[kmcclary]

If you are going to use ultrasonics, be careful, for a number of reasons.

1) Try to keep the sonic environment relatively "closed"/"close". By that, I mean just as with active IR rangers, the more localized the sensor's effect, the better. Example: Sensing the spider's endplate with something on your gripper is OK. Blanketing the entire field with a slew of ultrasonic sensors pointing in all directions looking for the rack is questionable. The latter is prone to interference from reflections, and background noise. It could also potentially interact with other robot's sensors. This is not only Ungratious, it could cause a judge to rule your sensor system illegal.

2) Be aware that pneumatic venting "whistles" loudly in the ultrasonic. If your sensor is anywhere near a venting pneumatic's air output (yours, a partner's, OR an opponent's) , it can potentially be swamped out by the "dog whistle effect". (Yet another reason to keep your sensing "local".) Verify your sensor(s) aren't affected by your pneumatics venting.

If they are affected, there are some simple things you can do about your OWN interference:

A) Point your valve's vents away from your ultrasonic system. That may be sufficient to prevent interference.

B) If (A) isn't sufficient, combine all of your pneumatic vent outputs together with T-connectors and add a foam "muffler"/"silencer" to the resulting output vent tube. They're COTS - search for "pneumatics muffler", "air exhaust silencer" etc...

C) Run a short "exhaust" vent tube to/toward the far end of your robot and point the pneumatic exhaust opening away from your sensor system.

D) Do both B&C (locate a pnaumatics muffler far from your sensors).

<edit>
3) The PIAB vacuum generators MAY swamp out ultrasonics for this contest! I haven't tested them, but venturi vacuum generators must vent constantly to work at all. Ultrasonic systems on your robot MAY then be hearing nothing but serious dog whistles from a significant number of bots on the field in every round.

Anyone happen to have the equipment to check to see if they whistle anywhere near 40 KHz? (That's roughly where most ultrasonic systems run.)
</edit>

I hope this helps!

- Keith