基于多采样率控制的伺服系统摩擦补偿研究

Friction Compensator Based on Multi-rate Control in Servo Drives System

摩擦是造成伺服系统在低速、速度换向等条件下精度严重下降的强非线性因素之一。采用基于模型的摩擦补偿可以有效地预测摩擦力,并实现误差补偿。在高速、高加速度的条件下,换向时摩擦变化剧烈,且过渡时间较短,采用单采样率控制补偿器结构很难实现较好的补偿效果,因此提出一种基于多采样率的摩擦补偿器结构。该补偿器利用伺服系统多环、多采样率的结构特点和指令轨迹细化方法,在不改变系统控制器结构和稳定性的条件下,通过分离前馈补偿器和反馈控制器的采样周期,以实现更为精细的前馈摩擦补偿量计算。实验结果表明,多采样率摩擦补偿器结构能够充分利用伺服控制器的结构特点和摩擦模型的预测结果,而且避免了复杂控制器的设计过程,取得了更有效的摩擦误差补偿效果。

Friction is a kind of strong nonlinear factor that severely degrades accuracy in the condition of low speed, velocity reverse, etc. The friction compensation based on model can effectively predict the friction amplitude and compensate the dynamic error. But the transition time of velocity reverse is very short at high speed and high acceleration condition, so the traditional single-rate friction compensation methods have deficient output control. A novel multi-rate friction compensator was proposed. By utilizing the multi-rate controller structure and trajectory refinement, the compensator could output more elaborate compensation component through separating the sample cycle of the friction feedforward compensator and feedback controller without altering feedback control cycle. The complex control system design process was avoided. The experimental result demonstrates that the better effect of error compensation control can be achieved with the nmlti-rate friction compensator in a wide speed range.