Position Detection Using One Photodiode and Multiple LED Makers

Abstract

This paper describes a new approach for controlling an autonomous mobile robot indoors. In recent years, many studies are being done in order to solve the problem of an autonomous mobile robot indoors. The position detection of a mobile robot requires many artificial landmarks. Thus, the conventional method have to create landmark database which is stored large amount of landmark data. As a result, the conventional method takes much time to detect the position of a mobile robot. Moreover, preparation of many artificial markers is a cumbersome task for the user. Therefore, we propose the new landmark system which is able to detect position simply, quickly and accurately. In recent years, Light Emitting Diode (LED) lighting is spreading rapidly as an indoor lighting. So, the proposal method uses frequency modulated LED lightings as landmarks indoors. It can distinguish between LED lightings quickly and accurately by difference of the frequency. The measurement system consists of a light projecting unit and a light receiving unit. The light projecting unit consists of a frequency modulation circuit and LEDs. The light receiving unit can detect the position of the mobile robot quickly from the receiving amount of a photodiode mounted on the mobile robot without the image processing. We verified the accuracy of the position detection. The proposal method could distinguish between multiple LED lightings accurately. In addition, the maximum error of the position detection was 2.70 cm. The maximum error rate was 1.45 %. The accuracy was considerably high. Measurement time was only 55 msec. The efficacy of the proposal method was confirmed by the experiment.