axis angular and velocity increment voltage values, wherein in said angular integrating means and said accelerating integrating means, said X axis, Y axis and Z axis analog angular voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals are each reset to accumulate from a zero value at an initial point of every said predetermined time interval.

30. A micro inertial measurement unit, as recited in claim 29, wherein said resetting means comprises an oscillator, wherein said angular reset voltage pulse and said velocity reset voltage pulse are implemented by producing a timing pulse by said oscillator.

31. A micro inertial measurement unit, as recited in claim 30, wherein said angular increment and velocity increment measurement means, which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments, comprises an analog/digital converter to substantially digitize said raw X axis, Y axis and Z axis angular increment and velocity increment voltage values into digital X axis, Y axis and Z axis angular increment and velocity increments.

32. A micro inertial measurement unit, as recited in claim 31, said angular increment and velocity increment producer further comprises an angular amplifying circuit for amplifying said X axis, Y axis and Z axis analog angular rate voltage signals to form amplified X axis, Y axis and Z axis analog angular rate signals and an acceleration amplifying circuit for amplifying said X axis, Y axis and Z axis analog acceleration voltage signals to form amplified X axis, Y axis and Z axis analog acceleration signals.

33. A micro inertial measurement unit, as recited in claim 32, wherein said angular integrating means of said angular increment and velocity increment producer comprises an angular integrator circuit for receiving said amplified X axis, Y axis and Z axis analog angular rate signals from said angular amplifier circuit and integrating to form said accumulated angular increments, and said acceleration integrating means of said angular increment and velocity increment producer comprises an acceleration integrator circuit for receiving said amplified X axis, Y axis and Z axis analog acceleration signals from said acceleration amplifier circuit and integrating to form said accumulated velocity increments.

34. A micro inertial measurement unit, as recited in claim 33, wherein said analog/digital converter of said angular increment and velocity increment producer further includes an angular analog/digital converter, a velocity analog/digital converter and an input/output interface circuit, wherein said accumulated angular increments output from said angular integrator circuit and said accumulated velocity increments output from said acceleration integrator circuit are input into said angular analog/digital converter and said velocity analog/digital converter respectively, wherein said accumulated angular increments is digitized by said angular analog/digital converter by measuring said accumulated angular increments with said angular reset voltage pulse to form a digital angular measurements of voltage in terms of said angular increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis angular increment voltage values, wherein said accumulated velocity increments are digitized by said velocity analog/digital converter by measuring said accumulated velocity increments with said velocity reset voltage pulse to form digital velocity measurements of voltage in terms of said velocity increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis velocity increment voltage values.

35. A micro inertial measurement unit, as recited in claim 28, wherein said resetting means comprises an oscillator, wherein said angular reset voltage pulse and said velocity reset voltage pulse are implemented by producing a timing pulse by said oscillator.

36. A micro inertial measurement unit, as recited in claim 35, wherein said angular increment and velocity increment measurement means, which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments, comprises an analog/digital converter to substantially digitize said raw X axis, Y axis and Z axis angular increment and velocity increment voltage values into digital X axis, Y axis and Z axis angular increment and velocity increments.

37. A micro inertial measurement unit, as recited in one of claims 28 to 36, said angular increment and velocity increment producer further comprises an angular amplifying circuit for amplifying said X axis, Y axis and Z axis analog angular rate voltage signals to form amplified X axis, Y axis and Z axis analog angular rate signals and an acceleration amplifying circuit for amplifying said X axis, Y axis and Z axis analog acceleration voltage signals to form amplified X axis, Y axis and Z axis analog acceleration signals.

38. A micro inertial measurement unit, as recited in claim 37, wherein said angular integrating means of said angular increment and velocity increment producer comprises an angular integrator circuit for receiving said amplified X axis, Y axis and Z axis analog angular rate signals from said angular amplifier circuit and integrating to form said accumulated angular increments, and said acceleration integrating means of said angular increment and velocity increment producer comprises an acceleration integrator circuit for receiving said amplified X axis, Y axis and Z axis analog acceleration signals from said acceleration amplifier circuit and integrating to form said accumulated velocity increments.

39. A micro inertial measurement unit, comprising:

an angular rate producer for producing X axis, Y axis and Z axis angular rate electrical signals;

an acceleration producer for producing X axis, Y axis and Z axis acceleration electrical signals; and

an angular increment and velocity increment producer for converting said X axis, Y axis and Z axis angular rate electrical signals into digital angular increments and converting said input X axis, Y axis and Z axis acceleration electrical signals into digital velocity increments;

wherein said micro IMU further comprises a first circuit board, a second circuit board, a third circuit board, and a control circuit board arranged inside a case, said first circuit board being connected with said third circuit board for producing X axis angular sensing signal and Y axis acceleration sensing signal to said control circuit board, said second circuit board being connected with said third circuit board for producing Y axis angular sensing signal and X axis acceleration sensing signal to said control circuit board, said third circuit board being connected with said control circuit board for producing Z axis angular sensing signal and Z axis acceleration sensing signals to said control circuit board, wherein said control circuit board is connected with said first circuit board and then said second circuit board through said third circuit board for processing said X axis, Y axis and Z axis angular sensing signals and said X axis, Y axis and Z axis acceleration sensing signals from said first, second and control circuit board to produce digital angular increments and velocity increments, position, velocity, and attitude solution.

40. A micro inertial measurement unit, as recited in claim 39, wherein said angular producer comprises:

a X axis vibrating type angular rate detecting unit and a first front-end circuit connected on said first circuit board;

a Y axis vibrating type angular rate detecting unit and a second front-end circuit connected on said second circuit board;

a Z axis vibrating type angular rate detecting unit and a third front-end circuit connected on said third circuit board;

three angular signal loop circuitries which are provided on said control circuit board for said first, second and third circuit boards respectively;

three dither motion control circuitries which are provided on in said control circuit board for said first, second and third circuit boards respectively;

an oscillator adapted for providing reference pickoff signals for said X axis vibrating type angular rate detecting unit, said Y axis vibrating type angular rate detecting unit, said Z axis vibrating type angular rate detecting unit, said angle signal loop circuitry, and said dither motion control circuitry; and

three dither motion processing modules provided on said control circuit board, for said first, second and third circuit boards respectively.

