Time-constrained failure diagnosis in distributed embedded systems

Advanced automotive control applications such as steer and brake-by-wire are typically implemented as distributed systems comprising many embedded processors, sensors, and actuators interconnected via a communication bus. They have severe cost constraints but demand a high level of safety and performance. Motivated by the need for timely diagnosis of faulty actuators in such systems, we present a general method to implement failure diagnosis under deadline and resource constraints. Actuators are diagnosed in distributed fashion by processors to provide a global view of their fault status. The diagnostic tests are implemented in software using analytical redundancy and execute concurrently with the control tasks. The proposed method solves the test scheduling problem using a static list-based approach which guarantees actuator diagnosis within designer-specified deadlines while meeting control performance goals. As a secondary objective, it also minimizes the number of required processors. We present simulation results evaluating the effectiveness of the proposed method under various design constraints.