Building an environment map using a sweeping system based on a single ultrasonic sensor

We present an efficient and cheap approach to building a sonar based map for autonomous mobile robots in indoor environments. The system uses one ultrasonic sensor (emitter and receiver are separated) mounted on a motorization constituted by two motors allowing horizontal and vertical scanning. The reading is modelled as probability profiles projected on a two-dimensional map. These readings provide information concerning empty and occupied areas in the sensor cone. The world is modelled as a grid of cells. Using a raster-based approach to computer graphics, we determine the cells of the area occupied by the sensor cone. The map can be used to plan paths and for landmark recognition. Results from actual runs are presented