41. A micro inertial measurement unit, as recited in claim 40, wherein said third circuit board is bonded to a supporting structure by means of a conductive epoxy, and said first circuit board, said second circuit board, and said control circuit board are arranged parallelly to bond to said third circuit board perpendicularly by a non conductive epoxy, wherein said first circuit board, said second circuit board, and said control circuit board are soldered to said third circuit board in such a manner as to use said third circuit board as an interconnect board.

42. A micro inertial measurement unit, as recited in claim 40, wherein said acceleration producer comprises:

a X axis accelerometer, which is provided on said second circuit board and connected with said angular increment and velocity increment producer provided on said control circuit board;

a Y axis accelerometer, which is provided on said first circuit board and connected with said angular increment and velocity increment producer provided on said control circuit board; and

a Z axis accelerometer, which is provided on said third circuit board and connected with said angular increment and velocity increment producer provided on said control circuit board.

43. A micro inertial measurement unit, as recited in claim 42, wherein said first, second and third front-end circuits are used to condition said output signal of said X axis, Y axis and Z axis vibrating type angular rate detecting units respectively and each further comprises:

a trans impedance amplifier circuit, which is connected to said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit for changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs, wherein said two dither displacement signals are output to said dither motion control circuitry; and

a high-pass filter circuit, which is connected with said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit for removing residual dither drive signals and noise from said dither displacement differential signal to form a filtered dither displacement differential signal to said angular signal loop circuitry.

44. A micro inertial measurement unit, as recited in claim 43, wherein each of said X axis, Y axis and Z axis angular rate detecting units is a vibratory device, which comprises at least one set of vibrating inertial elements, including tuning forks and associated supporting structures and means, including capacitive readout means, and uses Coriolis effects to detect angular rates of said carrier, wherein each of said X axis, Y axis and Z axis vibrating type angular rate detecting units receives dither drive signals from said respective dither motion control circuitry, keeping said inertial elements oscillating;

and carrier reference oscillation signals from said oscillator, including capacitive pickoff excitation signals, wherein each of said X axis, Y axis and Z axis vibrating type angular rate detecting units detects said angular motion in X axis, Y axis and Z axis respectively of said carrier in accordance with said dynamic theory, wherein each of said X axis, Y axis and Z axis vibrating type angular rate detecting units outputs angular motion-induced signals, including rate displacement signals which may be modulated carrier reference oscillation signals to said trans Impedance amplifier circuit of said respective first, second or third front-end circuits; and

inertial element dither motion signals thereof, including dither displacement signals, to said high-pass filter of said respective first, second or third front-end circuit.

45. A micro inertial measurement unit, as recited in claim 44, wherein said three dither motion control circuitries receive said inertial element dither motion signals from said X axis, Y axis and Z axis vibrating type angular rate detecting units respectively, reference pickoff signals from said oscillator, and produce digital inertial element displacement signals with known phase, wherein each said dither motion control circuitries comprises:

an amplifier and summer circuit connected to said trans impedance amplifier circuit of said respective first, second or third front-end circuit for amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

a high-pass filter circuit connected to said amplifier and summer circuit for removing residual dither drive signals and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

a demodulator circuit connected to said high-pass filter circuit for receiving said capacitive pickoff excitation signals as phase reference signals from said oscillator and said filtered dither displacement differential signal from said high-pass filter and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

a low-pass filter connected to said demodulator circuit for removing high frequency noise from said inertial element displacement signal input thereto to form a low frequency inertial element displacement signal;

an analog/digital converter connected to said low-pass filter for converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal to said respective dither motion processing module;

a digital/analog converter processing said selected amplitude from said respective dither motion processing module to form a dither drive signal with correct amplitude; and

an amplifier which generates and amplifies said dither drive signal to said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

46. A micro inertial measurement unit, as recited in claim 45, wherein said oscillation of said inertial elements residing inside each of said X axis, Y axis and Z axis vibrating type angular rate detecting units is generally driven by a high frequency sinusoidal signal with precise amplitude, wherein each of said dither motion processing module receives digital inertial element displacement signals with known phase from said analog/digital converter of said dither motion control circuitry for finding said frequencies which have highest Quality Factor (Q) Values, locking said frequency, and locking said amplitude to produce a dither drive signal, including high frequency sinusoidal signals with a precise amplitude, to said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit to keep said inertial elements oscillating at said pre-determined resonant frequency.

47. A micro inertial measurement unit, as recited in claim 46, wherein said dither motion processing module further includes a discrete Fast Fourier Transform (FFT) module, a memory array of frequency and amplitude data module, a maxima detection logic module, and a Q analysis and selection logic module to find said frequencies which have highest Quality Factor (Q) Values;

wherein said discrete Fast Fourier Transform (FFT) module is arranged for transforming said digitized low frequency inertial element displacement signal from said analog/digital converter of said dither motion control circuitry to form amplitude data with said frequency spectrum of said input inertial element displacement signal;

wherein said memory array of frequency and amplitude data module receives said amplitude data with frequency spectrum to form an array of amplitude data with frequency spectrum;

wherein said maxima detection logic module is adapted for partitioning said frequency spectrum from said array of said amplitude data with frequency into plural spectrum segments, and choosing said frequencies with said largest amplitudes in said local segments of said frequency spectrum; and

wherein said Q analysis and selection logic module is adapted for performing Q analysis on said chosen frequencies to select frequency and amplitude by computing said ratio of amplitude/bandwidth, wherein a range for computing bandwidth is between +−

1/2 of said peek for each maximum frequency point.

48. A micro inertial measurement unit, as recited in claim 47, wherein said dither motion processing module further includes a phase-lock loop to reject noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter, locking said frequency;

wherein said angle signal loop circuitries receive said angular motion-induced signals from said X axis, Y axis and Z axis vibrating type angular rate detecting units respectively, reference pickoff signals from said oscillator, and transform said angular motion-induced signals into angular rate signals, wherein each of said angle signal loop circuitries for said respective first, second or third circuit board comprises;

a voltage amplifier circuit, which amplifies said filtered angular motion-induced signals from said high-pass filter circuit of said respective first, second or third front-end circuit to an extent of at least 100 milivolts to form amplified angular motion-induced signals;

an amplifier and summer circuit, which subtracts said difference between said angle rates of said amplified angular motion-induced signals to produce a differential angle rate signal;

a demodulator, which is connected to said amplifier and summer circuit, extracting said amplitude of said in-phase differential angle rate signal from said differential angle rate signal and said capacitive pickoff excitation signals from said oscillator;

a low-pass filter, which is connected to said demodulator, removing said high frequency noise of said amplitude signal of said in-phase differential angle rate signal to form said angular rate signal output to said angular increment and velocity increment producer.

