So that the demining robot will not get stuck behind an obstacle and be unable to complete its mission, we have mounted a series of sonar transducers on the robot for obstacle detection. Each transducer sends out a wave (called a ping) which bounces off the nearest obstacle and sends an echo back to the sensor. Depending on how long that echo takes to return, our sonar controller, a 68HC16 microcontroller, can figure out how far away the obstacle is.

The interface between the sonar controller and the actual sonar sensors is a simple circuit which pings one sonar after another and waits for the echo to be returned. The microcontroller gets the data and saves it. We are working on getting a custom etched board for the sonar circuit so that the robot will be robust and easily reproducible.

This is a view of the prototype sonar board. The small circuit on top is the ranging board, which receives the echos from the transducers. The larger circuit on the bottom is the sonar board, which selects a sonar to ping. once we make sure that this works perfectly we will have a much more permanent circuit board etched. The silver cubes in the background are some of the connectors we use to actually plug the sonars into.

This is a view of the top of the prototype sonar board. You are mainly seeing the ranging board, which is a commercial part.