The position servo system, also known as the tracking system or the servo system, is usually a closed-loop control system. It takes the displacement as the controlled object and realizes the real-time matching of the input signal and the output displacement through components such as detection devices, signal conversion circuits, amplification devices, compensation devices, actuators, and power supply devices [1] [4]. Its core control structure adopts a triple closed-loop consisting of the position loop, the speed loop, and the current loop. Among them, the position loop is the outer control layer, and the servo stiffness depends on the position loop gain and the low-speed torque performance of the speed control unit [2]. According to the differences in detection devices, it can be divided into semi-closed and full-closed types: the former detects the motor shaft angle through a rotary encoder, while the latter directly measures the worktable displacement using a grating ruler [1].
The system control methods include error control, compound control, and model tracking control [4]. The actuators mostly use DC torque motors combined with servo amplifiers, and achieve digital position/velocity adjustment through multi-machine distributed control [5]. The application fields cover mechanical processing positioning, instrument recorders control, and computer peripheral devices. Typical technical solutions include the combined optimization of state feedback H∞ stability control and variable-domain fuzzy PID tracking control [3]. The performance indicators mainly assess the steady-state following error, positioning accuracy, and anti-interference ability. The debugging process requires coordinating the gain of the position loop and the position feedforward correction link [5]. The system operation also relies on energy equipment, protection devices, and other auxiliary equipment to ensure stable operation.