The servo motor

Definition of servo motor

A servo motor is an electro-mechanical device that uses feedback control to accurately and precisely control the movement of a shaft or output. It consists of a DC motor, a gearbox, a control circuit, and a potentiometer or an encoder for feedback. Servo motors are commonly used in various industrial applications, robotics, and hobbyist projects.

The control circuit of a servo motor receives an input signal, usually in the form of a pulse-width modulation (PWM) signal, which determines the desired position of the output shaft. The control circuit then compares the desired position to the actual position, which is determined by the feedback device, and adjusts the speed and direction of the motor to move the output shaft to the desired position. This closed-loop control system allows servo motors to provide accurate and precise control of movement.

Servo motors are available in various types and sizes, with different torque, speed, and accuracy specifications. They can rotate over a limited range of angles, typically from 0 to 180 degrees, or in some cases, provide continuous rotation. Servo motors are widely used in robotics, automation, CNC machines, cameras, remote-controlled vehicles, and other applications that require precise and controlled movement.

Types of servo motors

There are several types of servo motors, each with its own characteristics and applications. Here are some of the most common types:

MINI SERVO MOTOR SG-90 SG90

How to operate the servo motor?

To operate a servo motor, you typically need to provide it with a control signal that contains information about the desired position or angle of rotation. This is done using a microcontroller or other electronic device capable of generating the necessary signal.

The most common way to control a servo motor is to use a Pulse-Width Modulation (PWM) signal. The PWM signal consists of a series of pulses with varying width, where the width of each pulse corresponds to a specific position or angle of rotation. For example, a pulse with a width of 1ms might correspond to a position of 0 degrees, while a pulse with a width of 2ms might correspond to a position of 180 degrees.

To generate a PWM signal, you need to determine the appropriate frequency and duty cycle for your servo motor. The frequency should typically be between 50Hz and 300Hz, while the duty cycle should be between 5% and 10%. You can adjust the duty cycle to change the position or angle of rotation of the servo motor.

Once you have generated the PWM signal, you need to send it to the servo motor using a signal wire. The servo motor will then use the information in the signal to adjust its position or angle of rotation accordingly.

How to control the servomotor by the microcontroller ?

To control a servo motor with a microcontroller, you typically need to follow these steps:

1- Connect the servo motor to the microcontroller: The servo motor should have three wires, usually colored red, black, and yellow or white. The red wire should be connected to a power source, usually 5V or 6V, while the black wire should be connected to ground. The yellow or white wire should be connected to a digital pin on the microcontroller that is capable of generating a PWM signal.

2- Initialize the PWM signal: In the setup() function of your microcontroller code, you should initialize a PWM signal on the digital pin connected to the servo motor. The exact code for this will depend on the microcontroller you are using, but it typically involves setting the pin mode to OUTPUT and configuring the frequency and duty cycle of the PWM signal.

3- Set the position of the servo motor: In the loop() function of your code, you can set the position of the servo motor by adjusting the duty cycle of the PWM signal. To do this, you can use the analogWrite() function in Arduino or a similar function in other microcontroller platforms. The exact values you need to use will depend on the specifications of your servo motor, so you may need to experiment with different values to achieve the desired position.

4- Repeat as necessary: You can repeat step 3 as necessary to continuously adjust the position of the servo motor. You can also add additional code to control the servo motor based on input from sensors or other devices connected to the microcontroller.

Why do we use the servo motor ?

Servo motors are used in many applications where precise position or angle control of a mechanism is required. They are often used in motion control systems for robots, drones, remote control planes and cars, 3D printers, and CNC machines.

The main advantage of servo motors is their ability to provide precise position control. Using a feedback loop, the servo motor can adjust its position in real-time to follow a command signal with high accuracy. Servo motors are also very efficient in terms of energy consumption, as they only use energy when the position needs to be adjusted.

Due to their precision and energy efficiency, servo motors are widely used in the fields of robotics, automation, and motion control.

The servomotor and robotics

Servo motors play a crucial role in robotics as they provide precise control over the movement of robotic systems. In robotics, servo motors are often used to control the position and movement of robotic arms, grippers, and other end-effectors. By controlling the servo motor, a robot can achieve precise movements and positions required for various tasks such as assembly, manipulation, and pick-and-place operations.

Servo motors are also used in mobile robots to control their movement and steering. In such cases, servo motors are used in conjunction with wheels or other locomotion mechanisms to provide precise control over the speed and direction of the robot's movement.

In addition to their precise control capabilities, servo motors are also highly reliable and efficient, making them an ideal choice for use in robotics. They can operate for long periods without requiring maintenance or repairs, and can provide the high torque necessary for many robotic applications.