In this paper, the issue of position tracking control of servo system with external disturbance is studied. A novel fractional-order sliding mode control (FOSMC) strategy is proposed. To be specific, firstly, the motor parameter drift, additional unknown disturbance and the uncertainty of load torque are considered as lumped disturbance, and a nonlinear disturbance observer (NDO) is designed to estimate the disturbance. Secondly, fractional-order terminal sliding mode surfaces (FOTSMS) are designed for the current loop and the position–velocity loop, respectively, as well as the FOSMC is presented based on NDO, in which FOSMC of position–velocity loop introduces second-order super-twisting term to reduce the chattering of the system. Furthermore, the stability of the FOSMC is analyzed. Finally, the effectiveness of the proposed algorithm is verified by simulations and experiments.

本文研究了带有外部干扰的伺服系统的位置跟踪控制问题。提出了一种新颖的分数阶滑模控制策略。具体来说，首先，将电机参数漂移，附加的未知扰动和负载转矩的不确定性视为集总扰动，并设计了一个非线性扰动观测器（NDO）来估计扰动。其次，分别为电流环和位置-速度环设计了分数阶终端滑模面（FOTSMS），并基于NDO提出了FOSMC，其中位置-速度环的FOSMC引入了二阶超级扭转术语可减少系统的抖动。此外，分析了FOSMC的稳定性。最后，