基于简化非线性观测器的LuGre动态摩擦力补偿

Simple nonlinear observer based dynamic LuGre friction compensation

针对机械手臂控制中使用LuGre模型进行动态摩擦力补偿时的内部摩擦力状态识别问题,在已有的非线性观测器和基于滑模的观测器的研究基础上,缩减非线性观测器中的冗余部分,提出简化非线性观测器.采用Lya-punov方法分析基于该观测器的自适应控制算法的稳定性,说明简化观测器的使用条件为加入合适的低通滤波器,消除速度采样高频波动对观测结果的影响.实验结果对比了3种内部摩擦力状态观测器在动态LuGre摩擦力补偿中对手臂控制效果的影响,采用3种观测器进行自适应跟踪控制时的位置跟踪精度分别可以达到0.010、0.009和0.004rad.实验表明,采用简化观测器可以取得比前2种观测器更好的自适应控制效果.

Obtaining the internal bristle-deflection state of the LuGre model is difficult in the control design when using the LuGre model to achieve dynamic friction compensation in the manipulator control.The observation result differs while using different observers to get the state.A simple nonlinear observer,which is a simplification of De Wit＇s nonlinear observer,was developed.The stability of the adaptive control was analyzed using the second Lyapunov theory.A low-pass filter was added to remove the influence of the high frequency noise of joint velocities measurements.The tracking accuracy using the nonlinear observer,the sliding-mode based observer and the simple nonlinear observer were 0.010,0.009 and 0.004 rad respectively.The better position tracking performance with simple nonlinear observer was verified through a series of experimental results.