can we use ultrasonic sensors?

[Dancing_Chuck]

Yeah, I'm gonna get some military sensors and our robot is gonna home in on the spider like.... a bomb. Hehe!

[Donut]

The Maxbotix sonar sensors are available from Sparkfun, who is a pretty large hobby robotics distributor, so I'd say there at least decent if Sparkfun is willing to carry them.

As for IR Range sensors, you can get ones made by Sharp (easily the biggest maker of them) from either Acroname or Digikey. Just search for any of these companies and you'll find their websites.

[DonRotolo]

Originally Posted by JBotAlan

I too would like a Maxbotix sensor..(drool)...but I'm a little leery about buying from a distributor I have never heard of.

See http://www.chiefdelphi.com/forums/sh...ad.php?t=46912

Originally Posted by Netherlander

This sensor looks good but I do have some qualms about using the ultrasonic sensor. First of all there are potentially way to many things that the signal could bounce off of and secondly if any other robot is using ultrasonic sensors they have a good chance of interfering with each other.

How very true, you have hit upon their greatest weaknesses.

Originally Posted by Dancing_Chuck

So, lemme get this straight. We can use up to, but not including 900 mega hertz (or however you spell that, you get the drift). Does this include any camera? Can we use military-style cameras? Or is that out of the question?

Not sure what you refer to, but ultrasonic (sonar) sensors (the subject of this thread) operate in the high audio range, far far below the Radio Frequencies you mention. Use the flowchart to determine what is legal.

Don

[DavidGitz]

Originally Posted by Don Rotolo

See http://www.chiefdelphi.com/forums/sh...ad.php?t=46912


How very true, you have hit upon their greatest weaknesses.

Not sure what you refer to, but ultrasonic (sonar) sensors (the subject of this thread) operate in the high audio range, far far below the Radio Frequencies you mention. Use the flowchart to determine what is legal.

Don

um ultrasonic is still sound, which is pressure waves, radio is electro-magnetic waves.. Sound waves won't ever interfere with radio waves, no matter if the "frequencies" are the same.

[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

[kaszeta]

Originally Posted by JBotAlan

I too would like a Maxbotix sensor..(drool)...but I'm a little leery about buying from a distributor I have never heard of.

Does anyone here know of a reputable distributor of this type of sensor, or an IR distance sensor? I am interested in getting one, but I don't know where to look. Parallax has one, but its range doesn't seem high enough for the application I have in mind.

Thanks,
JBot

I've ordered all sorts of IR stuff and other sensors from Sparkfun.com with no problems.