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

Patent metadata

Field	Value
Publication number	US-10317421-B2
Application number	US-201514656408-A
Country	US
Kind code	B2
Filing date	Mar 12, 2015
Priority date	Mar 31, 2014
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

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.

First claim

The invention claimed is:

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.

Assignees

• St Microelectronics Srl

Inventors

• Palella Nicola Matteo
• Colombo Leonardo

Classifications

• G01C19/5684

  the devices involving a micromechanical structure · CPC title

• G01P1/006 Primary

  used for thermal compensation · CPC title

• G01C25/00

  Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass (testing, calibrating or compensating compasses G01C17/38) · CPC title

• G01C19/5621 Primary

  the devices involving a micromechanical structure · CPC title

• G01C19/5712

  the devices involving a micromechanical structure · CPC title