Thread: pic: 6WD Module
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Unread 09-12-2006, 17:48
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Madison Madison is offline
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Re: pic: 6WD Module

Quote:
Originally Posted by 114ManualLabor View Post
I like! Reminds me of a design I did... But anywhoo, about what speed do you get out of it? Also, with how rough the games seem to be getting, aren't you worried it's a little flimsy?
This is based heavily on our drive from last season. It looks considerably different because we now have the capability to plasma cut much larger parts, but the design is informed by what we learned from our effort last season. The single largest problem we had with that drive was borne from my stupid, aesthetically-driven decision to expose the ends of each module and extend them beyond the frame. As a result of that design decision, we sometimes had the modules bent inward at their ends when they were hit by other robots. The frame this will sit in will resolve that issue. I'm otherwise not concerned at all about its resiliency. I think most teams in FIRST overbuild their machines to an absurd degree, but sometimes that's the only method they have available to them to compensate for a lack of engineering support.

Quote:
Originally Posted by mtaman02 View Post
If welded / screwed together properly it should not break all that easily. I Like that design and have another question. The Drive System seems to be well organized and hopefully built but what about the many other modules this robot will have, will there be enough space inside the robot to do a motor transplant w/o having to move anything out of the way? Is the CIMs easy to get to? Will other modules be easily able to be gotten to? If not will all the other modules be modular so that they can be taken out quickly and easily with little to no hassle?
I didn't explain the gearboxes in too much depth in the caption. They are wholly self-contained and can be quickly removed from the outside face of each module. Replacing a motor, which we've never had to do, shouldn't take more than a few minutes.

Quote:
Originally Posted by Ben Piecuch View Post
Looks nice and compact! I've always loved these double plate designs, something we've yet to integrate into one of our robots.
If they're properly supported by the rest of the robot frame, these are a great way of compartmentalizing the function and assembly of the robots. We've found that it's much easier and goes much faster to have two teams of students assembling the individual modules than to have them all huddled around a single frame. It also allows other folks to do their thing with the frame without getting in the way.

Of course, there's also a pretty big advantage to repairability and that sort of thing as well. In the short time we've done this, we've not had to replace an entire module, but I'm sure that we'd need to as soon as we abandon this design


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As I understand it, there are two chain runs that go over the motors? How much clearance do you have b/w the chain and the motors? Are you concerned about a) tensioning the longest run b) having the chain (even properly tensioned) slapping against the motors?
Admittedly, I'm always bad at accomodating chain. I like things to be snug and compact and chain doesn't always cooperate. If it turns out that the chain is banging against the motor casing, I imagine we'll make a sleeve or something to minimize the noise and losses out of delrin.

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The hex shaft is nice as well. How are you adapting the sprockets to the shaft, as it looks as though the sprockets are either AM's, or kit sprockets. Neither of which come with a bore you could use.
Since we're building our own omniwheels, they'll have a hex bore in them and we'll just bolt the sprockets right onto the wheels. The center wheel, if we again use a Skyway wheel, will have 3/16" aluminum "hubs" that'll be hex bored and they'll tie that whole thing together. It means that the wheels are tapered toward the middle, but I don't think that's a bad thing.

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Finally, I'm calculating about 6.5ft/sec, right around the kitbot speed. Have you found this to be a good balance b/w speed and torque?

BEN
That seems about right. Feedback from our drivers last year suggested that the kitbot arrangement was even a bit too fast for their liking. I'm hesitant to slow it down too much, though, as I think there's some range where the machines are too slow to outrun defensive machines, but too weak to fight their way through them.
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Last edited by Madison : 09-12-2006 at 17:58.