Processing method for motion measurement

• US 6,427,131 B1
• Filed: 11/22/1999
• Issued: 07/30/2002
• Est. Priority Date: 08/18/1999
• Status: Expired due to Term

• Current Assignee: American GNC Corporation
• Original Assignee: American GNC Corporation
• Inventors: McCall, Hiram, Lin, Ching-Fang
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Charioui, Mohamed
• Application Number:
  US09/444,440
• Time in Patent Office: 981 Days
• Field of Search: 702/141, 702/150, 702/151, 702/152, 702/93, 702/94, 702/95, 701/11, 701/220
• US Class Current: 702/150
• CPC Class Codes: G01C 21/183 Compensation of inertial measurements, e.g. for temperature effects

Abstract

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

Claims

1. A processing method for motion measurement, comprising the steps of:

(1) producing three-axis angular rate signals by an angular rate producer and three-axis acceleration signals by an acceleration producer;

(2) converting said three-axis angular rate signals into digital angular increments and converting said three-axis acceleration signals into digital velocity increments by an angular increment and velocity increment producer;

(3) computing attitude and heading angle measurements using said three-axis digital angular increments and three-axis velocity increments by an attitude and heading processor; and

(4) producing temperature signals by a thermal sensing producer to a thermal processor;

computing temperature control commands using said input temperature signals, temperature scale factor, and pre-determined operating temperature of said angular rate producer and said acceleration producer;

producing driving signals to a heater device using said temperature control commands;

outputting said driving signals to said heater device, wherein the step (4) is performed in parallel with the steps (1) to (3) in order to further obtain stable said digital three-axis angular increment values, digital three-axis velocity increment values, and attitude and heading angle measurements.

2. A processing method for motion measurement, as recited in claim 1, wherein, in preferable applications, output signals of said angular rate producer and said acceleration producer in the step (1), which are preferable MEMS angular rate device array and acceleration device array, are analog angular rate voltage signals and analog acceleration voltage, wherein the step (2) further comprises the steps of:

(2.1) integrating three-axis angular rate analog voltage signals from angular rate producer and three-axis acceleration analog voltage signals from said acceleration producer for a predetermined time interval to accumulate said three-axis angular analog voltage and said three-axis velocity voltage as raw three-axis angular increment and three-axis velocity increment for said predetermined time interval,

(2.2) forming a reset signal for said integrating processing to accumulate said three-axis angular voltage signal and three-axis velocity voltage signal from zero values at initial point of next said predetermined time interval,

(2.3) measuring said raw three-angular increment and velocity increment voltage values in digital fashion.

3. A processing method for motion measurement, as recited as claims 2, after step (2.3), further comprising an additional processing step of:

(2.4) scaling the raw three-axis angular velocity increment voltage values into real three-axis angular and velocity increment values.

4. A processing method for motion measurement, as recited in claim 3, wherein the step (4) further comprises the steps of:

(4.1) producing voltage signals by a thermal sensing producer to an analog/digital converter,

(4.2) sampling said voltage signals in said analog/digital converter; and

digitizing said sampled voltage signals; and

said digital signals are output to an temperature controller,

(4.3) computing digital temperature commands in said temperature controller using input said digital temperature voltage signals, temperature sensor scale factor, and pre-determined operating temperature of said angular rate producer and acceleration producer; and

said digital temperature commands are fed back to a digital/analog converter, and

(4.4) converting said digital temperature commands from said temperature controller by said digital/analog converter into analog signals; and

said analog signals are output to a heater device.

5. A processing method for motion measurement, as recited in claim 4, wherein the step (3) further comprises the steps of:

inputting said real digital three-axis angular increment values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in the coning correction module using said input digital three-axis angular increment values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment values at reduced data rate (long interval), which are called three-axis long-interval angular increment values, into a angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment values from said coning correction module and angular rate device misalignment parameters and fine angular rate bias from the angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

compensating definite errors in the input three-axis long-interval angular increment values using said input coning effect errors, angular rate device misalignment parameters, fine angular rate bias, and coning correction scale factor; and

outputting said real three-axis angular increments to an alignment rotation vector computation module, and

inputting said three-axis velocity increment values from the step (2) and acceleration device misalignment, and acceleration device bias from the angular rate producer and acceleration producer calibration procedure to accelerometer compensation module;

compensating definite errors in said three-axis velocity increments using said input acceleration device misalignment, accelerometer bias;

outputting compensated three-axis velocity increments to a level acceleration computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

