Method and apparatus for diagnosing and isolating faulty sensors in a redundant sensor system
First Claim
1. A sensor diagnostic apparatus for detecting faults, said sensor diagnostic apparatus coupled to a voltage source and comprising:
- a sensor means coupled to the voltage source and having an output signal proportional to a variable monitored by said sensor means;
a switching means having an off position and an on position, said switching means coupled between the voltage source and said sensor for providing a reference voltage to said sensor when said switching means is in an on position; and
a control means coupled to said switching means and to said sensor means for selectively turning said switching means to an off state to disconnect the reference voltage from said sensor means, and for monitoring the rate of voltage decay at the output signal of said sensor means and comparing the monitored rate of voltage decay to a preset rate of voltage decay to produce an error indication when the monitored rate of voltage decay does not match the preset rate of voltage decay.
2 Assignments
0 Petitions
Accused Products
Abstract
A sensor failure and detection apparatus and method for use in a redundant sensor system are disclosed. A control circuit disconnects reference power supplied to a sensor and then monitors the voltage decay output by the sensor. The monitored rate of voltage decay of the sensor is compared to the expected natural voltage decay of the sensor to detect failures caused by short or open circuits. An error counter keeps track of the number of failures. After a threshold number of times in which the monitored voltage decay does not compare to a predicted rate of decay, power to the sensor is removed and the sensor is isolated from the system.
-
Citations
12 Claims
-
1. A sensor diagnostic apparatus for detecting faults, said sensor diagnostic apparatus coupled to a voltage source and comprising:
-
a sensor means coupled to the voltage source and having an output signal proportional to a variable monitored by said sensor means; a switching means having an off position and an on position, said switching means coupled between the voltage source and said sensor for providing a reference voltage to said sensor when said switching means is in an on position; and a control means coupled to said switching means and to said sensor means for selectively turning said switching means to an off state to disconnect the reference voltage from said sensor means, and for monitoring the rate of voltage decay at the output signal of said sensor means and comparing the monitored rate of voltage decay to a preset rate of voltage decay to produce an error indication when the monitored rate of voltage decay does not match the preset rate of voltage decay. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A method of diagnosing a faulty sensor, said sensor having an output signal and being coupled to a reference voltage through a switch, said switch being responsive to a control circuit, said control circuit further coupled to the output signal of said sensor, wherein said method comprises the steps of:
-
disconnecting the reference voltage to said sensor by turning said switch to an open position; monitoring the rate of voltage decay in the output signal of said sensor; comparing the monitored rate of voltage decay to an expected rate of voltage decay; and indicating a fault condition for said sensor when the monitored rate of voltage decay does not match the expected rate of voltage decay. - View Dependent Claims (9, 10, 11, 12)
-
Specification