Fault-tolerant control synthesis and verification of distributed embedded systems

We deal with synthesis of distributed embedded control systems closed over a faulty or severely constrained communication network. Such overloaded communication networks are common in cost-sensitive domains such as automotive. Design of such systems aims to meet all deadlines following the traditional notion of schedulability. In this work, we aim to exploit robustness of the controller and propose a novel implementation approach to achieve a tighter design. Toward this, we answer two research questions: (i) given a distributed architecture, how to characterize and formally verify the bound on deadline misses, (ii) given such a bound, how to design a controller such that desired stability and Quality of Control (QoC) requirements are met. We address question (i) by modeling a distributed embedded architecture as a network of Event Count Automata (ECA), and subsequently introducing and formally verifying a property formulation with reduced complexity. We address question (ii) by introducing a novel fault-tolerant control strategy which adjusts the control input at runtime based on the occurrence of fault or drop. We show that QoC under faulty communication improves significantly using the proposed fault-tolerant strategy.