Method for continuous sensor self-test

• US 20050183489A1
• Filed: 02/24/2004
• Published: 08/25/2005
• Est. Priority Date: 02/24/2004
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Geen, John A., Weinberg, Harvey
• Granted Patent: US 7,086,270 B2
• Time in Patent Office: Days
• US Class Current: 73/1.380
• CPC Class Codes: G01D 18/002 Automatic recalibration G01D18/008 takes precedence
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G01D 3/08 with provision for safeguarding the apparatus, e.g. against abnormal operation, against breakdown

Abstract

A method and device for self-test of a sensor. The method includes stimulating the sensor with signals that generate sensor outputs at a frequency that differs from the frequency of expected sensed parameter signals. The sensor output is filtered to remove the effects of the stimulation inputs, generating a sensed parameter signal. The unfiltered sensor output is compared to the expected output of the sensor with the stimulus input. A malfunctioning sensor may be detected by the comparison and appropriate action may then be taken.

Claims

1. A method for determining a sensed parameter using a sensor, the sensor generating a signal, the method comprising:

a. stimulating the sensor;

b. filtering the sensor signal; and

c. determining the sensed parameter based on the filtered sensor signal.

d. comparing the sensor signal to an expected signal and generating a sensor self-test signal based at least in part on the comparison.

e. periodically repeating steps a through d.

2. A method according to claim 1, wherein the sensor stimulation is characterized by a stimulation frequency and the stimulation frequency and the signal frequency of the sensed parameter differ substantially.

3. A method according to claim 1, wherein the sensor includes complementary self-test inputs.

4. A method according to claim 1 wherein the sensor stimulation is characterized by a stimulation on-period and a stimulation off-period and the sensed parameter value is determined substantially during the sensor stimulation off-period.

5. A method according to claim 4, further including comparing the sensor signal to an expected sensor signal during the sensor stimulation on-period and generating a sensor self-test signal based at least in part on the comparison.

6. A method according to claim 1 wherein the sensed parameter is at least one of an acceleration and a rotation.

7. A sensor assembly for determining a sensed parameter while testing a sensor, the sensor assembly comprising:

a. the sensor, the sensor including an output for generating an output signal;

b. a stimulator connected to the sensor for injecting a stimulation signal;

c. a filter connected to the sensor output, such that the filter substantially removes the portion of the output signal due to the stimulation signal; and

d. a comparator connected to the sensor output, the comparator generating a sensor self-test signal.

8. A sensor assembly according to claim 7, wherein the sensor includes complementary self-test stimulation inputs.

9. A sensor assembly according to claim 7, wherein the stimulation signal is characterized by a stimulation frequency and the stimulation frequency and the signal frequency of the sensed parameter differ substantially.

10. A sensor assembly according to claim 7 wherein the stimulation signal is characterized by an on-period and an off-period;

and the filter transmits the sensor output only during the stimulation off-period.

11. A sensor assembly according to claim 7 wherein the sensed parameter is at least one of an acceleration and a rotation.

12. A sensor assembly according to claim 7 wherein the assembly includes a self-test output signal.

13. A computer program product for use on a computer system for determining a sensed parameter value while performing sensor self-test, the system including a sensor, the computer program product comprising a computer usable medium having computer readable program code thereon, the computer readable program code including program code for:

a. stimulating the sensor;

b. filtering a sensor output signal;

c. determining the sensed parameter value based on the filtered sensor signal; and

d. comparing the sensor signal to an expected signal and generating a sensor self-test signal based at least in part on the comparison.

14. A computer program product according to claim 13 further including program code for:

e. periodically repeating steps a through d.

15. A computer program product according to claim 13 wherein the sensor includes complementary self-test inputs.

16. A computer program product according to claim 13 wherein the sensed parameter is at least one of an acceleration and a rotation.