A Low-Cost Obstacle Avoidance System Prototype for Autonomous Wheelchairs Using a Servo-Mounted Ultrasonic Sensor

Abstract

This research presents the development of a low-cost obstacle avoidance prototype designed for mobile robotic applications, with a potential use case in autonomous wheelchairs. The system utilizes a single ultrasonic sensor mounted on a servo motor to perform multi-directional distance scanning, allowing the robot to detect and avoid obstacles in real time. An Arduino-based control algorithm interprets distance measurements at four predefined angles (30°, 60°, 120°, and 150°), enabling the robot to make navigation decisions including forward movement, turns, and retreating actions. The system was tested under various conditions: with obstacles in front, in front-left, and in all directions (front, left, and right). Results showed a 100% success rate in the simple frontal obstacle scenario, 80% in the front-left obstacle case, and 60% in the most complex environment with obstacles on three sides. The primary cause of failure was the sensor’s limitation in detecting very close objects (less than 2 cm). The findings confirm the feasibility of implementing this single-sensor approach in low-cost assistive mobility devices. The prototype demonstrates effective navigation capabilities and provides a practical foundation for future development of intelligent obstacle-avoidance systems for autonomous wheelchairs.