直线电机驱动六自由度并联机构动力学特性研究

Dynamic Characteristics of 6-DOF Parallel Mechanism Driven by Linear Motor

直线电机驱动的六自由度并联机构可以实现高精度宽频带运动,在惯性单元校准、振动测试等领域具有广阔的应用前景。为了减小直线电机驱动对六自由度并联机构造成的幅值衰减问题,对机构进行动力学前馈控制分析。首先利用牛顿-欧拉法建立并联机构的动力学模型,简化动力学方程获得机构驱动力关系,在实验平台上进行实验,验证动力学模型准确性。利用传统运动学控制系统,结合动力学模型,设计一种动力学前馈控制方法,降低给定轨迹运动误差。实验结果表明,直线电机驱动的六自由度并联机构增加动力学前馈控制后,在沿X、Y、Z轴进行单自由度正弦运动时,运动误差分别下降55.5%、54.2%、59.8%。

Six-degrees of freedom parallel mechanisms driven by linear motors can realize high-precision and wide-band movements, and it had broad application prospects in inertial unit calibration, vibration testing and other fields. In order to reduce the amplitude attenuation of 6-DOF parallel mechanism caused by linear motor drive, dynamic feedforward control was analyzed for the mechanism. Firstly, the parameter model of the 6-DOF parallel mechanism was determined, and then the vector method was used to analyze the kinematic of the mechanism. Secondly, the dynamics model of the parallel mechanism used Newton-Euler principle. The driving force relationship of the mechanism was obtained by simplifying the dynamics equation. The driving force simulation curve was obtained by numerical analysis, and the experimental platform was built to obtain the experimental curve of the device driving force, which verified the accuracy of the dynamic model. Based on the classical motion closed loop control system and the dynamics model, a dynamic feedforward control method was designed to reduce the motion error of a given trajectory. Finally, experimental analysis of mechanism’s motion error in traditional kinematic control was done, and the motion error of the mechanism was compared. The experiment results showed that after added the dynamic feedforward control to the 6-DOF parallel mechanism driven by linear motor, the kinematic errors of the mechanism were reduced by 55.5%, 54.2% and 59.8%, when the mechanism carried out sinusoidal motion in X, Y and Z axes.