Research On Motion Control Of Parallel Machine Tool Based On PA Numerical Control System

The traditional CNC system exist many defect:Different products are incompatible, resulting in the operating cycle shortened and the cost increased; Lacking of connection with other network equipment, blocked the information channel of the enterprise; Users can not develop new functions according to their own needs, while the CNC system fails can only turn to the manufacturer,etc. The research on open CNC system is of great practical significance to solve these defect.In this paper, the open CNC system of the 3-(2SPS) parallel milling machine is analyzed and researched, the main content are followings:Firstly, the kinematics analyzing of the machine tool is carried out according to the characteristics of machine tools and related parameters, The position equations of the machine tool is derived, in order to solve the positive and inverse solutions;And the method of transformation of workpiece coordinate into machine tool coordinate is discussed.Secondly, this paper introduces the PA open CNC system, describes the traditional CNC system interpolation method, and summarizes the shortcomings,then a new interpolation method-NURBS interpolation method is given, which can effectively make up the deficiency of the traditional interpolation method.Again, due to the uneven distribution of the stiffness in the space,the main cutting force should be processed at good stiffness direction, which the path planning of the moving platform needs to be carried out. Several common motion laws of the moving platform are given, and a more stable and smooth motion law is put forward based on these laws.Finally, in view of a redundant slider added to this machine tool, leading to the existence of a variety of inverse motion combination, which need to choose a best form according to a certain optimization criteria, so that the machine can maintain a good performance while it works.