10-01-2015 21:38

AdamHeard

Re: pic: 1710's Recycle Rush Chassis

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.

10-01-2015 21:48

Breakaway3937

Re: pic: 1710's Recycle Rush Chassis

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!

10-01-2015 22:04

Jpatterson1710

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.

10-01-2015 22:07

Jpatterson1710

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)^

10-01-2015 22:13

Arpan

Re: pic: 1710's Recycle Rush Chassis

Why, though, when omnis will accomplish the same effect without the added weirdness?

10-01-2015 22:19

HerbertTreff

Re: pic: 1710's Recycle Rush Chassis

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.

10-01-2015 22:52

ThunderousPrime

Re: pic: 1710's Recycle Rush Chassis

Your code affecting the driven wheels right? I don't see anything hooked up to the castors in that picture.

10-01-2015 22:52

AdamHeard

Re: pic: 1710's Recycle Rush Chassis

Please elaborate.

10-01-2015 22:55

IronicDeadBird

Re: pic: 1710's Recycle Rush Chassis

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!

10-01-2015 23:09

IndySam

Re: pic: 1710's Recycle Rush Chassis

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.

11-01-2015 01:02

Gregor

Re: pic: 1710's Recycle Rush Chassis

While I think that's a good idea for most games, and I would almost never choose castors myself for a drivetrain, I don't think that's a fair bias to have this year.

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.

11-01-2015 01:03

JorgeReyes

Re: pic: 1710's Recycle Rush Chassis

How large is the traction wheel and how many wheels are there per side?

11-01-2015 01:15

nighterfighter

Re: pic: 1710's Recycle Rush Chassis

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....

11-01-2015 01:31

Jpatterson1710

That would be interesting. Blue bot will be for drive practice, black bot goes in the bag.

11-01-2015 01:33

Chief Hedgehog

Re: pic: 1710's Recycle Rush Chassis

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.

11-01-2015 01:34

Jpatterson1710

Arcade style drive on the controller.
Turtle mode for precise driving.
Encoders on either side to match RPMs when needed.

11-01-2015 01:38

Jpatterson1710

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.

11-01-2015 01:39

CalTran

Re: pic: 1710's Recycle Rush Chassis

Perhaps I'm missing something, but how does that prevent the castor from free spinning and scrubbing while turning or traversing the scoring platform?

11-01-2015 01:43

Nuttyman54

Re: pic: 1710's Recycle Rush Chassis

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.

11-01-2015 01:46

Jpatterson1710

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.

11-01-2015 02:09

JorgeReyes

Re: pic: 1710's Recycle Rush Chassis

Can this go over the scoring platform? And what size is the rear wheel?

11-01-2015 02:14

Jpatterson1710

Re: pic: 1710's Recycle Rush Chassis

Yes it drives over the platform. Traction wheels are 6in.

11-01-2015 02:18

Jpatterson1710

Re: pic: 1710's Recycle Rush Chassis

Yes, code only controls traction wheels. The way we drive the traction wheels solves any potential issues caster wheels could introduce.

11-01-2015 02:23

Amar Shah

Re: pic: 1710's Recycle Rush Chassis

Try pushing a wheeled swivel chair in an arbitrary direction. You should notice a bit of resistance and a pull sideways before the wheels all align in the correct direction.

11-01-2015 03:58

Woolly

Re: pic: 1710's Recycle Rush Chassis

While it's great to think outside the box, it might be an idea to replace the casters with omni wheels for reliability sake. In the event of a code, electrical, or general sensor issue, it would be trivial to have a way of toggling back to a simpler teleop drive code that doesn't use the encoders. That way if something of that nature goes wrong, the robot doesn't become completely un-drivable, nor would it make the robot control like a wet mop on a 54 foot pole.

11-01-2015 10:34

Kevin Kolodziej

Re: pic: 1710's Recycle Rush Chassis

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.

11-01-2015 11:13

IndySam

Re: pic: 1710's Recycle Rush Chassis

I said "almost"

11-01-2015 11:38

Madison

Re: pic: 1710's Recycle Rush Chassis

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.

