A simulation model of indoor environments for ultrasonic sensors

Abstract

This thesis addresses the problem of extracting the map of an unknown environment from echo signals received by ultrasonic transducers. A new map-building method is developed and demonstrated through simulations for ultrasonic sensors. Ultrasonic transducer arrays are used for scanning the environment. The method uses ultrasonic range and amplitude data to build a two-dimensional map of an unknown environment. All of the amplitude information is taken into account in the simulation studies. The received echo amplitude where it exceeds a predefined threshold is used for drawing the map. The method can extract the surface profiles from the received echoes with knowledge of transducers’ position. With this method, sonar signal returns from arbitrary indoor environments can be represented realistically and with relatively low computation time. Different types of environments composed of planar surfaces, corners, edges, cylinders, and arbitrarily curved surfaces have been considered. An error criterion is developed to assess the accuracy of the extracted maps. Randomly located and randomly oriented configuration of transducers gives the best estimate of the surface pro- files. Most of the closed room models is a continuous combination of basic shapes. The wall-following algorithm is employed to extract the profiles of indoor environments. The results indicate that many of the indoor environment profiles can be accurately extracted by this method. The method is fast and suitable for real-time map building applications.