Positioning apparatus comprising an inertial sensor and inertial sensor temperature compensation method
A positioning apparatus includes: a reference device configured to provide a measured current motion angle of a vehicle; an inertial sensor configured to provide a current input angular rate of the vehicle and associated with at least one inertial sensor behavior parameter dependent on inertial sensor temperature; a temperature sensor configured to provide an input temperature variation of the inertial sensor on a time interval; and a digital estimator configured to recursively computing an estimated current motion angle of the vehicle and at least one previously estimated inertial sensor behavior parameter as function of: the measured current motion angle, a previously estimated motion angle, the current input angular rate, and the input temperature variation.
1. An apparatus, comprising:
an inertial sensor configured to output a current angular rate and associated with at least one inertial sensor behavior parameter dependent on inertial sensor temperature;
a temperature sensor configured to output an indication of a time derivative of a temperature of the inertial sensor; and
position-estimation circuitry configured to recursively compute an estimated current motion angle of a vehicle and an estimated inertial sensor behavior parameter as a function of:
an indication of a measured current motion angle;
a previously estimated motion angle;
the current angular rate; and
the indication of the time derivative of the temperature.
2. The apparatus according to claim 1 wherein the at least one inertial sensor behavior parameter comprises at least one of the following parameters:
inertial sensor sensitivity; or
inertial sensor zero-rate level.
3. The apparatus according to claim 1 wherein the measured current motion angle comprises one of:
a heading angle;
a pitch angle;
a roll angle; or
a linear combination of at least two of said heading angle, pitch angle and roll angle.
4. The apparatus according to claim 1 wherein the inertial sensor comprises a gyroscope.
5. The apparatus according to claim 1 wherein the indication of the measured current motion angle is based on a Global Navigation Satellite System (GNSS) receiver output signal.
6. The apparatus according to claim 1 wherein the indication of the measured current motion angle is based on a magnetometer sensor output signal.
7. The apparatus according to claim 1 wherein the position-estimation circuitry comprises at least one of:
a Least Square Estimator (LSE) filter;
a Kalman filter;
an extended Kalman filter; or
a particle filter.
8. The apparatus according to claim 1 wherein the position estimation circuitry comprises an extended Kalman filter including:
an update section having a differential node module configured to receive the indication of the measured current motion angle, a Kalman gain matrix module and a measurement transformation module; and
a prediction section having a sum node, a delay module, a dynamic matrix module and output configured to provide the estimated current motion angle.
9. The apparatus according to claim 1 wherein the position-estimation circuitry is configured as to generate position information based on Global Navigation Satellite System (GNSS) signals and dead-reckoning positioning system signals.
10. The apparatus according to claim 1 , comprising circuitry configured to provide at least one of:
Automatic Driver Assistance;
Vehicle to Vehicle Communications; or
Autonomous Pilot and Telematics services.
11. The apparatus of claim 1 , wherein the position-estimation circuitry is configured to recursively compute a plurality of estimated inertial sensor behavior parameters as a function of:
the indication of a measured current motion angle;
the previously estimated motion angle;
the current angular rate; and
the indication of the time derivative of the temperature.
12. The apparatus according to claim 4 wherein the inertial sensor includes a MEMs gyroscope structured to provide the current angular rate.
13. The apparatus according to claim 8 wherein:
the Kalman gain matrix module receives a measurement noise indicator; and
the position-estimation circuitry comprises a measurement noise module associated with a Global Navigation Satellite System (GNSS) receiver and configured to compute said measurement noise indicator as a weighted combination of:
a signal strength computed from GNSS visible satellite signal power;
a Root-mean-square of pseudorange errors;
a Root-mean-square of Doppler errors;
a number of tracked satellites;
a Standard Deviation of vehicle position values; and
vehicle velocity values received from the GNSS receiver.
14. The apparatus according to claim 8 wherein the position-estimation circuitry is configured to compute a covariance matrix including a system noise matrix and to compute elements of the system noise matrix as function of measured vehicle dynamic quantities.
