IR Sensors- will they attack hot Chiaphuas?

[Wayne C.]

Scenario- it has been a long hard day and your Chiaphuas are too hot to touch- its the elimination rounds

what will an IR sensor home in on? A light bulb 20 feet away or your neighbors drive system 5 feet away.

Now that might be a real Frenzy- when robots attack!!

Just a thought......he he


WC

[Pierson]

I had a similar question: What about all of the other IR interference that comes from the cameras and camcorders in the stands. What about the Media who bring cameras and video cameras into the area right around the outside of the field? What about the cameras that feed the big screen?

For those of you who don't know, the auto-focus on your camera relies on an IR signal being bounced from the camera to the object and back. This tells the camera the focal point.

Will we see robots attempting to leave the field to attack the media? Or, has FIRST put the IR on a different frequency or spectrum (I don't know if this is possible)?

[Pteryxx]

Originally Posted by Peciv

....
Will we see robots attempting to leave the field to attack the media? Or, has FIRST put the IR on a different frequency or spectrum (I don't know if this is possible)?

From TheArena, 3.2.5: "Each beacon emits at the same IR frequency, but sends pulse trains of different widths.... FIRST has supplied appropriate code that allows teams to program their robot's controller to make decisions based on a received signal and discriminate between the two Tee locations."

The beacons are not just a flashlight IR source, they send a modulated signal on a particular frequency. Robots using the code should be able to ignore most IR interference - though IMHO, testing with interference would be a good idea. I notice the humans were careful to stand far far away from the demonstration 'bot ; ) -Piece, Pteryx

[Mike AA]

These IR sensors detect light not heat so there isn't a possibility about them being attracted to another robot or something hot

[Gabriel]

Thank you for pointing this out! I don't know the answer, but
at some point I'm definitely going to ask the filmmaking people at my college to bring in some cameras so that we can test this.

This is my first year as a team leader and I feel a little like the guys on Apollo 13. There's a line from the movie where one of the astronauts (Swaggert I think) is concerned that they will overshoot the Earth. Lovell replies "there are about 1000 things that have to happen for us to get home. We're working on number six, you're worrying about number 520." Its just one more item on the giant list of things to worry about

[KyleGilbert45]

One other thing I've thought about. What about the Night Shot on some camcorders such as Sony. Are those IR devices? Even though you wouldn't be using it at a competition, could someone use it to knock a robot off it's course?

[Mike AA]

To put it simply THE INFRARED SENSORS WILL NOT DETECT ANYTHING OTHER THAN WHAT THEY HAVE BEEN DISIGNED FOR! ie. AN INFRARED EMITTER EMMITING AT THE FREQUENCY THE INFRARED DETECTOR HAS BEEN SET AT. I worked for 3/4 years designing and programing a pinewood derby racetrack finishline that uses infrared. We have not had any problem with extra light or other types fo thigns that interfere.

[pauluffel]

As these sensors on the robot will be much more receptive (as they're designed to seach a wide area for the beacon) I think they would be much more prone to interference (I remember at the FLL Competition there was trouble with all of the people downloading programs with IR to the Mindstorms at the same time and accidentally downloading over other teams' programs and the overhead lights interfering somehow) but since these detectors are designed to pick out a specific pattern, I think the interference will not be a problem unless someone in the crowd has a beacon (since we're to be given the specs for a beacon so we can make one for testing).

Also, since picking out the proper pattern of a beacon is a programming thing, I see the potential for someone to make a custom beacon and program their autonomous to follow that around so someone could remotely control their robot during the first 15 seconds, but I think we're just going to have to trust in GP that no one will do that.

[Wayne C.]

Originally Posted by Mike AA

These IR sensors detect light not heat so there isn't a possibility about them being attracted to another robot or something hot

IR is a form of light beyond the range of human vision but it is a form of radiant heat. My question is- does a heat source emit a specific wavelength or a broader spectrum of wavelengths including the ones sensed by the sensors?

Second scenario- the processors of the sideline computer control station emit a heat source or maybe have IR networking.

It would be fun to see all the IR sensors in the arena make a beeline for the control team. A real frenzy- who can hit who first- the robots take out the controls or the operators hit the stop buttons.

I'm sitting way up in the stands this season...
WC

[Mike AA]

Originally Posted by Wayne C.

IR is a form of light beyond the range of human visionbut it is a form or radiant heat. My question is- does a heat source emit a specific wavelength or a broader spectrum of wavelengths including the one sensed by the sensors?

Second scenario- the processors of the sideline computer control station emit a heat source or maybe have IR networking.

It would be fun to see all the IR sensors in the arena make a beeline for the control team. A real frenzy- who can hit who first- the robots take out the controls or the operators hit the stop buttons.

I'm sitting way up in the stands this season...
WC

Ok, you should experiment with infrared sensors and a detection card to see what it does. These infrared emmitters and detectors OPERATE AT A SPECIFIC FREQUENCY. Thus the emmiter (on the sideline above the balls in the center) does bursts of light, on and off repetidly at a certain speed. simmilar to your TV remote. you cant take any remote and make it work with your TV it MUST be on the correct frequency.

Just believe me, the robots WILL NOT go for heat.

by the way. it would NOT be fun for a robot to take off after a control table. note the words CONTROL TABLE. if this happened it would take time to fix everything.

[Rich Kressly]

Originally Posted by Wayne C.

I'm sitting way up in the stands this season...
WC

Don't you every year Wayne?
Get some sleep, you are getting goofy already
Have that 9 ft arm built yet?

[Anthony Kesich]

40khz is the wavelength at which the beacons will be transmitting (I'll find the quote in the manual later). If I ma not completely mistaken, that is on the high end of the infared spectrum, just below the visible spectrum, so for someting to emit infared light from being hot, it would need to be REALLY hot, and i think most CIMs will die before getting that hot.

[Greg]

Originally Posted by Mike AA

To put it simply THE INFRARED SENSORS WILL NOT DETECT ANYTHING OTHER THAN WHAT THEY HAVE BEEN DISIGNED FOR!

It depends on the quality of the sensor really. I have experimented with building a LIRC-style universal IR receiver once and I can say that some detectors are actually affected by direct sunlight and fluorescent lights. Others are not affected as much. However, even if this does happen, the demodulated data is garbage, and will never be equal to the signal sent out by the beacon. So the robot will more than likely never consider a camera or a hot motor a beacon. However, strong interference may not allow a bot to recognize a beacon. This should not be a problem, however, since the playing field is usually quite dark.

[Anthony Kesich]

if it is a problem, you can get some aftermarket IR sensors that give back an analog signal, not just YES/NO. Then you can figure out what is strongest and most likely the beacon. And if you have a good programmer, with sensors attached to servos, he can make the bot check to make sure the IR it is detecting is comming from the right direction relitave to your starting position.

[Greg]

I dont think this is possible. As has been said before, the signal is modulated. It is not just a "light on/light off" thing. The beacon is likely sending out modulated binary data, and the receiver gets the pulses, demodulates them, and then the software compares the binary signature. This is how a TV remote works. An analog detector would just get the average brightness of a pulsating source. Of course, all of this is unconfirmed - I have not seen the code yet and all the IR stuff is missing from our kit