Abstract: For machine tools,the contour tracking performance could be degraded due to the change of friction force and inertia in feed drive system.LuGre friction model was modified,and an adaptive robust control method based on this modified model was proposed.The modified model defined the transient deviation of bristle deformation as state variable so that static friction and dynamic friction were presented in parallel form in the model.It simplified the implementation of adaptation on system parameters and made the online estimates reflect their realistic physical meanings.The controller was synthesized with adaptive estimation and compensation while transient performance was guaranteed.A nonlinear feedback control with two segmental coefficients was introduced to replace the constant sliding-mode band design when robust control was synthesized,and difficulties to balance between steady accuracy and chattering near slide-mode surface were avoided during tuning process.The implementation of the proposed controller with the modified model was validated with hardware-in-loop experiments.Experimental comparisons in regard to the tracking performance with an amplitude-change sinusoidal reference indicated that the quadrant glitches due to friction disturbance could be considerably suppressed by the proposed controller.

Key words: friction model, numerical-control machine, adaptive estimation, slide-mode control, adaptive robust control

摘要： 针对数控进给中摩擦力和转动惯量变化导致伺服轨迹跟踪性能降低的问题,对摩擦力LuGre模型进行改进,并基于改进模型提出一种自适应鲁棒控制方法。改进模型定义棕毛体变形瞬态偏差为状态变量,使静态摩擦和动态摩擦分量平行地体现于摩擦力模型中;模型具有简化系统参数自适应手段、实现实际物理意义下参数在线估计的优点。控制器在完成自适应估计和补偿的同时能够保证瞬态特性,并采用双区间变量非线性反馈替代恒定近似滑模带设计,从而避免因权衡稳态精度与滑模抖动带来的整定困难。硬件在环实验验证了理论的有效性和可行性,变幅值正弦轨迹跟踪对比实验表明控制器对摩擦力跨象限误差具有显著的抑制作用。

关键词: 摩擦力模型, 数控机床, 自适应估计, 滑模控制, 自适应鲁棒控制