49. A micro inertial measurement unit, as recited in claim 39, wherein said acceleration producer comprises:

a X axis accelerometer, which is provided on said second circuit board and connected with said angular increment and velocity increment producer provided on said control circuit board;

a Y axis accelerometer, which is provided on said first circuit board and connected with said angular increment and velocity increment producer provided on said control circuit board; and

a Z axis accelerometer, which is provided on said third circuit board and connected with said angular increment and velocity increment producer provided on said control circuit board.

50. A micro inertial measurement unit, as recited in claim 49, wherein said first, second and third front-end circuits are used to condition said output signal of said X axis, Y axis and Z axis vibrating type angular rate detecting units respectively and each further comprises:

a trans impedance amplifier circuit, which is connected to said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit for changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs, wherein said two dither displacement signals are output to said dither motion control circuitry; and

a high-pass filter circuit, which is connected with said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit for removing residual dither drive signals and noise from said dither displacement differential signal to form a filtered dither displacement differential signal to said angular signal loop circuitry.

51. A micro inertial measurement unit, as recited in claim 50, wherein each of said X axis, Y axis and Z axis angular rate detecting units is a vibratory device, which comprises at least one set of vibrating inertial elements, including tuning forks, and associated supporting structures and means, including capacitive readout means, and uses Coriolis effects to detect angular rates of said carrier, wherein each of said X axis, Y axis and Z axis vibrating type angular rate detecting units receives dither drive signals from said respective dither motion control circuitry, keeping said inertial elements oscillating;

and carrier reference oscillation signals from said oscillator, including capacitive pickoff excitation signals, wherein each of said X axis, Y axis and Z axis vibrating type angular rate detecting units detects said angular motion in X axis, Y axis and Z axis respectively of said carrier in accordance with said dynamic theory, wherein each of said X axis, Y axis and Z axis vibrating type angular rate detecting units outputs angular motion-induced signals, including rate displacement signals which may be modulated carrier reference oscillation signals to said trans Impedance amplifier circuit of said respective first, second or third front-end circuits; and

inertial element dither motion signals thereof, including dither displacement signals, to said high-pass filter of said respective first, second or third front-end circuit.

52. A micro inertial measurement unit, as recited in claim 51, wherein said three dither motion control circuitries receive said inertial element dither motion signals from said X axis, Y axis and Z axis vibrating type angular rate detecting units respectively, reference pickoff signals from said oscillator, and produce digital inertial element displacement signals with known phase, wherein each said dither motion control circuitries comprises:

an amplifier and summer circuit connected to said trans impedance amplifier circuit of said respective first, second or third front-end circuit for amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

a high-pass filter circuit connected to said amplifier and summer circuit for removing residual dither drive signals and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

a demodulator circuit connected to said high-pass filter circuit for receiving said capacitive pickoff excitation signals as phase reference signals from said oscillator and said filtered dither displacement differential signal from said high-pass filter and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

a low-pass filter connected to said demodulator circuit for removing high frequency noise from said inertial element displacement signal input thereto to form a low frequency inertial element displacement signal;

an analog/digital converter connected to said low-pass filter for converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal to said respective dither motion processing module;

a digital/analog converter processing said selected amplitude from said respective dither motion processing module to form a dither drive signal with correct amplitude; and

an amplifier which generates and amplifies said dither drive signal to said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

53. A micro inertial measurement unit, as recited in claim 52, wherein said oscillation of said inertial elements residing inside each of said X axis, Y axis and Z axis vibrating type angular rate detecting units is generally driven by a high frequency sinusoidal signal with precise amplitude, wherein each of said dither motion processing module receives digital inertial element displacement signals with known phase from said analog/digital converter of said dither motion control circuitry for finding said frequencies which have highest Quality Factor (Q) Values, locking said frequency, and locking said amplitude to produce a dither drive signal, including high frequency sinusoidal signals with a precise amplitude, to said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit to keep said inertial elements oscillating at said pre-determined resonant frequency.

54. A micro inertial measurement unit, as recited in claim 53, wherein said dither motion processing module further includes a discrete Fast Fourier Transform (FFT) module, a memory array of frequency and amplitude data module, a maxima detection logic module, and a Q analysis and selection logic module to find said frequencies which have highest Quality Factor (Q) Values;

wherein said discrete Fast Fourier Transform (FFT) module is arranged for transforming said digitized low frequency inertial element displacement signal from said analog/digital converter of said dither motion control circuitry to form amplitude data with said frequency spectrum of said input inertial element displacement signal;

wherein said memory array of frequency and amplitude data module receives said amplitude data with frequency spectrum to form an array of amplitude data with frequency spectrum;

wherein said maxima detection logic module is adapted for partitioning said frequency spectrum from said array of said amplitude data with frequency into plural spectrum segments, and choosing said frequencies with said largest amplitudes in said local segments of said frequency spectrum; and

wherein said Q analysis and selection logic module is adapted for performing Q analysis on said chosen frequencies to select frequency and amplitude by computing said ratio of amplitude/bandwidth, wherein a range for computing bandwidth is between +−

1/2 of said peek for each maximum frequency point.

55. A micro inertial measurement unit, as recited in claim 54 or 47, wherein a position and attitude processor is adapted to further connect with said micro inertial measurement unit for computing position, attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments, wherein said thermal controlling means comprises a thermal sensing producer and an analog/digital converter connected to said thermal sensing producer device to receive said analog voltage output from said thermal sensing producer device, wherein said position, attitude, and heading processor is adapted for accessing temperature characteristic parameters of said angular rate producer and said acceleration producer using a current temperature of said angular rate producer and said acceleration producer from said temperature digitizer, and compensating said errors induced by thermal effects in said input digital angular and velocity increments and computing attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments in said attitude and heading processor.

56. A micro inertial measurement unit, as recited in claim 55, wherein said thermal controlling means further comprises an additional amplifier circuit connected between said thermal sensing producer device and said digital/analog converter for amplifying said analog voltage signals and suppressing said noise residing in said voltage signals and improving said voltage signal-to-noise ratio, wherein said amplified voltage signals are output to said analog/digital converter and sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals outputting to said attitude and heading processor.

