Vehicle self-carried positioning method and system thereof

• US 6,477,465 B1
• Filed: 10/31/2000
• Issued: 11/05/2002
• Est. Priority Date: 11/29/1999
• Status: Expired due to Term

• Current Assignee: American GNC Corporation
• Original Assignee: American GNC Corporation
• Inventors: McCall, Hiram, Lin, Ching-Fang
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US09/704,211
• Time in Patent Office: 735 Days
• Field of Search: 701/220, 701/221, 701/217, 701/207, 731/78.R, 734/30, 342/357.14, 342/357.01, 342/357.05, 340/990, 340/995
• US Class Current: 701/220
• CPC Class Codes: G01C 21/188 for accumulated errors, e.g. by coupling inertial systems with absolute positioning systems

Abstract

A vehicle self-carried positioning system, carried in a vehicle, includes an inertial measurement unit, a north finder, a velocity producer, a navigation processor, a wireless communication device, and a display device and map database. Output signals of the inertial measurement unit, the velocity producer, and the north finder are processed to obtain highly accurate position measurements of a vehicle on land and in water, and the vehicle position information can be exchanged with other users through the wireless communication device, and the location and surrounding information can be displayed on the display device by accessing a map database with the vehicle position information.

Claims

1. A vehicle self-carried positioning system, comprising:

an inertial measurement unit, carried in a vehicle, for sensing traveling displacement motions of said vehicle so as to produce digital angular increments and velocity increments signals in response to said traveling displacement motions of said vehicle;

a north finder, carried in said vehicle, to produce a heading measurement of said vehicle;

a velocity producer, carried in said vehicle, for producing a current axis velocity data of a body frame of said vehicle; and

a navigation processor, which is connected with said inertial measurement unit, said north finder, and said velocity producer so as to receive said digital angular increments and velocity increments signals, heading measurement, and current axis velocity data of said body frame, for

comparing an IMU position deduced from said digital angular increments and velocity increments signals with a measured position deduced from said heading measurement and current axis velocity data of said body frame, so as to obtain a position difference; and

feeding back said position difference to correct said IMU position to output a corrected IMU position when said position difference is bigger than a predetermined scale value;

wherein said navigation processor further comprises;

an INS computation module, using said digital angular increments and velocity increments signals from said inertial measurement unit to produce inertial positioning measurements;

a magnetic sensor processing module for producing a heading angle;

a vehicle producer processing module for producing relative position error measurements for a Kalman filter; and

an integration Kalman filter for estimating errors of said inertial positioning measurements to calibrate inertial positioning measurement errors;

wherein said INS computation module further comprises;

a sensor compensation module for calibrating errors of said digital angular increments and velocity increments signals; and

an inertial navigation algorithm module for computing IMU position, velocity and attitude data;

wherein said inertial navigation algorithm module further comprises;

an attitude integration module for integrating said angular increments into said attitude data;

a velocity integration module for transforming said measured velocity increments into a suitable navigation coordinate frame by using said attitude data, wherein said transformed velocity increments is integrated into said velocity data; and

a position module for integrating said navigation frame velocity data into said position data;

wherein said velocity producer processing module further comprises;

a transformation module for transforming an input velocity data expressed in said body frame to a velocity expressed in a navigation frame;

a scale factor and misalignment error compensation module for compensating scale factor and misalignment errors in said velocity; and

a relative position computation for receiving said IMU velocity and attitude data and compensated velocity to form said relative position error measurements for said Kalman filter;

wherein said Kalman filter module further comprises;

a motion test module for determining whether said vehicle stops automatically;

a measurement and time varying matrix formation module for formulating measurement and time varying matrix for a state estimation module according to motion status of said vehicle from said motion test module; and

a state estimation module for filtering said measurement and obtaining optimal estimates of said IMU position errors.

2. The vehicle self-carried positioning system, as recited in claim 1, wherein said state estimation module further comprises:

a horizontal filter for obtaining estimates of horizontal IMU position errors; and

a vertical filter for obtaining estimates of vertical IMU position errors.

3. The vehicle self-carried positioning system, as recited in claim 2, wherein said motion test module comprises:

an velocity producer change test module for receiving velocity reading to determining whether said vehicle stops or restarts;

a system velocity change test module for comparing system velocity change between a current interval and a previous interval to determining whether said vehicle stops or restarts;

a system velocity test module for comparing a system velocity magnitude with a predetermined value to determine whether said vehicle stops or restarts; and

an attitude change test module for comparing a system attitude magnitude with a predetermined value to determine whether said vehicle stops or restarts.

