The semi-closed loop of CNC grinder only reads the pulse number of the encoder at the end of the servo motor to be the actual position pulse, not the real position loop. If the encoder feedback of the servo motor is used, it is the semi-closed loop. The full closed-loop of NC machine tool is to read the load distance parameters directly, such as the actual position pulse of the screw grating ruler, which is the real closed-loop of the position loop. The control precision is high. If the grating ruler feedback on the screw rod is used, then it is closed loop.
In short, the semi-closed loop is the rotating part and the full-closed loop is the moving part. Do you understand?