In this paper, an ultrasonic-based localization method for mobile robots is proposed. Experiment environment includes a mobile robot and four emitter poles forming a square around the measuring site. Ultrasonic sensors built on the top of the emitter poles serve as transmitters and the mobile robot as a receiver. A Zig-Bee module is integrated with each of the ultrasonic sensor so as to provide wireless communication between the robot and the emitter poles for transmitting commands and receiving measurements. To avoid interference of ultrasonic signals simultaneously transmitted, the ultrasonic sensors on the emitter poles are instructed to transmit signals in a sequential order. The ultrasonic sensor in the robot can then measure the time-of-flight (TOF) without interference to calculate the distance between the receiver and transmitter ends. According to an established three dimensional coordinate model, position of the robot can be obtained based on the distance measurements. To process the distance measurements for calculating the 3D coordinates, a H8tiny-3694 processor is built into the robot. Thanks to Zig-Bee modules, position information of the robot can be instantly conveyed to a remote PC for monitoring the robot and path planning. Extensive experiments conducted have shown a satisfactory accuracy of the coordinates of the mobile robot can be obtained via the proposed localization scheme.
Journal of Harbin Institute of Technology 15(2), pp.185-189