Motor Selection in Robotics

In this post on Motor Selection in Robotics, you will learn about different types of motors that the robots use and which type of motor is best suitable for a particular robot. Basically, the motor is an essential component of a robot and is responsible for making a robot move.

Every robot exhibits some kind of movement. Even if, it is a stationary robotic arm, it needs to move for the purpose of picking an object. Therefore, we use motors for imparting movement mechanism in a robot. In particular, Motors are used for a wide variety of movements in robots. Basically, motors convert electrical energy to mechanical energy which causes rotation in the motor.

Common Robotic Motors

There are many different types of motors available for building robots. The most common types of motors used in robotics are the stepper motor, the servo motor, the brushed DC motor, the brushless DC motor, AC Induction Motors, and the AC synchronous motors. In fact, the Motor Selection in Robotics is a significant aspect of building robots. With this purpose in mind, we explain each of these motors and their applications in robotics Each of these motors is explained below.below.

Stepper Motor
Stepper Motor

The Stepper Motor

You need a stepper motor in those robotic applications where the movement is required in steps since these motors rotate in steps. A stepper motor is capable of taking full rotation. However, the rotation is divided into an equal number of steps that we can control with great accuracy without any feedback mechanism. Also, the movement can be repeated.

The stepper motor is best suitable in applications where precise positioning and speed control is required. Hence, 3D printing equipment makes use of the stepper motor.

A stepper motor transforms an electric pulse into angular displacement which causes the motor to rotate. With every pulse of electricity, the rotor of the motor moves for 15o . Therefore a total of 24 electricity pulses will make the complete rotation.

The Servo Motor

Servo Motor
Servo Motor

The servo motor is another mother that we use in robots to control the angular and linear speed and position. The electric signal sent by the microcontroller determines the amount of movement and in turn, determines the desired position of the servo shaft. The Pulse Width Modulation (PWM) signal controls the position of the servo motor. The servo motor receives the PWM signal from a microcontroller like the one present in the Arduino board. Servo motors are high-speed motors however they have the drawback of having the high cost and not precisely control the rotation.

In robotics, we use servo motors to actuate movements. They are used in conveyor belts and robotic arms for various applications like packaging etc.

Brushed DC Motor

Brushed DC Motor
Brushed DC Motor

The Brushed DC motors use DC power to adjust the voltage and current level to move. A coil generates a magnetic field around the armature. Basically, the opposing polarity and attraction of rotor and stator cause rotation. The permanent magnet DC motors use brushes to acquire the voltage and current for the rotating armature. Actually the brush conducts the current from the source to the armature. However, they have the drawback of having low speed and poor heat dissipation.

Specifically, the mobile robots use the brushed DC motors and typically use the battery source to power the motor. Robotic cars also us the brushed DC motor in order to move the wheel.

Brushless DC Motor

Although, the brushless DC motor also works on the same principle as the brushed DC motor. However, both have a different construction. In the case of brushless DC motors, the permanent magnets rotate around a fixed armature causing the change in polarity in the coil. As a result, the motor rotates.

Brushless DC motors don’t use carbon brushes. As a result, there is much lesser internal resistance and therefore the better heat dissipation. Moreover, the brushless DC motors require low maintenance, are less noisy, and smaller in size. However, they are more expensive than the brushed DC motors.

AS the brushless DC motors are smaller in size, they make a good choice in Drones and Multicopters. Since they require low maintenance, brushless motors are also used in space robots. The other applications of brushless DC motors are the humanoid robots and radio-controlled vehicles.

AC Induction Motor

Basically, the AC induction motor is an asynchronous motor. They drive the electric current by electromagnetic induction from the magnetic field developed by the stator winding. The current, thus produced, generates the torque.

The construction of the AC induction motor is simple and inexpensive. In fact, they are more reliable, smaller in size, and require low maintenance.

In particular, the heavy load picking robots use AC Induction motors. Also, these motors also have applications in electrical vehicles and industrial robotics.

Summary

Motor Selection in Robotics depends on the type of robot that we are making along with its applications. In particular, bigger industrial robots use AC induction motors, whereas the smaller ones use lightweight motors. For instance, if we want to control the angular and linear movement, then we should use a servo motor. However, if want to do it in steps then the stepper motor is more suitable. For rotating a robotic wheel we may use a brushed DC motor. However, for building Drones we may use the lightweight brushless DC motors.


Related Topics

Industrial Robotics

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