Your guide to reading the Robot Rules after kickoff

To go along with @Foster’s excellent annual thread, I thought one on parsing the robot rules could be useful for many.

With the complete rulebook clocking in at ~130 pages each year, it can be tempting to skip sections right after kickoff. DON’T DO THIS! If you skip it after kickoff, odds are you’ll keep skipping it long into build season, and that can land you in a tough spot later on. With the robot rules taking up ~30 pages, and many of the rules not changing from one year to the next, it can be very tempting to skip them.

There are a few key pieces of information you’ll want to know immediately after kickoff:

  • How big can my robot be?
  • How heavy can my robot be?
  • How far can my robot extend?
  • What do I need to do about bumpers?

While all of the Robot Rules are important, finding the answers to these questions early is critical to being successful. There’s no point in discussing a strategy that requires a robot that’s too large, or needs to extend too far. There’s certainly no point in starting to build one! I’m going to break down each of these questions further for you.

How big can my robot be?
Robot size can be given to us in many different ways. In recent year’s, we’ve had:

  • A fixed length, width, and height
  • A fixed length, width, and height that included the bumpers
  • A fixed length, width, and height for transportation to and from the field
  • A fixed height along with a maximum frame perimeter measurement

Regardless of the exact specs, build 1" under in every dimension. If it wasn’t for Team Update 11 last year, a lot of teams would have been too big. By building under, you automatically take into account any legal protrusions (bolt heads, etc, up to 1/4" in past years) that would otherwise increase the size of your robot. You automatically take into account any looseness in your bumpers that may increase the size of your robot. You automatically take into account any possible difference or error between your measurement device and the device the inspectors are using.

In short, think of having to put your robot into a large steel box. By building 1" under in every dimension, it slides right in, no lubrication or pushing required! And honestly… having that 1" is not going to be critical to the success of your design.

How heavy can my robot be?
Weight can be a huge issue for teams. Do you have any idea how many 1" holes you need to drill in your 1/8" aluminum to reduce your weight by 1 lb? Doing so will take a lot of time, possibly compromise the strength of your robot, create metal shavings that could destroy your electronics, and overall not be very fun. And if you need to drop more weight… you’re looking at redesigning something, or even removing capability just so you can play.

So please, weigh your robot early and often. And make sure you’re at least 1 lb under weight when you bag it! Things like sponsor panels do weight something, and are often forgotten in your weight calculations. Plus, your scale could be calibrated differently from my scale at the inspection station - you don’t want that 1/10th of a lb of calibration to be the difference between passing and failing inspection your first time through!

How far can my robot extend?
We’ve had several different ways this rule has been specified in the past.

  • A specified diameter right cylinder
  • A specified distance from the frame perimeter
  • One year we even had a specified amount of time you could extend out at once

Be aware of the rule, whatever it is, and make sure you understand how it applies to your robot. If you have an arm that swings out, make sure you look at it at all points through the swing, not just all the way up/down. If you’re going to be controlling this with software, make sure you can easily demonstrate the limits for the inspector.

What do I need to do about bumpers?
So many teams leave bumpers until the end (like I did in this post)… and yet they are a critical part of your robot. They protect you in the big impacts on the field. They leave an impression on those that look at your robot (like scouts!) - if you put time and care into your bumpers, then you did into your robot. If your bumpers look shoddy, then so is your robot! And they can easily impact how you interact with the game piece. they can impact how big of an opening you have for an intake, how large your arm needs to be, or even your intake’s ability to rotate the game piece into its desired angle. Build your bumpers early, make them look good, and make sure you can take them on/off quickly!

Finally, an offer for any team out there, at any point in the build season: Contact me. While the Q&A won’t rule on any specific designs, I am more than happy to look at pictures and tell you what rules I think may apply, help you understand a particular rule better, or even help you craft a question for the Q&A. If you find yourself in a tight spot, where a particular rule is keeping your design from working, I’ll do my best to help you find a way to fix it.

I dream of the day I’m at an event where every single team passes inspection on their first try, 2 hours after pits open. Please help me make that a reality!

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Thanks for this,a lot of hard-won lessons here! However, as we are still expecting similar bag & withholding rules as the past few years…

Even if everyone paid attention to the rules and didn’t have to rebuild, we’ll still have teams spending more than two hours installing the withholding allowance this year. Maybe in 2020!

I would say that another thing to add on to here is quantity of motors permitted. I could easily see a 2018 rookie team who are only used to unlimited motors missing some sort of limit on CIMs and having their first competition ruined or at least a team needing to scrap their design after about a week because they didn’t read up on how many motors they can use.

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A non-comprehensive guide :wink: I have an hour+ long presentation I give to teams every december on how to pass inspection, this post just scratches the surface!

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I’d say something like “I echo everything that Jon said”, but that would not be nearly enough, so picture me jumping up and down screaming everything Jon said at the top of my lungs :slight_smile:

I give a very similar presentation to Jon’s every year, it takes about 2 hours, and I spend the first hour just on weight, size, and bumpers.

Remember: just because it was one way last year, does not mean that it’s that way this year!!!

