Tank tracks vs bumper rules?

Is it possible to build a chassis similar to this and still be “legal” under the bumper rules? I find the rules confusing for a first year newbie.

R25 states bumpers don’t have to be parallel to the ground. But, is there a maximum height bumpers can be off the ground? Is it 7.5 inches above the floor?

With R25 Bumpers have to be between the ground and 7.5" off the ground.

R33 is the tricky one because it states that gaps in your frame perimeter deeper than 1/4" cannot be more than 8" long. If you go with treads like that, make sure that your frame perimeter doesn’t have a gap like that. You could add standoffs to your frame perimeter inside the tracks to fill in these gaps.

Let me try to help you out here: https://www.andymark.com/products/raptor-track-drive?via=Z2lkOi8vYW5keW1hcmsvV29ya2FyZWE6OkNhdGFsb2c6OkNhdGVnb3J5LzVhZjhlNDRjYmM2ZjZkNWUzNmYyMzlmZg

Bumpers are fun :wink:

Look at R25. Except as allowed per G23, BUMPERS must be located entirely within the BUMPER ZONE, which is the volume contained between the floor and a virtual horizontal plane 71⁄2 in. (~19 cm) Above the floor in reference to the ROBOT standing normally on a flat floor. BUMPERS do not have to be parallel to the floor.

This measurement is intended to be made as if the ROBOT is resting on a flat floor (without changing the ROBOT configuration), not relative to the height of the ROBOT from the FIELD carpet. Examples include:

Example 1: A ROBOT that is at an angle while navigating the FIELD has its BUMPERS outside the BUMPER ZONE. If this ROBOT were virtually transposed onto a flat floor, and its BUMPERS are in the BUMPER ZONE, it meets the requirements of R25.

Example 2: A ROBOT deploys a MECHANISM which lifts the BUMPERS outside the BUMPER ZONE (when virtually transposed onto a flat floor). This violates R25.

When being inspected your Robot is on a flat floor, all bumpers must be between 0 - 7.5in The bumper may not be higher than this before the match.

Look at rule G23 for HAB zone exempts

R25. Except as allowed per G23, BUMPERS must be located entirely within the BUMPER ZONE, which
is the volume contained between the floor and a virtual horizontal plane 7½ in. (~19 cm) above the
floor in reference to the ROBOT standing normally on a flat floor. BUMPERS do not have to be
parallel to the floor.

So yes, the top of the bumper has to be 7.5" off the floor or less.

Just going off that picture, I would be concerned with a few other rules as well.

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

If those front forks are intended to rotate forward in order to pick up the front of the robot, you’ll definitely run into an issue - you need to have bumpers in front of them! Moving the forks towards the center line of the robot would help you get around this - you could have 6" from each outside corner and a gap in the middle that allows the forks to rotate through.

R33. BUMPERS must be supported by the structure/frame of the ROBOT (see Figure 10-8). To be
considered supported, a minimum of ½ in. (~13 mm) at each end of each BUMPER wood segment
must be backed by the FRAME PERIMETER (≤¼ in. gap). “Ends” exclude hard BUMPER parts
which extend past the FRAME PERIMETER permitted by R31-B. Additionally, any gap between the
backing material and the frame:
A. must not be greater than ¼ in. (~6 mm) deep, or
B. not more than 8 in. (~20 cm) wide

While certainly doable, building in supports for your bumper could be difficult with that design. You need support material going across the front/back of the tread and extending into the corner of the robot. You would also need supports extending out inside the tread.

Needing that support across the front/back is also required for R1:

R1. The ROBOT (excluding BUMPERS) must have a FRAME PERIMETER, contained within the
BUMPER ZONE, that is comprised of fixed, non-articulated structural elements of the ROBOT.

So it’s doable, but I would suggest a thorough reading of the rules and planning on how to meet them before you make any purchases or decisions!


Now I have another question. If the AndyMark tank drive system is $769, does this break the $500 COTS rule? Or am I reading that wrong?

I really appreciate the help!


Nope It’s two individual sections, Left/Right each section is its own thing but you can buy the whole kit which I recommend. I hear the black tread is super grippy so it may be nice to get that one.

(Im going to double check the rules on COTS parts now and edit this in a bit)

(R13) No individual, non-KOP item shall have a value that exceeds $500 USD. The total cost of COMPONENTS purchased in bulk may exceed $500 USD as long as the cost of an individual COMPONENT does not exceed $500 USD. [Makes the kit purchase legal]

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I went to the rules so I could quote what made this legal, and now I’m not so sure. From the blue box under R13:

Example 2: VENDOR B sells a robotic arm assembly that the team wants to use.
However, it costs $700 USD, so they cannot use it. The VENDOR sells the “hand”,
“wrist”, and “arm” as separate assemblies, for $200 USD each. A team wishes to
purchase the three items separately, then reassemble them. This would not be legal, as
they are really buying and using the entire assembly, which has a Fair Market Value of
$700 USD.

AndyMark sells the halves separately - left half for $399, right half for $399, with the full chassis (also includes cross braces between) for $769. That sounds an awful lot like the example given.

That said, many teams have used the Rhino Track system in past years, and I’ve never seen that ruled illegal. This would be a good one to clear up through the Q&A.

Yeah I was looking at this to. This hopefully gets cleared up in the Q&A / Team Updates

I do not like this new system too much confusion.