Discrete Sliding Mode Control of Spacecraft with Parametric Uncertainty Using Delay-Ahead Prediction

The continuous-time sliding mode controller has a good performance only for very small sampling period. In real-world conditions, we are interested in such controllers which take into account the sampling period in the design procedure. This paper deals with the optimal discrete-time sliding mode controller of a micro- spacecraft. In this regard, the mathematical model of a spacecraft has been presented in the state space form, and then an optimal sliding surface equation is chosen as a linear function of the system-state error. A delay ahead predictor and corrector are used in order to compensate the (i)actuators time-delay and (ii)plant–model mismatch and/or uncertainties. The stability condition is analyzed based on Lyapunov approach. Finally, the usefulness of the proposed controller monitored by the simulation.