What wheel types are you considering? I would say omnis, but much of my team disagrees. Pros, cons? I’m a relatively new member and have only used different wheels a handful of times. Thanks.
We’re thinking using pneumatic wheels.
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My team originally thought of omni, but the issue is that defense is not completely off the table. Whether you get pushed around, or if you need to push around the opponent, omnis will give you issues. Rhino treds was one idea but most of my team is leaning to pneumatic wheels. Pneumatic wheels are strong and faster than treds, but movement will be a bit more jerky without omnis. However I think most are going with Pneumatic wheels.
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Thanks for the info. Omnis would especially be counter productive if an opposing alliance had heavy defense. Also, many bots will use lifts this year, leaving not much weight on the Lower half of the bot, top heaviness will be an issue.
My team is also leaning towards pnuematic wheels. We think they will assist in cushioning the impact of driving off the level 2 platform without the need for an additional mechanism as well as provide grip for climbing the platform/Hab.
Intialy I thought Omni wheels might be nice but because of the reasons above and because it’s an open field with the possibility of defense, I’m having second thoughts about them.
But is the exchange of accuracy and ease counteract the cons, especially with an inexperienced driver (ours)?
Personally, I’ve always been a fan of standard traction wheels like these over at VexPro. When used in a 6-wheel west coast drive with a dropped middle wheel, it gives superior traction and doesn’t take forever to design and build (leaving more time for prototyping manipulators and other parts of the robot). I’ve never seen one break at competition, but when we have need to replace the tread, doing so is as simple as switching out their plug and play traction treads or replacing the custom tread around the outside of the wheel. Using custom tread like the Pebbletop tread at AndyMark also gives you a lot more customizability in regards to the friction between your wheels and the carpet. So yeah. They are my go-to wheels.
With the nearly flat field (with the exception of the Hab and the cable protector of course), there really isn’t that much of a need to deal with super shock-resistant drivetrains either. Thus, if I were actually able to build a robot this year, I’d likely go for something fast and maneuverable but with superior traction for the defense that will definitely sprout up as we get closer to hitting the point cap later on in the season.
Either Traction wheels or Omni’s is usually a good choice, although many teams were successful with Colson wheels last year. With no rough field, pneumatic wheels and rhino tracks aren’t really needed.
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Thanks for your knowledge. Makes sense. We have used some traction wheels in the past, and they’ve worked well. I just might want to use omnis just for less stress and time at delivery spots.
At that point you just have to worry about being bashed around too much. Omni’s only have traction in one plane, but even in the plane they do rotate in, they are not that difficult to push around. Thus, when defense comes around, it’s a lot easier to frustrate anything you are trying to do. The real tradeoff is whether the less stress and easier movement or the ability to hold your ground is more important and beneficial to your strategy.
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Depends on if and how you intend to start/end the match above level 1. If you’re driving up or down one of those steps, pneumatic or tread make sense. Otherwise, solid (traction/colson) unless something else makes you decide omnis are worth the loss of lateral traction, or you find the need to drive sideways. I’m thinking that a 4 wheel robot, with solid wheels on the hatch panel pickup/scoring end and omnis on the other would be easier to auto-guide in using the alignment lines and reflective targets.
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I think maneuverability this year is extremely important especially when aligning to the cargo ship and rockets, therefore having mecanum drive base would be very beneficial with auto aligning to the bays
They would be nice for aligning, but from what I remember from last year. Some teams that used mecanum had problems getting onto the platform.
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getting onto the first platform is very possible with mecanum especially with enough speed as I have seen many teams manage to do so, but you are right going any higher is a potential problem
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Just be careful with mechanum. Maneuverability is nice, but I’ve seen it be the disqualifier in getting picked for playoffs way too many times to be comfortable.
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re: mecanum for alignment:
why not just add a lateral slide to your pickup/scoring device? That adds one relatively low power actuator rather than two high power ones.
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This is actually a great idea. Mind if I steal it?
You can’t steal it if I give it away.
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If youre looking for inspiration for this, both team 8 and 4513 had this on their gear mechanisms in 2017.
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Thanks for the recommendation, I’ll take a look!