Core inertial measurement unit

• US 6,516,283 B2
• Filed: 06/11/2002
• Issued: 02/04/2003
• Est. Priority Date: 07/25/2000
• Status: Expired due to Term

• Current Assignee: American GNC Corporation
• Original Assignee: American GNC Corporation
• Inventors: McCall, Hiram, Lin, Ching-Fang
• Primary Examiner(s): SHAH, KAMINI S
• Application Number:
  US10/170,035
• Publication Number:
  US 20020183958A1
• Time in Patent Office: 238 Days
• Field of Search: 702/141, 701/220, 701/222, 342/357.06, 342/357.08, 342/357.11, 342/355
• US Class Current: 702/141
• CPC Class Codes: G01C 21/166 Mechanical, construction or arrangement details of inertial navigation systems
• CPC Class Codes: G01C 21/183 Compensation of inertial measurements, e.g. for temperature effects

Abstract

A core 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 core inertial measurement unit, comprising:

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

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

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

an Earth'"'"'s magnetic field detector producing Earth'"'"'s magnetic field vector measurements; and

a position, attitude and heading processor connected with said angular rate producer, said acceleration producer and said Earth'"'"'s magnetic field detector, so as to use said three-axis digital angular increments, said three-axis digital velocity increments and said position, attitude and heading angle measurements to compute motion measurements including position, attitude and heading angle measurements.

2. A core inertial measurement unit, as recited in claim 1, further comprising a communication module, which is connected with said position, attitude and heading processor, providing external systems with said motion measurements, including said position, attitude and heading angle measurements, of said core inertial measurement unit.

3. A core inertial measurement unit, as recited in claim 1, further comprising a LCD display module, which is connected with said position, attitude and heading processor, providing a display of said motion measurements of said core inertial measurement unit in terms of position, velocity, and attitude data.

4. A core inertial measurement unit, as recited in claim 2, further comprising a LCD display module, which is connected with said position, attitude and heading processor, providing a display of said motion measurements of said core inertial measurement unit in terms of position, velocity, and attitude data.

5. A core inertial measurement unit, as recited in claim 2, wherein said communication module comprises a wireless communication transmitter/receiver.

6. A core inertial measurement unit, as recited in claim 4, wherein said communication module comprises a wireless communication transmitter/receiver.

7. A core inertial measurement unit, as recited in claim 2, wherein said communication module comprises an I/O interface circuit and connector for outputting said motion measurements.

8. A core inertial measurement unit, as recited in claim 4, wherein said communication module comprises an I/O interface circuit and connector for outputting said motion measurements.

9. The core inertial measurement unit, as recited in claim 3, 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.

10. A core inertial measurement unit, as recited in claim 4, 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 position, attitude, and heading processor is a DSP chipset arranged on a control board;

wherein said communication module is interfaced with said DSP chipset;

wherein said Earth'"'"'s magnetic field detector is interfaced with said DSP chipset through an Earth'"'"'s magnetic field detector interface circuit of an ASIC chip and arranged on said control board;

wherein said LCD display module is interfaced with said DSP chipset through a LCD interface circuit of said ASIC chip and arranged on said control board.

11. A core inertial measurement unit, as recited in claim 10, wherein said position, attitude and heading processor is further interfaced with:

a flash memory, which is connected with said DSP chipset and arranged on said control board for providing a storage means of the executable software code of the control and computation tasks of said DSP chipset when said core IMU is powered off; and

a JTAG connector, which is connected with said DSP chipset and arranged on said control board for providing an on-board programming function of said flash memory of said control circuit board, wherein said on-board programming function is that said flash memory is able to be programmed on board through said JATG connector.

12. A core inertial measurement unit, as recited in claim 11, wherein said Earth'"'"'s magnetic field detector interface circuit is capable of:

acquiring electronic analog signals proportional to Earth'"'"'s magnetic field from said Earth'"'"'s magnetic field detector;

amplifying said electronic analog signals to suppress noise in said electronic analog signal to form amplified signals which are not proportional to said Earth'"'"'s magnetic field;

converting said amplified signals to form three-axis digital Earth'"'"'s magnetic field signals which are input to said DSP chipset; and

providing data bus connection and producing an address decode function so that said DSP chipset is able to access said Earth'"'"'s magnetic field detector interface circuit and pickup said three-axis digital Earth'"'"'s magnetic field signals.

