Obstacle Avoidance

This is a small program that allows Ozobot Evo to avoid obstacles in front of it, using the two front facing proximity sensors.

import asyncio

import pyozo


FORWARD_SPEED = 0.05
TURN_SPEED = 0.03
TURN_DURATION = 200
MOVE_DURATION = 200
PROXIMITY_THRESHOLD = 80


async def main() -> None:
    async with pyozo.get_robot() as robot:
        while True:

            proximity = await robot.get_ir_proximity()

            if proximity.left_front > PROXIMITY_THRESHOLD or proximity.right_front > PROXIMITY_THRESHOLD:

                if proximity.left_front > PROXIMITY_THRESHOLD and proximity.right_front <= PROXIMITY_THRESHOLD:
                    print("Turning right to avoid left obstacle.")
                    await robot.move_wheels(TURN_SPEED, -TURN_SPEED, duration_ms=TURN_DURATION)
                elif proximity.left_front <= PROXIMITY_THRESHOLD and proximity.right_front > PROXIMITY_THRESHOLD:
                    print("Turning left to avoid right obstacle.")
                    await robot.move_wheels(-TURN_SPEED, TURN_SPEED, duration_ms=TURN_DURATION)
                else:
                    print("Turning right (default) to avoid forward obstacle.")
                    await robot.move_wheels(-TURN_SPEED, TURN_SPEED, duration_ms=TURN_DURATION)

            else:
                print("No obstacles. Moving forward.")
                await robot.move_wheels(FORWARD_SPEED, FORWARD_SPEED, duration_ms=MOVE_DURATION)


asyncio.run(main())

Algorithm:

• Read proximity sensor values.
• Consider there is an obstacle ahead if one of the two front facing sensors has a reading above 80.
  • If the obstacle is on the left side, turn a bit to the right
  • If the obstacle is on the right side, turn a bit to the left
  • If the obstacle is directly in front, still turn to the right as an obstacle avoidance strategy
• Otherwise, move forward a bit.

Main ideas:

• reading proximity sensors
• controlling wheel speed to move forward and turn
• control loop