Sensor fault detection by activity monitoring

Claim 1

An activity-monitored sensor system comprising: a first sensor providing a first output signal indicative of a given physical parameter; and a second sensor providing a second output signal indicative of a second parameter related to said given physical parameter so that said second output signal is also indicative of whether said first output signal should or should not be changing as a function of time; characterized by: signal processing means connected for response to the output signals of said first and second sensors, for providing signals indicative of first, second and third predetermined threshold signal magnitudes, responsive to said second output signal for providing a first excess signal indicative of said second parameter being in excess of a first one of said predetermined threshold signal magnitudes for providing a second excess signal indicative of a change in the magnitude of said first output signal in excess of a second one of said predetermined threshold signal magnitudes, for providing a signal indicative of null fault in response to presence of said first excess signal concurrently with absence of said second excess signal for a predetermined interval of time, for providing in response to said first output signal a rate limited signal indicative of said given physical parameter limited as to the rate of change thereof with respect to time, for comparing said rate limited signal with said first output signal, and for providing a signal indicative of excess rate fault in the event that said rate limited signal differs from said first output signal by more than a third one of said predetermined threshold signal magnitudes.