So our builders were wondering what the minimum ground clearance is.
-I also heard that the field will be uneven, if anyone knows if this is true or not, I would also like to know.
Minimum ground clearance: None. Just keep everything other than rover wheels off the ground if there is a chance of traction being added.
Uneven field: only where the carpet and regolith meet. There will be a slight unevenness due to the fact that the regolith is on top of the carpet. 1/8", IIRC. It’ll be covered by fiberglass tape.
There may be some slight imperfections in the liner or the carpet underneath it, so you don’t want to plan on extremely small clearances. The field surface itself is pebbled, but if you’re trying to hug the ground so closely to have that be a difference, I’d say you will be having other problems with your clearance. You can’t design so closely that the slightest bend in your frame from a collision means next round you’re scraping the ground.
We have a local sponsor (Sonic Tools) who has built a field with 3 pieces of regolith. The edges on the long axis tend to curl up no matter what he has tried. I understand that first has come up with a solution for this, though I haven’t seen it. We have a clearance of about 1/2" and were getting caught on these edges. Also the material is very brittle and sharp when broken. I think before the regionals are each over we will see damage to the fields as the tournaments progress. Small, hard objects falling off robots and being run over may punch holes in the surface, so the fields should be meticulously cleaned between matches…IMHO…
The edges of the regolith will be taped down with gaffers tape to the carpet. Hopefully that will keep the robots from getting caught on the edge. In addition, the field will repaired and cleaned as necessary.
Scott at Sonic tried that from underneath, but it just pulls away over time. I think it will need to be addressed from the top, but they may have come up with something better… YMMV…
They are taping it down from the top, they also have 50’ long rolls to minimize seams.
The material is 3/32" thick as well I believe.
1/2" of ground clearance will be sufficient on the actual field I imagine.
Are gaffers tape and fiberglass tape the same? Because in Q&A, they spec’d fiberglass tape.
“Edges of the FRP surface material will be taped down and the seams between the three pieces will be taped together with fiberglass tape with a friction characteristic similar to the FRP material.”
Hmm… a little hard to get out of that wording, but the edges will be taped down with gaffers tape (The same kind of tape used on the carpet seams for the previous years) and the seams between the three pieces will use the fiberglass tape.
Yeah, it is a little hard to get out of that… By the grammar, it sounds like both types of join will be the fiberglass tape. But if you have other info, say from an official position, then that’s what we need to go by.
The GDC needs a grammarian to check their work…
Agreed, could go both ways from the Q&A answer. Of course, I’m not an “official” source so anyone who’s really concerned may want to post an Q&A to clarify exactly what they mean or just check it out on the competition field.
We have about 1/4" clearance, and regularly wander off our little patch of regolith. We get back on without problems. We haven’t experienced the curling on the edge of the glassliner material though, so hopefully that’s not an issue at the competition.