Positioning apparatus comprising an inertial sensor and inertial sensor temperature compensation method

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 at least one estimated inertial sensor behavior parameter as 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 output by the temperature sensor, wherein the at least one inertial sensor behavior parameter includes an inertial sensor sensitivity and an inertial sensor zero-rate level and the position-estimation circuitry is configured to generate position information based on Global Navigation Satellite System (GNSS) signals and dead-reckoning positioning system signals.

2. The apparatus according to claim 1 wherein the measured current motion angle comprises one of:

a heading angle;

a pitch angle;

a roll angle; and

a linear combination of at least two of said heading angle, pitch angle and roll angle.

3. The apparatus according to claim 1 wherein the inertial sensor comprises a gyroscope.

4. 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.

5. The apparatus according to claim 1 wherein the indication of the measured current motion angle is based on a magnetometer sensor output signal.

6. 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; and

a particle filter.

7. 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.

8. The apparatus according to claim 1 , comprising circuitry configured to provide at least one of:

Automatic Driver Assistance;

Vehicle to Vehicle Communications; and

Autonomous Pilot and Telematics services.

9. The apparatus of claim 1 wherein the recursively computing the estimated current motion angle compensates for a thermal drift of the inertial sensor.

10. The apparatus of claim 1 wherein the position estimation circuitry, in operation, generates control signals based on the estimated current motion angle.

11. The apparatus according to claim 3 wherein the inertial sensor includes a MEMs gyroscope structured to provide the current angular rate.

12. The apparatus according to claim 7 wherein:

the Kalman gain matrix module receives a measurement noise indicator;

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.

13. The apparatus according to claim 7 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.

14. The apparatus of claim 10 wherein the control signals include navigation control signals.

15. The apparatus according to claim 13 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 method, comprising:

sensing, using an inertial sensor having at least one inertial sensor behavior parameter dependent on inertial sensor temperature, a current angular rate;

receiving a time derivative of a temperature of the inertial sensor output by a temperature sensor; and

recursively computing, using one or more processing devices, an estimated current motion angle of a vehicle and at least one estimated inertial sensor behavior parameter as 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 output by the temperature sensor, wherein the at least one inertial sensor behavior parameter includes an inertial sensor sensitivity and an inertial sensor zero-rate level and the method includes generating position information based on GNSS signals and dead-reckoning positioning system signals.

17. The method of claim 16 wherein the recursively computing the estimated current motion angle compensates for a thermal drift of the inertial sensor.

18. The method of claim 16 , comprising:

generating, by the one or more processing device, control signals based on the estimated current motion angle.

19. The method of claim 18 wherein the control signals include navigation control signals.