3-D Obstacle Detection Using Laser Range Finder with Polygonal Mirror for Powered Wheelchair

Abstract

Because a large number of accidents with electric wheelchairs are due to operational errors, steering assistance systems for wheelchairs have been studied in a variety of ways. One of the basic systems is 3-D obstacle detection around the wheelchair. One method uses a stereo camera for detecting obstacles by image processing. However, this method is less reliable under varying light conditions. A laser range sensor is another useful device for obstacle detection. However, it requires a complex swinging mechanism for 3-D positioning which makes the measuring time too long. Therefore, this paper presents a 3-D obstacle detection system for electric wheelchairs using a 2-D laser range sensor. We set up only one 2-D laser range sensor over the wheelchair, and attached mirrors around it to reflect the laser light obliquely downwards. Then, we gathered obstacle points while the electric wheelchair was moving and made a 3-D obstacle map to assist steering. We built a prototype device and confirmed by experimentation that it is able to detect obstacles in 3-D.