FPGA-based reliable TMR controller design for S2A architectures

Fault-tolerance is becoming an essential feature in the design of Networked Control Systems (NCSs). Furthermore, Sensor-to-Actuator (S2A) architectures have shown some advantages over conventional In-Loop architectures. This paper focuses on fault-tolerant controllers in the context of S2A systems. It proposes the use of Triple Modular Redundancy at the controller level. The fault-tolerant controller will be hosted in an FPGA that has a spare location. The voter in this TMR scheme is fault-secure to guarantee that the controllers never produce an undetected incorrect control action. Finally, system reliability is calculated using Markov models to quantitatively show, via case studies, the advantage of the proposed technique in terms of extended lifetime.