Sliding and Terminal Sliding Mode control of a 3-axis flight motion simulator

Flight motion simulators are used to simulate the motion of flying objects in a laboratory setting. A 3-axis flight motion simulator as a three degrees-of-freedom table is a nonlinear, multivariable system. Most research and control methods have been proposed for these types of tables are based on linearized models of these systems and then using linear control methods. Furthermore for dealing with the problem of being multivariable, these tables are considered as a three single input-single output systems, with neglecting and minimizing coupling effects among gimbals. In this paper, unlike previous researches, we use the complete and full dynamic equations of a 3-axis flight motion simulator as a real plant, including the effect of wobble, unbalancy, missing the orthogonality of axes and gravity terms. It is also clear that because of uncertainty, robust control methods are needed. These equations are highly nonlinear and multivariable. Two nonlinear multivariable robust methods are developed for tracking and regulation purposes; include Sliding Mode and Terminal Sliding Mode controls. In the presence of external disturbances, the simulation results are presented to verify the efficiency of the proposed control systems.