Different Types of Motors Used in Industrial Robotics

Industrial robotics plays a key role in global economics. In 2024, over 4.2 million robotic units were working in factories worldwide. These units standardize production processes, carrying them out with efficiency and precision. Many industries, from the automotive to the medical, leverage these capabilities to keep pace with demand.

All units rely on a motor to power their various functions, but these motors come in many forms and have unique pros and cons. A robot’s accuracy, speed, and longevity are largely informed by its motor.

Below, we will introduce you to the primary motors used in robotics and what you should do if a unit fails.

The Core Robotic Motor Types

The different types of motors in industrial robotics fall into a few distinct categories. The motors within those categories share a general design philosophy. Most robotic units rely on a single motor type, but some — such as a 6-axis arm — utilize multiple types.

Learn more about the motor types used in robotic arms below.

Servo Motors

Servo motors are among the most common motors in industrial robotics today. This is largely due to their extreme speed, precision and high power-to-weight ratio. These traits make them perfect for multi-axis robotic arms and for companies looking to get maximum value for their investment.

Servo motors get their name from the rotary actuator at their core. This mechanism facilitates the extreme precision that servo motors are known for by converting rotational motion into linear motion and vice versa. Velocity and acceleration are also controlled by the rotary actuator.

The actuator coordinates with other mechanisms within the servo motor, such as the shaft, controller and encoder or resolver, via a closed-loop system. The controller assesses the motor position in real time and makes adjustments to ensure it consistently aligns with the commanded position. This process keeps the motor moving properly and safely. As a result, servo motors are able to near perfectly repeat motions.

Servo motors and the units they power can cost more than other motor types, but they more than make up for that with their high-quality performance, speed and accuracy.

The following are common applications of servo motors:

• Computer numerical control (CNC) machining
• Automated welding
• Material handling
• Autonomous vehicle operation

Some of the most common servo motors include:

• Continuous rotation servo motors.
• Positional rotation servo motors.
• Linear servo motors.

Stepper Motors

Stepper motors are workhorses. They are precise and have high repeatability, allowing them to perform a wide range of actions over and over with great accuracy. They are not as fast as servo motors, but they do offer robust holding torque. Stepper motors leverage this holding torque to press against heavier loads and keep them in place when necessary. These motors are also simple to wire and control, which makes them easy to set up for less complex automated tasks.

This type of motor gets its name from the way its shaft rotates. The shaft always moves a fixed number of degrees, each of which is referred to as a step. The step system makes it easy to determine the shaft’s angular position while also simplifying the wiring and controlling processes. The simplicity of the motor also lowers its overall cost.

Where most servo motors use a closed-loop system, stepper motors use an open-loop system. The controller does not receive real-time feedback from the rest of the motor and adjust accordingly. Instead, the controller simply assumes the motor has moved based on the issued commands. This approach can result in positional errors and motor overheating in some cases.

Stepper motors are widely used due to their cost-effectiveness and reliable precision. Some of the most common applications include:

• Indexing conveyor belts.
• Powering 3D printer axes.
• Driving lead screws in linear actuators.
• Regulating apertures in digital single-lens reflex (DSLR) cameras.

The three main stepper motor sub-types include:

• Permanent magnet stepper motors.
• Variable reluctance stepper motors.
• Hybrid stepper motors.

Direct Current Motors

Many motors are powered by direct currents. Both servo and stepper motors are technically DC motors, as they use direct rather than alternating currents. Motors with direct currents are known for their high starting torque and simple speed control systems.

The category of DC motors in robotics is a bit narrower. It tends to refer to brushed and brushless DC motors specifically. Both of these types have unique performance and maintenance needs that set them apart from other motors that use direct currents.

Brushless DC motors are extremely common in modern robotics due to their lengthy lifespan, low maintenance requirements and high levels of efficiency. They use a system of rotors, magnets and stators to generate power. This architecture leads to less physical wear and electrical arcing, but a more complex controller is needed to manage the motor windings as a result.

Brushless DC motors are often used in:

• High-speed spindles.
• Robotic joints that rely on sustained torque.
• Drone propellers.

Brushed DC motors are simpler and more cost-effective than their brushless counterparts. As a result, they are easier to wire and control. These systems also rely on magnets and rotors to generate power, but they use a driver to supply the driving current the motor needs rather than an electronic commutation. The speed of these motors is then adjusted by altering the supply voltage that is transmitted through the motor’s brushes.

Brushed DC motors are often used in:

• Autonomous mobile robots (AMRs).
• Simple grippers.
• Automated security cameras.

What to Do When Robotic Motors Fail

The type of motor used in robotics will directly affect the maintenance protocols. Motor failure can be highly problematic for companies that rely on robotics. It can cause unplanned downtime and production losses, leading to unnecessary expenses. While we would all like to avoid this problem entirely, it is a natural part of the life cycle of all robotics motors.

What should you do when repairs are necessary? Some companies are content to simply replace the motor entirely. This approach is not recommended, as it is unnecessarily expensive and can result in additional downtime.

The better option is to partner with a service and repair company. Professional repair is often much faster and less expensive. The repair technicians will also assess the health of the motor as a whole and determine if it is living up to its performance specifications after the repair.

Contact Global Electronic Services Today

Global Electronic Services has repaired industrial electronics and motors for over 60,000 of the world’s best manufacturers and distributors. Send in an RMA Submission form or contact us at 877-249-1701 to learn how we can service your machines.