13. The core inertial measurement unit, as recited in claim 9, 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 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 core inertial measurement unit.

14. The core inertial measurement unit, as recited in claim 10, 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 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 core inertial measurement unit.

15. The core inertial measurement unit, as recited in claim 11, 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 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 core inertial measurement unit.

16. The core inertial measurement unit, as recited in claim 12, 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 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 core inertial measurement unit.

17. A core inertial measurement unit, as recited in claim 13, 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 core 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.

18. A core inertial measurement unit, as recited in claim 14, 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 core 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.

19. A core inertial measurement unit, as recited in claim 15, 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 core 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.

20. A core inertial measurement unit, as recited in claim 16, 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 core 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.

21. A core inertial measurement unit, as recited in claim 17, 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.

22. A core inertial measurement unit, as recited in claim 18, 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.

23. A core inertial measurement unit, as recited in claim 19, 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.

24. A core inertial measurement unit, as recited in claim 20, 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.

25. A core inertial measurement unit, as recited in claim 21, 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.

26. A core inertial measurement unit, as recited in claim 22, 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.

27. A core inertial measurement unit, as recited in claim 23, 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.

28. A core inertial measurement unit, as recited in claim 24, 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.

29. A core inertial measurement unit, as recited in claim 25, 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.

30. A core inertial measurement unit, as recited in claim 26, 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 core inertial measurement unit, as recited in claim 27, 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.

32. A core 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.

33. A core inertial measurement unit, as recited in claim 29, 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.

34. A core 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.

35. A core inertial measurement unit, as recited in claim 31, 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.

36. A core inertial measurement unit, as recited in claim 32, 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 core inertial measurement unit, as recited in claim 33, wherein 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 core inertial measurement unit, as recited in claim 34, wherein 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.

39. A core inertial measurement unit, as recited in claim 35, wherein 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.

40. A core inertial measurement unit, as recited in claim 36, wherein 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.

41. A core 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.

42. A core inertial measurement unit, as recited in claim 38, 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.

43. A core inertial measurement unit, as recited in claim 39, 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.

44. A core inertial measurement unit, as recited in claim 40, 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.

45. A core inertial measurement unit, as recited in claim 41, 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.

46. A core inertial measurement unit, as recited in claim 42, 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.

47. A core inertial measurement unit, as recited in claim 43, 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.

48. A core inertial measurement unit, as recited in claim 44, 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.

49. A core inertial measurement unit, as recited in claim 45, 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 core inertial measurement unit.

50. A core inertial measurement unit, as recited in claim 46, 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 core inertial measurement unit.

51. A core inertial measurement unit, as recited in claim 47, 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 core inertial measurement unit.

52. A core inertial measurement unit, as recited in claim 48, 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 core inertial measurement unit.

53. A core inertial measurement unit, as recited in claim 49, 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.

54. A core inertial measurement unit, as recited in claim 50, 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.

55. A core inertial measurement unit, as recited in claim 51, 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.

56. A core inertial measurement unit, as recited in claim 52, 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.

57. A core inertial measurement unit, as recited in claim 53, wherein 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 core inertial measurement unit.

58. A core inertial measurement unit, as recited in claim 54, wherein 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 core inertial measurement unit.

59. A core inertial measurement unit, as recited in claim 55, wherein 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 predetermined 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 core inertial measurement unit.

60. A core inertial measurement unit, as recited in claim 56, wherein 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 core inertial measurement unit.

61. A core inertial measurement unit, as recited in claim 3, wherein said core IMU 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.

62. A core inertial measurement unit, as recited in claim 4, wherein said position, attitude, and heading processor is a DSP chipset arranged on a control board;

wherein said communication module is interfaced with said DSP chipset;

wherein said Earth'"'"'s magnetic field detector is interfaced with said DSP chipset through an Earth'"'"'s magnetic field detector interface circuit of an ASIC chip and arranged on said control board;

wherein said LCD display module is interfaced with said DSP chipset through a LCD interface circuit of said ASIC chip and arranged on said control board, wherein said core IMU 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.

63. A core inertial measurement unit, as recited in claim 62, wherein said position, attitude and heading processor is further interfaced with:

a flash memory, which is connected with said DSP chipset and arranged on said control board for providing a storage means of the executable software code of the control and computation tasks of said DSP chipset when said core IMU is powered off; and

a JTAG connector, which is connected with said DSP chipset and arranged on said control board for providing an on-board programming function of said flash memory of said control circuit board, wherein said on-board programming function is that said flash memory is able to be programmed on board through said JATG connector.

