Micro integrated global positioning system/inertial measurement unit system

• US 20020008661A1
• Filed: 07/20/2001
• Published: 01/24/2002
• Est. Priority Date: 07/20/2000
• Status: Abandoned Application

• Current Assignee: American GNC Corporation
• Original Assignee: American GNC Corporation
• Inventors: McCall, Hiram, Lin, Ching-Fang
• Application Number:
  US09/911,571
• Publication Number:
  US 20020008661A1
• Time in Patent Office: Days
• US Class Current: 342/357.14
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01S 19/35 Constructional details or hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• CPC Class Codes: G01S 19/52 Determining velocity
• CPC Class Codes: G01S 19/53 Determining attitude

Abstract

A micro integrated Global Positioning System (GPS)/Inertial Measurement Unit (IMU) System, which is adapted to apply to output signals proportional to rotation and translational motion of a carrier and GPS measurements of the carrier, respectively from angular rate sensors, acceleration sensors, and GPS chipset, is employed with MEMS angular rate and acceleration sensors and GPS chipset. Compared with a conventional IMU/GPS system, the system of the present invention uses an integrated processing scheme by means of digital closed loop control of the dither driver signals for MEMS angular rate sensors, a feedforward open-loop signal processing scheme of the IMU, digital temperature control and compensation, the earth'"'"'s magnetic field-based heading damping, robust error estimator, and compact sensor and circuit architecture and dramatically shrinks the size of mechanical and electronic hardware and power consumption, meanwhile, obtains highly accurate motion measurements.

Claims

1. A micro integrated GPS/IMU system for a carrier, comprising:

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

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

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

a GPS chipset, providing GPS measurements from at least a GPS satellite;

an Earth'"'"'s magnetic field detector, producing Earth'"'"'s magnetic field vector electrical measurement signals, including X, Y, Z axes signals of an Earth'"'"'s magnetic field vector measurement for said carrier; and

a position and attitude processor, computing position, attitude and heading angle measurements using said digital angular increments, said digital velocity increments, said GPS measurements, and said Earth magnetic field vector measurement.

2. The micro integrated GPS/IMU system, as recited in claim 1, wherein said GPS chipset comprises a GPS RF (Radio Frequency) IC (Integrated Circuit), a correlation IC and a GPS microprocessor,

said GPS RF (Radio Frequency) IC (Integrated Circuit) receiving GPS RF signals from a GPS antenna, downconverting and sampling said RF GPS signals, and providing Sign and Magnitude digital output to said correlation IC,

said correlation IC correlating said Sign and Magnitude digital output with a appropriate local carrier and code to de-spread to output I and Q (in-phase and quadraphase) samples to said GPS microprocessor,

said GPS microprocessor processing said I and Q samples to close GPS signal tracking loops and to derive GPS raw measurements and a navigation solution.

3. The micro integrated GPS/IMU system, as recited in claim 1, wherein said GPS chipset comprises a GPS RF (Radio Frequency) IC (Integrated Circuit), a correlation IC, a data link IC, a data demodulation module, a GPS microprocessor,

said GPS RF (Radio Frequency) IC (Integrated Circuit) receiving GPS RF signals from an antenna, downconverting and sampling said RF GPS signal, and providing Sign and Magnitude digital output to said Correlation IC,

said correlation IC correlating said Sign and Magnitude digital output with a appropriate carrier and code to de-spread to output I and Q (in-phase and quadraphase) samples to said GPS microprocessor,

said data link IC receiving a RF signal from a differential GPS site and downconverting said RF signal to an IF (Intermediate Frequency IF) signal to said Data link demodulation module,

said data demodulation module demodulating said IF signal to output GPS differential correction data to said GPS microprocessor,

said GPS microprocessor processing said I and Q samples and said GPS differential correction data to close GPS signal tracking loops and to derive a GPS navigation solution.

4. The micro integrated GPS/IMU system, as recited in claim 1, wherein said position and attitude processor comprises:

an ASIC chip comprising an Earth'"'"'s magnetic field detector interface circuit to condition said Earth'"'"'s magnetic field vector electrical measurement signals of said Earth'"'"'s magnetic field detector and digitize said Earth'"'"'s magnetic field vector electrical measurement of said Earth'"'"'s magnetic field detector to output digital Earth'"'"'s magnetic field vector data;

a DSP chip receiving said digital Earth'"'"'s magnetic field vector data from said Earth'"'"'s magnetic field detector interface circuit and performing computation and control tasks for said micro integrated GPS/IMU system;

a power supply module for receiving an external power to provide required voltages.

5. The micro integrated GPS/IMU system, as recited in claim 4, wherein said position and attitude processor further comprises:

a communication module providing an input/output interface between said micro integrated GPS/IMU system and an external user, and

a connector which is connected with said communication module and provides proper pine configuration which is compatible with said external user, moreover said external power is received in said power supply module through said connector.

6. The micro integrated GPS/IMU system, as recited in claim 2, wherein said position and attitude processor comprises:

an ASIC chip comprising an Earth'"'"'s magnetic field detector interface circuit to condition said Earth'"'"'s magnetic field vector electrical measurement signals of said Earth'"'"'s magnetic field detector and digitize said Earth'"'"'s magnetic field vector electrical measurement of said Earth'"'"'s magnetic field detector to output digital Earth'"'"'s magnetic field vector data;

a DSP chip receiving said digital Earth'"'"'s magnetic field vector data from said Earth'"'"'s magnetic field detector interface circuit and performing computation and control tasks for said micro integrated GPS/IMU system;

a power supply module for receiving an external power to provide required voltages.

