Semi-closed loop servo system is the mostly used
system in CNC machine tool servo systems; Semi-closed loop servo system works
the same with closed loop servo system, it similarly uses stepper
motor as motor driver like closed loop servo system, you can use
the pulse motor installed in encoder, brushless resolver
or tachometer generator works as the position / speed detection device to form
semi-closed loop position control system, The feedback signal of the system get
from the system or screw on the motor shaft, Feeding system in the mechanical
transmission device is outside the feedback loop, the nonlinear stiffness has
not influence on the system stability, installation is more convenient for the
operation. Machine tool’s positioning accuracy has relationship with the
mechanical transmission precision. In the case of non-high precision
transmission, compensation function can be used to improve the accuracy of the
process satisfaction. Therefore, semi-closed loop servo system is widely used
in CNC machine tools.