5-Axis A-Spline Iterpolation Function and Its Realization Strategy

The current 5-axis coordinated linear interpolation method results in low-speed, low-accuracy and enormous numerical control (NC) files in sculptured surface machining. An instruction format with AKIMA spline curves suitable for 5-axis coordinated real-time interpolation is presented by making use of the advantages of AKIMA curves to represent spatial curves. Curve through position vectors in the machining path is constructed using AKIMA spline method. The related orientation vector to each position vector is calculated by angles of the machine tool rotation axis. Then curve through orientation vectors is achieved by AKIMA method too. Real-time interpolation of these curves is accomplished with a method of truncated Taylor series expansion. A controller with this interpolation method is developed in an open computer numerical control (CNC) system developed by ourselves. The performance of the proposed controller is demonstrated using a practical example.