Vision system is generally used in robot soccer to measure the robot position and orientation. In this paper, as the replaceable method we propose the 2D pose measuring system using ultrasonic sensors.
In the proposed system, there are two ultrasonic transmitters and photo diodes on the robot. Ultrasonic receivers and IR LEDs are located at the robot soccer stadium. The position of transmitter is calculated by measuring the distance between transmitter and receivers. From positions of two transmitters on the robot, center position and rotation angle of the robot are calculated.
Since ultrasonic sensor has the limitation of measurable range, for expanding measurable range multiple sensors are needed. By attaching the reflector in front of the transmitter and spreading the ultrasonic wave in the omni-direction, in spite of using only one transmitter it is possible th detect the ultrasonic wave at any position.
It is important to make the wireless sychronizatioin of tramsmitting and receiving parts and recognize the identification of each robot in there being multiple robots. For this purpose, the pulse trains generated from the signal generator are emitted to all the robots through the IR LEDs. After all the robots receiver these pulses, each robot selects the pulses corresponding to the given order and respond to only these. Ultrasonic waves are emitted from robots sequentially, and we can calculated positions of each robot seqentially.