57. A micro inertial measurement unit, as recited in claim 56, wherein an input/output interface circuit is connected between said analog/digital converter and said attitude and heading processor, wherein said input amplified voltage signals are sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals outputting to said input/output interface circuit before inputting into said attitude and heading processor.

58. A micro inertial measurement unit, as recited in claim 54, wherein said dither motion processing module further includes a phase-lock loop to reject noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter, locking said frequency;

wherein said angle signal loop circuitries receive said angular motion-induced signals from said X axis, Y axis and Z axis vibrating type angular rate detecting units respectively, reference pickoff signals from said oscillator, and transform said angular motion-induced signals into angular rate signals, wherein each of said angle signal loop circuitries for said respective first, second or third circuit board comprises;

a voltage amplifier circuit, which amplifies said filtered angular motion-induced signals from said high-pass filter circuit of said respective first, second or third front-end circuit to an extent of at least 100 milivolts to form amplified angular motion-induced signals;

an amplifier and summer circuit, which subtracts said difference between said angle rates of said amplified angular motion-induced signals to produce a differential angle rate signal;

a demodulator, which is connected to said amplifier and summer circuit, extracting said amplitude of said in-phase differential angle rate signal from said differential angle rate signal and said capacitive pickoff excitation signals from said oscillator;

a low-pass filter, which is connected to said demodulator, removing said high frequency noise of said amplitude signal of said in-phase differential angle rate signal to form said angular rate signal output to said angular increment and velocity increment producer.

59. A micro inertial measurement unit, as recited in one of claims 49, 42, 58, and 48, further comprising a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer, wherein said thermal controlling means comprises:

a thermal sensing producer device, comprising;

a first thermal sensing producing unit for sensing said temperature of said X axis angular rate detecting unit and said Y axis accelerometer,

a second thermal sensing producer for sensing said temperature of said Y axis angular rate detecting unit and said X axis accelerometer, and

a third thermal sensing producer for sensing said temperature of said Z axis angular rate detecting unit and said Z axis accelerometer;

a heater device, comprising;

a first heater, which is connected with said X axis angular rate detecting unit, said Y axis accelerometer, and said first front-end circuit, for maintaining said predetermined operational temperature of said X axis angular rate detecting unit, said Y axis accelerometer, and said first front-end circuit,

a second heater, which is connected with said Y axis angular rate detecting unit, said X axis accelerometer, and said second front-end circuit, for maintaining said predetermined operational temperature of said X axis angular rate detecting unit, said X axis accelerometer, and said second front-end circuit, and

a third heater, which is connected with said Z axis angular rate detecting unit, said Z axis accelerometer, and said third front-end circuit, for maintaining said predetermined operational temperature of said Z axis angular rate detecting unit, said Z axis accelerometer, and said third front-end circuit; and

a thermal processor which comprises three identical thermal control circuitries and said thermal control computation module provided on said control circuit board, wherein

each of said thermal control circuitries further comprises;

a first amplifier circuit, which is connected with said respective X axis, Y axis or Z axis thermal sensing producer, for amplifying said signals and suppressing said noise residing in said temperature voltage signals from said respective X axis, Y axis or Z axis thermal sensing producer and improving said signal-to-noise ratio,

an analog/digital converter, which is connected with said amplifier circuit, for sampling said temperature voltage signals and digitizing said sampled temperature voltage signals to digital signals, which are output to said thermal control computation module,

a digital/analog converter which converts said digital temperature commands input from said thermal control computation module into analog signals, and

a second amplifier circuit, which receives said analog signals from said digital/analog converter, amplifying said input analog signals from said digital/analog converter for driving said respective first, second or third heater; and

closing said temperature controlling loop,

wherein said thermal control computation module computes digital temperature commands using said digital temperature voltage signals from said analog/digital converter, said temperature sensor scale factor, and said pre-determined operating temperature of said angular rate producer and acceleration producer, wherein said digital temperature commands are fed back to said digital/analog converter.

60. A micro inertial measurement unit, as recited in one of claims 49, 42, 58, and 48, further comprising a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer, wherein said thermal controlling means comprises a thermal sensing producer device, a heater device and a thermal processor, wherein said thermal sensing producer device, which produces temperature signals, is processed in parallel with said angular rate producer and said acceleration producer for maintaining a predetermined operating temperature of said angular rate producer and said acceleration producer and angular increment and velocity increment producer, wherein said predetermined operating temperature is a constant designated temperature selected between 150°

F. and 185°

F., wherein said temperature signals produced from said thermal sensing producer device are inputted to said thermal processor for computing temperature control commands using said temperature signals, a temperature scale factor, and a predetermined operating temperature of said angular rate producer and said acceleration producer, and produce driving signals to said heater device using said temperature control commands for controlling said heater device to provide adequate heat for maintaining said predetermined operating temperature in said micro inertial measurement unit.

61. A micro inertial measurement unit, as recited in one of claims 49, 42, 58, and 48, wherein said angular increment and velocity increment producer comprises:

an angular integrating means and an acceleration integrating means, which are adapted for respectively integrating said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals for a predetermined time interval to accumulate said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals as a raw X axis, Y axis and Z axis angular increment and a raw X axis, Y axis and Z axis velocity increment for a predetermined time interval to achieve accumulated angular increments and accumulated velocity increments, wherein said integration is performed to remove noise signals that are non-directly proportional to said carrier angular rate and acceleration within said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals, to improve signal-to-noise ratio, and to remove said high frequency signals in said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals;

a resetting means which forms an angular reset voltage pulse and a velocity reset voltage pulse as an angular scale and a velocity scale which are input into said angular integrating means and said acceleration integrating means respectively; and

an angular increment and velocity increment measurement means which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular increments and said X axis, Y axis and Z axis accumulated velocity increments with said angular reset voltage pulse and said velocity reset voltage pulse respectively to acquire angular increment counts and velocity increment counts as a digital form of angular increment and velocity increment measurements respectively.

62. A micro inertial measurement unit, as recited in claim 61, wherein said angular increment and velocity increment measurement means also scales said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments into real X axis, Y axis and Z axis angular and velocity increment voltage values, wherein in said angular integrating means and said accelerating integrating means, said X axis, Y axis and Z axis analog angular voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals are each reset to accumulate from a zero value at an initial point of every said predetermined time interval.

