Second order sliding mode controller for twin rotor MIMO system

In this paper a twisting algorithm based second order sliding mode controller (SMC) is proposed to control a laboratory helicopter called the twin rotor multi-input multi-output (MIMO) system (TRMS). The TRMS model is pseudo decomposed into two subsystems and the coupling between them is considered as an uncertainty. A proportional integral based sliding surface is used for the vertical subsystem to reduce the steady state error. The proposed second order sliding mode technique shows robustness against the uncertainties and disturbances present in the TRMS system. Apart from imparting robustness, the proposed second order SMC law reduces the chattering effect in the control input. The performance of the proposed control scheme is demonstrated through simulation.