Banner Sensor Problems?

[Josh Hambright]

So i have been thinking about it...and it would seem alot of teams are using banner sensors this year...

Now if any of you are familiar with the FLL competitions, cameras and flash photography are banned....

This is for 2 reasons...the flashes from the cameras can really really screw up the lego optical sensors and freak out a program ruining their autonomous programs progress...the second reason is the auto focusing on some cameras uses infrared to detect distance, atleast i think so if i remeber correctly, this could also pose problems to the sensors.

Has anyone thought of this?

Could we see a ban on flashes and such at competition?

In the FLL they have a certain type of light mounted a certain distance above the field to illuminate the field equaly in all parts. But from experience i know that first playing fields always vary alot as far as lighting rigs go....

What do you guys think will happen?

[E. The Kidd]

I'm almost sure FIRST has looked into this matter before this year's competition

FIRST can ban it if they want to, but it would be totally stupid. W/O flashes in a dim building = crummy pictures, unless some new technology has been developed to take pictures in the dark w/o a flash. I remember last year at the Midwest Regional, I took a few pictures not realizing that the flash was off, and they turned out very bad. If FIRST wants to get good publicity and media attention in newspapers, magazines and online, the photographers need their flashes to produce some good pictures

[Dave Flowerday]

Originally posted by oneangrydwarf
the second reason is the auto focusing on some cameras uses infrared to detect distance, atleast i think so if i remeber correctly, this could also pose problems to the sensors.

I think the problem with the autofocus was not with the light sensors but rather with the IR port. I think they were worried about an infrared autofocus accidentally "reprogramming" the RCX. Here in Illinois there was a story about a team's robot that lost its programming every night, and they supposedly traced it to the infrared illuminators used by the security cameras that were only turned on at night.

[Andy A.]

I don't know much about the Banner sensors, but I was under the impresion that each one ran on its own specific phased light and only registerd that phase. That is why two sensors generly don't 'see' each other unless they happen to use the same phase.

Shouldn't this render them pretty 'flash' proof?

-Andy A.

[Josh Hambright]

what if the flashes hit the carpet as they are trying to dead the color....
if its sensing color and there is a white flash right then...it could confuse it...

I dont forsee this being a big problem but it just seems like it could be.

[Robb Gerber]

Forget about flash camera's...the bigger problem is the
diamond patterned plated aluminum that's below the glass.

These sensors trigger on reflected signals from the wall.

Good Luck.

[Rob Colatutto]

i can see this being a problem if your using the sensors to find and destroy a stack, but not if you have them mounted under the bot for a line tracking device

[Josh Hambright]

it may just be because it was my first competition and i was in awe but if i remeber correctly 2 years ago in chicago didn't they have computer controller lights that moved around?

If they had anything like this at the competitions it could cause real havoc because the field would be lighted differently at different points...

[Al Skierkiewicz]

The banner sensors are not phased nor do they use any other type of signal identification. They emit visible red light with a sensor that is optimized for use with retroflective objects. (i.e. reflective objects that reflect some light in all directions.) They have a distinct area of view that for our sensors is at maximum 8 inches in diameter. Signals that appear outside that area of sensitivity are not picked up by the sensor. As to "seeing the diamond plate under the player's station this is possible if the sensor to plate angle is close enough to perpendicular that a significant amount of light is reflected back to the sensor. Another sensor emitting light in the direction of the receiver (and within the diameter of sensitivity) could produce a false trigger. Bright lights may also confuse the sensor but camera flashes are very short duration and would not normally do much in the way of interference.
In FLL there were a number of devices that would at the very least confuse the Mindstorm product. Many security cameras and palmcorders have Infrared illuminators and range finders that would swamp the IR communication port or set the controller to think it was being communicated with. In addition, the latest Mindstorms are also addressable with a handheld infrared remote control to override internal programming. In an effort to minimize such interference, teams were advised to cover the IR ports with electrical tape to prevent any interference during competition.

[MikeDubreuil]

Somethink cool to try...

I forgot what the exact specification for the Banner sensor was but I'm pretty sure it is around 20 feet. We turned the lights off in one of our rooms and put a box with reflective tape about 20 feet from the box. When the banner's light hits the tape it makes a pretty big red spot on it and sure enough the inidicator light on the banner goes on.

I dunno, I thought it was pretty cool that it works from so far away ;o)