Servo systems are frequently used actuators in industrial automation control projects. What is an actuator? It's the part that actually does the work. Taking a PLC and a servo system as an example, the PLC is the controller, equivalent to the brain of a person, while the servo system is equivalent to the hands and feet. When a person wants to walk, the brain sends neural signals for walking, which are transmitted to the legs and feet through the nervous system. During actual walking, the tactile sensations from walking are fed back to the brain through the nervous system, forming a closed circuit. The working process of a servo system is similar, which we will briefly explain.
A typical servo system consists of three parts: the motor body, the driver, and the encoder. The driver is responsible for driving the motor; the motor moves a certain position each time it receives a pulse signal. A pulse signal is generated simultaneously with the motor's rotation. The encoder in the servo system exists to compare the pulses received by the servo motor with the generated pulses. If the two pulses differ significantly, the encoder will correct the error. Through this closed-loop control, the servo motor can move precisely.
Modern servo systems mostly use brushless AC motors. Because they lack brushes, they consume less power, generate less electromagnetic interference, and experience virtually no wear, avoiding the inconvenience of internal cleaning after prolonged operation. So, how do servo motors connect to a PLC? The CANopen bus is sufficient, enabling master-slave control and allowing the servo motor to perform position, torque, and speed control.
