In recent years, servo motors have become increasingly popular, with their superior performance receiving widespread praise from users. Servo motors are a type of motor that also includes stepper motors, brushless DC motors, torque motors, and asynchronous motors. Servo motors are widely used in various control systems, converting input voltage signals into mechanical outputs on the motor shaft to drive controlled components, thereby achieving control objectives.
A servo motor encoder is a sensor installed on a servo motor to measure the position of the magnetic poles and the rotation angle and speed of the servo motor. On a servo motor, the encoder serves as a component for speed and position feedback in the servo system.
Based on the different physical media, servo motor encoders can be divided into photoelectric encoders and magnetoelectric encoders. In addition, rotary transformers are also a special type of servo encoder. The market mainly uses photoelectric encoders, but magnetoelectric encoders, as a rising star, have the characteristics of reliability, low price, and resistance to pollution, and are trending towards surpassing photoelectric encoders.
So, what is the working principle of a servo motor encoder?
Simply put, the shaft encoder of a servo motor is used to feed back the rotation angle (position) of the servo motor to the servo driver. The servo driver receives the feedback signal to control the rotation of the servo motor, forming a closed-loop control to precisely control the rotation position and speed of the servo motor.
For high-precision positioning, a PLC typically sends pulses, which are then driven by a dedicated servo motor to achieve the positioning effect. The encoder behind the dedicated servo motor can provide feedback on the servo motor's stroke and compare it with the pulses sent by the PLC to achieve a closed-loop system.
A servo motor only accepts instructions to complete a specific action of a motor. While ordinary motors can also be used as servo motors, servo systems are far more complex. Adding an encoder to a DC motor only achieves a closed-loop operation; a servo system involves many control details, such as torque and over-torque. After the encoder generates an electrical signal, it is processed by a digital control unit (CNC), a programmable logic controller (PLC), and other control systems. These sensors are mainly used in machine tools, material processing, motor feedback systems, and measurement and control equipment.
The reading system is based on the rotation of a radially graduated dial, which consists of alternating transparent and opaque windows. The entire system is vertically illuminated by an infrared light source so that the light projects the image on the plate onto the surface of a receiver covered with a grating called a collimator, which has the same window as the optical disc.
The receiver's function is to sense the changes in light caused by the rotation of the optical disc, and then convert these changes in light into corresponding changes in electricity.
Generally, a rotary encoder can also obtain a speed signal, which is fed back to the frequency converter to adjust the output data of the frequency converter.
Precautions for using servo motor encoders: Servo encoders are generally quite fragile inside servo motors, so do not easily open the encoder code disk and circuit. If repair is needed, please have it handled by a professional.
In addition, avoid directly affecting the shaft during installation to prevent damage to the encoder.
Flexible connectors should be used to connect the encoder shaft of the servo motor to the machine.
Do not press the connector too hard when installing it.
Even when using connectors, improper installation may still increase the load on the shaft beyond its allowable capacity or cause core pulling, so special care should be taken.
Do not disassemble the encoder, as this will damage the oil residue and compromise its protective properties. Drip-proof products should not be immersed in water or surface water, and oil should be kept clean regularly.