64. A core inertial measurement unit, as recited in claim 63, wherein said Earth'"'"'s magnetic field detector interface circuit is capable of:

acquiring electronic analog signals proportional to Earth'"'"'s magnetic field from said Earth'"'"'s magnetic field detector;

amplifying said electronic analog signals to suppress noise in said electronic analog signal to form amplified signals which are not proportional to said Earth'"'"'s magnetic field;

converting said amplified signals to form three-axis digital Earth'"'"'s magnetic field signals which are input to said DSP chipset; and

providing data bus connection and producing an address decode function so that said DSP chipset is able to access said Earth'"'"'s magnetic field detector interface circuit and pickup said three-axis digital Earth'"'"'s magnetic field signals.

65. A core inertial measurement unit, as recited in claim 61, wherein said first circuit board, said second circuit board, said third circuit board, and said control circuit board are spatially arranged inside a metal cubic case respectively, where said first circuit board and said second circuit board are assembled in top and bottom, said third circuit board is assembled in left or right side to be connected with said first circuit board and said second circuit board in orthogonal way to achieve three sensing axis of the angular rate producer and acceleration producer, said control circuit board is assembled in the front or back side to be connected with said first circuit board, said second circuit board and said third circuit board.

66. A core inertial measurement unit, as recited in claim 62, wherein said first circuit board, said second circuit board, said third circuit board, and said control circuit board are spatially arranged inside a metal cubic case respectively, where said first circuit board and said second circuit board are assembled in top and bottom, said third circuit board is assembled in right or left side to be connected with said first circuit board and said second circuit board in orthogonal way to achieve three sensing axis of the angular rate producer and acceleration producer, said control circuit board is assembled in the front or back side to be connected with said first circuit board, said second circuit board and said third circuit board.

67. A core inertial measurement unit, as recited in claim 63, wherein said first circuit board, said second circuit board, said third circuit board, and said control circuit board are spatially arranged inside a metal cubic case respectively, where said first circuit board and said second circuit board are assembled in top and bottom, said third circuit board is assembled in right or left side to be connected with said first circuit board and said second circuit board in orthogonal way to achieve three sensing axis of the angular rate producer and acceleration producer, said control circuit board is assembled in the front or back side to be connected with said first circuit board, said second circuit board and said third circuit board.

68. A core inertial measurement unit, as recited in claim 64, wherein said first circuit board, said second circuit board, said third circuit board, and said control circuit board are spatially arranged inside a metal cubic case respectively, where said first circuit board and said second circuit board are assembled in top and bottom, said third circuit board is assembled in right or left side to be connected with said first circuit board and said second circuit board in orthogonal way to achieve three sensing axis of the angular rate producer and acceleration producer, said control circuit board is assembled in the front or back side to be connected with said first circuit board, said second circuit board and said third circuit board.

69. A core inertial measurement unit, as recited in claim 61, wherein said first circuit board, said second circuit board, said third circuit board, and said control circuit board are spatially arranged to achieve a flat metal case, wherein said third circuit board is assembled vertically in said flat metal case, said first circuit board, said second circuit board, and said control circuit board are scattered in both sides of the third circuit board.

70. A core inertial measurement unit, as recited in claim 62, wherein said first circuit board, said second circuit board, said third circuit board, and said control circuit board are spatially arranged to achieve a flat metal case, wherein said third circuit board is assembled vertically in said flat metal case, said first circuit board, said second circuit board, and said control circuit board are scattered in both sides of the third circuit board.

71. A core inertial measurement unit, as recited in claim 63, wherein said first circuit board, said second circuit board, said third circuit board, and said control circuit board are spatially arranged to achieve a flat metal case, wherein said third circuit board is assembled vertically in said flat metal case, said first circuit board, said second circuit board, and said control circuit board are scattered in both sides of the third circuit board.

72. A core inertial measurement unit, as recited in claim 64, wherein said first circuit board, said second circuit board, said third circuit board, and said control circuit board are spatially arranged to achieve a flat metal case, wherein said third circuit board is assembled vertically in said flat metal case, said first circuit board, said second circuit board, and said control circuit board are scattered in both sides of the third circuit board.

