Open loop control: the control mode without position feedback device. The machining accuracy is generally about 0.02-0.05mm accuracy.
Semi-closed-loop control: refers to the angular displacement detection device installed on the open-loop control servo motor shaft.
Closed-loop control: It is a linear or rotary detection device directly at the corresponding position of the final moving part of the machine tool, and the directly measured displacement or angular displacement value is fed back to the comparator of the numerical control device for comparison with the input command displacement.
