摩擦诱发极限环的分析与自适应主动控制

Analysis and Adaptive Active Control of Friction-induced Limit Cycle

摩擦诱发的自激振动对工程系统有很大的危害性。理解摩擦自激振动的成因以及寻找相应的振动控制策略对工程系统设计具有重要的理论和实际意义。通过对常用的两类摩擦模型数值特征分析探讨了摩擦自激振动问题,并提出一种基于模糊建模的自适应主动控制策略。讨论摩擦自激振动的解析解并对Coulomb摩擦和Stribeck摩擦产生的极限环进行数值仿真研究。考虑到传统摩擦力模型的缺陷以及不具备自学习和自适应环境的能力,提出采用自适应模糊建模技术在线逼近摩擦力并将辨识结果用在振动的主动控制器设计中。数值仿真结果表明基于自适应模糊系统补偿的PD主动控制技术的有效性,该主动控制对抑制极限环的振幅具有良好的效果,不但可以消除极限环,而且也可以消除稳态误差。

Friction-induced self-excited vibration is harmful to engineering systems.Understanding this phenomenon and developing some strategies to effectively control the vibration,has theoretical and practical significances.The reasons of friction self-excited vibration are explored through analyzing some numerical characteristics of two kinds of friction models.A fuzzy modeling technique based adaptive active control strategy is proposed to eliminate or reduce the amplitude of limit cycle and steady-state error.Analytic solutions of friction self-excited vibration are discussed and numerical simulations of limit cycles caused by Coulomb friction and Stribeck friction are carried out.In view of the defects and lack of self-learning ability and environmental adaptability of conventional friction models,it is proposed that the adaptive fuzzy modeling technique is adopted for on-line approximating the friction force,and the identification result is then employed in the active controller design.Simulation results demonstrate the effectiveness of the PD active control technique based on the adaptive fuzzy system compensation,which can effectively restrain the amplitude of limit cycle and eliminate the system steady-state error.