State estimation and finite-frequency fault detection for interconnected switched cyber-physical systems

For switched cyber-physical systems with disturbances and actuator faults, we address fault detection and isolation problems. First, the preconditions relative to subsystems are discussed in detail, and the original subsystems are turned into an overall system. Second, the frequency ranges of faults are considered to belong to the finite-frequency domain, and the observer, which makes the residual robust against disturbances and sensitive to faults, is designed by combining the finite-frequency H− technique with the mixed L2 − L∞/H∞ technique. Third, design conditions, which guarantee that the error system is stable and satisfies the mixed performance, are derived using the average dwell time method and Lyapunov functionals. Finally, a traffic density dynamic model is proposed to demonstrate the validity and effectiveness of the proposed method.