高精度定位系统的摩擦力自适应前馈补偿

为了有效抑制机电系统摩擦力等外部扰动对系统动态性能的影响,针对直驱伺服系统中往复定位存在的摩擦力,提出了一种基于自适应前馈控制器的摩擦力补偿策略,此方法能够有效利用参考模型与被控对象的位置跟踪误差等信息,在线实时确定自适应控制率,在保证系统稳定的条件下,能够有效克服系统摩擦力及模型慢时变等引起的系统动态性能异常。针对直驱伺服系统建立其数学模型,根据数学模型确定自适应补偿环节的数学形式,并利用Lyapunov函数证明了自适应控制率的稳定性。最后通过试验表明,在跟踪正弦位置指令时,基于自适应前馈补偿的方法动态跟踪误差的均方根值为4.8μm,与PID无摩擦补偿控制方法相比,提高了47.3%,与传统模型参考自适应控制方法相比,提高了17.9%。综上所述,所提方法可以有效抑制系统摩擦力干扰,提高系统动态跟踪精度。

Friction Adaptive Feedforward Compensation for High Precision Positioning System

In order to suppress the influence of external disturbances such as friction on the dynamic performance of electromechanical systems,considering friction force for reciprocating positioning in direct drive servo system,a friction compensation strategy based on adaptive feedforward controller was proposed.The method can effectively utilize the information of reference model and position tracking error of controlled object and determine the control rate on line.Under the condition of guaranteeing the stability of the system,it can effectively overcome the abnormal dynamic performance of the system caused by system friction and slow time-varying model.The mathematical model of direct drive servo system and adaptive compensation component were established.Lyapunov function was adopted to guarantee the stability of the adaptive control rate.Finally,experiments show that the root mean square value of dynamic tracking error based on adaptive feedforward compensation is 4.8μm when tracking sinusoidal position commands,which is 47.3%higher than that of PID friction-free compensation control method and 17.9%higher than that of traditional model reference adaptive control method.In conclusion,the proposed method can effectively suppress the friction interference and improve the dynamic tracking accuracy of the system.