Smart actuator-based fault-tolerant control for networked safety-critical embedded systems

In this paper, a fault-tolerant control method is presented with an application to steer-by-wire (SBW) system. SBW is a network-based vehicle steering system in which the mechanical linkage and hydraulics are replaced by electrical motors and fieldbus networks. Since failure of a steering system may result in a catastrophic accident, SBW can be considered as a safety-critical embedded system for which very high level of dependability must be satisfied. This paper proposes an effective control strategy to tolerate faulty actuators. The proposed method has a simple structure to be implemented on low cost embedded processors. The reconfiguration strategy consists of two fold: i) a smart actuator of which embedded microprocessor provides the fast and accurate diagnostic information through a time-triggered fieldbus, and ii) an IMCPID controller which is capable of tolerating the effect of faults based on the diagnostic information being sent from the smart actuator. Simulation results with a SBW model show that the proposed method can enhance the system dependability in the presence of faults without using any redundant actuators.