基于扰动和摩擦补偿的柔性机械臂系统非奇异快速终端滑模控制

本文针对系统中存在的关节摩擦、动力学参数不确定性和外部负载干扰等因素引起的柔性机械臂系统控制性能下降的问题,提出了一种基于扰动和摩擦补偿的非奇异快速终端滑模控制方法(NFTSMC-DE-FC).首先,设计扰动估计器(DE)对系统未知动态参数和负载干扰进行估计.然后,针对扰动估计器不能精确估计的关节摩擦力矩进行辨识.最后,利用滑模控制技术设计非奇异快速终端滑模控制器,并将扰动估计值和摩擦力辨识值以前馈的方式进行补偿,实现对柔性机械臂系统给定参考轨迹跟踪的准确性以及对外界扰动的鲁棒性.值得注意的是,与传统只使用扰动估计器的方法相比,本文考虑到了摩擦力等非线性因素的影响,并利用辨识技术对摩擦力进行辨识,提高了控制精度.利用Lyapunov稳定性定理从理论上证明了所设计的控制器可以保证闭环系统的稳定性.实验结果表明,相较于非奇异快速终端滑模控制方法(NFTSMC)和基于扰动估计器的非奇异快速终端滑模控制方法(NFTSMC-DE),所提方法提高了柔性机械臂系统的轨迹跟踪性能.

Nonsingular fast terminal-sliding-mode control for flexible manipulator system based on disturbance and friction compensation

To deal with the problem of degradation in control performance of the flexible manipulator system caused by joint friction, dynamic parameter uncertainty and external load disturbance, this paper proposes a nonsingular fast terminalsliding-mode control method based on the disturbance and friction compensation (NFTSMC-DE-FC). Firstly, a disturbance estimator (DE) is designed to estimate the unknown dynamic parameters and load disturbance of the system. Then the joint friction torques which can not be accurately estimated by disturbance estimator are identified. Finally, a nonsingular fast terminal sliding mode controller is designed by using the sliding mode control technology, and the disturbance estimates and friction identification values are compensated in a feedforward way to achieve the accuracy of tracking the given reference trajectory of the flexible manipulator system and the robustness to external disturbances. It is worth noting that compared with the traditional method which only uses disturbance estimator, the influence of nonlinear factors such as friction force is considered in this paper, and the friction is identified by using the identification technology, which improves the control accuracy. The Lyapunov stability theorem is used to prove that the designed controller can guarantee the stability of the closed-loop system. Experimental results show that compared with NFTSMC and NFTSMC-DE, the proposed method improves the trajectory tracking performance of the flexible manipulator system.