Integration of a 5-axis Spline Interpolation Controller in an Open CNC System

A 5-axis controller with curve interpolation function is developed to satisfy high-speed and high-precision computer numerical control (CNC) machining of machine parts with complex shapes in the authors-devised open CNC system. The instruction format of this interpolation method and the generation procedure of the numerical control (NC) files are introduced. The interpolation curves of both position vectors and orientation vectors constructed by the controller are C² continuous and independent of machine tool kinematics. The controller fits in with any 5-axis machine tools by configuring the related kinematics transformation module. The position curve is to be discretized in realtime using a truncated Taylor series expansion. Coordinated motions of linear axes and rotary axes are achieved by relating the orientation curve parameter to the position curve parameter in the machining process. The performance of the proposed controller is demonstrated by a practical example.