Design and Implementation of a Binocular-Vision System for Locating Footholds of a Multi-Legged Walking Robot

A binocular-vision system designed and built for a six-legged mobile robot, the OSU Hexapod, is described. The vision system recognizes footholds specified by an operator by pointing a laser beam to the desired spot for one of the front feet. The front foot then steps onto this foothold and the other feet follow the footprints. This type of locomotion, called the Follow-the-Leader operation, is suitable for rough terrain traversing. The vision system consists of two charge injection device (CID) television cameras with controllers and a special purpose interface circuit. The image of the laser spot is detected by both cameras on the CID sensor plane. The special purpose interface circuit processes the pixel intensity data and calculates the coordinates of the pixel which has an intensity level above an external threshold. Special purpose hardware is needed as new pixel data is ready every 222 ns. The interface circuit also handles the synchronization of image detection and transmission of the coordinates to the PDP 11/70 computer. These coordinates are then used to compute the three dimensional coordinates of the foothold by using triangulation. The PDP 11/70 computer controls the vision system and the motions of the Hexapod.