6. A processing method for motion measurement, as recited in claim 2, wherein the step (4) further comprises the steps of:

(4.1) producing voltage signals by a thermal sensing producer to an analog/digital converter,

(4.2) sampling said voltage signals in said analog/digital converter; and

digitizing said sampled voltage signals; and

said digital signals are output to an temperature controller,

(4.3) computing digital temperature commands in said temperature controller using input said digital temperature voltage signals, temperature sensor scale factor, and pre-determined operating temperature of said angular rate producer and acceleration producer; and

said digital temperature commands are fed back to a digital/analog converter,

(4.4) converting said digital temperature commands from said temperature controller by said digital/analog converter into analog signals; and

said analog signals are output to a heater device.

7. A processing method for motion measurement, as recited in claim 6, wherein the step (3) further comprises the steps of:

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from the step (2) and acceleration device misalignment, acceleration bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to an accelerometer compensation module;

transforming said input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, acceleration bias;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

8. A processing method for motion measurement, as recited in claim 2, wherein the step (3) further comprises the steps of:

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from the step (2) and acceleration device misalignment, acceleration bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to an accelerometer compensation module;

transforming said input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, acceleration bias;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module, feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

9. A processing method for motion measurement, as recited in claim 1, wherein the step (4) further comprises the steps of:

(4.1) producing voltage signals by a thermal sensing producer to an analog/digital converter,

(4.2) sampling said voltage signals in said analog/digital converter; and

digitizing said sampled voltage signals; and

said digital signals are output to an temperature controller,

(4.3) computing digital temperature commands in said temperature controller using input said digital temperature voltage signals, temperature sensor scale factor, and pre-determined operating temperature of said angular rate producer and acceleration producer; and

said digital temperature commands are fed back to a digital/analog converter,

(4.4) converting said digital temperature commands from said temperature controller by said digital/analog converter into analog signals; and

said analog signals are output to a heater device.

10. A processing method for motion measurement, as recited in claim 9, wherein the step 3 further comprises the steps of:

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of said angular rate producer;

accessing angular rate producer temperature characteristic parameters using said current temperature of said angular rate producer;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor;

compensating temperature-induced errors in said real three-axis long-interval angular increments using said angular rate producer temperature characteristic parameters; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from the step (2) and acceleration device misalignment, acceleration device bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to accelerometer compensation module;

inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of acceleration producer;

accessing acceleration producer temperature characteristic parameters using the current temperature of acceleration producer;

transforming the input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, said accelerometer bias;

compensating temperature-induced errors in the real three-axis velocity increments using said acceleration producer temperature characteristic parameters;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

11. A processing method for motion measurement, as recited in claim 1, wherein the step (3) further comprises the steps of:

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from the step (2) and acceleration device misalignment, acceleration bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to an accelerometer compensation module;

transforming said input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, acceleration bias;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

12. A processing method for motion measurement, comprising the steps of:

(1) producing three-axis angular rate signals by an angular rate producer and three-axis acceleration signals by an acceleration producer;

(2) converting said three-axis angular rate signals into digital angular increments and converting said three-axis acceleration signals into digital velocity increments by an angular increment and velocity increment producer; and

(3) computing attitude and heading angle measurements using said three-axis digital angular increments and three-axis velocity increments by an attitude and heading processor, wherein in order to compensate said angular rate producer and acceleration producer measurement errors induced by a variety of temperature environments without a temperature control loop processing step and to further obtain stable said digital three-axis angular increment values, digital three-axis velocity increment values, and attitude and heading angle measurements, wherein the step (3) further comprises the steps of;

(3A.1) producing temperature signals of said angular rate producer and said acceleration producer by a thermal sensing producer and outputting digitized temperature signal values to an attitude and heading processor by an temperature digitizer, and

(3A.2) accessing temperature characteristic parameters of said angular rate producers and acceleration producer using said current temperature of angular rate producer and acceleration producer from said temperature digitizer;

compensating the errors induced by thermal effects in input said digital three-axis angular and velocity increments;

computing attitude and heading angle measurements using said three-axis digital angular increments and three-axis velocity increments in said attitude and heading processor.