4. The vehicle self-carried positioning system, as recited in claim 3, wherein said velocity producer is an odometer which measures a relative velocity with respect to a ground on which said vehicle travels when said vehicle is a land vehicle.

5. The vehicle self-carried positioning system, as recited in claim 3, wherein said velocity producer is a velocimeter which measures a relative velocity with respect to water where said vehicle travels when said vehicle is a water vehicle.

6. The vehicle self-carried positioning system, as recited in claim 3, wherein said north finder is a magnetic sensor detecting a magnetic field vector of the earth to form said magnetic heading measurement.

7. The vehicle self-carried positioning system, as recited in claim 3, further comprising a wireless communication device for exchanging said IMU position and said corrected IMU position with other vehicle self-carried positioning systems carried by other vehicles.

8. The vehicle self-carried positioning system, as recited in claim 7, further comprising a map database and a display device for displaying a location of said vehicle on a map and obtaining surrounding information by accessing said map database using said IMU position and said corrected IMU position.

9. The vehicle self-carried positioning system, as recited in claim 3, further comprising a map database and a display device for displaying a location of said vehicle on a map and obtaining surrounding information by accessing said map database using said IMU position and said corrected IMU position.

10. The vehicle self-carried positioning system, as recited in claim 1, further comprising a wireless communication device for exchanging said IMU position and said corrected IMU position with other vehicle self-carried positioning systems carried by other vehicles.

11. A vehicle self-carried positioning system, comprising:

an inertial measurement unit, carried in a vehicle, for sensing traveling displacement motions of said vehicle so as to produce digital angular increments and velocity increments signals in response to said traveling displacement motions of said vehicle;

a north finder, carried in said vehicle, to produce a heading measurement of said vehicle;

a velocity producer, carried in said vehicle, for producing a current axis velocity data of a body frame of said vehicle, wherein said velocity producer is an odometer which measures a relative velocity with respect to a ground on which said vehicle travels when said vehicle is a land vehicle; and

a navigation processor, which is connected with said inertial measurement unit, said north finder, and said velocity producer so as to receive said digital angular increments and velocity increments signals, heading measurement, and current axis velocity data of said body frame, for

comparing an IMU position deduced from said digital angular increments and velocity increments signals with a measured position deduced from said heading measurement and current axis velocity data of said body frame, so as to obtain a position difference; and

feeding back said position difference to correct said IMU position to output a corrected IMU position when said position difference is bigger than a predetermined scale value.

12. A vehicle self-carried positioning system, comprising:

an inertial measurement unit, carried in a vehicle, for sensing traveling displacement motions of said vehicle so as to produce digital angular increments and velocity increments signals in response to said traveling displacement motions of said vehicle;

a north finder, carried in said vehicle, to produce a heading measurement of said vehicle;

a velocity producer, carried in said vehicle, for producing a current axis velocity data of a body frame of said vehicle, wherein said velocity producer is a velocimeter which measures a relative velocity with respect to water where said vehicle travels when said vehicle is a water vehicle; and

a navigation processor, which is connected with said inertial measurement unit, said north finder, and said velocity producer so as to receive said digital angular increments and velocity increments signals, heading measurement, and current axis velocity data of said body frame, for

comparing an IMU position deduced from said digital angular increments and velocity increments signals with a measured position deduced from said heading measurement and current axis velocity data of said body frame, so as to obtain a position difference; and

feeding back said position difference to correct said IMU position to output a corrected IMU position when said position difference is bigger than a predetermined scale value.

13. A vehicle self-carried positioning system, comprising:

an inertial measurement unit, carried in a vehicle, for sensing traveling displacement motions of said vehicle so as to produce digital angular increments and velocity increments signals in response to said traveling displacement motions of said vehicle;

a north finder, carried in said vehicle, to produce a heading measurement of said vehicle;

a velocity producer, carried in said vehicle, for producing a current axis velocity data of a body frame of said vehicle; and

a navigation processor, which is connected with said inertial measurement unit, said north finder, and said velocity producer so as to receive said digital angular increments and velocity increments signals, heading measurement, and current axis velocity data of said body frame, for

comparing an IMU position deduced from said digital angular increments and velocity increments signals with a measured position deduced from said heading measurement and current axis velocity data of said body frame, so as to obtain a position difference; and

feeding back said position difference to correct said IMU position to output a corrected IMU position when said position difference is bigger than a predetermined scale value;

wherein said inertial measurement unit is a micro inertial measurement unit which comprises;

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

14. The vehicle self-carried positioning system, as recited in claim 13, 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 micro inertial measurement unit.

