System and method for monitoring a gyroscope
View Patent ↗Systems and methods are provided for monitoring operation of MEMS gyroscopes ( 110 ). A test signal generator ( 124 ) is configured to generate and apply a test signal to the rate feedback loop ( 112 ) of a MEMS gyroscope ( 110 ). A test signal detector ( 126 ) is coupled to the quadrature feedback loop ( 114 ) of the MEMS gyroscope ( 110 ) and is configured to receive a quadrature output signal from the quadrature feedback loop ( 114 ). The test signal detector ( 126 ) demodulates the quadrature output signal to detect effects of the test signal. Finally, the test signal detector ( 126 ) is configured to generate a monitor output indicative of the operation of the sensing device based at least in part on the detected effects of the test signal in the quadrature output signal. Thus, the system is able to provide for the continuous monitoring of the operation of the MEMS gyroscope ( 110 ).
1. A system for monitoring operation of a sensing device, where the sensing device includes microelectromechanical (MEMS) gyroscope, a rate feedback loop coupled to the MEMS gyroscope and a quadrature feedback loop coupled the MEMS gyroscope, the system comprising:
a test signal generator, the test signal generator configured to generate a test signal and apply the test signal to the rate feedback loop during operation of the MEMS gyroscope; and
a test signal detector, the test signal detector coupled to the quadrature feedback loop and configured to receive a quadrature output signal from the quadrature feedback loop and detect effects of the test signal in the quadrature output signal, the test signal detector further configured to generate a monitor output indicative of the operation of the sensing device based at least in part on the detected effects of the test signal.
2. The system of claim 1 wherein the test signal generator is coupled to the test signal detector to provide a demodulation signal to the test signal detector, where the demodulation signal is equivalent to the test signal, and wherein the test signal detector is configured to detect the effects of the test signal in the quadrature output signal by demodulating the quadrature output signal using the demodulation signal.
3. The system of claim 1 wherein the test signal generated by the test signal generator is a modulated signal.
4. The system of claim 1 wherein the test signal generated by the test signal generator is generated with a carrier in quadrature phase to a carrier on a rate feedback signal that is fed back to the MEMS gyroscope.
5. The system of claim 1 wherein the test signal generator combines square waves with different frequencies to generate the test signal.
6. The system of claim 1 wherein the test signal generator is additionally configured to set an amplitude of the test signal.
7. The system of claim 6 wherein the test signal detector is additionally configured to detect the amplitude of the detected test signal.
8. The system of claim 1 wherein the test signal detector is configured to detect the effects of the test signal in the quadrature output signal by demodulating the quadrature output signal using a demodulation signal received from the test signal generator.
9. The system of claim 8 wherein the test signal detector includes a comparator and an accumulator, and wherein the test signal detector compares the demodulated output signal to a threshold value using the comparator, and wherein the test signal detector accumulates an output of the comparator using the accumulator, and wherein the monitor output is generated based at least in part of the accumulated output of the comparator.
10. A sensing device, comprising:
a microelectromechanical (MEMS) gyroscope;
a rate feedback loop coupled to the MEMS gyroscope, the rate feedback loop generating a rate output signal and feeding back a rate feedback signal to the MEMS gyroscope;
a quadrature feedback loop coupled to the MEMS gyroscope, the quadrature feedback loop generating a quadrature output signal and feeding back a quadrature feedback signal to the MEMS gyroscope;
a test signal generator, the test signal generator configured to generate a test signal and a demodulation signal, the test signal generated with a carrier in quadrature phase with respect to a phase of a carrier of the rate feedback signal, the test signal generator configured to apply the test signal to the rate feedback loop during operation of the sensing device; and
a test signal detector, the test signal detector configured to receive the quadrature output signal from the quadrature feedback loop and demodulate the quadrature output signal using the demodulation signal to detect effects of the test signal, the test signal detector further configured to generate a monitor output indicative of the operation of the sensing device based at least in part on the detected effects of the test signal.
11. The sensing device of claim 10 wherein the test signal generator combines square waves with different frequencies to generate the test signal.
12. The sensing device of claim 11 wherein the test signal detector is additionally configured to determine a measure of an amplitude of the detected effects of the test signal.
13. The sensing device of claim 10 wherein the test signal detector includes a comparator and an accumulator, and wherein the test signal detector detect effects of the test signal by comparing the demodulated output signal to a threshold value using the comparator, and wherein the test signal detector accumulates an output of the comparator using the accumulator, and wherein the monitor output is generated based at least in part of the accumulated output of the comparator.
14. A method of monitoring operation of a sensing device, where the sensing device includes microelectromechanical (MEMS) gyroscope, a rate feedback loop coupled to the MEMS gyroscope and a quadrature feedback loop coupled the MEMS gyroscope, the method comprising:
generating a test signal;
applying the test signal to the rate feedback loop during operation of the MEMS gyroscope;
receiving a quadrature output signal from the quadrature feedback loop;
detecting effects of the test signal in the quadrature output signal; and
generating a monitor output indicative of the operation of the sensing device based at least in part on the detected effects of the test signal.
15. The method of claim 14 wherein the step of detecting effects of the test signal in the quadrature output signal comprises demodulating the quadrature output signal using a demodulating signal equivalent to the test signal.
16. The method of claim 14 wherein the test signal comprises a modulated signal.
17. The method of claim 14 wherein the step of applying the test signal comprises modulating a carrier in quadrature phase with respect to the phase of a carrier on a rate feedback signal that is fed back to the MEMS gyroscope.
18. The method of claim 14 wherein the step of generating the test signal comprises setting an amplitude of the test signal and wherein the step of detecting effects of the test signal in the quadrature output signal comprises determining a measure of an amplitude of the detected effects of the test signal.
19. The method of claim 18 wherein the step of generating the monitor output indicative of the operation of the sensing device based at least in part on the detected effects of the test signal comprises generating the monitor output based on the determined measure of the amplitude in detected effects of the test signal.
20. The method of claim 14 wherein the step of generating the monitor output indicative of the operation of the sensing device based at least in part on the detected effects of the test signal comprises comparing the detected effects of the test signal to a threshold value using a comparator and accumulating an output of the comparator.