Fully Automatic Control of Electric Wheelchair by Measuring Obstacle Shape Using Monocular Camera and Laser

Abstract

This study proposed a fully automatic electric wheelchair control system based on an obstacle-shape measurement algorithm using a monocular camera and laser. When the electric wheelchair, equipped with the camera and laser, encounters an obstacle, the control system automatically avoids it in real time by measuring the distance and depth to the obstacle. As this research focuses on obstacle avoidance, a simple pathfinding algorithm is used. When an obstacle is detected, the system creates an avoidance path corresponding to the depth length of the obstacle, updates the current position, and moves to the goal point. The novelty of this system is that it calculates not only the distance to the obstacle but also the depth of the obstacle, which is three-dimensional information. Meanwhile, the minimum and maximum distances from the camera to the obstacle are detected by laser. The distance formula for the proposed method is not the straight-line distance from the camera, but the distance from the position in which the camera is moved horizontally parallel to the obstacle in front of the camera. Therefore, the obstacle depth can be calculated by the difference between the maximum and minimum distances from the camera to the obstacle. The effectiveness of the proposed method was verified by preparing obstacles with different depths and verifying whether the electric wheelchair could generate an avoidance route for each obstacle in the route search and still move to the goal point. We confirmed that the wheelchair stops when the distance to the obstacle reaches an arbitrary length, acquires information on the obstacle depth, creates an avoidance route according to the depth, avoids the obstacle, updates its current position, and automatically moves to the goal point. By further improving the effectiveness of the proposed method, a fully automatic electric wheelchair that can detect the shape of obstacles and avoid them appropriately in hospitals and on roads without depending on the illumination of the measurement environment can be realized.