7. The micro integrated GPS/IMU system, as recited in claim 6, wherein said position and attitude processor further comprises:

a communication module providing an input/output interface between said micro integrated GPS/IMU system and an external user, and

a connector which is connected with said communication module and provides proper pine configuration which is compatible with said external user, moreover said external power is received in said power supply module through said connector.

8. The micro integrated GPS/IMU system, as recited in claim 3, wherein said position and attitude processor comprises:

an ASIC chip comprising an Earth'"'"'s magnetic field detector interface circuit to condition said Earth'"'"'s magnetic field vector electrical measurement signals of said Earth'"'"'s magnetic field detector and digitize said Earth'"'"'s magnetic field vector electrical measurement of said Earth'"'"'s magnetic field detector to output digital Earth'"'"'s magnetic field vector data;

a DSP chip receiving said digital Earth'"'"'s magnetic field vector data from said Earth'"'"'s magnetic field detector interface circuit and performing computation and control tasks for said micro integrated GPS/IMU system;

a power supply module for receiving an external power to provide required voltages.

9. The micro integrated GPS/IMU system, as recited in claim 8, wherein said position and attitude processor further comprises:

a communication module providing an input/output interface between said micro integrated GPS/IMU system and an external user, and

a connector which is connected with said communication module and provides proper pine configuration which is compatible with said external user, moreover said external power is received in said power supply module through said connector.

10. The micro integrated GPS/IMU system, as recited in claim 4, wherein said DSP chip comprises:

means for executing a thermal control computation for closing a control loop of a thermal control means;

means for performing a dither motion processing for closing said control loop of dither drive signals for said angular rate producer;

a position, velocity and attitude module for processing said digital angular increment and said digital velocity increment to obtain inertial position, velocity and attitude data and performing error correction using optimal estimates of inertial position, velocity and attitude errors to obtain position, velocity, and attitude solution data;

an error estimator module for processing said position, velocity, and attitude solution data from said position, velocity and attitude module, said GPS measurements from said GPS chipset, computing magnetic heading data to said error estimator module to produce optimal estimates of inertial position, velocity, and attitude errors;

an input/output communication producer, managing input and output data with external users; and

a magnetic heading computation module, receiving said digital Earth'"'"'s magnetic field vector data from said Earth'"'"'s magnetic field detector interface circuit of said ASIC chip and pitch and roll angle data from said position, velocity and attitude module and computing magnetic heading data to said error estimator module.

11. The micro integrated GPS/IMU system, as recited in claim 6, wherein said DSP chip comprises:

means for executing a thermal control computation for closing a control loop of a thermal control means;

means for performing a dither motion processing for closing said control loop of dither drive signals for said angular rate producer;

a position, velocity and attitude module for processing said digital angular increment and said digital velocity increment to obtain inertial position, velocity and attitude data and performing error correction using optimal estimates of inertial position, velocity and attitude errors to obtain position, velocity, and attitude solution data;

an error estimator module for processing said position, velocity, and attitude solution data from said position, velocity and attitude module, said GPS measurements from said GPS chipset, computing magnetic heading data to said error estimator module to produce optimal estimates of inertial position, velocity, and attitude errors;

an input/output communication producer, managing input and output data with external users; and

a magnetic heading computation module, receiving said digital Earth'"'"'s magnetic field vector data from said Earth'"'"'s magnetic field detector interface circuit of said ASIC chip and pitch and roll angle data from said position, velocity and attitude module and computing magnetic heading data to said error estimator module.

12. The micro integrated GPS/IMU system, as recited in claim 8, wherein said DSP chip comprises:

means for executing a thermal control computation for closing a control loop of a thermal control means;

means for performing a dither motion processing for closing said control loop of dither drive signals for said angular rate producer;

a position, velocity and attitude module for processing said digital angular increment and said digital velocity increment to obtain inertial position, velocity and attitude data and performing error correction using optimal estimates of inertial position, velocity and attitude errors to obtain position, velocity, and attitude solution data;

an error estimator module for processing said position, velocity, and attitude solution data from said position, velocity and attitude module, said GPS measurements from said GPS chipset, computing magnetic heading data to said error estimator module to produce optimal estimates of inertial position, velocity, and attitude errors;

an input/output communication producer, managing input and output data with external users; and

a magnetic heading computation module, receiving said digital Earth'"'"'s magnetic field vector data from said Earth'"'"'s magnetic field detector interface circuit of said ASIC chip and pitch and roll angle data from said position, velocity and attitude module and computing magnetic heading data to said error estimator module.

13. The micro integrated GPS/IMU system, as recited in claim 4, wherein said Earth'"'"'s magnetic field detector interface circuit is connected between said Earth'"'"'s magnetic field detector and said DSP chip, said Earth'"'"'s magnetic field detector interface circuit:

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

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

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

providing data/address/control bus connection and producing an address decode function, wherein said DSP chip accesses said Earth'"'"'s magnetic field detector interface circuit and pickups said three-axis digital Earth'"'"'s magnetic field data.

14. The micro integrated GPS/IMU system, as recited in claim 6, wherein said Earth'"'"'s magnetic field detector interface circuit is connected between said Earth'"'"'s magnetic field detector and said DSP chip, said Earth'"'"'s magnetic field detector interface circuit:

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

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

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

providing data/address/control bus connection and producing an address decode function, wherein said DSP chip accesses said Earth'"'"'s magnetic field detector interface circuit and pickups said three-axis digital Earth'"'"'s magnetic field data.

15. The micro integrated GPS/IMU system, as recited in claim 8, wherein said Earth'"'"'s magnetic field detector interface circuit is connected between said Earth'"'"'s magnetic field detector and said DSP chip, said Earth'"'"'s magnetic field detector interface circuit:

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

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

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

providing data/address/control bus connection and producing an address decode function, wherein said DSP chip accesses said Earth'"'"'s magnetic field detector interface circuit and pickups said three-axis digital Earth'"'"'s magnetic field data.