15. The apparatus according to claim 14 wherein the position-estimation circuitry is configured to compute said elements as function of parameters provided by a Global Navigation Satellite System (GNSS) receiver.
16. A system, comprising:
motion angle measurement circuitry configured to generate at least one indication of a measured current motion angle;
an inertial sensor configured to output a current angular rate and associated with at least one inertial sensor behavior parameter dependent on inertial sensor temperature;
a temperature sensor configured to output a time derivative of a temperature of the inertial sensor; and
position-estimation circuitry configured to recursively compute an estimated current motion angle of a vehicle and an estimated inertial sensor behavior parameter as a function of:
the at least one indication of a measured current motion angle;
a previously estimated motion angle;
the current angular rate; and
the time derivative of the temperature.
17. The system according to claim 16 wherein the measured current motion angle comprises at least one of:
a heading angle;
a pitch angle;
a roll angle; or
a linear combination of at least two of said heading angle, pitch angle and roll angle.
18. The system according to claim 16 wherein the inertial sensor comprises a MEMs gyroscope.
19. The system of claim 16 wherein the motion angle measurement circuitry comprises a Global Navigation Satellite System (GNSS) receiver.
20. The system of claim 16 wherein the position-estimation circuitry comprises at least one of:
a Least Square Estimator (LSE) filter;
a Kalman filter;
an extended Kalman filter; or
a particle filter.
21. The system of claim 16 , comprising:
a Global Navigation Satellite System (GNSS) receiver; and
a dead reckoning positioning system.
22. The system of claim 16 , wherein the position-estimation circuitry is configured to recursively compute a plurality of estimated inertial sensor behavior parameters as a function of:
the indication of a measured current motion angle;
the previously estimated motion angle;
the current angular rate; and
the indication of the time derivative of the temperature.
23. A method, comprising:
sensing, using an inertial sensor having at least one inertial sensor behavior parameter dependent on inertial sensor temperature, a current angular rate;
sensing, using a temperature sensor, a time derivative of a temperature of the inertial sensor; and
recursively computing, using one or more processing devices, an estimated current motion angle of a vehicle and an estimated inertial sensor behavior parameter as a function of:
an indication of a measured current motion angle;
a previously estimated motion angle;
the current angular rate; and
the time derivative of the temperature.
24. The method of claim 23 wherein the at least one inertial sensor behavior parameter comprises at least one of the following parameters:
inertial sensor sensitivity; and
inertial sensor zero-rate level.
25. The method of claim 23 , comprising:
generating, using the one or more processing devices, vehicle position information based on a Global Navigation Satellite System (GNSS) receiver signal and a dead reckoning positioning system signal.
26. The method of claim 23 wherein the recursively computing the estimated current motion angle compensates for a thermal drift of the inertial sensor.
27. A non-transitory computer-readable medium having contents which configure a sensor system to perform a method, the method comprising:
sensing, using an inertial sensor of the sensor system having at least one inertial sensor behavior parameter dependent on inertial sensor temperature, a current angular rate;
sensing, using a temperature sensor of the sensor system, a time derivative of a temperature of the inertial sensor; and
recursively computing an estimated current motion angle of a vehicle and an estimated inertial sensor behavior parameter as a function of:
an indication of a measured current motion angle;
a previously estimated motion angle;
the current angular rate; and
the time derivative of the temperature.
28. The non-transitory computer-readable medium of claim 27 wherein the at least one inertial sensor behavior parameter comprises at least one of the following parameters:
inertial sensor sensitivity; and
inertial sensor zero-rate level.
29. The non-transitory computer-readable medium of claim 27 wherein the method comprises:
generating vehicle position information based on a Global Navigation Satellite System (GNSS) receiver signal and a dead reckoning positioning system signal.
30. The non-transitory computer-readable medium of claim 27 wherein the recursively computing the estimated current motion angle compensates for a thermal drift of the inertial sensor.