Quote:
Originally Posted by Alan Anderson
Velcro holds the field to the carpet, and there's quite a lot of square yards of the stuff doing it. Good luck getting that much holding area on a robot.
Zip ties on the field are used for wire management, not structure. Unless you're talking about the lexan side panels on the original field design, in which case you might be interested to find out that several of them do break on average every event, and they have been replaced with rivets in the new design.
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In last year's field zip ties and gravity were the only things holding the high goal and its support structure above the heads of the drive team. This year the tote chute's ramp and cover are held together by zip ties and gravity. From my understanding the original AndyMark fields did ocassionally break the rivets that held the polycarb panels which are a structural element in the AM field. I believe that they uprated the rivets used in the production versions because of this.
Quote:
Originally Posted by Jon Stratis
The only parts being held together on the field by zip ties are the Lexan covers (NOT structural, these are intended for shielding and to provide a smooth playing surface). In those cases, the physics are well understood - most of the force against those covers will come from head-on collisions with robots, in which case they are pushed against the pipes supporting them. Sliding force has been known to break zip ties on the field, and they are replaced as needed. Additionally, if those zip ties break and the Lexan comes lose, it's not exactly moving - it just flops to the ground. The structural elements to the field (all the aluminum piping) is held together by slotting pieces inside of each other and locking them in place with pins. There is a firm mechanical joint between every part of the field structure, and it's designed so it can only come apart in a very specific way.
Contrast that to a weight attached to a robot. The weight is constantly experiencing acceleration and deceleration as the robot moves around. It can take an impact from another robot, in which case this is two robots hitting each other, not one robot hitting a stationary target. If the robot is spinning in a circle full speed when the zip tie lets go, the weight isn't just going to fall to the floor - it's going to be thrown across the field (and possibly outside of it). This is a much more dangerous situation.
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There are zero pins holding the traditional field together this season. Last season there were a hand full of pins used to keep the high goal together but not to keep it supported above the driver's head. The shelf that the high goal structure sat on was attached to the driver's station uprights by zip ties. Yes the shelf had semi circle notches that kept them centered on the upright and served to transfer the load, however without the zip tie it would have been very possible to bump it in a manner that could send the entire structure crashing down. Yes those zip ties were heavy duty, rated for 150lb load IIRC and there were several, but still zip ties were an integral structural element in last year's design. With the impacts the driver's station wall saw last season I was always a little afraid of what could happen during one of those sever impacts. It was normal for the field to grow a couple of inches over the course of an event due to those impacts. I saw many cases where a substantial lump formed in the carpet behind the driver's station due to the impacts stretching the carpet.
I do not know for certain if there are any pins in the AndyMark field because I have only seen the flyer and not seen one in the flesh.