Fault tolerant PID control based on software redundancy for nonlinear uncertain processes

The fault diagnosis and close-loop tolerant PID control for nonlinear multi-variables system under multiple sensor failures are investigated in the paper. A complete FDT architecture based on software redundancy is proposed to efficiently handle the fault diagnosis and the accommodation for multiple sensor failures in online situations. The methods colligates the adaptive threshold technique with the envelope and weighting moving average residual to detect multi-type sensor fault, use fault propagation technique, variable structure analyzing technique and neural network techniques to online reconstruct sensor signal, and achieves the tolerant PID control through recombining feedback loop of PID controller. The three-tank with multiple sensor fault concurrence is simulated, the simulating result shows that the fault detection and tolerant control strategy has stronger robustness and tolerant fault ability.