73. A core inertial measurement unit, as recited in claim 3, 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.

74. A core inertial measurement unit, as recited in claim 4, wherein said position, attitude, and heading processor is a DSP chipset arranged on a control board;

wherein said communication module is interfaced with said DSP chipset;

wherein said Earth'"'"'s magnetic field detector is interfaced with said DSP chipset through an Earth'"'"'s magnetic field detector interface circuit of an ASIC chip and arranged on said control board;

wherein said LCD display module is interfaced with said DSP chipset through a LCD interface circuit of said ASIC chip and arranged on said control board;

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.

75. A core inertial measurement unit, as recited in claim 74, wherein said position, attitude and heading processor is further interfaced with:

a flash memory, which is connected with said DSP chipset and arranged on said control board for providing a storage means of the executable software code of the control and computation tasks of said DSP chipset when said core IMU is powered off; and

a JTAG connector, which is connected with said DSP chipset and arranged on said control board for providing an on-board programming function of said flash memory of said control circuit board, wherein said on-board programming function is that said flash memory is able to be programmed on board through said JATG connector.

76. A core inertial measurement unit, as recited in claim 75, wherein said Earth'"'"'s magnetic field detector interface circuit is capable of:

acquiring electronic analog signals proportional to Earth'"'"'s magnetic field from said Earth'"'"'s magnetic field detector;

amplifying said electronic analog signals to suppress noise in said electronic analog signal to form amplified signals which are not proportional to said Earth'"'"'s magnetic field;

converting said amplified signals to form three-axis digital Earth'"'"'s magnetic field signals which are input to said DSP chipset; and

providing data bus connection and producing an address decode function so that said DSP chipset is able to access said Earth'"'"'s magnetic field detector interface circuit and pickup said three-axis digital Earth'"'"'s magnetic field signals.

77. A core inertial measurement unit, as recited in claim 73, wherein said angular increment and velocity increment producer further comprises:

a shield means, covering all of said angular rate producer dither drive circuitry to prevent said angular rate producer dither drive circuitry from interfering with said angular rate producer output signals; and

a guard means, covering output pin of the angular rate producer and input pin of said amplifier to minimize acquisition of unwanted electromagnetic signals.

78. A core inertial measurement unit, as recited in claim 74, wherein said angular increment and velocity increment producer further comprises:

a shield means, covering all of said angular rate producer dither drive circuitry to prevent said angular rate producer dither drive circuitry from interfering with said angular rate producer output signals; and

a guard means, covering output pin of the angular rate producer and input pin of said amplifier to minimize acquisition of unwanted electromagnetic signals.

79. A core inertial measurement unit, as recited in claim 75, wherein said angular increment and velocity increment producer further comprises:

a shield means, covering all of said angular rate producer dither drive circuitry to prevent said angular rate producer dither drive circuitry from interfering with said angular rate producer output signals; and

a guard means, covering output pin of the angular rate producer and input pin of said amplifier to minimize acquisition of unwanted electromagnetic signals.

80. A core inertial measurement unit, as recited in claim 76, wherein said angular increment and velocity increment producer further comprises:

a shield means, covering all of said angular rate producer dither drive circuitry to prevent said angular rate producer dither drive circuitry from interfering with said angular rate producer output signals; and

a guard means, covering output pin of the angular rate producer and input pin of said amplifier to minimize acquisition of unwanted electromagnetic signals.

81. A core inertial measurement unit, as recited in claim 3, 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 and comprising a first pair of temperature sensors,

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

a third thermal sensing producer for sensing said temperature of said Z axis angular rate detecting unit and said Z axis accelerometer and comprising a third pair of temperature sensors,

a heater device, comprising;

a first heater, which is connected with a X axis angular rate detecting unit, a Y axis accelerometer, and a 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 a Y axis angular rate detecting unit, a X axis accelerometer, and a 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 a Z axis angular rate detecting unit, a Z axis accelerometer, and a 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 a 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 selectively driving said first, second, and third heaters, and closing said temperature controlling loop.

