Secure state estimation and actuator attack reconstruction for cyber-physical systems based on sliding-mode observer

In this paper, the secure state estimation attack and reconstruction problems are considered for linear cyber-physical systems (CPSs) under actuator attacks and unknown disturbances. By introducing a continuous sliding mode observer with an exponential reaching law strategy, the dynamic quality of approach motion is greatly improved and the chattering is eliminated. Then by transforming the original system into a special attack channel separation form so that an improved sliding mode observer with disturbance compensation is obtained to solve the secure state estimation problem. In addition, with the obtained observer's information, not only the actuator attack can be reconstructed but also the estimation of the disturbance can be obtained. Meanwhile, the influence of disturbance estimation error on attack reconstruction can be attenuated. Finally, simulations on a VTOL aircraft are presented to verify the effectiveness of the proposed scheme.