16. The micro integrated GPS/IMU system, as recited in claim 10, wherein said Earth'"'"'s magnetic field detector interface circuit is connected between said Earth'"'"'s magnetic field detector and said DSP chip, said Earth'"'"'s magnetic field detector interface circuit:

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

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

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

providing data/address/control bus connection and producing an address decode function, wherein said DSP chip accesses said Earth'"'"'s magnetic field detector interface circuit and pickups said three-axis digital Earth'"'"'s magnetic field data.

17. The micro integrated GPS/IMU system, as recited in claim 11, wherein said Earth'"'"'s magnetic field detector interface circuit is connected between said Earth'"'"'s magnetic field detector and said DSP chip, said Earth'"'"'s magnetic field detector interface circuit:

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

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

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

providing data/address/control bus connection and producing an address decode function, wherein said DSP chip accesses said Earth'"'"'s magnetic field detector interface circuit and pickups said three-axis digital Earth'"'"'s magnetic field data.

18. The micro integrated GPS/IMU system, as recited in claim 12, wherein said Earth'"'"'s magnetic field detector interface circuit is connected between said Earth'"'"'s magnetic field detector and said DSP chip, said Earth'"'"'s magnetic field detector interface circuit:

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

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

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

providing data/address/control bus connection and producing an address decode function, wherein said DSP chip accesses said Earth'"'"'s magnetic field detector interface circuit and pickups said three-axis digital Earth'"'"'s magnetic field data.

19. The micro integrated GPS/IMU system, as recited in claim 10, wherein said position, velocity, and attitude module comprises:

a coning correction module for accepting said digital angular increments from said angular increment and velocity increment producer and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure at a high data rate in short interval and for computing coning effect errors using said digital angular increment and coarse angular rate bias, and outputting coning effect data and angular increment data at a reduced data rate in long interval, which are long-interval angular increment values;

an angular rate compensation module, receiving said coning effect errors and said long-interval angular increment values from said coning correction module and angular rate device misalignment parameters and fine angular rate bias from said angular rate producer and acceleration producer calibration procedure, and compensating definite errors in said long-interval angular increment values using said coning effect errors, angular rate device misalignment parameters, fine angular rate bias, and coning correction scale factor in said long-interval angular increments and outputting real angular increments;

an alignment rotation vector computation module, receiving said real angular increments from said angular rate compensation module and said rotation rate vector of said local navigation frame (n frame) of said carrier relative to said inertial frame (i frame) from an earth and carrier rate computation module and updating a quaternion, which is a vector representing rotation angle of said carrier and outputting said updated quaternion;

a direction cosine matrix computation module, which is connected to said updated quaternion, for computing said direction cosine matrix by using said updated quaternion and receiving said optimal estimates of said attitude errors from error estimator to correct said direction cosine matrix;

an acceleration compensation module, compensating said definite errors in said velocity increments using said acceleration device misalignment, accelerometer bias, wherein said compensated velocity increments are connected to said level acceleration computation module;

a level acceleration computation module, receiving said compensated velocity increments and computing level velocity increments using said compensated velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

an attitude and heading angle extract module, extracting attitude and heading angle using said corrected direction cosine matrix;

a position and velocity update module, accepting said level velocity increments from said level acceleration computation module and computing a position and velocity solution and receiving said optimal estimates of said position and velocity errors from error estimator to compensate said errors in said position and velocity solution; and

an earth and carrier rate computation module, accepting said position and velocity solution from said position and velocity update module and computing said rotation rate vector of said local navigation frame (n frame) of said carrier relative to said inertial frame (i frame), which is connected to said alignment rotation vector computation module.

20. The micro integrated GPS/IMU system, as recited in claim 11, wherein said position, velocity, and attitude module comprises:

a coning correction module for accepting said digital angular increments from said angular increment and velocity increment producer and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure at a high data rate in short interval and for computing coning effect errors using said digital angular increment and coarse angular rate bias, and outputting coning effect data and angular increment data at a reduced data rate in long interval, which are long-interval angular increment values;

an angular rate compensation module, receiving said coning effect errors and said long-interval angular increment values from said coning correction module and angular rate device misalignment parameters and fine angular rate bias from said angular rate producer and acceleration producer calibration procedure, and compensating definite errors in said long-interval angular increment values using said coning effect errors, angular rate device misalignment parameters, fine angular rate bias, and coning correction scale factor in said long-interval angular increments and outputting real angular increments;

an alignment rotation vector computation module, receiving said real angular increments from said angular rate compensation module and said rotation rate vector of said local navigation frame (n frame) of said carrier relative to said inertial frame (i frame) from an earth and carrier rate computation module and updating a quaternion, which is a vector representing rotation angle of said carrier and outputting said updated quaternion;

a direction cosine matrix computation module, which is connected to said updated quaternion, for computing said direction cosine matrix by using said updated quaternion and receiving said optimal estimates of said attitude errors from error estimator to correct said direction cosine matrix;

an acceleration compensation module, compensating said definite errors in said velocity increments using said acceleration device misalignment, accelerometer bias, wherein said compensated velocity increments are connected to said level acceleration computation module;

a level acceleration computation module, receiving said compensated velocity increments and computing level velocity increments using said compensated velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

an attitude and heading angle extract module, extracting attitude and heading angle using said corrected direction cosine matrix;

a position and velocity update module, accepting said level velocity increments from said level acceleration computation module and computing a position and velocity solution and receiving said optimal estimates of said position and velocity errors from error estimator to compensate said errors in said position and velocity solution; and

an earth and carrier rate computation module, accepting said position and velocity solution from said position and velocity update module and computing said rotation rate vector of said local navigation frame (n frame) of said carrier relative to said inertial frame (i frame), which is connected to said alignment rotation vector computation module.