11-01-2015 11:38

weaversam8

Re: pic: 1710's Recycle Rush Chassis

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.

11-01-2015 15:37

Jpatterson1710

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.

11-01-2015 15:41

Jpatterson1710

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.

11-01-2015 15:43

Re: pic: 1710's Recycle Rush Chassis

Or maybe you shouldn't show an unfinished design and expect people to think you know what you're doing with it when you've shown no evidence whatsoever to prove that statement. These people are trying to provide helpful advice given what you've shown, and you're putting on a pompous attitude as if your unfinished design is the greatest thing ever. Your entire thread is a disappointment.

11-01-2015 15:49

safiq10

Re: pic: 1710's Recycle Rush Chassis

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!

11-01-2015 16:17

EricH

Re: pic: 1710's Recycle Rush Chassis

Allow me to put it this way: It is very rare for a team to use casters and not regret it. I can think of maybe one exception (56 in 2005 comes to mind, using ball casters instead of regular casters). On the other hand, using omnis to accomplish the same purpose very rarely results in regrets. (I would also note that I would be very, very, VERY careful with the weight distribution given what is shown--that drive wheel is just a little far forwards, assuming the open end is the front, for my liking with no visible support behind it in case of sudden acceleration over a ramp going the wrong way. Again, this is just what is shown, so I can't comment on final designs.)

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*

11-01-2015 16:31

Jpatterson1710

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.

11-01-2015 16:31

JosephC

Re: pic: 1710's Recycle Rush Chassis

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*

11-01-2015 16:35

Cory

Re: pic: 1710's Recycle Rush Chassis

Came here just to say this...if you're set on casters, use ball casters. There is no advantage to regular casters and ball casters eliminate some of the problems associated with the kind you have pictured.

11-01-2015 16:40

Jpatterson1710

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.

11-01-2015 16:42

Jpatterson1710

I have considers ball casters. I don't really want the omnis. These were the only casters at the local hardware store.

11-01-2015 17:04

Jpatterson1710

Anyone know of a team that used ball casters? I would like to look at some video of that.

11-01-2015 17:05

mrnoble

Re: pic: 1710's Recycle Rush Chassis

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.

11-01-2015 17:06

Cory

Re: pic: 1710's Recycle Rush Chassis

469 in 2004. Someone earlier in the thread mentioned 56 in 2005.

11-01-2015 17:09

Gregor

Re: pic: 1710's Recycle Rush Chassis

This reminds me of a good quote from JVN

"I don't really want omnis" isn't a great reason, especially if you were to use this kind of argument in a professional environment post graduation, which I assume is a goal of your team given your high student involvement.

11-01-2015 17:15

Jpatterson1710

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.

11-01-2015 17:20

orangemoore

Re: pic: 1710's Recycle Rush Chassis

I have never heard of an omni wheel breaking a roller. Has this really happened before?

11-01-2015 17:22

mrnoble

Re: pic: 1710's Recycle Rush Chassis

I've never seen it. We've been using them since 2007.

11-01-2015 17:26

JosephC

Re: pic: 1710's Recycle Rush Chassis

I've been field reset every week for the past 2 years, and have never once personally seen an omni break a roller.

11-01-2015 17:27

Jpatterson1710

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.

11-01-2015 17:30

Jpatterson1710

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.

11-01-2015 17:30

JosephC

Re: pic: 1710's Recycle Rush Chassis

With no defense in this years game, It should be difficult to break ANY type of wheel, unless you're flying off bumps.

11-01-2015 17:32

mrnoble

Re: pic: 1710's Recycle Rush Chassis

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.

11-01-2015 17:39

EricH

Re: pic: 1710's Recycle Rush Chassis

I haven't seen an omni break, but I've picked mecanum rollers out of the field reset box. OTOH, I've also been on a team that managed to break the hubs out of some wheels.

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.

11-01-2015 17:53

Jpatterson1710

That's the beauty of two robots. If we decide after drive practice that it isn't working, we can make adjustments.

11-01-2015 18:26

D_Price

Re: pic: 1710's Recycle Rush Chassis

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.

11-01-2015 18:49

Jpatterson1710

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