IR Sensors

[simrat.s]

How many IR sensors can are you allowed to have on the 2008 Robot?

In the rules (<R65>) it states:
"communicate no more than four messages, states or conditions to the ROBOT (please refer to Rule <R69> and Rule <G01> for additional information) during any single MATCH."

[RyanN]

By the rules, you can have as many IR Receiver boards as you want, as long as you do not use more than 4 commands total, so there is no reason to have more than one since you cannot use more than one.

[fimmel]

you could have one on each end of the bot (front and back) so the robocoach will always be able to signal

...forest

[lukevanoort]

Originally Posted by fimmel

you could have one on each end of the bot (front and back) so the robocoach will always be able to signal

...forest

There are other solutions too that might, hypothetically, involve gyro, encoders, and servos....I really like StangPS

[ccsingle07]

If you can have as many IR sensors as you want. Does that mean you can have as many Remotes as you want. As long as there are 4 signals of course.

[neutrino15]

I actually would like to know if you could combing the output PWMs from 2 IR recievers (for front and back) in such a way that it does not violate first restrictions.. I mean, if a digital signal is just +5v to 0, why couldn't you just combine the digital pins? This way you don't have to burn 8 inputs..

--

[tlawless]

Two things.

1. I believe the output from the IR board is simply a digital signal, not a PWM output (if you're unsure of the difference let me know, I'd be happy to explain!).

2. I don't think you'd be violating any rules by joining the digital inputs from two (or more) IR receivers. Just keep in mind that your digital pin would be exerted when either of the two boards receives the signal. This essentially doubles your chances for signal interference. Also keep in mind that you can use an analog input for a digital signal, just not the other way around.

[Schooj]

As far as multiple boards for reception go, they are not necessary. I did extensive experimenting with these when they came out a few years ago and discovered that despite the "window" in the front, the whole sensor case is fairly transparent to IR. This may have changed though since that was one of the main problems of the original IR sensor.

[popo308]

Originally Posted by ccsingle07

If you can have as many IR sensors as you want. Does that mean you can have as many Remotes as you want. As long as there are 4 signals of course.

The manual clearly states 1 remote per team.

[tlawless]

Out of curiosity, where does it state that you are only allowed 1 IR board? I ran a few searches through the manual and found nothing.

[fimmel]

Originally Posted by popo308

The manual clearly states 1 remote per team.

can you tell me which rule says that? from what i read you can have as many as you want but only 4 commands can be used.

...forest

[Alan Anderson]

Originally Posted by tlawless

Out of curiosity, where does it state that you are only allowed 1 IR board? I ran a few searches through the manual and found nothing.

I think the fact that the board is only available in the Kit of Parts, and only one of them is provided, clearly indicates that only one may be used.

This could change if the board became available for purchase as an off-the-shelf item.

[tlawless]

If you're not able to find additional boards thre's nothing stopping you from building a similar device. I haven't found anything in the rules that states that you can't use more than 1 of the supplied boards though, regardless of how difficult they may be to find.

[Al Skierkiewicz]

R69 seems to be the definitive command although it is referenced by other rules. My boldface added...

<R69> Reaction of the ROBOT to communications received from the SIGNALING DEVICE must
meet all of the following criteria:
 For a single MATCH, the ROBOT shall be limited to react to a maximum of four distinct
commands - either through hardware or software limitations, or a combination of the two.
 The ROBOT shall not dynamically change the recognized command set during a MATCH.
 The ROBOT may only seek out and react to permitted SIGNALING DEVICES belonging to
the assigned ALLIANCE (as defined in Rule <R65>). Intentionally reacting to other
SIGNALING DEVICES is prohibited.

See also R65 for specifics on the interaction with THE robocoach and size limitations. Additionally, R65 implies that the you are not limited to using the IR board.
<R65> SIGNALING DEVICES shall be designed to communicate signals from the ROBOCOACH
to the ROBOT. SIGNALING DEVICES are excluded from Rule <R64>. SIGNALING
DEVICES shall:
use either passive (no emission of any electromagnetic radiation) or active (emits some
restricted form of electromagnetic radiation) means of communication

[Ziaholic]

Originally Posted by neutrino15

I actually would like to know if you could combing the output PWMs from 2 IR recievers (for front and back) in such a way that it does not violate first restrictions.. I mean, if a digital signal is just +5v to 0, why couldn't you just combine the digital pins? This way you don't have to burn 8 inputs..

--

It is normally not a good electrical practice to directly wire 2 outputs together ... as one of them can drive a signal into the other. It can be especially damaging if the INPUT that they are connected to has a high impedance.

I haven't looked at these circuits specificially, but typically outputs don't like to get external excitation. It all depends on the type of output circuits ... and whether or not you add external circuitry to isolate/protect the drivers.

Will it work? Maybe. Will if fry the board? Maybe, maybe not. I'd have to look at the driver circuits to see if they have protective circuitry.