21. The micro integrated GPS/IMU system, as recited in claim 12, wherein said position, velocity, and attitude module comprises:

a coning correction module for accepting said digital angular increments from said angular increment and velocity increment producer and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure at a high data rate in short interval and for computing coning effect errors using said digital angular increment and coarse angular rate bias, and outputting coning effect data and angular increment data at a reduced data rate in long interval, which are long-interval angular increment values;

an angular rate compensation module, receiving said coning effect errors and said long-interval angular increment values from said coning correction module and angular rate device misalignment parameters and fine angular rate bias from said angular rate producer and acceleration producer calibration procedure, and compensating definite errors in said long-interval angular increment values using said coning effect errors, angular rate device misalignment parameters, fine angular rate bias, and coning correction scale factor in said long-interval angular increments and outputting real angular increments;

an alignment rotation vector computation module, receiving said real angular increments from said angular rate compensation module and said rotation rate vector of said local navigation frame (n frame) of said carrier relative to said inertial frame (i frame) from an earth and carrier rate computation module and updating a quaternion, which is a vector representing rotation angle of said carrier and outputting said updated quaternion;

a direction cosine matrix computation module, which is connected to said updated quaternion, for computing said direction cosine matrix by using said updated quaternion and receiving said optimal estimates of said attitude errors from error estimator to correct said direction cosine matrix;

an acceleration compensation module, compensating said definite errors in said velocity increments using said acceleration device misalignment, accelerometer bias, wherein said compensated velocity increments are connected to said level acceleration computation module;

a level acceleration computation module, receiving said compensated velocity increments and computing level velocity increments using said compensated velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

an attitude and heading angle extract module, extracting attitude and heading angle using said corrected direction cosine matrix;

a position and velocity update module, accepting said level velocity increments from said level acceleration computation module and computing a position and velocity solution and receiving said optimal estimates of said position and velocity errors from error estimator to compensate said errors in said position and velocity solution; and

an earth and carrier rate computation module, accepting said position and velocity solution from said position and velocity update module and computing said rotation rate vector of said local navigation frame (n frame) of said carrier relative to said inertial frame (i frame), which is connected to said alignment rotation vector computation module.

22. The micro integrated GPS/IMU system, as recited in claim 10, wherein said error estimator comprises a Kalman filter which comprises:

a GPS error compensation module, gathering said GPS measurements from said GPS microprocessor, which is alternatively corrected with said differential GPS data, and said position and velocity corrections from an updating state vector module to perform GPS error compensation;

a preprocessing module, receiving said GPS satellite ephemeris from said GPS microprocessor, said corrected GPS raw data from said GPS error compensation module, and INS solutions from said position, velocity and attitude module, wherein said preprocessing module performs a calculation of said state transition matrix which is sent with said previous state vector to a state vector prediction module. Said calculated state transit matrix is also sent to a covariance propagation module. Said preprocessing module calculates said measurement matrix and said current measurement vector according to said computed measurement matrix and said measurement model, wherein said measurement matrix and said computed current measurement vector are passed to a computing measurement residue module;

wherein

said state vector prediction module receives said state transition matrix and said previous state vector from said preprocessing module to perform state prediction of said current epoch, wherein said predicted current state vector is passed to said computing measurement residue module;

said computing measurement residue module receives said predicted current state vector from said state vector prediction module and said measurement matrix and said current measurement vector from said preprocessing module, wherein said computing measurement residue module calculates said measurement residues by subtracting said multiplication of said measurement matrix and said predicted current state vector from said current measurement vector, wherein said measurement residues are sent to a residue monitor module as well as said updating state vector module;

said residue monitor module performs a discrimination on said measurement residues received from said computing measurement residue module, wherein said discrimination law is whether a square of said measurement residues divided by said residual variance larger than a given threshold, wherein when said square of said measurement residues divided by said residual variance is larger than said given threshold, said current measurement leads to a divergence of said Kalman filter and then said residue monitor module selectively calculates a new covariance of said system process and rejects said current measurement, wherein when said square of said measurement residues divided by said residual variance is less than said given threshold, said current measurement is used by said Kalman filter without changing said current covariance of system process to obtain a current navigation solution, wherein said covariance of said system process is sent to said covariance propagation module;

said covariance propagation module gathers said covariance of said system process from said residue monitor module, said state transition matrix from said preprocessing module, and said previous covariance of estimated error to calculate said current covariance of said estimated error, wherein said computed current covariance of said estimated error is sent to a computing optimal gain module;

said computing optimal gain module receives said current covariance of said estimated error from said covariance computing module to compute an optimal gain which is passed to a covariance updating module as well as said updating state vector module, wherein said covariance updating module updates said covariance of said estimated error to send to said covariance propagation module;

said updating state vector module receives said optimal gain from said computing optimal gain module and said measurement residues from said computing measurement residue module, wherein said updating state vector module calculates said current estimate of state vector including position, velocity and attitude errors and sends to said GPS error compensation module and said position velocity and attitude module.

