How Servo Motors Work

How Servo Motors Work

Servo motors are the heart of electrically operated equipment such as elevators, rudders, walking robots and operating grippers.serve motor They are capable of delivering high torque over a range of speeds, making them ideal for precise motion control.serve motor They work in close conjunction with sensors that provide feedback to the closed-loop system. These sensors can be a potentiometer, a Hall-effect device, a tachometer, an encoder or a linear transducer. They are also powered by control electronics that power the motors and compare the feedback data to a command reference to ensure they are performing as expected.

An electric current is sent through a coil in the stator of the motor, creating magnetic fields.serve motor This generates current in the rotor, causing it to follow the magnetic field and rotate. When the rotor is at the desired position, the current in the coil stops and the motor halts rotation. If the rotor is not at the desired position, an electrical pulse of proper width is sent via a control wire to change its direction.

The servo controller (also called a servo amplifier or a servo converter) is a key component of this type of closed-loop system.serve motor It converts a software user interface signal into the appropriate signals to control the motor’s speed, position and torque. It also controls how much current is being applied to the servo motor and at what frequency, which affects torque. The higher the frequency, the greater the amount of torque produced and the faster the response time.

A potentiometer mounted on the servo motor output shaft provides a feedback signal that is proportional to its angular position.serve motor The feedback signal generated by the potentiometer is sent to the servo amplifier, which then compares it with an externally-applied input voltage that is proportional to the commanded position of the rotor. When the servo amplifier sees that the motor is at its target position, it stops sending current to the motor.

This is known as closed-loop angular position control.serve motor The servo motor is also paired with a sensor that detects the number of rotations of the rotor shaft, called an encoder or an optical encoder. An encoder can measure up to 28,000 rotations per second, providing very accurate position feedback for the motor.

As the motor turns, it generates an error signal that is proportional to its angular velocity.serve motor The servo amplifier calculates the difference between the error signal and an externally-applied voltage that is proportional to the desired velocity, which it sends to the servo motor through a control wire. The motor will accelerate, maintain and decelerate to the desired position based on this feedback information. The entire process takes place within milliseconds, which makes servo motors ideal for precise motion control. The system can be tuned to a very fine level of detail, which makes it highly suitable for complex work such as robotic arms or machine tools. In fact, these types of systems are ideally suited for high-precision work in the aerospace and medical industries.