Abstract
When used for the FMS (Flexible Manufacturing System) and for the automated hospital tasks, robots should move freely in order to improve their working ability or to increase their productivity. When a robot must move on a limited plane, it is able to carry out various kinds of locomotion if it can measure its position and direction in the coordinates fixed to this plane.
Generally the position (or location) and the direction of a robot can be calculated by using the principle of trigonometrical survey. In this method we use the values obtained by measuring the direction angle of three fixed points from the robot.
In this paper we will introduce the Measuring Equipment for Location and Direction (MELODI) which uses ultrasonic waves according to the above principle. Its basic characteristics and the algorithm for calculating the position and the direction will be explained.
The directions of three points should be measured at the same time in order to control the movement of the robot on real time. For this purpose, each fixed point has a speaker that transmits an ultrasonic wave of a different frequency. The measuring equipment is provided with three sensors that can receive the corresponding ultrasonic wave and follow the corresponding point independently.
From the experiment, the following observations have been made:
Each sensor can search for and locate the direction of the corresponding point correctly from the time the equipment is switched on.
It can follow the direction of the corresponding point accurately at the angular speed of 20 degrees per second.
Where the three points are set in the vertexes of the regular triangle with a 400cm side, the positional error is within about 5cm.