23. The micro integrated GPS/IMU system, as recited in claim 11, wherein said error estimator comprises a Kalman filter which comprises:

a GPS error compensation module, gathering said GPS measurements from said GPS microprocessor, which is alternatively corrected with said differential GPS data, and said position and velocity corrections from an updating state vector module to perform GPS error compensation;

a preprocessing module, receiving said GPS satellite ephemeris from said GPS microprocessor, said corrected GPS raw data from said GPS error compensation module, and INS solutions from said position, velocity and attitude module, wherein said preprocessing module performs a calculation of said state transition matrix which is sent with said previous state vector to a state vector prediction module. Said calculated state transit matrix is also sent to a covariance propagation module. Said preprocessing module calculates said measurement matrix and said current measurement vector according to said computed measurement matrix and said measurement model, wherein said measurement matrix and said computed current measurement vector are passed to a computing measurement residue module;

wherein

said state vector prediction module receives said state transition matrix and said previous state vector from said preprocessing module to perform state prediction of said current epoch, wherein said predicted current state vector is passed to said computing measurement residue module;

said computing measurement residue module receives said predicted current state vector from said state vector prediction module and said measurement matrix and said current measurement vector from said preprocessing module, wherein said computing measurement residue module calculates said measurement residues by subtracting said multiplication of said measurement matrix and said predicted current state vector from said current measurement vector, wherein said measurement residues are sent to a residue monitor module as well as said updating state vector module;

said residue monitor module performs a discrimination on said measurement residues received from said computing measurement residue module, wherein said discrimination law is whether a square of said measurement residues divided by said residual variance larger than a given threshold, wherein when said square of said measurement residues divided by said residual variance is larger than said given threshold, said current measurement leads to a divergence of said Kalman filter and then said residue monitor module selectively calculates a new covariance of said system process and rejects said current measurement, wherein when said square of said measurement residues divided by said residual variance is less than said given threshold, said current measurement is used by said Kalman filter without changing said current covariance of system process to obtain a current navigation solution, wherein said covariance of said system process is sent to said covariance propagation module;

said covariance propagation module gathers said covariance of said system process from said residue monitor module, said state transition matrix from said preprocessing module, and said previous covariance of estimated error to calculate said current covariance of said estimated error, wherein said computed current covariance of said estimated error is sent to a computing optimal gain module;

said computing optimal gain module receives said current covariance of said estimated error from said covariance computing module to compute an optimal gain which is passed to a covariance updating module as well as said updating state vector module, wherein said covariance updating module updates said covariance of said estimated error to send to said covariance propagation module;

said updating state vector module receives said optimal gain from said computing optimal gain module and said measurement residues from said computing measurement residue module, wherein said updating state vector module calculates said current estimate of state vector including position, velocity and attitude errors and sends to said GPS error compensation module and said position velocity and attitude module.

24. The micro integrated GPS/IMU system, as recited in claim 12, wherein said error estimator comprises a Kalman filter which comprises:

a GPS error compensation module, gathering said GPS measurements from said GPS microprocessor, which is alternatively corrected with said differential GPS data, and said position and velocity corrections from an updating state vector module to perform GPS error compensation;

a preprocessing module, receiving said GPS satellite ephemeris from said GPS microprocessor, said corrected GPS raw data from said GPS error compensation module, and INS solutions from said position, velocity and attitude module, wherein said preprocessing module performs a calculation of said state transition matrix which is sent with said previous state vector to a state vector prediction module. Said calculated state transit matrix is also sent to a covariance propagation module. Said preprocessing module calculates said measurement matrix and said current measurement vector according to said computed measurement matrix and said measurement model, wherein said measurement matrix and said computed current measurement vector are passed to a computing measurement residue module;

wherein

said state vector prediction module receives said state transition matrix and said previous state vector from said preprocessing module to perform state prediction of said current epoch, wherein said predicted current state vector is passed to said computing measurement residue module;

said computing measurement residue module receives said predicted current state vector from said state vector prediction module and said measurement matrix and said current measurement vector from said preprocessing module, wherein said computing measurement residue module calculates said measurement residues by subtracting said multiplication of said measurement matrix and said predicted current state vector from said current measurement vector, wherein said measurement residues are sent to a residue monitor module as well as said updating state vector module;

said residue monitor module performs a discrimination on said measurement residues received from said computing measurement residue module, wherein said discrimination law is whether a square of said measurement residues divided by said residual variance larger than a given threshold, wherein when said square of said measurement residues divided by said residual variance is larger than said given threshold, said current measurement leads to a divergence of said Kalman filter and then said residue monitor module selectively calculates a new covariance of said system process and rejects said current measurement, wherein when said square of said measurement residues divided by said residual variance is less than said given threshold, said current measurement is used by said Kalman filter without changing said current covariance of system process to obtain a current navigation solution, wherein said covariance of said system process is sent to said covariance propagation module;

said covariance propagation module gathers said covariance of said system process from said residue monitor module, said state transition matrix from said preprocessing module, and said previous covariance of estimated error to calculate said current covariance of said estimated error, wherein said computed current covariance of said estimated error is sent to a computing optimal gain module;

said computing optimal gain module receives said current covariance of said estimated error from said covariance computing module to compute an optimal gain which is passed to a covariance updating module as well as said updating state vector module, wherein said covariance updating module updates said covariance of said estimated error to send to said covariance propagation module;

said updating state vector module receives said optimal gain from said computing optimal gain module and said measurement residues from said computing measurement residue module, wherein said updating state vector module calculates said current estimate of state vector including position, velocity and attitude errors and sends to said GPS error compensation module and said position velocity and attitude module.