13. A processing method for motion measurement, as recited in claim 12, wherein, in preferable applications, output signals of said angular rate producer and said acceleration producer in step (1), which are preferable MEMS angular rate device array and acceleration device array, are analog angular rate voltage signals and analog acceleration voltage, wherein the step (2) further comprises the following steps:

(2.1) integrating three-axis angular rate analog voltage signals from angular rate producer and three-axis acceleration analog voltage signals from said acceleration producer for a predetermined time interval to accumulate said three-axis angular analog voltage and said three-axis velocity voltage as raw three-axis angular increment and three-axis velocity increment for said predetermined time interval,

(2.2) forming a reset signal for said integrating processing to accumulate said three-axis angular voltage signal and three-axis velocity voltage signal from zero values at initial point of next said predetermined time interval, and

(2.3) measuring said raw three-angular increment and velocity increment voltage values in digital fashion.

14. A processing method for motion measurement, as recited as claim 13, after the step (2.3), further comprising an additional processing step of:

(2.4) scaling the raw three-axis angular velocity increment voltage values into real three-axis angular and velocity increment values.

15. A processing method for motion measurement, as recited in claim 14, wherein the step (3A.1) further comprises the steps of:

(3A.1.1) acquiring voltage signals from a thermal sensing producer to an amplifier circuit for amplifying said signals and suppressing noises residing within input said signals and improving signal-to-noise ratio of said signals; and

said amplified signals are output to an analog/digital converter, and

(3A.1.2) sampling input said amplified voltage signals in said analog/digital converters; and

digitizing said sampled voltage signals; and

said digital signals are output to an attitude and heading processor.

16. A processing method for motion measurement, as recited in claim 15, wherein the step (3A.2) further comprises the steps of:

inputting said digital three-axis angular increment values from of the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment values in reduced data rate (long interval), which are called three-axis long-interval angular increment values, into a angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment values from said coning correction module and angular rate device misalignment parameters and fine angular rate bias from an angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

inputting the digital temperature signals of the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of said angular rate producer;

accessing angular rate producer temperature characteristic parameters using said current temperature of angular rate producer;

compensating definite errors in said input three-axis long-interval angular increment values using said input coning effect errors, angular rate device misalignment parameters, fine angular rate bias, and coning correction scale factor;

compensating temperature-induced errors in said real three-axis long-interval angular increments using the angular rate producer temperature characteristic parameters; and

outputting said real three-axis angular increments to an alignment rotation vector computation module, and

inputting said three-axis velocity increment values from the step (2) and acceleration device misalignment and acceleration bias from said angular rate producer and acceleration producer calibration procedure to an acceleration compensation module;

inputting said digital temperature signals from the step (3A.1) and temperature sensor scale factor;

computing current temperature of acceleration producer;

accessing acceleration producer temperature characteristic parameters using said current temperature of acceleration producer;

compensating the definite errors in three-axis velocity increments using said input acceleration device misalignment, acceleration bias;

compensating temperature-induced errors in said real three-axis velocity increments using said acceleration producer temperature characteristic parameters; and

outputting said compensated three-axis velocity increments to a level acceleration computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module, outputting said heading angle into said vertical damping rate computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

17. A processing method for motion measurement, as recited in claim 13, wherein the step (3A.1) further comprises the steps of:

(3A.1.1) acquiring voltage signals from a thermal sensing producer to an amplifier circuit for amplifying said signals and suppressing noises residing within input said signals and improving signal-to-noise ratio of said signals; and

said amplified signals are output to an analog/digital converter, and

(3A.1.2) sampling input said amplified voltage signals in said analog/digital converters; and

digitizing said sampled voltage signals; and

said digital signals are output to an attitude and heading processor.

