Patent ID: 6016465
Filing Date: 2000-01-18
Classification: G05B

Abstract:
A method of detecting sensor faults in a system having at least one sensor providing a sensor signal for monitoring or controlling system parameters, the method comprising the following steps:(a) generating reference signals of the system;(b) recording the value of each sensor signal and the corresponding reference signals at time intervals;(c) comparing the shape of an outline formed from a series of values of each sensor signal with the shape of an outline formed from a series of corresponding modified reference signals by means of a correlation coefficient;(d) continuously updating the respective series of signals with the most recent values and(e) declaring a fault when the correlation coefficient falls outside a prescribed range, wherein the modified reference signal is generated by:(f) multiplying the reference signal by a scaling factor to convert each sensor signal and its corresponding reference signal;(g) calculating the mean values of each sensor signal and its corresponding reference signal;(h) subtracting the respective mean values from each sensor signal and its corresponding reference signal to obtain new values for each sensor signal and its corresponding reference signal;(i) applying deviation thresholds to either side of the new values for each sensor signal;(j) superimposing the value of each reference signal over the thresholds around the new value of its corresponding sensor signal, and(k) formulating a modified reference signal from a hybrid of values of the new sensor signal and the new reference signal.