平面3-RRR柔性并联机构自激振动智能控制

Self-excited Vibration Control of Planar 3-RRR Flexible Parallel Manipulator Based on Intelligent Controllers

平面3-RRR柔性并联机构的闭链耦合约束作用导致其奇异性复杂,而机构在逆向雅可比奇异位形附近易发生自激振动,严重影响机构的精度并对其结构造成破坏。为了让并联机构重新恢复正常工作,设计振动主动控制算法对自激振动进行抑制。首先,建立了机构的逆向运动学模型,并基于速度雅可比矩阵获得并联机构的奇异判定条件;其次,在完成自激振动产生机理分析的基础上,对振动加速度信号进行了滤波和移相处理;然后,结合加速度反馈与位置误差补偿,设计了模糊神经网络非线性控制器、反向传播(back propagation,简称BP)神经网络自抗扰控制器;最后,通过振动主动控制实验,验证了2种智能控制算法的有效性。实验结果表明,所设计的2种控制算法能够在保障并联机构位置精度的条件下,对自激振动进行快速且有效的抑制。

The singularity of the planar 3-RRR flexible parallel manipulator is complicated due to the closedchain coupling effect.The parallel manipulator is easy to occur self-excited vibration near the inverse Jacobian singular configurations,which seriously affects the accuracy of the mechanism and damages its structure.In order to restore the parallel mechanism to normal operation,active vibration controllers are designed to suppress the self-excited vibration.Firstly,the inverse kinematics model of the mechanism is established,and the singularity judgement conditions of the parallel mechanism are obtained based on the velocity Jacobian matrix.On the basis of analyzing the mechanism of self-excited vibration,the vibration acceleration signal is filtered and phase shifted.Combining acceleration feedback and position error compensation,a fuzzy neural network nonlinear controller and BP neural network active disturbance rejection controller are designed.Finally,the effectiveness of the two intelligent controllers is verified by conducting active vibration control experiments.The experimental results show that the two control algorithms can quickly and effectively suppress the self-excited vibration while ensuring the positioning accuracy of the parallel manipulator.