Model of a CNC Feed Drive for On-Site Tuning of the Controllers for Single Axis Motion

The accuracy of CNC machine-tools is heavily influenced by the correct tuning of the feed drives controllers. While an initial tuning is performed by the machine-tool manufactures, in time the values have to be changed by the user in order to preserve positioning and contouring accuracy of the machine. This paper presents a model of a CNC feed drive, for a particular CNC machine-tool, but with a high degree of generality. The objective is to provide the user the necessary knowledge, together with a simple, yet accurate simulation tool, in order to assist him in the process of tuning the controllers.

Simulation Study of Motion Control for X-Y Table with a Novel Direct Contour Controller

Contouring accuracy is important in multi-axis computerized numerical control (CNC) machining. This paper proposed a direct contouring control (DCC) strategy for CNC contouring applications. The DCC implements velocity control in the tangential direction and position control in the normal direction, which is different from conventional axis-based position control schemes. The real-time contouring state monitoring method is introduced to obtain the necessary information for DCC. The motion profile is defined as a velocity-displacement function along the tool path. A new velocity interpolator is proposed to generate the tangential velocity command for DCC. A simulation experiment based on X-Y table model with circular trajectory is conducted to test the performance of the proposed method. The results show that the DCC can achieve high contour accuracy with a simple structure.