18. A processing method for motion measurement, as recited in claim 17, wherein the step (3A.2) further comprises the steps of:

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of said angular rate producer;

accessing angular rate producer temperature characteristic parameters using said current temperature of said angular rate producer;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor;

compensating temperature-induced errors in said real three-axis long-interval angular increments using said angular rate producer temperature characteristic parameters; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from the step (2) and acceleration device misalignment, acceleration device bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to accelerometer compensation module;

inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of acceleration producer;

accessing acceleration producer temperature characteristic parameters using the current temperature of acceleration producer;

transforming the input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, said accelerometer bias;

compensating temperature-induced errors in the real three-axis velocity increments using said acceleration producer temperature characteristic parameters;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

19. A processing method for motion measurement, as recited in claim 13, wherein the step (3A.2) further comprises the steps of:

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation modules inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of said angular rate producer;

accessing angular rate producer temperature characteristic parameters using said current temperature of said angular rate producer;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor;

compensating temperature-induced errors in said real three-axis long-interval angular increments using said angular rate producer temperature characteristic parameters; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from Step 2 and acceleration device misalignment, acceleration device bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to accelerometer compensation module;

inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of acceleration producer;

accessing acceleration producer temperature characteristic parameters using the current temperature of acceleration producer;

transforming the input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, said accelerometer bias;

compensating temperature-induced errors in the real three-axis velocity increments using said acceleration producer temperature characteristic parameters;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east dam ping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

20. A processing method for motion measurement, as recited in claim 12, wherein the step (3A.1) further comprises the steps of:

(3A.1.1) acquiring voltage signals from a thermal sensing producer to an amplifier circuit for amplifying said signals and suppressing noises residing within input said signals and improving signal-to-noise ratio of said signals; and

said amplified signals are output to an analog/digital converter, and

(3A.1.2) sampling input said amplified voltage signals in said analog/digital converters; and

digitizing said sampled voltage signals; and

said digital signals are output to an attitude and heading processor.

21. A processing method for motion measurement, as recited in claim 20, wherein the step (3A.2) further comprises the steps of:

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of said angular rate producer;

accessing angular rate producer temperature characteristic parameters using said current temperature of said angular rate producer;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor;

compensating temperature-induced errors in said real three-axis long-interval angular increments using said angular rate producer temperature characteristic parameters; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from the step (2) and acceleration device misalignment, acceleration device bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to accelerometer compensation module;

inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of acceleration producer;

accessing acceleration producer temperature characteristic parameters using the current temperature of acceleration producer;

transforming the input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, said accelerometer bias;

compensating temperature-induced errors in the real three-axis velocity increments using said acceleration producer temperature characteristic parameters;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

22. A processing method for motion measurement, as recited in claim 12, wherein the step (3A.2) further comprises the steps of:

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of said angular rate producer;

accessing angular rate producer temperature characteristic parameters using said current temperature of said angular rate producer;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor;

compensating temperature-induced errors in said real three-axis long-interval angular increments using said angular rate producer temperature characteristic parameters; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from the step (2) and acceleration device misalignment, acceleration device bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to accelerometer compensation module;

inputting said digital temperature signals from the step (3A.1.2) and temperature sensor scale factor;

computing current temperature of acceleration producer;

accessing acceleration producer temperature characteristic parameters using the current temperature of acceleration producer;

transforming the input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, said accelerometer bias;

compensating temperature-induced errors in the real three-axis velocity increments using said acceleration producer temperature characteristic parameters;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

23. A processing method for motion measurement, comprising the steps of:

(1) producing three-axis angular rate signals by an angular rate producer and three-axis acceleration signals by an acceleration producer;

(2) converting said three-axis angular rate signals into digital angular increments and converting said three-axis acceleration signals into digital velocity increments by an angular increment and velocity increment producer; and

(3) computing attitude and heading angle measurements using said three-axis digital angular increments and three-axis velocity increments by an attitude and heading processor; and

wherein, in preferable applications, output signals of said angular rate producer and said acceleration producer in the step (1), which are preferable MEMS angular rate device array and acceleration device array, are analog angular rate voltage signals and analog acceleration voltage, wherein the step (2) further comprises the steps of;

(2.1) integrating three-axis angular rate analog voltage signals from angular rate producer and three-axis acceleration analog voltage signals from said acceleration producer for a predetermined time interval to accumulate said three-axis angular analog voltage and said three-axis velocity voltage as raw three-axis angular increment and three-axis velocity increment for said predetermined time interval,

(2.2) forming a reset signal for said integrating processing to accumulate said three-axis angular voltage signal and three-axis velocity voltage signal from zero values at initial point of next said predetermined time interval, and

(2.3) measuring said raw three-angular increment and velocity increment voltage values in digital fashion.

