Different types of Drives and Motors Used in Robotics

Robotics is the most trending topic and technology in the modern world. From any background, it does not matter but you have a basic knowledge of robotics. That is why today we bring an important topic from robotics technology which is the different types of drives and motors used in Robotics. We know the motor is a very important part of any robotics system. In fact, the definition also tells us that a device that is movable, sensible, actionable, and controllable can be called a robot.

First of all, let's know what is a motor. The motor is an electromechanical device that converts electrical energy into mechanical energy in terms of movements or rotation. The motor is used in robots to move their arms, fingers, legs, or any portion as per requirements. In fact, we cannot think of a robot without any robot. In robotics applications, the electrical motors are controlled using 'H' Bridge circuits, microprocessors or microcontrollers, driver circuits, etc. The torque and speed of the motor are the most important factors when choosing a motor for robotics.

Types of Motor Used in Robotics

The common types of motors used in robots are,

1. Brushed DC Motor
2. Brushless DC Motor
3. Stepper Motor
4. Servo Motor
5. Geared DC Motor
6. AC Motor

Read Also: How Armature Reaction effects the DC Machine Explained

Brushed DC Motor

A brushed DC motor is a very simple type of DC motor that has two brushes to conduct current to the rotor part. It has two brushes placed on the commutator of the motor. Generally, the power supply is applied to these brushes, and the current conducts through these brushes to the rotor. Brushed DC motors are also available in various types but permanent magnet motors are mostly used. You will see the uses of brushed DC motors in kid's toys, adjustable car seats, wing controllers, fans, etc.

Brushed motors are very easy to control they do not need any special types of control circuits. Just applying a DC voltage to the brush can rotate the DC Motor and we get a proportional speed to the voltage.

The brushed DC motor has two main parts - 1. Stator Parts and 2. Rotor Parts

The stator contains a permanent magnet to create magnetic flux. The rotor contains armature windings and coils. The stator part is stationary but the rotor part means the armature rotates with respect to the brush. We apply DC supply to the motor but in actual armature gets the alternating current and this happens due to the commutator.

Advantages:

• Low Cost
• Easy to Construct and install
• Good Efficiency
• Low power consumption

Disadvantages:

• Limited lifespan of the brush
• Electrical noise
• Spark at the brush and commutator
• Not precise control

Read Also: How DC Motor Works on the Principle of Lorentz Law?

Brushless DC Motor or BLDC Motor

BLDC motor is also a very important type of motor widely used in Robotics applications. As its name suggests there are no brush arrangements for the current conduction. It also has two main parts stator parts and rotor parts. The rotor part is built with permanent magnets whereas the stator parts are built with magnetic coils. These stator coils are connected with a dedicated electronic circuit. The electronic circuit controls those stator coils in such a way that the motor rotates according to desired outputs.

Generally, energizing the coils in a sequence causes to rotate the rotor. Here, the polarization of the coils is obtained by changing the direction of the current flow. Here, a feedback circuit plays a very important role because the measurement of angular position is must required.

Advantages:

• Precise Control
• Less Noisy
• faster
• high efficiency
• more reliable

Disadvantages:

• Complex in design
• Complex control system
• Costlier

Read Also: DC Motor Diagram and Constructional Parts

Geared DC Motor

The geared motor has the same internal construction as other motors in fact it has an additional gear mechanism. Basically, the gear mechanism is used to vary the speed and torque. We know that speed and torque are opposite to each other which means if the speed has increased the torque will be decreased and vice versa. So the mechanism also does the same. It increases or decreases torque at the output. RPM is not only controlled by the gear mechanism but it can be controlled electrically also. RPM is directly proportional to the applied voltage. For example, a 6-12V rated motor will give east RPM at 6V and maximum RPM at 12V.

Stepper Motor

The Stepper motor is also a widely used motor. It is an electromechanical device that mainly converts the pulse signal into discrete mechanical movement. Yes, its operation little bit different from the other motors. Other motors operate with a continuous signal and provide a continuous rotation whereas the stepper provides a discrete rotation. For example, position control in printers, plotter machines, Milling Machines, etc where stepper is very helpful. The electronic pulse signal is applied to the stepper motor in a proper sequence and the direction of the motor shaft rotation is directly related to these applied pulses. On the other hand, the speed of the rotor shaft is directly related to the frequency of the applied pulses. A stepper motor can give a better performance in an open loop system.

Read Also: Actual Difference between Servo Motor and Stepper Motor

Servo Motor

A Servo motor is almost similar to a stepper motor. The Stepper motor is associated with precise movement whereas the servo motor is associated with precise rotation. Yes, it can rotate an object with greater precision. It is very helpful to rotate an object at a specific angle or distance. The main advantage of a servo motor is it can provide very high torque in a small package. There are both AC and DC servo motors available in the market. DC servo motors are mostly used in robotics applications because they are powered by a DC Supply.

You can see the applications of servo motors in a toy car, CD, DVD players, etc. Servo Motor works in a closed-loop control system. 

AC Motor

AC Motors are those that operate with an alternating power supply. In robotics applications, AC motors are rarely used. In a large system such as an industrial application, AC motors are used. Otherwise, most of the robotic machines and devices use DC motors only as they are powered by a DC supply. So it is easy to distribute power to all equipment.

Read Also: Electric Motor Control Procedure, Methods, Devices, Circuits

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