Team 5720 Frame Perimeter Question

[mjv5720]

Since this years robot requirements rely so much on measurements, I was curious about the frame perimeter.

Here is a link to pictures of our robot: http://imgur.com/a/pu6jp

When measuring the frame perimeter, does it have to be an exact rectangle? By that I mean can it curve in a little bit. Right now as you can see our robot's front two wheels aren't as thick as our tank treads and so if we put a string around it it has a more trapezoidal shape to it. Does that matter? Or should we be measuring it from outside edge of the tank treads all the way down the side of the robot?

[Christopher149]

Frame perimeter is a convex polygon from wrapping a string around the outermost, fixed portions of your robot. But, you need at least 8" of bumper to extend to each side of every corner. So, you could have a hexagonal frame perimeter if needed.

[EricH]

Originally Posted by mjv5720

Since this years robot requirements rely so much on measurements, I was curious about the frame perimeter.

Here is a link to pictures of our robot: http://imgur.com/a/pu6jp

When measuring the frame perimeter, does it have to be an exact rectangle? By that I mean can it curve in a little bit. Right now as you can see our robot's front two wheels aren't as thick as our tank treads and so if we put a string around it it has a more trapezoidal shape to it. Does that matter? Or should we be measuring it from outside edge of the tank treads all the way down the side of the robot?

It is a convex polygon. No concave, no curve in, nothing.

Now, there's an easy way to make it rectangular: Take a piece of aluminum of the proper length and mount it in front of the wheels, sticking out to the proper width to match the tracks. Bingo, rectangular frame perimeter. (You'll need to figure out support, though.) You'll want to do the same at the back, behind the tracks.

[GaryVoshol]

The FRAME PERIMETER doesn't need to be rectangular. It can have more angles and they don't all have to be regular. But it does have to be convex.

It is defined by the outermost points of your ROBOT. Right now that includes the treads and wheels. You'll need to be able to mount your BUMPERS around them.

If the wheels and treads are below the BUMPER ZONE (lower than 4 inches) then you have another problem. You can't have anything outside your FRAME PERIMETER at the start of the match (Rule G7 D). You will need to make a FRAME PERIMETER that will encompass the space that the wheels and tread occupy. If it can't be fixed you'll be disabled.

[jimwick]

There is no requirement for the shape of the perimeter but your basic configuration is illegal. A rigid, fixed frame has to be the OUTERMOST element of your bot in starting configuration. You have to attach the bumpers to the frame, at the corners. In starting configuration everything needs to be inside that metal. See rule R2, R3, R4.

So you need to install sturdy, rigid metal OUTSIDE your tracks.

[mjv5720]

We decided to scrap our old idea and we are now using the Rhino tank treads from AndyMark.com. I was just wondering and wanted to make clear that when measuring the frame perimeter for these. e would take the length with the legs up. By that I mean that we would measure the length along the ground of the treads while they are inclined up and not laying flat. By our measurements it is about 29inches long while inclined and I'm just double checking that that would be a legal measurement.

[GeeTwo]

Originally Posted by mjv5720

We decided to scrap our old idea and we are now using the Rhino tank treads from AndyMark.com. I was just wondering and wanted to make clear that when measuring the frame perimeter for these. e would take the length with the legs up. By that I mean that we would measure the length along the ground of the treads while they are inclined up and not laying flat. By our measurements it is about 29inches long while inclined and I'm just double checking that that would be a legal measurement.

Containment within the frame perimeter is only required at the initial configuration of the robot, so if you start with the treads in that configuration, that should be OK. Note however that the bumpers have to remain in the bumper zone in any configuration you normally assume.

[Jon Stratis]

Originally Posted by mjv5720

We decided to scrap our old idea and we are now using the Rhino tank treads from AndyMark.com. I was just wondering and wanted to make clear that when measuring the frame perimeter for these. e would take the length with the legs up. By that I mean that we would measure the length along the ground of the treads while they are inclined up and not laying flat. By our measurements it is about 29inches long while inclined and I'm just double checking that that would be a legal measurement.

