Periodic rate sensor self test

Abstract

A periodic test signal is injected into a motion sensor and the sensor output is compared to a threshold to determine whether the sensor is functioning properly.

1 . A method for verifying proper operation of a motion sensor comprising the steps of: 
 (a) providing a motion sensor;    (b) injecting a test pulse into the motion sensor;    (c) measuring the output of the motion sensor after a predetermined delay period;    (d) comparing the motion sensor output to an acceptable output range; and    (e) declaring a fault upon determining that the sensor output measured in step (a) is outside of the acceptable output range.    
   
   
       2 . The method of  claim 1  wherein the test signal is periodically applied to the motion sensor.  
   
   
       3 . The method of  claim 2  wherein an error signal is generated subsequent to step (e) after a predetermined number of faults caused by consecutive test signals have been detected.  
   
   
       4 . The method of  claim 3  wherein the motion sensor provided in step (a) is an accelerometer.  
   
   
       5 . The method of  claim 3  wherein the periodic test signal is alternately positive and negative.  
   
   
       6 . The method of  claim 4  wherein an error signal is generated subsequent to step (e) after a predetermined number of faults caused by consecutive positive test signals have been detected.  
   
   
       7 . The method of  claim 6  wherein the motion sensor provided in step (a) is an angular rate sensor.  
   
   
       8 . The method of  claim 4  wherein an error signal is generated subsequent to step (e) after a predetermined number of faults caused by consecutive negative test signals have been detected.  
   
   
       10 . The method of  claim 4  wherein an error signal is generated subsequent to step (e) after a predetermined number of total faults caused by consecutive positive and negative test signals have been detected.  
   
   
       11 . The method of  claim 2  wherein the upper and lower limits of the acceptable output range utilized in step (d) are based upon at least one variable parameter.  
   
   
       12 . The method of  claim 11  wherein the upper and lower limits of acceptable output range utilized in step (d) are based upon at least the ambient temperature.  
   
   
       13 . The method of  claim 11  wherein the upper and lower limits of acceptable output range utilized in step (d) are based upon at least the variation of parts parameters.  
   
   
       14 . The method of  claim 11  wherein the upper and lower limits of acceptable output range utilized in step (d) are based upon at least vehicle dynamics.  
   
   
       15 . The method of  claim 3  wherein the output of the motion sensor is sampled at a rate of N 1  and, during step (b), the test signal is injected into the motion sensor at a rate of N 3 , with N 3  being greater than N 1 .  
   
   
       16 . The method of clam  15  wherein the injected test signal from step (b) is passed through a digital filter prior and further wherein the digital filter generates an output signal at a rate of N 2  with N 1 <N 2 <N 3 .  
   
   
       17 . The method of  claim 16  further including, subsequent to finding that the motion sensor output is within an acceptable output range in step (d), supplying the output of the digital filter to at least one vehicle control system.  
   
   
       18 . The method of  claim 17  wherein the at least one vehicle control system includes an electronically controlled vehicle brake system.  
   
   
       19 . The method of  claim 3  wherein the periodic test signal includes sequenced positive and negative signals.  
   
   
       20 . The method of  claim 3  wherein the periodic test signal includes random positive and negative signals.