干扰观测器在一种非线性刚度驱动器中的应用

摘要

According to"low load,low stiffness;high load,high stiffness",nonlinear stiffness compliant actuators (NSCA)are developed to optimize the workspace of variable stiffness actuators (VSA).Besides, NSCAs are able to perform high force resolution under small interactive force and fast response under large in-teractive force.However,because it is difficult to set up accurate mathematic models for interference and noise in the complex human robot interaction environment,control accuracy of the system is deteriorated se-verely.Thus,disturbance observer (DOB),which evaluates disturbance based on observation and then com-pensates error,is discussed in this paper to settle these problems for NSCA.First,control system state func-tion and DOB are built up according to dynamic model of NSCA.Lyapunov stability is used to analyze system stability and stable conditions are given.Second,based on the stable conditions,DOB control scheme is ap-plied in NSCA control system to obtain experimental data.Finally,the experimental results shows that,using DOB reduces stiffness error of NSCA by 85 .7 1% in the mode of impedance control and enhances control pre-cision of the actuator obviously.%基于"小负载,低刚度;大负载,高刚度"的非线性刚度驱动器(NSCA)优化了可变刚度驱动器(VSA)的工作区间,具有交互力小时力分辨率高,交互力大时响应速度快的优点.但在复杂的人机交互控制过程中,由于难以对干扰和噪声建立准确的数学模型,故而严重影响到系统的控制精度.因此,本文利用基于观测估计干扰并实施补偿的干扰观测器(DOB)解决非线性刚度驱动器的此类问题.首先,根据非线性刚度驱动器动力学模型建立了控制系统状态方程以及干扰观测器,利用李雅普诺夫方法分析系统稳定性并给出了稳定条件;然后,根据该稳定条件将干扰观测器算法应用于非线性刚度驱动器控制系统中得到实验数据.最后,实验结果表明,采用干扰观测器算法将非线性刚度驱动器在阻抗控制模式下的刚度误差降低了85 .7 1%,大幅度提高了驱动器控制精度.