Patent Document ID: 4509110
Application ID: 06386136
Patent Flag: 1

Claim One:
1. A system for detecting the failure of apparatus, said apparatus including control means and an object of said control means, said system comprising: model means simulating the input/output characteristics of said apparatus; means for providing the same input to said apparatus and to said model means; means for continuously comparing the output of said object to the apparatus input and for operating on said object to eliminate any difference between the compared input and output; means for continuously comparing the output of said object to the output of said model means and for calculating error signals corresponding to the differences therebetween; means for integrating, over time, the absolute value of said error signals which are outside a predetermined deadband having limits -a and +b; means for generating a failure signal when said integral exceeds a predetermined value; and means for resetting said integral to zero whenever the value of the error signal is within predetermined limits -c and +d, where the absolute value of c is less than or equal to the absolute value of a, and the absolute value of d is less than or equal to the absolute value of b.