新型五自由度并联机床回零研究

Homing Research of a New Type of 5-DOF Parallel Machine Tool

基于栅格法提出了一种适合新型五自由度并联机床的两步回零法,即首先控制各驱动杆运动到事先经过标定的校准位置,并以此位置的标准值分别校准当前各个驱动杆的杆长,然后再驱动各杆回到规划好的初始零位,从而实现机床刀具的回零操作。同时,开发了相应的回零软件模块。该方法已应用于5-UPS/PRPU并联机床,实验证明:通过此方法可以准确可靠地实现该并联机床的回零操作。两步回零法避免了复杂的正解运算,且具有一定的通用性,对其它类型的并联机床也具有重要的参考价值。

Homing function is an important foundation on precision machining, and has a great effective on machining accuracy directly. Homing function becomes one of difficulty in the application of Parallel Machine Tool （PMT） because it＇s a kind of virtual axis machine tools. A two-step homing method was presented for a new kind of 5-DOF parallel machine tool based on the grid homing method which is that, at first, all the poles are driven to the position calibrated previously and the values of the pole length are updated by the standard values respectively, then the limbs are driven to the initial positions which can be gotten by the inverse kinematics solution of the home pose of the manipulator, and the manipulator comes to the home position. A software module was developed to realize the homing function. Two-step homing method avoids the complicated forward kinematics and has been applied to a 5-UPS/PRPU PMT successfully. The convenience and reliability are verified by the practice. The two-step homing method is a universal method and can be used in other type of parallel mechanisms.