Abstract
For the explicit purpose of guiding autonomous mobile robots on wide and flat planes, we propose a specially designed guiding sign. It consists of a cylinder with four slits on its surface, and a fluorescent light on the center axis of the cylinder. Two outer slits are parallel to each other, and the other two inner slits are angled. A robot takes an image of the sign with a TV camera. By the threshold operation, it has four bright sets of pixels each of which corresponds to one of the four slits of the cylinder. By measuring the relative distances between those four bright blobs in the image plane, the robot can compute its distance and angle to the direction of the sign using two simple geometrical equations.
We have built a mobile robot and a sign. Using a personal computer with an image processor, we have evaluated the accuracy of the proposed method of position and angle measurement, and compared them with the theoretical analysis. The data show good coincidence with the analytical results. We have programmed the characteristics of the measurement, which is called the simulation program. First, the parameters in the simulation program are adjusted. Next, we have done several trajectory following experiments using this simulation program. The simulation program provides us with the results which could not be taken in the actual experiment.