15. The vehicle self-carried positioning system, 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 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.

16. The vehicle self-carried positioning system, 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 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.

17. The vehicle self-carried positioning system, as recited in claim 16, 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. The vehicle self-carried positioning system, 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. The vehicle self-carried positioning system, 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. The vehicle self-carried positioning system, 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. The vehicle self-carried positioning system, as recited in claim 20, 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.

22. The vehicle self-carried positioning system, as recited in claim 21, 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.

23. The vehicle self-carried positioning system, as recited in claim 22, 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.

24. The vehicle self-carried positioning system, as recited in claim 23, 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.

25. The vehicle self-carried positioning system, as recited in claim 24, 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.

26. The vehicle self-carried positioning system, as recited in claim 25, 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.

27. The vehicle self-carried positioning system, as recited in claim 26, 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 micro inertial measurement unit.

28. A vehicle self-carried positioning system, comprising:

an inertial measurement unit, carried in a vehicle, for sensing traveling displacement motions of said vehicle so as to produce digital angular increments and velocity increments signals in response to said traveling displacement motions of said vehicle;

a north finder, carried in said vehicle, to produce a heading measurement of said vehicle;

a velocity producer, carried in said vehicle, for producing a current axis velocity data of a body frame of said vehicle, wherein said velocity producer is a velocimeter which measures a relative velocity with respect to water where said vehicle travels when said vehicle is a water vehicle; and

a navigation processor, which is connected with said inertial measurement unit, said north finder, and said velocity producer so as to receive said digital angular increments and velocity increments signals, heading measurement, and current axis velocity data of said body frame, for

comparing an IMU position deduced from said digital angular increments and velocity increments signals with a measured position deduced from said heading measurement and current axis velocity data of said body frame, so as to obtain a position difference; and

feeding back said position difference to correct said IMU position to output a corrected IMU position when said position difference is bigger than a predetermined scale value;

wherein said micro 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.

29. The vehicle self-carried positioning system, as recited in claim 28, 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.

30. The vehicle self-carried positioning system, as recited in claim 29, 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 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 angular increment and velocity increment producer provided on said control circuit board.

31. The vehicle self-carried positioning system, as recited in claim 30, 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.

32. The vehicle self-carried positioning system, as recited in claim 31, 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.

33. The vehicle self-carried positioning system, as recited in claim 32, 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.

34. The vehicle self-carried positioning system, as recited in claim 33, 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.

35. The vehicle self-carried positioning system, as recited in claim 34, 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 +−

½

of said peek for each maximum frequency point.

36. A vehicle self-carried positioning method, comprising the steps of:

(a) sensing traveling displacement motions of a vehicle and producing digital angular increments and velocity increments signals in response to said traveling displacement motions by an inertial measurement unit;

(b) sensing magnetic field of the earth to measure a heading angle of said vehicle by a north finder;

(c) measuring a relative velocity of said vehicle relative to a transportation surface where said vehicle moving thereon by a velocity producer, and

(d) deducing position data in an integration processor, using said digital angular increments and velocity increments signals, said heading angle, said relative velocity of said vehicle relative to said transportation surface, wherein the deducing step (d) further comprises the steps of;

(d.1) computing inertial positioning measurements using said digital angular increments and velocity increments signals;

(d.2) computing said heading angle using said earth'"'"'s magnetic field measurements;

(d.3) creating a relative position error measurement in a velocity producer processing module of said navigation processor using said relative velocity of said vehicle relative to said transportation surface for a Kalman filter;

(d.4) creating a relative position error measurement in said velocity producer processing module using said relative velocity of said user relative to said water for a Kalman filter; and

(d.5) estimating errors of said inertial positioning measurements to calibrate inertial positioning measurement errors;

wherein the estimating step (d.5) further comprises the steps of;

(d.5.1) performing motion tests to determine whether said vehicle stops to initiate a zero-velocity update,

(d.5.2) formulating measurement equations and time varying matrix for said Kalman filter, and

(d.5.3) computing estimates of error states using said Kalman filter.

