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Unread 05-02-2009, 12:39
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Re: Ultrasonic Sensors

Please be aware there are some issues using the Analog output of the Maxbotix sensor.

#1 There is a "bump" if you have a large change in distance. The sensor will overshoot the actual distance and then ramp back down to the correct one. You can filter this using averaging, but it will slow the response.
#2 Don't expect to be able to use these to track or range other robots. They respond too slowly. Last year, at full speed using these sensors, we had to stop when the sensor hit 48 inches because of the response time. If we did so, it was actually hitting the brakes at about 18 inches, and stopping with 3 or 4 inches to spare.

What you CAN do with these is use them for collision detection. You can also aim them at a continuing obstruction. For instance - aim it a wall that you're traveling next to. You can keep track of how close you are to it.

I do not know if the other outputs of the Maxbotix will exhibit the same behavior. I'd suggest purchasing one and working with it before you decide it will solve your problems.

For static ranging, however, they are VERY accurate. Consistently within less that an inch.

Last edited by Tom Line : 05-02-2009 at 22:33.
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