Two-stage Kalman filter for simultaneous fault and delay estimation in networked control systems

Networked Control Systems are becoming very popular nowadays. However, the use of networks in the control loop induces extra difficulties in diagnosis. In this paper we propose a method for estimate fault as well delay induced by the network. Inspired from the Kalman filter previously proposed by Sinopoli et al. and Hsieh et al., two solutions are presented; the augmented and the two-stage Kalman filter. Main attention is paid for the last one. The delay and the fault are integrated as a state variable. It is supposed that the delay and the fault are random variables. In addition, we provide some analytic results to demonstrate the computational advantages of two-stage Kalman filter over augmented ones. An example illustrates the obtained results is given.