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pic: 1710's Recycle Rush Chassis
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It's still week 1.... not too late to ditch those casters!
You'll get a much more predictable drive if you pull them, even if you just switch them to unpowered omnis. |
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I think I know where you are going with your design.... Anyway, have you tried the caster wheels on the edge of the scoring ramp. We use casters as part of our prototyping for quick chassis builds and the casters always want to go down the ramp and when you are driving parallel to the ramp, you will be scrubbing your wheels causing a lot on inconsistency in you drive. Just want to throw our testing out there. Good luck with the rest of your design. You have a good start!
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pic: 1710's Recycle Rush Chassis
We have some programming in place to make the casters easily controllable. We did drive this chassis before it was stripped back down the the basics. I'm confident in the chassis and our driver. And, believe me, unless you have some inside information, this chassis will tell you nothing about our strat or design.
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After prototyping and a design review by our mentors, we WILL be playing offense this year,
http://www.chiefdelphi.com/forums/sh...d.php?t=126704 ^(Link to story)^ |
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In 2013 we tried to used casters, but due to their inconsistencies while driving we sub for a huge chunk of shaved down of HDPE for a sort of stand. we found they worked great and just slid across the carpet.
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Going to have to mirror what everyone else is saying I'd rather see a pair of skis on the front of that then casters. Not to knock your work though. Fantastic job!
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Casters are evil and should be avoided at all cost.
If I see them on a robot they are almost automatically removed from my pick list. |
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This year needs to be approached differently in every aspect of it, including alliance selection. Don't let years of bias creep into this year, when some things actually don't matter. If 1710 scores more points that x 6 wheel tank, or y 4 wheel mecanum (and fills the void that my alliance needs), I'll pick them. |
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How large is the traction wheel and how many wheels are there per side?
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Obviously the 2 separate chassis combine together to form one large chassis!
With a large rectangle void in the middle, perfect for storing and stacking rectangular objects.... |
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That would be interesting. Blue bot will be for drive practice, black bot goes in the bag. |
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Your first problem is Apple. If you couldn't reconfig the pic, then the second problem is more suspect.
Your second problem is the casters. But since you couldn't realize the problem with the use of Apple (really? posted upside down?) then you do have problems. But wait - maybe the misuse of the apple machine and your problems posting a right-side-up machine may be a hint! Auggghhh! A red-herring! Your are planning to use your posted frames as intake mechs and use the casters as feeders. Really - I give up. What in the heck is going on? Good Luck and I wish you the best! Edit - yes, there is a lot of sarcasm in this post. |
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Arcade style drive on the controller. Turtle mode for precise driving. Encoders on either side to match RPMs when needed. |
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As far as the iPhone issue, if I flipped it it would post upside down, and if I didn't, it would post upside down. I gave up. As far as the robot, check back on the Saturday before bag day. |
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Interesting to note that if I open just the image itself in Chrome, it flips it right side up for me.
I also second those saying casters will be difficult to control. They like to do funny things when changing direction, and will provide inconsistent turning resistance. At the very least, make them ball casters so they ride smoother. Omnis will drive nicer still. |
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If our traction wheels are spinning at our desired RPM, it doesn't matter what the casters do as long as they're supporting the front of the bot. They're simply used as a low friction support to the front of the bot. |
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Can this go over the scoring platform? And what size is the rear wheel?
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OP, if you have tested this drive (or will be) and find that it does what you want it to do with the casters, then more power to you! Casters ARE NOT inherently a bad thing. Be aware of what the casters can do while going over the scoring bump, especially if you're turning into the bump rather than going straight at it from any distance away (this would give the casters time to straighten and align with your direction of travel). There is good advice in this thread, but don't be scared to try things!!
I drove a robot (casters in the back) in 2001 and never had any alignment or drive issues caused by the casters. We did, however, have a second set of drop-down traction wheels to aid in going over the teeter-totter however, but those were engaged for maybe 10 seconds of any given match. |
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There is a lot here that can be improved. I'd encourage you to heed some of the advice you're getting in this thread.
Casters make driving unpredictable. You can mitigate the effect of that unpredictability better over long distances than over short ones using feedback. The casters may not be a problem if they're never touching the ground, though. Your weight distribution is, so far, bonkers. You want your points of contact with the floor to be as far from your center of mass as possible, generally. Putting your gearboxes and CIM motors outside your points of contact is negatively impacting your center of mass in a big way. If you continue to add structure between or over those gearboxes, it'll only get worse. It's not too late to save yourselves a lot of headaches later. |
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Wouldn't having the battery off to one side like that affect driving? We moved our battery slightly to the side and our chassis turns due to the extra weight.