25. The micro integrated GPS/IMU system, as recited in claim 19, wherein said error estimator comprises a Kalman filter which comprises:

a GPS error compensation module, gathering said GPS measurements from said GPS microprocessor, which is alternatively corrected with said differential GPS data, and said position and velocity corrections from an updating state vector module to perform GPS error compensation;

a preprocessing module, receiving said GPS satellite ephemeris from said GPS microprocessor, said corrected GPS raw data from said GPS error compensation module, and INS solutions from said position, velocity and attitude module, wherein said preprocessing module performs a calculation of said state transition matrix which is sent with said previous state vector to a state vector prediction module. Said calculated state transit matrix is also sent to a covariance propagation module. Said preprocessing module calculates said measurement matrix and said current measurement vector according to said computed measurement matrix and said measurement model, wherein said measurement matrix and said computed current measurement vector are passed to a computing measurement residue module;

wherein

said state vector prediction module receives said state transition matrix and said previous state vector from said preprocessing module to perform state prediction of said current epoch, wherein said predicted current state vector is passed to said computing measurement residue module;

said computing measurement residue module receives said predicted current state vector from said state vector prediction module and said measurement matrix and said current measurement vector from said preprocessing module, wherein said computing measurement residue module calculates said measurement residues by subtracting said multiplication of said measurement matrix and said predicted current state vector from said current measurement vector, wherein said measurement residues are sent to a residue monitor module as well as said updating state vector module;

said residue monitor module performs a discrimination on said measurement residues received from said computing measurement residue module, wherein said discrimination law is whether a square of said measurement residues divided by said residual variance larger than a given threshold, wherein when said square of said measurement residues divided by said residual variance is larger than said given threshold, said current measurement leads to a divergence of said Kalman filter and then said residue monitor module selectively calculates a new covariance of said system process and rejects said current measurement, wherein when said square of said measurement residues divided by said residual variance is less than said given threshold, said current measurement is used by said Kalman filter without changing said current covariance of system process to obtain a current navigation solution, wherein said covariance of said system process is sent to said covariance propagation module;

said covariance propagation module gathers said covariance of said system process from said residue monitor module, said state transition matrix from said preprocessing module, and said previous covariance of estimated error to calculate said current covariance of said estimated error, wherein said computed current covariance of said estimated error is sent to a computing optimal gain module;

said computing optimal gain module receives said current covariance of said estimated error from said covariance computing module to compute an optimal gain which is passed to a covariance updating module as well as said updating state vector module, wherein said covariance updating module updates said covariance of said estimated error to send to said covariance propagation module;

said updating state vector module receives said optimal gain from said computing optimal gain module and said measurement residues from said computing measurement residue module, wherein said updating state vector module calculates said current estimate of state vector including position, velocity and attitude errors and sends to said GPS error compensation module and said position velocity and attitude module.

26. The micro integrated GPS/IMU system, as recited in claim 20, wherein said error estimator comprises a Kalman filter which comprises:

a GPS error compensation module, gathering said GPS measurements from said GPS microprocessor, which is alternatively corrected with said differential GPS data, and said position and velocity corrections from an updating state vector module to perform GPS error compensation;

a preprocessing module, receiving said GPS satellite ephemeris from said GPS microprocessor, said corrected GPS raw data from said GPS error compensation module, and INS solutions from said position, velocity and attitude module, wherein said preprocessing module performs a calculation of said state transition matrix which is sent with said previous state vector to a state vector prediction module. Said calculated state transit matrix is also sent to a covariance propagation module. Said preprocessing module calculates said measurement matrix and said current measurement vector according to said computed measurement matrix and said measurement model, wherein said measurement matrix and said computed current measurement vector are passed to a computing measurement residue module;

wherein

said state vector prediction module receives said state transition matrix and said previous state vector from said preprocessing module to perform state prediction of said current epoch, wherein said predicted current state vector is passed to said computing measurement residue module;

said computing measurement residue module receives said predicted current state vector from said state vector prediction module and said measurement matrix and said current measurement vector from said preprocessing module, wherein said computing measurement residue module calculates said measurement residues by subtracting said multiplication of said measurement matrix and said predicted current state vector from said current measurement vector, wherein said measurement residues are sent to a residue monitor module as well as said updating state vector module;

said residue monitor module performs a discrimination on said measurement residues received from said computing measurement residue module, wherein said discrimination law is whether a square of said measurement residues divided by said residual variance larger than a given threshold, wherein when said square of said measurement residues divided by said residual variance is larger than said given threshold, said current measurement leads to a divergence of said Kalman filter and then said residue monitor module selectively calculates a new covariance of said system process and rejects said current measurement, wherein when said square of said measurement residues divided by said residual variance is less than said given threshold, said current measurement is used by said Kalman filter without changing said current covariance of system process to obtain a current navigation solution, wherein said covariance of said system process is sent to said covariance propagation module;

said covariance propagation module gathers said covariance of said system process from said residue monitor module, said state transition matrix from said preprocessing module, and said previous covariance of estimated error to calculate said current covariance of said estimated error, wherein said computed current covariance of said estimated error is sent to a computing optimal gain module;

said computing optimal gain module receives said current covariance of said estimated error from said covariance computing module to compute an optimal gain which is passed to a covariance updating module as well as said updating state vector module, wherein said covariance updating module updates said covariance of said estimated error to send to said covariance propagation module;

said updating state vector module receives said optimal gain from said computing optimal gain module and said measurement residues from said computing measurement residue module, wherein said updating state vector module calculates said current estimate of state vector including position, velocity and attitude errors and sends to said GPS error compensation module and said position velocity and attitude module.

