Abstract: A new approach to fault tolerant estimation problem was derived for a class of closed-loop networked systems with sensor faults. Closed-loop networked systems implied that there could be network-induced phenomena of random delays and packet dropouts in both the sensor-to-estimator(S-E)channel and the controller-to-actuator(C-A)channel. An indicator function driven individually by two groups of random variables was introduced to characterize the network-induced phenomena in both channels. Then, sensor faults were considered in the estimator design process. A kind of fault tolerant estimator was developed in the unbiased minimum variance sense in order to deal with sensor faults in networked systems with closed loop. Simulations were carried out on a practical networked permanent magnet synchronous motor driving system to test the feasibility and effectiveness of the proposed techniques.

Key words: time delays, state estimation, closed loop, sensor faults tolerant, packet dropouts