P.S: The flipped image is due to iPhone EXIF data. Remove the EXIF data, or modify it, and it will not be flipped. |
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Ouch, maybe you shouldn't criticize a design until you know how the rest of it goes together. If you have a problem with us, then you can turn down the invitation to our alliance in Elims. |
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That's not final position for battery, also I made some battery-sized 14 pound weights, just in case. Thanks for the tip, perhaps android has at least a couple advantages. |
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Wow! This is an interesting design to say the least. I personally am terrified of Casters due to our experience with them in BEST Robotics. I personally would keep an extra pair of omni wheels just in case if something happens and your drive need to switched out.
But hey if you guys feel comfortable with this drive train and score the points your team needs then bring on the casters! Good luck this season! |
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But when someone insists that they've got it under control, gives no details or details that aren't necessarily related to the problem brought up, and then when people say "hey, those details you mentioned aren't going to help you", and that person responds with an attitude that basically says "You don't know what you're talking about, we're better than you"... That's a great way to end up on a lot of teams' lists of teams they don't want to pick. Reference the link below. And then you add in that a fair number of the commenters so far either have had experience with casters, or have seen teams that have, and have been doing this for quite a while... generally it isn't a bright idea to blow off advice from folks with lots of experience. *puts check in unmarked box on scouting sheet* |
This was not meant to be an advice thread. Although I take every comment into consideration, when they are phrased in a way that seems attacking toward us, it's hard not to become defensive. The replies to this thread in no way could be considered gracious or professional. I'm not looking for people to give us design advice at this point, if I was I would definitely provide more information. All I ask is that we refrain from attacking ideas any more. We may not be the best team, but our bot it 100% student designed and build with only slight direction from mentors, and we pride ourselves on that.
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Generally, people post week 1 designs and builds on CD for feedback, as you can tell by this thread. It's generally wise to take the experience of those who have been doing this much longer than you, or we wouldn't need mentor's would we?
Criticism can be constructive. If you can't take the suggestions of other people into consideration, you're doing something wrong. As for the design itself, I'd be wary of your CIMs being behind your wheels, I've seen a lot of teams do it before, and it generally leads to wheelies when accelerating. Check out 68 in the beginning of this video for example : Click *Please note that this was due to unbalanced CoG, not necessarily CIM location* |
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Exactly, check out some of our match footage from last year. We've learned a lot about "tippy" robots. That was one change I considered, CIMS could probably be moved. |
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I have considers ball casters. I don't really want the omnis. These were the only casters at the local hardware store. |
Anyone know of a team that used ball casters? I would like to look at some video of that.
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We can only work with what you show us. This far, we can see a frame, which (combined with your reticence about strategy and what sits on top of the frame) tells us little. Folks have pointed out that:
The gearboxes are behind the drive wheels, The battery is placed in a wing rather than centered, and Casters are being used in front. All three are worrisome, and folks want you to know that (from what we can see) there may be better ways to approach things. This year's game will certainly invite new and innovative designs, but listening to the concerns of veterans here who only want to help would be wise. I've had several experiences here over the years where I posted a photo and got feedback that I didn't want, but that I needed. |
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I guess I should have backed that up. I don't want to use omnis, because the rollers are more likely to break than a caster, and in the event of a break, casters are one easily accessible nut, rather than messing with collars or spacers with a shaft.
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It apparently happened on our team before I was around. We also broke an AndyMark rubber wheel in last year's game, so I wouldn't put it past us.
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I guess if it doesn't happen often, then it could be a possibility, I'm just a fan of the simplicity of the caster.
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I'm a teacher. I've seen a TON of broken casters on chairs in the school. No broken omnis. If your team broke one five years ago or so, see if you can track down the circumstances. AndyMark and Vex have improved their products each year and I sincerely doubt you'd find this year's wheels to have problems.
Also, no defense. |
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Just a random thought, see about some ball casters--for both chassis!--and maybe add some omnis to an order that comes in later for the practice chassis, and see how they all hold up. Video of 56 in 2005... http://www.thebluealliance.com/team/56/2005; be advised that you won't be able to see much of them. Best bet is the Q94 from Galileo Division, near the start. |
That's the beauty of two robots. If we decide after drive practice that it isn't working, we can make adjustments.
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Digging the chassis design and can definitely see the pick up potential but I will have to agree with a lot of the others on this thread in stating that; even with programming in place for the casters it still leaves a ton of inconsistency in using these wheels.
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Thanks. We're really digging it too. Clearly there is enough evidence here to look into other wheels. We'll mess around with all the options |
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