24. A processing method for motion measurement, as recited in claim 23, wherein the step (3) further comprises the steps of:

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from the step (2) and acceleration device misalignment, acceleration bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to an accelerometer compensation module;

transforming said input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, acceleration bias;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.

25. A processing method for motion measurement, as recited as claim 23, after the step (2.3), further comprising an additional processing step of:

(2.4) scaling the raw three-axis angular velocity increment voltage values into real three-axis angular and velocity increment values.

26. A processing method for motion measurement, comprising the steps of:

(1) producing three-axis angular rate signals by an angular rate producer and three-axis acceleration signals by an acceleration producer;

(2) converting said three-axis angular rate signals into digital angular increments and converting said three-axis acceleration signals into digital velocity increments by an angular increment and velocity increment producer; and

(3) computing attitude and heading angle measurements using said three-axis digital angular increments and three-axis velocity increments by an attitude and heading processor;

wherein the step (3) further comprises the steps of;

inputting digital three-axis angular increment voltage values from the step (2) and coarse angular rate bias obtained from an angular rate producer and acceleration producer calibration procedure in high data rate (short interval) into a coning correction module;

computing coning effect errors in said coning correction module using said input digital three-axis angular increment voltage values and coarse angular rate bias; and

outputting three-axis coning effect terms and three-axis angular increment voltage values at reduced data rate (long interval), which are called three-axis long-interval angular increment voltage values, into an angular rate compensation module,

inputting said coning effect errors and three-axis long-interval angular increment voltage values from said coning correction module and angular rate device misalignment parameters, fine angular rate bias, angular rate device scale factor, and coning correction scale factor from said angular rate producer and acceleration producer calibration procedure to said angular rate compensation module;

compensating definite errors in said input three-axis long-interval angular increment voltage values using input said coning effect errors, said angular rate device misalignment parameters, said fine angular rate bias, and said coning correction scale factor;

transforming said compensated three-axis long-interval angular increment voltage values to real three-axis long-interval angular increments using said angular rate device scale factor; and

outputting said real three-axis angular increments to an alignment rotation vector computation module,

updating a quaternion, which is a vector representing rotation motion of said vehicle, using said compensated three-axis angular increments from said angular rate compensation module, an east damping rate increment from an east damping computation module, a north damping rate increment from a north damping computation module, and vertical damping rate increment from a vertical damping computation module; and

said updated quaternion is output to a direction cosine matrix computation module,

computing a direction cosine matrix using input said updated quaternion; and

said computed direction cosine matrix is output to a level acceleration computation module and an attitude and heading angle extract module,

extracting attitude and heading angle using said direction cosine matrix from said direction cosine matrix computation module;

outputting said heading angle into said vertical damping rate computation module,

inputting said three-axis velocity increment voltage values from the step (2) and acceleration device misalignment, acceleration bias, and acceleration device scale factor from said angular rate producer and acceleration producer calibration procedure to an accelerometer compensation module;

transforming said input three-axis velocity increments voltage values into real three-axis velocity increments using said acceleration device scale factor;

compensating definite errors in said three-axis velocity increments using input said acceleration device misalignment, acceleration bias;

outputting said compensated three-axis velocity increments to said level acceleration computation module,

computing level velocity increments using input said compensated three-axis velocity increments from said acceleration compensation module and said direction cosine matrix from said direction cosine matrix computation module;

outputting said level velocity increments to said east damping rate computation module and north damping rate computation module,

computing said east damping rate increments using north velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said east damping rate increments to said alignment rotation vector computation module,

computing said north damping rate increments using east velocity increment of said input level velocity increments from said level acceleration computation module;

feeding back said north damping rate increments to said alignment rotation vector computation module, and

computing said vertical damping rate increments using said computed heading angle from said attitude and heading angle extract module and a measured heading angle from an external sensor; and

feeding back said vertical damping rate increments to said alignment rotation vector computation module.