Servo system performance requirements and parameters

Performance requirements

The basic requirements of the servo system are stability, accuracy and fast response.

Good stability: After the disturbance on the system disappears, the system can return to the original stable operation or the ability of the system to reach a new stable operation state under the action of the input command signal, under a given input or external interference After a short adjustment process, it can reach a new or return to the original equilibrium state;

High precision: The precision of the servo system refers to the accuracy with which the output can follow the input. As a precision machining CNC machine tool, the required positioning accuracy or contour machining accuracy is usually relatively high, and the allowable deviation is generally between 0.01 and 0.00lmm;

Good quick response: There are two meanings, one refers to how quickly the output changes with the input command signal during the dynamic response process, and the other refers to how quickly the dynamic response process ends. Fast response is one of the signs of the dynamic quality of the servo system, that is, the response of the tracking command signal is required to be fast. On the one hand, the transition process time is required to be short, generally within 200ms, or even less than tens of milliseconds; on the other hand, to meet the overshoot Requirements, the frontier of the transition process is required to be steep, that is, the rate of rise should be large.

High energy saving: Due to the rapid response of the servo system, the injection molding machine can quickly adjust the supply according to its own needs, which can effectively improve the power utilization rate of the injection molding machine, thereby achieving high efficiency and energy saving.

The main parameters

The main indicators to measure the performance of the servo system are bandwidth and accuracy. Bandwidth is abbreviated as bandwidth, which is specified by the frequency response characteristics of the system and reflects the fastness of the servo system's tracking. The greater the bandwidth, the better the speed. The bandwidth of the servo system is mainly limited by the inertia of the controlled object and the actuator. The greater the inertia, the narrower the bandwidth. The bandwidth of the general servo system is less than 15 Hz, and the bandwidth of the large-scale equipment servo system is below 1 to 2 Hz. Since the 1970s, due to the development of torque motors and high-sensitivity tachometers, the servo system has been directly driven, and non-linear factors such as backlash and elastic deformation have been eliminated or reduced, and the bandwidth has reached 50 Hz, which has been successfully applied In places such as long-range missiles, artificial satellites, and precision commanders. The accuracy of the servo system is mainly determined by the accuracy of the measuring components used.

Therefore, high-precision measuring components must be used in the servo system, such as precision potentiometers, self-aligning machines, resolvers, photoelectric encoders, gratings, magnetic grids, and ball grids. In addition, additional measures can also be taken to improve the accuracy of the system, such as connecting the measuring axis of the measuring element (such as a self-aligning machine) to the rotating shaft through a reducer, so that the rotation angle of the rotating shaft can be enlarged to improve the relative measurement accuracy. The servo system that adopts this kind of scheme is called fine measuring coarse measuring system or two-channel system. The angle measuring line that meshes with the rotating shaft through the reducer is called the fine reading channel, and the angle measuring line directly taken from the rotating shaft is called the coarse reading channel. 

Servo system application： 

1. Laser processing field

2. Robotics

3. The field of CNC lathes

4. Large-scale integrated circuit manufacturing office automation equipment

5. High-tech fields such as radar