Micro:bit two-wheeled robot avoiding obstacles

Tutorial plan

1- What is a robot avoiding obstacles ?

2- Operation of Micro:bit robot avoiding obstacles

3- Robot components

4- Mounting of robot

5- Programming Micro:bit board with Makecode

What is a robot avoiding obstacles ?

A robot avoiding obstacles refers to a robotic system designed to navigate through an environment while detecting and steering clear of objects or barriers in its path. Obstacle avoidance is a critical aspect of mobile robotics, enabling robots to move safely and autonomously without collisions.

How Obstacle Avoidance Works

1- Detection: The robot uses its sensors to scan the environment and identify obstacles in its path.

2- Decision-Making: Based on the data, the robot's software calculates the best way to avoid the obstacle while maintaining its destination.

3- Action: The robot adjusts its movement (e.g., slowing down, turning, or rerouting) to avoid the obstacle.

Applications

Autonomous Vehicles: Avoid pedestrians, other vehicles, and road obstacles.

Service Robots: Navigate safely in homes, hospitals, or offices.

Industrial Robots: Operate in dynamic environments, avoiding people and equipment.

Drones: Avoid trees, buildings, or other aerial obstacles.

Operation of Micro:bit robot avoiding obstacles

A Micro:bit two-wheeled robot avoiding obstacles integrates various components to autonomously detect and avoid obstacles using a servo motor, ultrasonic sensor (HC-SR04), driver expansion board, and a 9V battery.

How It Works

1- Initialization:

The Micro:bit initializes the motors, ultrasonic sensor, and servo motor.

Servo motor positions the ultrasonic sensor to scan the environment.

2- Obstacle Detection:

The HC-SR04 measures the distance to obstacles in the current direction.

If an obstacle is detected within a predefined range (e.g., < 20 cm), the Micro:bit triggers an avoidance maneuver. 3- Scanning and Decision Making:

The servo motor rotates the ultrasonic sensor to scan left and right.

The Micro:bit compares distances in different directions and determines the clearest path.

4- Navigation:

The robot adjusts its direction by controlling the DC motors via the driver expansion board:

- Moves forward if no obstacles are detected.

- Turns left or right based on the servo scan results.

- Stops if surrounded by obstacles.

Robot components

Micro:bit Board:

Acts as the main controller, running the obstacle avoidance logic.

HC-SR04 Ultrasonic Sensor:

Measures the distance to obstacles by emitting ultrasonic waves and calculating the time taken for the echo to return.

Servo Motor:

Rotates the HC-SR04 sensor to scan the environment (e.g., left, right, and forward).

Driver Expansion Board:

Interfaces the Micro:bit with the DC motors and servo motor.

Handles power distribution to the motors and sensors.

Two-Wheeled Chassis:

Provides mobility. Two DC motors drive the wheels for forward, backward, and turning movements.

9V Battery:

Provides power to the entire system.

Mounting of robot

Hardware Connections

Micro:bit to Driver Expansion Board:

The Micro:bit is mounted on the expansion board, which simplifies connections to motors and sensors.

DC Motors to Driver Board:

Motor terminals connect to the motor output pins on the expansion board.

HC-SR04 to Micro:bit (via Expansion Board):

Trigger Pin connects to a GPIO pin (e.g., P0).

Echo Pin connects to another GPIO pin (e.g., P1).

Power (Vcc) and Ground (GND) connect to the expansion board.

Servo Motor to Expansion Board:

The servo control signal pin connects to a GPIO pin (e.g., S1).

Power and ground pins connect to the expansion board.

9V Battery:

Supplies power to the expansion board, which distributes it to motors and sensors.

Programming Micro:bit board with Makecode

1- Go to Microsoft MakeCode and start a new project.

2- In MakeCode, open the Blocks Editor (https://makecode.microbit.org/).

3- Add the Micro:bit Driver Expansion Board extension:

Look for "Extensions" and click on it.

In the search box, insert this link "https://github.com/DFRobot/pxt-motor".

You can now use this blocs to controls the two motors.

4- Add the HC-SR04 extension:

Look for "Extensions" and click on it.

In the search box, type "sonar" to find the bluetooth extension.

5- Go to advanced :

6- Go to Pin and choose 'servo write pinP0 to 180' instruction :

7- Create This program who reads the ultrasonic sensor data and adjusts the robot’s movement.