27. The micro integrated GPS/IMU system, as recited in claim 21, wherein said error estimator comprises a Kalman filter which comprises:

a GPS error compensation module, gathering said GPS measurements from said GPS microprocessor, which is alternatively corrected with said differential GPS data, and said position and velocity corrections from an updating state vector module to perform GPS error compensation;

a preprocessing module, receiving said GPS satellite ephemeris from said GPS microprocessor, said corrected GPS raw data from said GPS error compensation module, and INS solutions from said position, velocity and attitude module, wherein said preprocessing module performs a calculation of said state transition matrix which is sent with said previous state vector to a state vector prediction module. Said calculated state transit matrix is also sent to a covariance propagation module. Said preprocessing module calculates said measurement matrix and said current measurement vector according to said computed measurement matrix and said measurement model, wherein said measurement matrix and said computed current measurement vector are passed to a computing measurement residue module;

wherein

said state vector prediction module receives said state transition matrix and said previous state vector from said preprocessing module to perform state prediction of said current epoch, wherein said predicted current state vector is passed to said computing measurement residue module;

said computing measurement residue module receives said predicted current state vector from said state vector prediction module and said measurement matrix and said current measurement vector from said preprocessing module, wherein said computing measurement residue module calculates said measurement residues by subtracting said multiplication of said measurement matrix and said predicted current state vector from said current measurement vector, wherein said measurement residues are sent to a residue monitor module as well as said updating state vector module;

said residue monitor module performs a discrimination on said measurement residues received from said computing measurement residue module, wherein said discrimination law is whether a square of said measurement residues divided by said residual variance larger than a given threshold, wherein when said square of said measurement residues divided by said residual variance is larger than said given threshold, said current measurement leads to a divergence of said Kalman filter and then said residue monitor module selectively calculates a new covariance of said system process and rejects said current measurement, wherein when said square of said measurement residues divided by said residual variance is less than said given threshold, said current measurement is used by said Kalman filter without changing said current covariance of system process to obtain a current navigation solution, wherein said covariance of said system process is sent to said covariance propagation module;

said covariance propagation module gathers said covariance of said system process from said residue monitor module, said state transition matrix from said preprocessing module, and said previous covariance of estimated error to calculate said current covariance of said estimated error, wherein said computed current covariance of said estimated error is sent to a computing optimal gain module;

said computing optimal gain module receives said current covariance of said estimated error from said covariance computing module to compute an optimal gain which is passed to a covariance updating module as well as said updating state vector module, wherein said covariance updating module updates said covariance of said estimated error to send to said covariance propagation module;

said updating state vector module receives said optimal gain from said computing optimal gain module and said measurement residues from said computing measurement residue module, wherein said updating state vector module calculates said current estimate of state vector including position, velocity and attitude errors and sends to said GPS error compensation module and said position velocity and attitude module.

28. The micro integrated GPS/IMU system, as recited in claim 10, wherein said magnetic heading computation module:

loads said calibration parameters of said Earth'"'"'s magnetic field detector from flash memory to form a calibration vector;

receives said three-axis digital Earth'"'"'s magnetic field signals from said Earth'"'"'s magnetic field detector interface circuit of said ASIC chip, which is expressed in said body frame, to form a measurement vector;

receives said pitch and roll angle data from said attitude and heading module or said position, velocity, and attitude module to form a transformation matrix from said body frame to level frame;

compensates said measurement vector with said calibration vector;

transforms said compensated measurement vector from said body frame to said level frame to form a measurement vector, which is expressed in said level frame; and

computes magnetic heading data using said measurement vector expressed in said level frame, which is output to error estimator.

29. The micro integrated GPS/IMU system, as recited in claim 11, wherein said magnetic heading computation module:

loads said calibration parameters of said Earth'"'"'s magnetic field detector from flash memory to form a calibration vector;

receives said three-axis digital Earth'"'"'s magnetic field signals from said Earth'"'"'s magnetic field detector interface circuit of said ASIC chip, which is expressed in said body frame, to form a measurement vector;

receives said pitch and roll angle data from said attitude and heading module or said position, velocity, and attitude module to form a transformation matrix from said body frame to level frame;

compensates said measurement vector with said calibration vector;

transforms said compensated measurement vector from said body frame to said level frame to form a measurement vector, which is expressed in said level frame; and

computes magnetic heading data using said measurement vector expressed in said level frame, which is output to error estimator.

30. The micro integrated GPS/IMU system, as recited in claim 12, wherein said magnetic heading computation module:

loads said calibration parameters of said Earth'"'"'s magnetic field detector from flash memory to form a calibration vector;

receives said three-axis digital Earth'"'"'s magnetic field signals from said Earth'"'"'s magnetic field detector interface circuit of said ASIC chip, which is expressed in said body frame, to form a measurement vector;

receives said pitch and roll angle data from said attitude and heading module or said position, velocity, and attitude module to form a transformation matrix from said body frame to level frame;

compensates said measurement vector with said calibration vector;

transforms said compensated measurement vector from said body frame to said level frame to form a measurement vector, which is expressed in said level frame; and

computes magnetic heading data using said measurement vector expressed in said level frame, which is output to error estimator.

31. The micro integrated GPS/IMU system, as recited in claim 25, wherein said magnetic heading computation module:

loads said calibration parameters of said Earth'"'"'s magnetic field detector from flash memory to form a calibration vector;

receives said three-axis digital Earth'"'"'s magnetic field signals from said Earth'"'"'s magnetic field detector interface circuit of said ASIC chip, which is expressed in said body frame, to form a measurement vector;

receives said pitch and roll angle data from said attitude and heading module or said position, velocity, and attitude module to form a transformation matrix from said body frame to level frame;

compensates said measurement vector with said calibration vector;

transforms said compensated measurement vector from said body frame to said level frame to form a measurement vector, which is expressed in said level frame; and

computes magnetic heading data using said measurement vector expressed in said level frame, which is output to error estimator.

32. The micro integrated GPS/IMU system, as recited in claim 26, wherein said magnetic heading computation module:

loads said calibration parameters of said Earth'"'"'s magnetic field detector from flash memory to form a calibration vector;

receives said three-axis digital Earth'"'"'s magnetic field signals from said Earth'"'"'s magnetic field detector interface circuit of said ASIC chip, which is expressed in said body frame, to form a measurement vector;

receives said pitch and roll angle data from said attitude and heading module or said position, velocity, and attitude module to form a transformation matrix from said body frame to level frame;

compensates said measurement vector with said calibration vector;

transforms said compensated measurement vector from said body frame to said level frame to form a measurement vector, which is expressed in said level frame; and

computes magnetic heading data using said measurement vector expressed in said level frame, which is output to error estimator.

