Re: IR Sensors- will they attack hot Chiaphuas?
 

ahh, good point. I'm used to constant signals, but who knows? I think some experimenting is in order. Maybe some interrupts to collect the strength for 2 ms... hrmmmm

-Kesich

Re: IR Sensors- will they attack hot Chiaphuas?
 

Wouldn't these things be as realiable as the sensors from last year we used to detect the reflective tape? I think they worked the same way.

Re: IR Sensors- will they attack hot Chiaphuas?
 

Didnt those use the visible light spectrum? And the light sensors projected, whereas the IR sensors just pickup, so there really isnt the chance of seeing reflection when there isn't one. I went straight dead reckoning, though. Getting to the top of the ramp and hitting boxes in 5 flat seemed better to me. Anyways, in the line vs IR arguement, i'd say IR because you can see the IR from anywhere. The line, on the other hand, can get smugged up, lost, and once you are done with it, the sensors are useless. Ir can triangulate though.... hehehe

-Kesich

Re: IR Sensors- will they attack hot Chiaphuas?
 

The signal from the beacons and receivers probably resemble the signals from a television remote. I have never encountered any interfernce from body heat on those things.

Re: IR Sensors- will they attack hot Chiaphuas?
 

Wouldn't that be funny. Walk by the TV with a candle and the tv turns on, mutes, unmutes, cranks the volume, then hacks the cable box and gets you free PPV for life. Heheheh :-D

-Kesich

Re: IR Sensors- will they attack hot Chiaphuas?
 

20 ft.....

Re: IR Sensors- will they attack hot Chiaphuas?
 

What I meant about last year's sensors is that they sent a specific pulse pattern to prevent picking up sources other than itself. Although my team didn't use them, I played with the sensors and found them pretty reliable. I dont think we have to worry about someone accidentally confusing the robots with a camera or furby.

Re: IR Sensors- will they attack hot Chiaphuas?
 

The IR Sensor is set to only detect the frequency emitted from the beacon. Similar to way your TV remote works, you won't get out side interference.

Re: IR Sensors- will they attack hot Chiaphuas?
 

OK,
Before you guys get too crazy, the IR emitters generate energy in the same area as heat but have one distinct difference. The emission will occur as 40kHz pulses for varying lengths of time. That is, bursts of 40kHz modulated IR energy. The night illuminators on cameras are just that, steady state, non modulated sources the same as hot bodies. The IR camera range finders and remote controls use modulated IR emitters at different frequencies so there should be no real problems if you keep in mind that you are looking for a 40kHz modulated source. The bandwidth of the IR is not 40kHz but likely is much wider than that since the bandwidth you are measuring is near visible light.

Re: IR Sensors- will they attack hot Chiaphuas?
 

Too late :).


Yes, as Al correctly (again) points out, the Vishay TSOP4840 sensors that are included in the kit and also used for the kick-off demo specifically discriminate against these type of energy sources. They also discriminate against non-modulated 40KHz sources. I've put a link to the data sheet here: http://kevin.org/frc. The modulation scheme is discussed in this thread.

-Kevin

Re: IR Sensors- will they attack hot Chiaphuas?
 

this is something that i asked about at the main kickoff because of the fll problem. the guy told me that he tested the ir sensors with 5 cameras that were said to have problems with the fll bots and none of them caused interference. he also mentioned that these ir sensors are the type used in high-end stereo equipment and the only thing to possibly worry about would be a flickering flourescent bulb.

Re: IR Sensors- will they attack hot Chiaphuas?
 

Kevin,
Thanks for the pdf, I am forwarding it to our electrical guys right now. Good info in the data sheet, too!

Re: IR Sensors- will they attack hot Chiaphuas?
 

yikes! 40 khz is not a wavelength - it's a frequency - and I don't think it is the frequency of the electromagnetic radiation coming from the source either. If that were the frequency, the wavelength would be about 10,000 meters. That's a real long radio wave, not infrared. So, yes, you ARE completely mistaken. Perhaps the infrared source is being pulsed at 40khz, but that's a whole difference animal. :D

Re: IR Sensors- will they attack hot Chiaphuas?
 

How many pulses must the sensor receive in order confirm which beacon it is seeing, and therefore, how fast can the sensors sweep the field and still detect the beacons?

And a less important issue, will the beacons appear as bright lights on videos of the matches since many camcorders are sensitive to IR light?

Re: IR Sensors- will they attack hot Chiaphuas?
 

You don't really have to worry about how many pulses they need to see. at 40khz, this will not even be an issue. You can basically assume the response is instantaneous.

yes. Some cameras more than others. It will show up as bluish white. Point a TV remote into your camera to get an idea of what i mean. You can prolly find IR filters if things are really bad.