为提高二自由度随动系统的跟踪精度,针对系统中存在的摩擦扰动问题,提出了一种基于LuGre模型的自适应摩擦补偿方法.该方法采用离线估计法对LuGre模型中未知参数进行估计,采用非线性观测器和自适应律估计LuGre摩擦模型中的不可测状态变量和易变未知参数.最后利用Lyapunov方法证明了整个闭环系统的渐进稳定性.仿真实验表明,该方法能有效补偿摩擦对二自由度随动系统低速性能的影响,从而提高跟踪精度.

In order to eliminate nonlinear effects of friction on 2-DOF tracking system and to improve its position-tracking accuracy, a novel adaptive friction compensation algorithm is proposed. Based on nonlinear characteristics of friction, a LuGre dynamic friction model is adopted to characterize friction in the 2-DOF tracking system. In this method, unknown parameters for the LuGre model are estimated in the manner of off-line; friction state and the inconstant parameters are estimated by using nonlinear observers and self-adaptive law. A Lyapunov-like argument proves the asymptotic stability of the whole closed-loop system. Experimental results indicate that the proposed method could effectively alleviate the influences of friction when the 2-DOF tracking system works with a lower speed, and could improve tracking accuracy for the 2-DOF tracking system accordingly.