A servo motor is a conventional motor with an additional control sensor installed as a feedback device. A stepper motor is a brushless motor that works in a board driver pair.

As mentioned earlier, a servo motor is a regular motor with an additional control sensor installed as a feedback device. During operation, the controller holds the motor in the set position. This interconnection principle makes it possible to achieve speeds and accuracies of up to 1 micron for the device.

In order to lock the movement in one position without moving it in the opposite direction, the controller must constantly switch the motor current to the opposite direction until the next command is received. In this way, skip steps are eliminated because the encoder constantly monitors the shaft deviation and corrects the error by reversing the direction of the motor each time.

Disadvantages of servo motors.

Expensive maintenance.

High cost.

A stepper motor is a brushless motor that operates in a board driver pair. Typically, stepper motors have several phases (windings) that are alternately turned on by the driver. The motor rotates by applying a short pulse to one of the stator windings to move the magnetic rotor.

Stepper motors are usually low power and are not suitable for high speed and continuous rotation.

Depending on the design of the rotor, the physical pitch of the motor can vary from 90 degrees to 0.9 degrees. Software tricks can be used to crush the angle, reduce drive noise, and improve accuracy by increasing the number of steps per revolution. Accuracy can be as high as 20 microns.

Despite their high accuracy, stepper motors have a significant disadvantage: they skip steps at higher loads because the motor has no feedback from the controller, and the latter cannot track the work of the stepper motor without an angle sensor.

Disadvantages of stepper motors.

Skipping steps at high accelerations and high loads.

Difficult to repair.

Except for the additional angle encoder lead, encoder stepper motors are no different from conventional motors. This solves the skip problem, but adds a lot of cost. In addition, a special controller with stepping error correction is necessary.

Despite these drawbacks, stepper motors are widely used in large industrial and domestic applications.

In heavy and high-precision machines (metal processing, laser cutting).

in light CNC (home 3D printers, engraving machines).

Robotics (robots with complex kinematics).

Toys (cars, airplanes).

Common problems

What are the similarities between stepper motors and servo motors?

Stepper motors are used in 3D printers and other devices that require precise control of movement. Servo motors are used in devices that need to move smoothly.

The similarity between stepper motors and servo motors is that they both use electromagnets to create motion.

What are the advantages of servo motors over stepper motors?

Servo motors can provide high levels of torque at high speeds. They are also easy to control and can be programmed to perform complex tasks, such as moving a robot arm in three dimensions. Servo controllers are also cheaper than stepper controllers and have lower power requirements, making them ideal for mobile robots such as automotive manufacturing or warehouse automation.

Why use stepper motors instead of servo motors?

The main difference between stepper motors and servo motors is that stepper motors are typically cheaper than servo motors. Stepper motors also do not require feedback from the load to determine how much power must be applied to the motor shaft.

Which is more powerful stepper or servo?

Stepper motors are not as powerful as servo motors because they are not as versatile. Servo motors can rotate continuously in any direction, while stepper motors can only rotate in discrete steps.

Stepper motors are more complex to design, but cheaper to manufacture and use. Servo motors are more expensive and require more power to work, but they offer better accuracy and control.