System and method for inertial sensor offset compensation
View Patent ↗The present invention provides an improved method and system for compensation of inertial sensors. In one implementation a modified moving average is applied to provide dynamic offset compensation for an inertial sensor output that is calculated when a vehicle is in motion.
1. A sensor compensation system for a motor vehicle comprising:
an inertial sensor configured to measure a rate of a vehicle;
a processing unit in communication with the inertial sensor;
a memory unit operably coupled to the processing unit; and
the processing unit including at least one module configured to:
sample a series of data from the inertial sensor;
calculate a modified moving average from the series of data and a current data sample from the series of data to calculate a compensation offset, wherein the modified moving average is an average based on a previously determined average; and
filter the compensation offset from the series of data to generate a compensated rate signal, wherein the memory unit stores a current average from the modified moving average to calculate a subsequent modified moving average for the series of data; and
wherein the modified moving averages, A k , for the sampled inertial sensor output, x k , where k is the sample number and n is the number of samples for a moving average window is determined by the following equations:
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(
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2. The sensor compensation system of claim 1 , wherein the series of data is sampled when the vehicle is in motion.
3. The sensor compensation system of claim 1 , wherein the inertial sensor is an angular rate sensor.
4. The sensor compensation system of claim 1 , further comprising a second sensor configured to detect motion of the vehicle in communication with the processor.
5. The sensor compensation system of claim 4 , wherein the second sensor configured to detect motion is a wheel speed sensor.
6. The sensor compensation system of claim 4 , wherein the second sensor configured to detect motion is an accelerometer.
7. The sensor compensation system of claim 4 , wherein the at least one module is configured to calculate a dynamic modified moving average in response to a signal from the sensor configured to detect motion.
8. The sensor compensation system of claim 7 , wherein the at least one module is configured to calculate a transition modified moving average between the static modified moving average and the dynamic modified moving average to calculate the compensation offset.
9. The sensor compensation system of claim 4 , wherein the at least one module is configured to calculate a static modified moving average in response to a signal from the sensor configured to detect motion.
10. A method of compensation for an inertial sensor comprising:
measuring a rate signal of a motor vehicle;
calculating an inertial sensor compensation offset including:
sampling a series of data from the rate signal;
calculating a dynamic modified moving average from the series of data measured in response to the vehicle in motion, and a static modified moving average in response the vehicle being stopped to calculate a compensation offset, wherein the static and dynamic modified moving averages are each an average based on a previously determined average;
filtering the compensation offset from the rate signal; and
generating a compensated rate signal; and
wherein each of the static and dynamic modified moving averages, A k , for the sampled inertial sensor output, x k , where k is the sample number and n is the number of samples for a moving average window is determined by the following equations:
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x
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11. The method of claim 10 , further comprising calculating a transition modified moving average between the static modified moving average and the dynamic modified moving average to calculate the compensation offset.
12. The method of claim 10 , wherein the modified moving average is filtered by a low pass filtering process.
13. The method of claim 10 , wherein the dynamic modified moving average is filtered separately from the static modified moving average.