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I think that in addition to what @Jon_Stratis posted, the three best things you can do to pass inspection quickly are:

  • Keep up with the team updates and Q&As so you stay on track with the rules
  • At least once a week, read through the [updated] rules again, specifically looking for issues which may impact your strategy and/or robot design
  • Download the inspection checklist when it is posted (usually around week four or five IIRC), and go through it yourself. (but keep doing the other two!)
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One trap I’ve seen people fall into before is getting into the habit of “over-paraphrasing” rules. By that I mean, yes reciting every rule verbatim all the time would be tedious and unnecessary, but certain rules can only be pared down so much before the intended meaning goes away. This becomes a problem when you retain the paraphrased version of a rule and not the actual rule, so you go around believing something slightly/significantly different than what it written. Rules don’t always roll off the tongue super nicely, but from time to time an extra word or two can make a difference.

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This was a real problem for my team (293) and influenced the final design of the robot. It wasn’t exactly that we didn’t read the rules, we just misinterpreted the rule about extensions outside of the original robot. Thinking that robot perimeter included robot height we went on to build one of the only shooter robots in our district.

Any chance someone could pin this for a week or two?

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bumping to move past all of the last min CAD and Code posts (as they try to become COTS compliant for 2019. Only a few hours to kickoff. Pinning this would be nice.

Second this.

So you’ve read the rules. Now what? Well, here’s some advice, based on previous experience. Please note that we haven’t had LRI training yet, there are going to be a bunch of rule updates and Q&A… understanding and enforcement could change!

Well, the next few days you’ll be planing and designing. Some of you will even be assembling your frame. Here are a few things to keep in mind:

R3. A ROBOT’S STARTING CONFIGURATION may not have a FRAME PERIMETER greater than 120
in. (~304 cm) and may not be more than 4 ft. (~121 cm) tall.

Make sure you meet this when you put together your frame. Plan for it, cut it, assemble it, and then measure it! With similar rules in the past, inspectors have used cloth measuring tapes - these can be purchased online or at your local Joann Fabrics (or similar store). They cost under $5. BUY ONE! Wrap it around your frame, and make sure you come in under 120". If you don’t… take the frame off and adjust until it does!

R4. ROBOTS may not extend more than 30 in. (~76 cm) beyond their FRAME PERIMETER (see Figure 10-1)

30" is a lot. But it’s not infinite. Whether you have an arm, an intake, a lifting mechanism or a ramp, make sure it meets these rules throughout the range of motion. I expect we’ll see teams that want to put down a ramp to help others drive up to the 3rd level. They’ll want those ramps to be as long as possible to keep the angle as small as possible, and this is where we’ll see the most issues with this rule! Another possibility is a long arm to lift the hatch or cargo to the top of the rocket. If you put your pivot point at the back of your robot, 4’ off the ground, and have a max length arm, that’ll be 58" long. Depending on the depth of your robot, that may be a problem! Of course, those numbers are all worst-case. Your pivot won’t be at the extreme edge of the robot, and it’ll be a little below 4’ so you fit within the starting configuration. All the same, this is a situation to pay attention to!

R5. The ROBOT weight must not exceed 125 lbs. (~56 kg). When determining weight, the basic
ROBOT structure and all elements of all additional MECHANISMS that might be used in different
configurations of the ROBOT shall be weighed together (see I3).

125 lbs is an increase over previous years. Do yourself a favor and forget about that. Plan for 120 lbs.

While your planning for your weight, consider what’ll happen if you drive up a ramp to get to the third level. Some basic math indicates 20 degrees is likely, 30 degrees is possible for some ramps. If your weight is too high, you’ll tip over! Be careful, and think about it as you build - we all hate seeing robots tipped over on the field!

R24. ROBOTS are required to use BUMPERS to protect all outside corners of the FRAME PERIMETER.
For adequate protection, at least 6 in. (~16 cm) of BUMPER must be placed on each side of each
outside corner (see Figure 8 2) and must extend to within ¼ in. (~6 mm) of the FRAME
PERIMETER corner. If a FRAME PERIMETER side is shorter than 12 in. (~31 cm), that entire side
must be protected by BUMPER (see Figure 10-3). A round or circular FRAME PERIMETER, or
segment of the FRAME PERIMETER, is considered to have an infinite number of corners, therefore
the entire frame or frame segment must be completely protected by BUMPER(S).

Teams misunderstand this rule all the time.

In this picture, the “side of the frame perimeter” spans from one side of the robot to the other. Each of those small segments is 6", but the side of the frame perimeter is 30", as it includes the opening! Do yourself a favor and put 6" of frame on either side of any opening like this. That’ll ensure your bumpers are properly supported AND meet the minimum requirements!

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I know that I must have missed this somewhere, but how high can the robot extend??

I know that I must have missed this somewhere, but how high can the robot extend??

R3. A ROBOT’S STARTING CONFIGURATION may not have a FRAME PERIMETER greater than 120 in. (~304 cm) and may not be more than 4 ft. (~121 cm) tall.

That rule only applies to starting configuration though. After the match starts, it can extend (theoretically) infinitely upward unless in the HAB zone:

G12. Duck in the HAB ZONES. A ROBOT with its BUMPERS fully in either HAB ZONE may not extend above the ALLIANCE STATION WALL, i.e. more than 6 ft. 6 in. (~198 cm) above the carpet.