Image Processing Based Low Cost Range Finder
Suat Karakaya, Hasan Ocak · 2013
Laser Imaging Detection and Ranging (Lidar) systems have started to be used more common in recent years. Lidar is used for surface and object detection, measuring distances and many other applications. In robotics and especially mobile robot applications Lidar plays a major role in obstacle detection, finding heading direction and path planning. The principle of Lidar is similar to radar systems. Different to radar, Lidar listens the response time of laser dots reflected from any surface. Lidar systems can reach high measurement resolution and frequency but these advantages cause a high cost. In this study, it is studied on an alternative system to Lidar. For this purpose, a mechanism which consists of a camera, a dot laser source, a controller and a servo motor was designed. Camera and laser source were mounted to each other and they were coupled to a servo motor which rotates 0 o -180 o range. Distance between focus of camera and objects were calculated by detecting laser point on physical environment. Physical distance between camera and laser dot is a function of the dot’s position on focal plane of the camera. In image processing step, RGB (Red Green Blue) and HSL (Hue Saturation Luminosity) color space filters were applied on image respectively. The algorithm was developed with image segmentation, median filter, thresholding methods and morphologic operations. Servo motor’s angular position and distance of related angle were matched via developed interface of image processing algorithm by transferring scanning angle to the controller in real time. By these operations, a simple and low cost Laser based range finder was realized. The algorithm was developed in Visual Studio 2010 Express Edition.