63. A micro inertial measurement unit, as recited in claim 62, wherein said resetting means comprises an oscillator, wherein said angular reset voltage pulse and said velocity reset voltage pulse are implemented by producing a timing pulse by said oscillator.

64. A micro inertial measurement unit, as recited in claims 62, said angular increment and velocity increment producer further comprises an angular amplifying circuit for amplifying said X axis, Y axis and Z axis analog angular rate voltage signals to form amplified X axis, Y axis and Z axis analog angular rate signals and an acceleration amplifying circuit for amplifying said X axis, Y axis and Z axis analog acceleration voltage signals to form amplified X axis, Y axis and Z axis analog acceleration signals.

65. A micro inertial measurement unit, as recited in claim 64, wherein said angular increment and velocity increment measurement means, which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments, comprises an analog/digital converter to substantially digitize said raw X axis, Y axis and Z axis angular increment and velocity increment voltage values into digital X axis, Y axis and Z axis angular increment and velocity increments.

66. A micro inertial measurement unit, as recited in claim 65, wherein said analog/digital converter of said angular increment and velocity increment producer further includes an angular analog/digital converter, a velocity analog/digital converter and an input/output interface circuit, wherein said accumulated angular increments output from said angular integrator circuit and said accumulated velocity increments output from said acceleration integrator circuit are input into said angular analog/digital converter and said velocity analog/digital converter respectively, wherein said accumulated angular increments is digitized by said angular analog/digital converter by measuring said accumulated angular increments with said angular reset voltage pulse to form a digital angular measurements of voltage in terms of said angular increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis angular increment voltage values, wherein said accumulated velocity increments are digitized by said velocity analog/digital converter by measuring said accumulated velocity increments with said velocity reset voltage pulse to form digital velocity measurements of voltage in terms of said velocity increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis velocity increment voltage values.

67. A micro inertial measurement unit, as recited in claim 66, further comprising a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer, wherein said thermal controlling means comprises a thermal sensing producer device, a heater device and a thermal processor, wherein said thermal sensing producer device, which produces temperature signals, is processed in parallel with said angular rate producer and said acceleration producer for maintaining a predetermined operating temperature of said angular rate producer and said acceleration producer and angular increment and velocity increment producer, wherein said predetermined operating temperature is a constant designated temperature selected between 150°

F. and 185°

F., wherein said temperature signals produced from said thermal sensing producer device are inputted to said thermal processor for computing temperature control commands using said temperature signals, a temperature scale factor, and a predetermined operating temperature of said angular rate producer and said acceleration producer, and produce driving signals to said heater device using said temperature control commands for controlling said heater device to provide adequate heat for maintaining said predetermined operating temperature in said micro inertial measurement unit.

68. A micro inertial measurement unit, as recited in claim 49 or 42, wherein a position and attitude processor is adapted to further connect with said micro inertial measurement unit for computing position, attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments, wherein said thermal controlling means comprises a thermal sensing producer and an analog/digital converter connected to said thermal sensing producer device to receive said analog voltage output from said thermal sensing producer device, wherein said position, attitude, and heading processor is adapted for accessing temperature characteristic parameters of said angular rate producer and said acceleration producer using a current temperature of said angular rate producer and said acceleration producer from said temperature digitizer, and compensating said errors induced by thermal effects in said input digital angular and velocity increments and computing attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments in said attitude and heading processor.

69. A micro inertial measurement unit, as recited in claim 68, wherein said thermal controlling means further comprises an additional amplifier circuit connected between said thermal sensing producer device and said digital/analog converter for amplifying said analog voltage signals and suppressing said noise residing in said voltage signals and improving said voltage signal-to-noise ratio, wherein said amplified voltage signals are output to said analog/digital converter and sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals ouputting to said attitude and heading processor.

70. A micro inertial measurement unit, as recited in claim 69, wherein an input/output interface circuit is connected between said analog/digital converter and said attitude and heading processor, wherein said input amplified voltage signals are sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals outputting to said input/output interface circuit before inputting into said attitude and heading processor.

71. A micro inertial measurement unit, as recited in claim 39 or 40, further comprising a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer.

72. A micro inertial measurement unit, comprising:

an angular rate producer for producing X axis, Y axis and Z axis angular rate electrical signals;

an acceleration producer for producing X axis, Y axis and Z axis acceleration electrical signals; and

an angular increment and velocity increment producer for converting said X axis, Y axis and Z axis angular rate electrical signals into digital angular increments and converting said input X axis, Y axis and Z axis acceleration electrical signals into digital velocity increments;

wherein said angular producer comprises;

a X axis vibrating type angular rate detecting unit and a first front-end circuit connected on a first circuit board;

a Y axis vibrating type angular rate detecting unit and a second front-end circuit connected on a second circuit board;

a Z axis vibrating type angular rate detecting unit and a third front-end circuit connected on a third circuit board;

three angular signal loop circuitries which are provided on a control circuit board for said first, second and third circuit boards respectively;

three dither motion control circuitries which are provided on in said control circuit board for said first, second and third circuit boards respectively;

an oscillator adapted for providing reference pickoff signals for said X axis vibrating type angular rate detecting unit, said Y axis vibrating type angular rate detecting unit, said Z axis vibrating type angular rate detecting unit, said angle signal loop circuitry, and said dither motion control circuitry; and

three dither motion processing modules provided on said control circuit board, for said first, second and third circuit boards respectively.

73. A micro inertial measurement unit, as recited in claim 72, wherein said acceleration producer comprises:

a X axis accelerometer, which is provided on said second circuit board and connected with said angular increment and velocity increment producer provided on said control circuit board;

a Y axis accelerometer, which is provided on said first circuit board and connected With said angular increment and velocity increment producer provided on said control circuit board; and

a Z axis accelerometer, which is provided on said third circuit board and connected with said angular increment and velocity increment producer provided on said control circuit board.

74. A micro inertial measurement unit, as recited in claim 73, wherein said first, second and third front-end circuits are used to condition said output signal of said X axis, Y axis and Z axis vibrating type angular rate detecting units respectively and each further comprises:

a trans impedance amplifier circuit, which is connected to said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit for changing said output impedance of said dither motion signals from a very high level, greater than 100 million ohms, to a low level, less than 100 ohms to achieve two dither displacement signals, which are A/C voltage signals representing said displacement between said inertial elements and said anchor combs, wherein said two dither displacement signals are output to said dither motion control circuitry; and

a high-pass filter circuit, which is connected with said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit for removing residual dither drive signals and noise from said dither displacement differential signal to form a filtered dither displacement differential signal to said angular signal loop circuitry.