The rhino tracks make me asking the frame perimeter interesting, as the frame elevation changes depending on where you're looking. To help determine your frame perimeter, think about what a bid to contain the robot would look like. The walls would be perpendicular to the floor, and pressed right up against the front, back, and sides of the robot. That box then defines the frame perimeter.

Please keep in mind the bumper mounting rules. Specifically 8" from each corner of the robot (including in front/behind the treads!), With the 1/2" of support at each end of the bumper. Depending on what your doing with your design for supporting the bumper, you may need to add more frame material to get everything properly supported - and that may change your frame perimeter!

Please feel free to PM me if you need more help with this. You're located a little less than an hour from my house, and I will be one of the LRI's in attendance in Duluth while you compete

[Stappy]

Does the "frame perimeter" requirement mean that I have to have my wheels/tires contained inside a frame besides the bumpers?
Robot has external mounted tires but the bumper will enclose it by design. Do we need to surround with a redundant metal framework and then the bumpers?

If no external frame is required, does the bumper have to follow the way the external dimensions of the robot would be measured without the bumper attached?

Say without the bumpers the robot is like a stop sign viewed from above but it is easiest/strongest to make the bumpers in a rectangle.

I am hoping this question is not hijacking Team 5720 original question but enhances it. If not let me know I will start a new thread.

[Jon Stratis]

Stappy-

There is no requirement that your wheels are contained, but there are other requirements that may apply to your situation.

First, the frame perimeter must consist of "fixed non-articulated structural elements" (R2). Basically, this means the outer most corners have to be some sort of structural frame, not a wheel, as a wheel is articulated. So you need some frame material that extends into the corner.

Second, the bumpers must protect at least 8" on each side of the FRAME perimeter (R19).

Third, bumpers must be supported by your robot frame/structure (R26), with specifics as to the allowable distance between the bumper plywood and the frame/structure of the robot. And a minimum of 1/2" must be supported on the end of each bumper segment (also R26).

When you put this all together, it means you can't have rectangular bumpers on an octagon - you couldn't properly support the corner of the bumpers and would likely have difficulty with the 8" rule as well. Plus, that could effectively increase the overall size of your robot beyond the allowed 120" frame perimeter. Now, if you have 8" wheels, you also may find it difficult to support the bumper with robot frame/structure every 8" down the side (or on the end of the bumper if you opt for an 8" "corner bymore" type design) without having robot frame that encloses your wheels.

[Stappy]

We planned full length bumpers down both sides with the bumper assy attaching at each end of the robot. We could easily extend the frame of the robot in front of and behind the wheels for additional support if needed. We do have 8" of bumper planned at each end, I guess we just need frame behind it now.

[Jon Stratis]

Originally Posted by Stappy

We planned full length bumpers down both sides with the bumper assy attaching at each end of the robot. We could easily extend the frame of the robot in front of and behind the wheels for additional support if needed. We do have 8" of bumper planned at each end, I guess we just need frame behind it now.

Sounds like you have a good plan, just need to pay careful attention to R26 for proper bumper support.

[eedoga]

Originally Posted by Stappy

We planned full length bumpers down both sides with the bumper assy attaching at each end of the robot. We could easily extend the frame of the robot in front of and behind the wheels for additional support if needed. We do have 8" of bumper planned at each end, I guess we just need frame behind it now.

I think we need to be careful to make sure we are being clear about this because I would hate to see a team show up to competition in violation of these rules which are pretty hard set and difficult to fix at competition.

The frame perimeter is the outer most edge of your robot at the start of the match. so currently in your picture your pneumatics, wheels, and treads are outside of your current frame perimeter.

The other thing to consider is the vulnerability of your robot parts and the purpose of the bumpers.

This year there are going to be a lot of relatively high speed collisions. Robots going over defenses into the courtyard are going to be hitting robots on the other side intentionally or otherwise, and robots doing defense are going to be hitting robots trying to score balls preventing them from achieving their goals.

You want to protect all the things with your frame perimeter. Consider anything sticking out fair game during a match. Heck...I've seen robots break themselves hitting the sides of the arena too hard. :-(

Best of luck to you!

Edoga