Placements of Signal Light, Radio, and Circuit Breaker

Don’t know if this is where i’d put this but, what are the rules for where the signal light, radio, and circuit breaker placements. Like where on the robot should they be placed for ~ like should it be where you can see it, and can be reached… or what?

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Your RSL must be visible at minimum 3ft away from the “front” of your robot. There are no rules on what the FRONT of your robot is.

The lights on the radio must be easily visible on the field, and the radio must be able to be detached in order to be flashed with the field firmware.

The breaker needs to be easily accessible and be safe to reach (i.e. not on the top stage of your elevator). Be careful with this though, “safe” to reach often means teams do not adequately cover the breaker and make it possible for other robots to accidentally break!

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Basically The gist of it was about to mention this. You can find these rules in the Inspection List I updated from last year shown below. Keep in mind this is a List without the CAW/Actuator/Pnuematics Rules but it covers what you need to know. sources of the rules can be found attached to each rule as in for example (which is the rule that @brennan-macaig mentions) Feel free to add/edit or use it for your team. :grin: 2019 FRC Inspection Checklist.docx (18.8 KB)
2019 FRC Inspection Checklist.pdf (546.3 KB)

The more visible the RSL is, the safer the surrounding environment is so as many people can see when the robot is enabled. For the main breaker, as others have said make it safely and easily accessible to a human, but not to other robots: try to isolate it away from mechanisms and add some shielding around it. I’d suggest shock mounting the radio, as it’s a delicate component, somewhere where the FTA can easily see it but shielded and protected from other robots. The radio should be able to be removed because you need to take it off and configure it at every event.

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On the robots I’ve been part of I always insist that the RSLs are visible from a person standing at just about any vantage point around the robot. This helps keep things safe, especially on the practice field. It also gives the drive team (and everyone else) a heads up if you lose connection.

Radio: lights visible is the rule, but it’s also a good idea to keep it away from motors and motor-sized power wiring to reduce RF interference.

Circuit Breaker: Easily identified and safely hit is the rule. Locate it away from arms, chains, and rollers, on a piece which is rigidly attached to the chassis. For a skid-steer, I also prefer NOT to put it on the front or back, but the side, because this is where you can approach the robot with the least chance of it being able to run into you. Shield it with something having a hole small enough to keep a game piece out, but large enough to safely let a hand in.

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If you need a quick fix for this problem, the breaker fits neatly into the ID of the cardboard bit of a duct tape roll, leaving the button and switch accessible, while protecting it from other robots. Source: an opposing robot turned our breaker off in a match last year.


Good idea for a quick fix! I’m a fan of the… er… creative use of duct tape!

This is not strictly necessary, and in some cases mounting the RSL somewhere more convenient is better. Don’t let your RSL restrict robot design.

Is this a rule or just a guideline? I’ve definitely read about a high-profile team (973 I think, but I’m not sure) who hot glues their connectors to the radio so the whole robot must be taken to flash the field firmware onto the radio.

I’m not sure if it’s a rule or guideline, but either way I’m sure your event staff would appreciate you just bring the radio.

When I flash radios, I’m usually fine if a robot comes along too. It saves a bit of time if the radio is already powered on. That said, there are space constraints, and I might be annoyed if a lot of teams did this, so making your radio easily removable (when you want it to be removed) is best. (Easily removable radios are also typically easily visible and replaceable.)

OBTW, I wasn’t just talking about the practice field at the competition, but even more the one at/near the build site. It doesn’t have walls around it. We’ve never found it necessary to contort robot design around it, apart from adding a second RSL for STRONGHOLD.

Many teams hot-glue the connectors to their radios, but this attachment is not permanent and the glue can usually be peeled off in a timely manner while still providing additional security. I tend to go a bit overboard when doing this, but some rubbing alcohol will help loosen the glue in a pinch.

We zip tie the wires to the same base as the radio with appropriate strain relief so there is no relative movement.This way we are not requiring the radio circuit board or connectors to be a strength member.

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The main breaker is easy, R50 specifies:

The 120A circuit breaker must be quickly and safely accessible from the exterior of the ROBOT

The RSL is easy too, as others mentioned. R72.A:

mounted on the ROBOT such that it is easily visible while standing three 3 ft. (~ 100 cm) in
front of the ROBOT,

The radio is a bit of a different beast. R71 specifies:

The Wireless Bridge must be mounted on the ROBOT such that the diagnostic lights are visible to ARENA personnel.

However, in practice there are more constraints you should put on yourself.

First, you want your radio to not only be visible, but accessible. The field staff may need to power cycle the radio, adjust your Ethernet cable, etc. I know your team would never re-flash the firmware on the radio in your pit, but when they do you’ll also want the radio to be accessible so that the field staff can help you flash it back (if they have the time to do so, of course).

While there are no rules requiring it, you shouldn’t place your radio on or immediately adjacent to things that generate electromagnetic fields, like motors. Also don’t place your robot in a metal cage. Generally you and your radio will be much happier when your radio is placed higher up and in an relatively open part of the robot.

Your RoboRIO should be accessible for the same reasons. If your robot doesn’t connect to the field but all your electronics are hidden under an opaque panel that is secured by a handful of bolts, it is much less likely that the field staff will be able to resolve the problem before they need to start the match.

I also generally recommend against hot glue. You really should be using PoE for your radio (you can still use the barrel connector as a backup), and that PoE cable should click into place on the radio. If you need hot glue to secure it, you would probably be better served with a new PoE cable. Again, hot glue makes it difficult to replace components if something goes wrong on the field, and depending on how much glue you used (typically far too much), it makes it more difficult to diagnose problems.

Think about it this way: If your radio fails right before a match and you don’t find until the robot is on the field, how easy would it be for someone to swap out the old radio for a new one?

While I understand the merits of this I firmly believe someone inspecting must cite a rule or specification when asking a team to change something on their robot. Please don’t insist, but suggest instead.

Then I suggest that you read the full sentence I posted. I wasn’t talking about inspection, but construction.

I would also HIGHLY recommend that if you have access to a 3D printer, and I prefer the red filament, print the 120A Breaker Shield that AM has posted on their website. This has been a great addition to our robots, and helps to quickly identify the breaker while providing a decent level of protection from accidental disengagement.

We seem to have a somewhat unhealthy love of lexan… We mount the majority of our electronics on it. Sometimes on both sides, plus use it for protective panels. We have can great success using the super thin stuff for sponsor panels. It is flexible to roll up out of the way, can see through it and yet it is strong enough to deal with the rigors of the game.

This year we have everything but the motor controllers mounted on lexan. The motor controls are frame mounted for heat sinking, but visible through the main electronics board. On one protective side panel we have air tanks, on the other the radio. Peel back the velcroed on sponsor panel and have full access to everything.

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