75. A micro inertial measurement unit, as recited in claim 74, wherein each of said X axis, Y axis and Z axis angular rate detecting units is a vibratory device, which comprises at least one set of vibrating inertial elements, including tuning forks, and associated supporting structures and means, including capacitive readout means, and uses Coriolis effects to detect angular rates of said carrier, wherein each of said X axis, Y axis and Z axis vibrating type angular rate detecting units receives dither drive signals from said respective dither motion control circuitry, keeping said inertial elements oscillating;

and carrier reference oscillation signals from said oscillator, including capacitive pickoff excitation signals, wherein each of said X axis, Y axis and Z axis vibrating type angular rate detecting units detects said angular motion in X axis, Y axis and Z axis respectively of said carrier in accordance with said dynamic theory, wherein each of said X axis, Y axis and Z axis vibrating type angular rate detecting units outputs angular motion-induced signals, including rate displacement signals which may be modulated carrier reference oscillation signals to said trans Impedance amplifier circuit of said respective first, second or third front-end circuits; and

inertial element dither motion signals thereof, including dither displacement signals, to said high-pass filter of said respective first, second or third front-end circuit.

76. A micro inertial measurement unit, as recited in claim 75, wherein said three dither motion control circuitries receive said inertial element dither motion signals from said X axis, Y axis and Z axis vibrating type angular rate detecting units respectively, reference pickoff signals from said oscillator, and produce digital inertial element displacement signals with known phase, wherein each said dither motion control circuitries comprises:

an amplifier and summer circuit connected to said trans impedance amplifier circuit of said respective first, second or third front-end circuit for amplifying said two dither displacement signals for more than ten times and enhancing said sensitivity for combining said two dither displacement signals to achieve a dither displacement differential signal by subtracting a center anchor comb signal with a side anchor comb signal;

a high-pass filter circuit connected to said amplifier and summer circuit for removing residual dither drive signals and noise from said dither displacement differential signal to form a filtered dither displacement differential signal;

a demodulator circuit connected to said high-pass filter circuit for receiving said capacitive pickoff excitation signals as phase reference signals from said oscillator and said filtered dither displacement differential signal from said high-pass filter and extracting said in-phase portion of said filtered dither displacement differential signal to produce an inertial element displacement signal with known phase;

a low-pass filter connected to said demodulator circuit for removing high frequency noise from said inertial element displacement signal input thereto to form a low frequency inertial element displacement signal;

an analog/digital converter connected to said low-pass filter for converting said low frequency inertial element displacement signal that is an analog signal to produce a digitized low frequency inertial element displacement signal to said respective dither motion processing module;

a digital/analog converter processing said selected amplitude from said respective dither motion processing module to form a dither drive signal with correct amplitude; and

an amplifier which generates and amplifies said dither drive signal to said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit based on said dither drive signal with said selected frequency and correct amplitude.

77. A micro inertial measurement unit, as recited in claim 76, wherein said oscillation of said inertial elements residing inside each of said X axis, Y axis and Z axis vibrating type angular rate detecting units is generally driven by a high frequency sinusoidal signal with precise amplitude, wherein each of said dither motion processing module receives digital inertial element displacement signals with known phase from said analog/digital converter of said dither motion control circuitry for finding said frequencies which have highest Quality Factor (Q) Values, locking said frequency, and locking said amplitude to produce a dither drive signal, including high frequency sinusoidal signals with a precise amplitude, to said respective X axis, Y axis or Z axis vibrating type angular rate detecting unit to keep said inertial elements oscillating at said pre-determined resonant frequency.

78. A micro inertial measurement unit, as recited in claim 77, wherein said dither motion processing module further includes a discrete Fast Fourier Transform (FFT) module, a memory array of frequency and amplitude data module, a maxima detection logic module, and a Q analysis and selection logic module to find said frequencies which have highest Quality Factor (Q) Values;

wherein said discrete Fast Fourier Transform (FFT) module is arranged for transforming said digitized low frequency inertial element displacement signal from said analog/digital converter of said dither motion control circuitry to form amplitude data with said frequency spectrum of said input inertial element displacement signal;

wherein said memory array of frequency and amplitude data module receives said amplitude data with frequency spectrum to form an array of amplitude data with frequency spectrum;

wherein said maxima detection logic module is adapted for partitioning said frequency spectrum from said array of said amplitude data with frequency into plural spectrum segments, and choosing said frequencies with said largest amplitudes in said local segments of said frequency spectrum; and

wherein said Q analysis and selection logic module is adapted for performing Q analysis on said chosen frequencies to select frequency and amplitude by computing said ratio of amplitude/bandwidth, wherein a range for computing bandwidth is between +−

1/2 of said peek for each maximum frequency point.

79. A micro inertial measurement unit, as recited in claim 78, wherein said dither motion processing module further includes a phase-lock loop to reject noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter, locking said frequency;

wherein said angle signal loop circuitries receive said angular motion-induced signals from said X axis, Y axis and Z axis vibrating type angular rate detecting units respectively, reference pickoff signals from said oscillator, and transform said angular motion-induced signals into angular rate signals, wherein each of said angle signal loop circuitries for said respective first, second or third circuit board comprises;

a voltage amplifier circuit, which amplifies said filtered angular motion-induced signals from said high-pass filter circuit of said respective first, second or third front-end circuit to an extent of at least 100 milivolts to form amplified angular motion-induced signals;

an amplifier and summer circuit, which subtracts said difference between said angle rates of said amplified angular motion-induced signals to produce a differential angle rate signal;

a demodulator, which is connected to said amplifier and summer circuit, extracting said amplitude of said in-phase differential angle rate signal from said differential angle rate signal and said capacitive pickoff excitation signals from said oscillator;

a low-pass filter, which is connected to said demodulator, removing said high frequency noise of said amplitude signal of said in-phase differential angle rate signal to form said angular rate signal output to said angular increment and velocity increment producer.

