Sensors & Motors in Robotics
A complete beginner guide to the sensors and motors that make robots work.
Introduction
Sensors and motors are the two most important components in any robot.
Sensors allow robots to understand their environment. They detect light, distance, temperature, and movement.
Motors allow robots to move and perform physical actions. They power wheels, arms, and grippers.
Understanding sensors and motors is essential for building any type of robot.
Types of Sensors
Ultrasonic Sensor (HC-SR04)
Measures distance using sound waves. It sends out a sound pulse and measures how long it takes to bounce back.
Range: 2cm to 400cm. Commonly used for obstacle detection in robots.
Infrared (IR) Sensor
Detects objects and surfaces using infrared light. Used in line following robots to detect black lines on white surfaces.
Also used for obstacle detection at short range (2cm to 30cm).
Light Sensor (LDR)
Light Dependent Resistor changes resistance based on light intensity. Used in light-following robots and automatic lighting systems.
Temperature Sensor (LM35)
Measures temperature and outputs an analog voltage. Used in weather stations and temperature monitoring robots.
PIR Motion Sensor
Detects movement of warm objects like humans and animals. Used in security robots and automatic door systems.
Accelerometer & Gyroscope (MPU6050)
Measures acceleration and rotation. Used in self-balancing robots and drones to maintain stability.
Types of Motors
DC Motor
The simplest type of motor. It spins continuously when powered. Speed is controlled by changing voltage.
Used for robot wheels and simple movement. Requires a motor driver (like L298N) to control from Arduino.
Servo Motor
A motor that can rotate to a specific angle (usually 0 to 180 degrees). It holds its position precisely.
Used for robot arms, grippers, and steering mechanisms. Controlled directly from Arduino using PWM signals.
Stepper Motor
Moves in precise steps rather than continuous rotation. Each step is a fixed angle (usually 1.8 degrees).
Used in 3D printers, CNC machines, and robots that need precise positioning.
Brushless Motor
High-speed, efficient motor commonly used in drones and high-performance robots.
Requires an Electronic Speed Controller (ESC) to operate.
Motor Drivers
Arduino cannot directly power motors because motors need more current than Arduino can provide.
Motor drivers act as a bridge between Arduino and motors, providing the necessary power.
L298N
Controls 2 DC motors or 1 stepper motor. Supports up to 2A per channel.
L293D
Controls 2 DC motors. Simpler and smaller than L298N. Up to 600mA per channel.
TB6612FNG
Modern motor driver. More efficient than L298N with less heat generation.
PCA9685
Controls up to 16 servo motors using I2C communication. Great for robot arms.
Choosing the Right Sensor
The sensor you choose depends on what you want your robot to do.
- Obstacle avoidance — use Ultrasonic (HC-SR04) or IR sensor
- Line following — use IR sensor array
- Light tracking — use LDR (Light Dependent Resistor)
- Temperature monitoring — use LM35 or DHT11
- Balance control — use MPU6050 accelerometer and gyroscope
- Object detection — use PIR sensor or camera module
Simple Summary
Sensors are the eyes and ears of a robot. They help robots understand their surroundings.
Motors are the muscles of a robot. They allow robots to move and perform actions.
Motor drivers are needed to connect motors to Arduino safely.
Start with simple sensors like ultrasonic and IR, and simple DC motors for your first robot projects.
!Key Points
- Ultrasonic sensors measure distance using sound waves
- IR sensors detect objects and lines using infrared light
- DC motors provide continuous rotation for wheels
- Servo motors rotate to specific angles for precise control
- Motor drivers are required to power motors from Arduino