Robust Self-repairing PID Control Against Measurement Noise

Our previous work has developed a self-repairing PID control (SRPIDC) for sensor failures. This detection method uses the I-controller (integrator) of the PID control and an auxiliary signal to detect failures of a stuck type. Since the auxiliary signal varies in the same direction (sign) as the feedback signal from the sensor, the magnitude of the integrator output increases when the feedback signal gets stuck. Such an unstable behavior is found by a threshold. However, when noise is mixed in the feedback signal, this detection function does not work well because the sign varies. In this paper, we quantitatively analyze the degradation of the detection performance of the SRPIDC due to noise and propose two methods using an on-off type dead zone and a piecewise constant switching signal, that can make the sign of the shaped signal fixed on periods to detect sensor failures in the presence of noise.