On-Line Monitor Design of Finite-State Machines

On-line monitoring is a useful technique for ensuring system reliability. By continuously supervising the system’s operation, a wide range of problems, such as physical defects, transient faults and design errors, can be detected. A monitor M∗’s behavior can be viewed as an abstraction of the target system M’s behavior, and can be represented by a homomorphic mapping from M to M∗. We present a systematic procedure to select homomorphisms for monitor design and measure their costs based on a behavioral fault model. Analysis of the method shows that monitors with very few states and low area can provide high fault coverage. Experimental results are presented which quantify the basic trade-off between area overhead and fault coverage. Simulation results under the industry-standard single stuck-at fault model are also reported.