Suboptimal Integral Sliding Mode Attitude Control of a Unmanned Aerial Vehicle Under Input Saturation

Abstract

In this paper, the attitude control problem for a nonlinear unmanned aerial vehicle (UAV) is investigated, and a suboptimal integral sliding mode controller is designed under input saturation. Firstly, it is illustrated that the constrained control is applicable in suboptimal sliding mode control, and the range of values for the suboptimal control is defined. Secondly, the online feedback of the input saturation is achieved by taking advantage of the state dependent Riccati equation (SDRE) method. The designed controller not only eliminates the tracking error both in attitude tracking of the UAV, but also approximately minimizes the cost function of the system. Simulation results are presented in the end of the paper to verify that the suboptimal integral sliding mode controller achieves a good performance and can reject the external disturbances efficiently under input saturation.