33. The micro integrated GPS/IMU system, as recited in claim 27, wherein said magnetic heading computation module:

loads said calibration parameters of said Earth'"'"'s magnetic field detector from flash memory to form a calibration vector;

receives said three-axis digital Earth'"'"'s magnetic field signals from said Earth'"'"'s magnetic field detector interface circuit of said ASIC chip, which is expressed in said body frame, to form a measurement vector;

receives said pitch and roll angle data from said attitude and heading module or said position, velocity, and attitude module to form a transformation matrix from said body frame to level frame;

compensates said measurement vector with said calibration vector;

transforms said compensated measurement vector from said body frame to said level frame to form a measurement vector, which is expressed in said level frame; and

computes magnetic heading data using said measurement vector expressed in said level frame, which is output to error estimator.

34. The micro integrated GPS/IMU system, as recited in claim 1, 2, 3, 4, 10, 13, 16, 19, 22, 25, 28, or 31, 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.

35. The micro integrated GPS/IMU system, as recited in claim 34, 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 said predetermined operating temperature of said angular rate producer, said acceleration producer and said 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 said predetermined operating temperature of said angular rate producer and said acceleration producer, and producing 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.

36. The micro integrated GPS/IMU system, as recited in claim 1, 2, 3, 4, 10, 13, 16, 19, 22, 25, 28, or 31, wherein said X axis, Y axis and Z axis electrical angular rate signals produced from said angular producer are analog angular rate voltage signals directly proportional to angular rates of said carrier carrying said micro inertial measurement unit, wherein said X axis, Y axis and Z axis electrical acceleration signals produced from said acceleration producer are analog acceleration voltage signals directly proportional to accelerations of said vehicle, wherein said X, Y, Z axes electrical signals of Earth'"'"'s magnetic field vector measurement in a body frame of said carrier are analog voltage signals.

37. The micro integrated GPS/IMU system, as recited in claim 34, wherein said X axis, Y axis and Z axis electrical angular rate signals produced from said angular producer are analog angular rate voltage signals directly proportional to angular rates of said carrier carrying said micro inertial measurement unit, wherein said X axis, Y axis and Z axis electrical acceleration signals produced from said acceleration producer are analog acceleration voltage signals directly proportional to accelerations of said vehicle, wherein said X, Y, Z axes electrical signals of Earth'"'"'s magnetic field vector measurement in a body frame of said carrier are analog voltage signals.

38. The micro integrated GPS/IMU system, as recited in claim 36, 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.

39. The micro integrated GPS/IMU system, as recited in claim 1, 2 or 3, wherein said micro integrated GPS/IMU system comprises a first circuit board, a second circuit board, a third circuit board, a GPS chipset 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, said GPS chipset board being connected with said control circuit board for providing said GPS measurements to said control circuit board, wherein said control circuit board is connected with said first circuit board, said second circuit board, and said GPS chipset 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 third board respectively.

40. The micro integrated GPS/IMU system, as recited in claim 4, 10, 13, 16, 19, 22, 25, 28, or 31, wherein said micro integrated GPS/IMU system comprises a first circuit board, a second circuit board, a third circuit board, a GPS chipset 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, said GPS chipset board being connected with said control circuit board for providing said GPS measurements to said control circuit board, wherein said control circuit board is connected with said first circuit board, said second circuit board, and said GPS chipset 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 third board respectively.

41. The micro integrated GPS/IMU system, as recited in claim 40, wherein said DSP chip, said Earth'"'"'s magnetic field detector, said ASIC chip, said power supply module are provided on said control circuit board, and said GPS chipset is provided on said GPS chipset board.

42. The micro integrated GPS/IMU system, as recited in claim 41, 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.

43. The micro integrated GPS/IMU system, as recited in claim 42, 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.

44. The micro integrated GPS/IMU system, as recited in claim 43, 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 units for receiving said angular motion-induced signals and removing low frequency noise of the angular motion-induced signals, which are AC voltage signals output from said vibrating type angular rate detecting unit to form filtered angular motion-induced signals to said angular signal loop circuitry.

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

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

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

46. The micro integrated GPS/IMU system, as recited in claim 43, 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.

47. The micro integrated GPS/IMU system, as recited in claim 43, 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.

48. The micro integrated GPS/IMU system, as recited in claim 43, wherein said dither motion processing module further includes a phase-lock loop to reject noise of said selected frequency to form a dither drive signal with said selected frequency by, which serves as a very narrow bandpass filter, locking said frequency;

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

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

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

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

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

49. The micro integrated GPS/IMU system, as recited in claim 43, further comprising a thermal controlling means for maintaining a predetermined operating temperature of said angular rate producer, said acceleration producer and said angular increment and velocity increment producer, wherein said thermal controlling means comprises:

a thermal sensing producer device, comprising;

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

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

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

a heater device, comprising;

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

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

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

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

each of said thermal control circuitries further comprises;

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

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

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

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

closing said temperature controlling loop,

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

50. The micro integrated GPS/IMU system, as recited in claim 43, wherein said third circuit board is bonded to a supporting structure by means of a conductive epoxy, and said first circuit board, said second circuit board, GPS chipset board, and said control circuit board are arranged parallelly to bond to said third circuit board perpendicularly by a non conductive epoxy, wherein said first circuit board, said second circuit board, and said control circuit board are soldered to said third circuit board in such a manner as to use said third circuit board as an interconnect board.