Abstract:

In order to reduce the machining accuracy caused by friction in a special-shaped surface grinding robot, an improved non-linear disturbance observer is proposed to observe and compensate it. The dynamic model of high-precision industrial manipulator is established. The nonlinear disturbance observer is designed based on the model and the stability analysis of the system is given by applying Lyapunov function stability theory. A typical friction model is introduced, and the observer is used to estimate the unmeasurable internal friction state, and the estimated value is applied to the friction compensation portion of the PD controller. Through simulation and experimental verification, the experimental results show that the observer can greatly improve the control precision of the system and reduce the tracking error of the simulation experiment. The control accuracy of the experimental platform is improved by more than 30%. The observer can greatly compensate the friction of the two-joint manipulator and track the joint position.

Key words: friction model, non-linear disturbance observer, curved surface processing robot, PD controller

摘要：

针对异型曲面打磨机器人中摩擦导致的加工精度降低的问题，提出了一种改进的非线性干扰观测器对其进行观测和补偿。建立了高精度工业机械臂的动力学模型，基于该模型设计非线性干扰观测器并应用李雅普诺夫函数稳定性理论给出了系统的稳定性分析。引入典型摩擦模型，利用观测器估计不可测的内部摩擦状态，并将估计值用于PD控制器中摩擦补偿部分。经过仿真以及实验验证，对比实验结果表明该观测器可以使系统的控制精度大幅提高，降低了仿真实验的跟踪误差，实验平台的控制精度提高了30%以上，能很好地补偿双关节机械手的摩擦力，更好地跟踪关节位置。

关键词: 摩擦模型, 非线性干扰观测器, 曲面加工机器人, PD控制器