Semi-closed loop CNC system and full closed loop CNC system:

1. A semi-closed loop control system is a control system in which an angular displacement detection device is installed in the servo mechanism of an open loop control system. By detecting the ball screw angle of the servo mechanism, the displacement of the moving part is indirectly detected, and then fed back to the comparator of the numerical control device, and compared with the input original command displacement value, the difference after comparison is used for control, so that the moving part supplements the displacement until the difference is eliminated. The accuracy, speed and dynamic characteristics that can be achieved by the servo mechanism of the semi-closed loop control system are better than those of the open loop servo mechanism, and are adopted by most small and medium-sized CNC machine tools;

2. A full closed loop control system is a type of control system. Specifically, it refers to sending part or all of the output of the control system back to the input end of the system through certain methods and devices, and then comparing the feedback information with the original input information, and applying the comparison result to the system for control to prevent the system from deviating from the predetermined target. The full closed loop control system uses a negative feedback mechanism, that is, an automatic control system with a closed loop composed of a signal forward path and a feedback path, also known as a feedback control system.