Extended State Observer-Based Robust Backstepping Sliding Mode Control for a Small-Size Helicopter

This paper addresses the design and application controller for a small-size unmanned aerial vehicle. A new robust sliding mode controller (SMC) is proposed to improve the performance under internal model uncertainty and external disturbance conditions. To precisely control the attitude and position, a new SMC based on the backstepping technique is formulated to guarantee the attitude system stability. To implement this controller, an extended state observer is used to estimate the unmeasurable states and external disturbances. Moreover, a new sliding mode control method with the backstepping technique is applied to ensure that the position system is stable. In addition, the Lyapunov theory demonstrates the stability of the attitude and position loops. Finally, the numerical experimental flight results are provided to illustrate the effectiveness and robustness of the proposed controller.