80. A micro inertial measurement unit, as recited in claim 73 or 79, wherein said angular increment and velocity increment producer comprises:

an angular integrating means and an acceleration integrating means, which are adapted for respectively integrating said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals for a predetermined time interval to accumulate said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals as a raw X axis, Y axis and Z axis angular increment and a raw X axis, Y axis and Z axis velocity increment for a predetermined time interval to achieve accumulated angular increments and accumulated velocity increments, wherein said integration is performed to remove noise signals that are non-directly proportional to said carrier angular rate and acceleration within said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals, to improve signal-to-noise ratio, and to remove said high frequency signals in said X axis, Y axis and Z axis analog angular rate voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals;

a resetting means which forms an angular reset voltage pulse and a velocity reset voltage pulse as an angular scale and a velocity scale which are input into said angular integrating means and said acceleration integrating means respectively; and

an angular increment and velocity increment measurement means which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular increments and said X axis, Y axis and Z axis accumulated velocity increments with said angular reset voltage pulse and said velocity reset voltage pulse respectively to acquire angular increment counts and velocity increment counts as a digital form of angular increment and velocity increment measurements respectively.

81. A micro inertial measurement unit, as recited in claim 80, wherein said angular increment and velocity increment measurement means also scales said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments into real X axis, Y axis and Z axis angular and velocity increment voltage values, wherein in said angular integrating means and said accelerating integrating means, said X axis, Y axis and Z axis analog angular voltage signals and said X axis, Y axis and Z axis analog acceleration voltage signals are each reset to accumulate from a zero value at an initial point of every said predetermined time interval.

82. A micro inertial measurement unit, as recited in claim 81, wherein said resetting means comprises an oscillator, wherein said angular reset voltage pulse and said velocity reset voltage pulse are implemented by producing a timing pulse by said oscillator.

83. A micro inertial measurement unit, as recited in claim 81, said angular increment and velocity increment producer further comprises an angular amplifying circuit for amplifying said X axis, Y axis and Z axis analog angular rate voltage signals to form amplified X axis, Y axis and Z axis analog angular rate signals and an acceleration amplifying circuit for amplifying said X axis, Y axis and Z axis analog acceleration voltage signals to form amplified X axis, Y axis and Z axis analog acceleration signals.

84. A micro inertial measurement unit, as recited in claim 83, wherein said angular increment and velocity increment measurement means, which is adapted for measuring said voltage values of said X axis, Y axis and Z axis accumulated angular and velocity increments, comprises an analog/digital converter to substantially digitize said raw X axis, Y axis and Z axis angular increment and velocity increment voltage values into digital X axis, Y axis and Z axis angular increment and velocity increments.

85. A micro inertial measurement unit, as recited in claim 84, wherein said analog/digital converter of said angular increment and velocity increment producer further includes an angular analog/digital converter, a velocity analog/digital converter and an input/output interface circuit, wherein said accumulated angular increments output from said angular integrator circuit and said accumulated velocity increments output from said acceleration integrator circuit are input into said angular analog/digital converter and said velocity analog/digital converter respectively, wherein said accumulated angular increments is digitized by said angular analog/digital converter by measuring said accumulated angular increments with said angular reset voltage pulse to form a digital angular measurements of voltage in terms of said angular increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis angular increment voltage values, wherein said accumulated velocity increments are digitized by said velocity analog/digital converter by measuring said accumulated velocity increments with said velocity reset voltage pulse to form digital velocity measurements of voltage in terms of said velocity increment counts which is output to said input/output interface circuit to generate digital X axis, Y axis and Z axis velocity increment voltage values.

86. A micro inertial measurement unit, as recited in claim 85, further comprising a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer, wherein said thermal controlling means comprises a thermal sensing producer device, a heater device and a thermal processor, wherein said thermal sensing producer device, which produces temperature signals, is processed in parallel with said angular rate producer and said acceleration producer for maintaining a predetermined operating temperature of said angular rate producer and said acceleration producer and angular increment and velocity increment producer, wherein said predetermined operating temperature is a constant designated temperature selected between 150°

F. and 185°

F., wherein said temperature signals produced from said thermal sensing producer device are inputted to said thermal processor for computing temperature control commands using said temperature signals, a temperature scale factor, and a predetermined operating temperature of said angular rate producer and said acceleration producer, and produce driving signals to said heater device using said temperature control commands for controlling said heater device to provide adequate heat for maintaining said predetermined operating temperature in said micro inertial measurement unit.

87. A micro inertial measurement unit, as recited in claim 73 or 79, further comprising a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer, wherein said thermal controlling means comprises a thermal sensing producer device, a heater device and a thermal processor, wherein said thermal sensing producer device, which produces temperature signals, is processed in parallel with said angular rate producer and said acceleration producer for maintaining a predetermined operating temperature of said angular rate producer and said acceleration producer and angular increment and velocity increment producer, wherein said predetermined operating temperature is a constant designated temperature selected between 150°

F. and 185°

F., wherein said temperature signals produced from said thermal sensing producer device are inputted to said thermal processor for computing temperature control commands using said temperature signals, a temperature scale factor, and a predetermined operating temperature of said angular rate producer and said acceleration producer, and produce driving signals to said heater device using said temperature control commands for controlling said heater device to provide adequate heat for maintaining said predetermined operating temperature in said micro inertial measurement unit.

88. A micro inertial measurement unit, as recited in claim 73 or 79, further comprising a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer, wherein said thermal controlling means comprises:

a thermal sensing producer device, comprising;

a first thermal sensing producing unit for sensing said temperature of said X axis angular rate detecting unit and said Y axis accelerometer,

a second thermal sensing producer for sensing said temperature of said Y axis angular rate detecting unit and said X axis accelerometer, and

a third thermal sensing producer for sensing said temperature of said Z axis angular rate detecting unit and said Z axis accelerometer;

a heater device, comprising;

a first heater, which is connected with said X axis angular rate detecting unit, said Y axis accelerometer, and said first front-end circuit, for maintaining said predetermined operational temperature of said X axis angular rate detecting unit, said Y axis accelerometer, and said first front-end circuit,

a second heater, which is connected with said Y axis angular rate detecting unit, said X axis accelerometer, and said second front-end circuit, for maintaining said predetermined operational temperature of said X axis angular rate detecting unit, said X axis accelerometer, and said second front-end circuit, and

a third heater, which is connected with said Z axis angular rate detecting unit, said Z axis accelerometer, and said third front-end circuit, for maintaining said predetermined operational temperature of said Z axis angular rate detecting unit, said Z axis accelerometer, and said third front-end circuit; and

