Ultrasonic sensor

[Tom Line]

Let me give you a warning about most ultrasonice sensors if you haven't used them before:

They do not have a fast enough response time to look at a ball or other robot as you close to really prevent a collision. The maxbotics sensor we used in 2008 lagged behind so much at the speeds we were running (13-14 FPS) that we had to tell it to stop the robot when it saw something at 6 feet ahead. There is a significant lag introduced throught the ping / process / analog signal process that you can only get a handful of updates a second. Move 15 feet in that second and you can see the problems.

If, however, you are using the sensor to try to see how far away the back wall is, you'll need to be careful that your beam is narrow enough that it doesn't pick up the bumps. The narrowest I remember was on the order of 2 feet or so.