82. A core inertial measurement unit, as recited in claim 4, wherein said position, attitude, and heading processor is a DSP chipset arranged on a control board;

wherein said communication module is interfaced with said DSP chipset;

wherein said Earth'"'"'s magnetic field detector is interfaced with said DSP chipset through an Earth'"'"'s magnetic field detector interface circuit of an ASIC chip and arranged on said control board;

wherein said LCD display module is interfaced with said DSP chipset through a LCD interface circuit of said ASIC chip and arranged on said control board,

wherein said core inertial measurement unit further comprises 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 and comprising a first pair of temperature sensors,

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

a third thermal sensing producer for sensing said temperature of said Z axis angular rate detecting unit and said Z axis accelerometer and comprising a third pair of temperature sensors,

a heater device, comprising;

a first heater, which is connected with a X axis angular rate detecting unit, a Y axis accelerometer, and a 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 a Y axis angular rate detecting unit, a X axis accelerometer, and a 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 a Z axis angular rate detecting unit, a Z axis accelerometer, and a 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 a 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 selectively driving said first, second, and third heaters, and closing said temperature controlling loop.

83. A core inertial measurement unit, as recited in claim 82, wherein said position, attitude and heading processor is further interfaced with:

a flash memory, which is connected with said DSP chipset and arranged on said control board for providing a storage means of the executable software code of the control and computation tasks of said DSP chipset when said core IMU is powered off; and

a JTAG connector, which is connected with said DSP chipset and arranged on said control board for providing an on-board programming function of said flash memory of said control circuit board, wherein said on-board programming function is that said flash memory is able to be programmed on board through said JATG connector.

84. A core inertial measurement unit, as recited in claim 83, wherein said Earth'"'"'s magnetic field detector interface circuit is capable of:

acquiring electronic analog signals proportional to Earth'"'"'s magnetic field from said Earth'"'"'s magnetic field detector;

amplifying said electronic analog signals to suppress noise in said electronic analog signal to form amplified signals which are not proportional to said Earth'"'"'s magnetic field;

converting said amplified signals to form three-axis digital Earth'"'"'s magnetic field signals which are input to said DSP chipset; and

providing data bus connection and producing an address decode function so that said DSP chipset is able to access said Earth'"'"'s magnetic field detector interface circuit and pickup said three-axis digital Earth'"'"'s magnetic field signals.

85. A core inertial measurement unit, as recited in claim 3, wherein a support bracket and shock mount are incorporated to minimize an effect of an extreme vibration and shock on output performance of said core inertial measurement unit, wherein said support bracket is directly strapped down in a carrier and said core inertial measurement unit is affixed in said carrier through four said shock mounts with said support bracket.

86. A core inertial measurement unit, as recited in claim 4, wherein a support bracket and shock mount are incorporated to minimize an effect of an extreme vibration and shock on output performance of said core inertial measurement unit, wherein said support bracket is directly strapped down in a carrier and said core inertial measurement unit is affixed in said carrier through four said shock mounts with said support bracket, wherein said position, attitude, and heading processor is a DSP chipset arranged on a control board;

wherein said communication module is interfaced with said DSP chipset;

wherein said Earth'"'"'s magnetic field detector is interfaced with said DSP chipset through an Earth'"'"'s magnetic field detector interface circuit of an ASIC chip and arranged on said control board;

wherein said LCD display module is interfaced with said DSP chipset through a LCD interface circuit of said ASIC chip and arranged on said control board.

87. A core inertial measurement unit, as recited in claim 86, wherein said position, attitude and heading processor is further interfaced with:

a flash memory, which is connected with said DSP chipset and arranged on said control board for providing a storage means of the executable software code of the control and computation tasks of said DSP chipset when said core IMU is powered off; and

a JTAG connector, which is connected with said DSP chipset and arranged on said control board for providing an on-board programming function of said flash memory of said control circuit board, wherein said on-board programming function is that said flash memory is able to be programmed on board through said JATG connector.

88. A core inertial measurement unit, as recited in claim 87, wherein said Earth'"'"'s magnetic field detector interface circuit is capable of:

acquiring electronic analog signals proportional to Earth'"'"'s magnetic field from said Earth'"'"'s magnetic field detector;

amplifying said electronic analog signals to suppress noise in said electronic analog signal to form amplified signals which are not proportional to said Earth'"'"'s magnetic field;

converting said amplified signals to form three-axis digital Earth'"'"'s magnetic field signals which are input to said DSP chipset; and

providing data bus connection and producing an address decode function so that said DSP chipset is able to access said Earth'"'"'s magnetic field detector interface circuit and pickup said three-axis digital Earth'"'"'s magnetic field signals.