a thermal processor which comprises three identical thermal control circuitries and said thermal control computation module provided on said control circuit board, wherein

each of said thermal control circuitries further comprises;

a first amplifier circuit, which is connected with said respective X axis, Y axis or Z axis thermal sensing producer, for amplifying said signals and suppressing said noise residing in said temperature voltage signals from said respective X axis, Y axis or Z axis thermal sensing producer and improving said signal-to-noise ratio,

an analog/digital converter, which is connected with said amplifier circuit, for sampling said temperature voltage signals and digitizing said sampled temperature voltage signals to digital signals, which are output to said thermal control computation module,

a digital/analog converter which converts said digital temperature commands input from said thermal control computation module into analog signals, and

a second amplifier circuit, which receives said analog signals from said digital/analog converter, amplifying said input analog signals from said digital/analog converter for driving said respective first, second or third heater; and

closing said temperature controlling loop,

wherein said thermal control computation module computes digital temperature commands using said digital temperature voltage signals from said analog/digital converter, said temperature sensor scale factor, and said pre-determined operating temperature of said angular rate producer and acceleration producer, wherein said digital temperature commands are fed back to said digital/analog converter.

89. A micro inertial measurement unit, as recited in claim 79, wherein a position and attitude processor is adapted to further connect with said micro inertial measurement unit for computing position, attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments, wherein said thermal controlling means comprises a thermal sensing producer and an analog/digital converter connected to said thermal sensing producer device to receive said analog voltage output from said thermal sensing producer device, wherein said position, attitude, and heading processor is adapted for accessing temperature characteristic parameters of said angular rate producer and said acceleration producer using a current temperature of said angular rate producer and said acceleration producer from said temperature digitizer, and compensating said errors induced by thermal effects in said input digital angular and velocity increments and computing attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments in said attitude and heading processor.

90. A micro inertial measurement unit, as recited in claim 89, wherein said thermal controlling means further comprises an additional amplifier circuit connected between said thermal sensing producer device and said digital/analog converter for amplifying said analog voltage signals and suppressing said noise residing in said voltage signals and improving said voltage signal-to-noise ratio, wherein said amplified voltage signals are output to said analog/digital converter and sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals outputting to said attitude and heading processor.

91. A micro inertial measurement unit, as recited in claim 90, wherein an input/output interface circuit is connected between said analog/digital converter and said attitude and heading processor, wherein said input amplified voltage signals are sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals ouputting to said input/output interface circuit before inputting into said attitude and heading processor.

92. A micro inertial measurement unit, as recited in claim 73, wherein a position and attitude processor is adapted to further connect with said micro inertial measurement unit for computing position, attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments, wherein said thermal controlling means comprises a thermal sensing producer and an analog/digital converter connected to said thermal sensing producer device to receive said analog voltage output from said thermal sensing producer device, wherein said position, attitude, and heading processor is adapted for accessing temperature characteristic parameters of said angular rate producer and said acceleration producer using a current temperature of said angular rate producer and said acceleration producer from said temperature digitizer, and compensating said errors induced by thermal effects in said input digital angular and velocity increments and computing attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments in said attitude and heading processor.

93. A micro inertial measurement unit, as recited in claim 92, wherein said thermal controlling means further comprises an additional amplifier circuit connected between said thermal sensing producer device and said digital/analog converter for amplifying said analog voltage signals and suppressing said noise residing in said voltage signals and improving said voltage signal-to-noise ratio, wherein said amplified voltage signals are output to said analog/digital converter and sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals outputting to said attitude and heading processor.

94. A micro inertial measurement unit, as recited in claim 93, wherein an input/output interface circuit is connected between said analog/digital converter and said attitude and heading processor, wherein said input amplified voltage signals are sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals outputting to said input/output interface circuit before inputting into said attitude and heading processor.

95. A micro inertial measurement unit, as recited in claim 72, further comprising a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer.

96. A micro inertial measurement unit, comprising:

an angular rate producer for producing X axis, Y axis and Z axis angular rate electrical signals;

an acceleration producer for producing X axis, Y axis and Z axis acceleration electrical signals;

an angular increment and velocity increment producer for converting said X axis, Y axis and Z axis angular rate electrical signals into digital angular increments and converting said input X axis, Y axis and Z axis acceleration electrical signals into digital velocity increments; and

a position and attitude processor connecting with said micro inertial measurement unit for computing position, attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments.

97. A micro inertial measurement unit, comprising:

an angular rate producer for producing X axis, Y axis and Z axis angular rate electrical signals;

an acceleration producer for producing X axis, Y axis and Z axis acceleration electrical signals;

an angular increment and velocity increment producer for converting said X axis, Y axis and Z axis angular rate electrical signals into digital angular increments and converting said input X axis, Y axis and Z axis acceleration electrical signals into digital velocity increments;

a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer; and

a position and attitude processor connected with said micro inertial measurement unit for computing position, attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments, wherein said thermal controlling means comprises a thermal sensing producer and an analog/digital converter connected to said thermal sensing producer device to receive said analog voltage output from said thermal sensing producer device, wherein said position, attitude, and heading processor is adapted for accessing temperature characteristic parameters of said angular rate producer and said acceleration producer using a current temperature of said angular rate producer and said acceleration producer from said temperature digitizer, and compensating said errors induced by thermal effects in said input digital angular and velocity increments and computing attitude and heading angle measurements using said X axis, Y axis and Z axis digital angular increments and X axis, Y axis and Z axis velocity increments in said attitude and heading processor.

98. A micro inertial measurement unit, as recited in claim 97, wherein said thermal controlling means further comprises an additional amplifier circuit connected between said thermal sensing producer device and said digital/analog converter for amplifying said analog voltage signals and suppressing said noise residing in said voltage signals and improving said voltage signal-to-noise ratio, wherein said amplified voltage signals are output to said analog/digital converter and sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals outputting to said attitude and heading processor.

99. A micro inertial measurement unit, as recited in claim 98, wherein an input/output interface circuit is connected between said analog/digital converter and said attitude and heading processor, wherein said input amplified voltage signals are sampled to form sampled voltage signals that are further digitized in said analog/digital converters to form digital signals outputting to said input/output interface circuit before inputting into said attitude and heading processor.