37. The vehicle self-carried positioning method, as recited in claim 36, wherein the step (d.3) further comprises the steps of:

(d.3.1) transforming an input velocity expressed in said body frame to a velocity expressed in a navigation frame;

(d.3.2) comparing said velocity with said IMU velocity to form a velocity difference; and

(d.3.3) integrating said velocity difference during a predetermined interval.

38. A vehicle self-carried positioning method, comprising the steps of:

(a) sensing traveling displacement motions of a vehicle and producing digital angular increments and velocity increments signals in response to said traveling displacement motions by an inertial measurement unit;

(b) sensing magnetic field of the earth to measure a heading angle of said vehicle by a north finder;

(c) measuring a relative velocity of said vehicle relative to a transportation surface where said vehicle moving thereon by a velocity producer, and

(d) deducing position data in an integration processor, using said digital angular increments and velocity increments signals, said heading angle, said relative velocity of said vehicle relative to said transportation surface, wherein the deducing step (d) further comprises the steps of;

(d.1) computing inertial positioning measurements using said digital angular increments and velocity increments signals;

(d.2) computing said heading angle using said earth'"'"'s magnetic field measurements;

(d.3) creating a relative position error measurement in a velocity producer processing module of said navigation processor using said relative velocity of said vehicle relative to said transportation surface for a Kalman filter;

(d.4) creating a relative position error measurement in said velocity producer processing module using said relative velocity of said user relative to said water for a Kalman filter; and

(d.5) estimating errors of said inertial positioning measurements to calibrate inertial positioning measurement errors;

wherein the computing step (d.1) further comprises said steps of;

(d.1.1) integrating said angular increments into attitude data;

(d.1.2) transforming measured velocity increments into a suitable navigation coordinate frame by use of said attitude data, wherein said transferred velocity increments are integrated into velocity data, denoted as velocity integration processing; and

(d.1.3) integrating said navigation frame velocity data into position data, denoted as position integration processing;

wherein the estimating step (d.5) further comprises the steps of;

(d.5.1) performing motion tests to determine whether said vehicle stops to initiate a zero-velocity update,

(d.5.2) formulating measurement equations and time varying matrix for said Kalman filter, and

(d.5.3) computing estimates of error states using said Kalman filter.

39. The vehicle self-carried positioning method, as recited in claim 38, wherein the step (d.3) further comprises the steps of:

(d.3.1) transforming an input velocity expressed in said body frame to a velocity expressed in a navigation frame;

(d.3.2) comparing said velocity with said IMU velocity to form a velocity difference; and

(d.3.3) integrating said velocity difference during a predetermined interval.

40. The vehicle self-carried positioning method, as recited claims 39, wherein said velocity producer is an odometer when said transportation surface is a ground surface.

41. The vehicle self-carried positioning method, as recited in claim 39, wherein said velocity producer is a velocimeter when said transportation surface is a water surface.

42. The vehicle self-carried positioning method, as recited in claim 41, further comprising a second additional processing step of displaying a location of said vehicle on a map and displaying surrounding information by accessing said map database using obtained position information.

43. The vehicle self-carried positioning method, as recited in claim 39, after the step (d), further comprising an additional processing step of exchanging obtained position information with other vehicles via a wireless communication device.

44. The vehicle self-carried positioning method, as recited in claim 43, further comprising an additional processing step of displaying a location of said vehicle on a map and displaying surrounding information by accessing said map database using obtained position information.

45. The vehicle self-carried positioning method, as recited in claim 43, further comprising a second additional processing step of displaying a location of said vehicle on a map and displaying surrounding information by accessing said map database using obtained position information.

46. The vehicle self-carried positioning method, as recited in claim 39, further comprising an additional processing step of displaying a location of said vehicle on a map and displaying surrounding information by accessing said map database using obtained position information.

47. The vehicle self-carried positioning method, as recited in claim 46, further comprising a second additional processing step of displaying a location of said vehicle on a map and displaying surrounding information by accessing said map database using obtained position information.

48. The vehicle self-carried positioning method, as recited in claim 39, further comprising a second additional processing step of displaying a location of said vehicle on a map and displaying surrounding information by accessing said map database using obtained position information.