Abstract : This paper introduces the structure and principle of the open motion controller PMAC and uses it as the CNC system of an experimental grinding machine. The grinding principle of elliptical parts and the time-base trigger control function of PMAC are explained. A mathematical model of the elliptical part is established, and its grinding program is compiled, realizing the precision grinding of this type of part. Keywords : ellipse; grinding; PMAC; linear motor; time-base control. With the development of modern industry, elliptical parts are widely used in mechanical, radio, and computer industries. For example, the pistons of modern automobile engines are no longer cylindrical but have an elliptical drum shape; mechanical shafts, due to increased strength and service life, are no longer cylindrical but rhomboids composed of several arc segments. However, traditional grinding machines can only process parts with circular cross-sections. In recent years, with the development of linear motors with high-frequency response characteristics, CNC grinding of non-circular cross-section parts has become possible, thus giving rise to CNC non-circular grinding technology. The time-base control function of PMAC is applied to enable the workpiece and the grinding wheel mounted on the linear motor to move in a time-base triggered manner, thereby grinding the required elliptical part contour. 1 PMAC Structure and Working Principle PMAC (programmable multi-axis controller) is an open multi-axis motion controller launched by DeitaTau in the 1990s. It provides basic CNC functions such as motion control, discrete control, internal processing, and interaction with the host machine. It is based on the Motorola 56001 (20/30MHz) 24-bit fixed-point DSP. It fully utilizes the powerful functions of DSP technology. Servo control includes PID plus Notch and speed and acceleration feedforward control. It allows programming in multiple languages ​​and is a truly open platform. In this study, the author used a two-axis Mini-PMAC control card as the CNC system of the grinding machine. Its structure is shown in Figure 1. [b][align=center]For more details, please click: Precision Grinding of Elliptical Parts Based on PMAC[/align][/b]