Improving Experimental Performance of Sliding Mode Control for a Two-Degree-of-Freedom Helicopter

In this paper, sliding mode control (SMC) is exploited to control pitch and yaw angles of a nonlinear two-degree-of-freedom (2-DOF) helicopter. Experimental results show that due to chattering phenomenon, SMC cannot control this plant. In order to remove this chattering, a boundary layer is considered around sliding surface but it causes steady-state error in outputs. Therefore, integral augmented is added to conventional SMC (SMC+I) to improve its performance. Finally, the experimental performance comparison between the conventional SMC, the integral augmented SMC and PID control based on linear quadratic regulator algorithm (LQR-PID) are discussed. The results imply to the superior performance of SMC+I method in improving input tracking, control effort, and steady state error for both pitch and yaw angles.