|
|
|
 i build robots. i like robots. i live with robots. i love robots. i AM a robot. - tgoral2826 [more] |
 |
|
|||||||
|
||||||||
Iteration is everything in design. We've been working to reimagine the 6WD design we've used for the past two seasons into something that's cheap, quick to manufacture in our shop, light and elegant. Naturally, as the latest iteration, I think this is the closest we've come to the perfect 6WD design for our team.
Discussion
view entire thread
02-01-2007 22:06
DanDon
Re: pic: FRC488 - Six Wheel Drive Chassis
A couple of questions:
Does that have any rocker in it? And is that 25 or 35 chain?
02-01-2007 22:30
EricH
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by Joel J.
Why omniwheels on a 6WD?
|
02-01-2007 22:31
Gdeaver
Re: pic: FRC488 - Six Wheel Drive Chassis
If the bumpers are back and the design is like 2006, then the next step is to add mounting to this frame that would allow the bumpers to be a structural element. If the rules allow forget home center plywood. Baltic birch "wood" be a good choice.
02-01-2007 22:32
Cody Carey
Re: pic: FRC488 - Six Wheel Drive Chassis
Not necessarily more maneuverable, But I bet it is nice to have the 'bot spin around it's center set of wheels instead of whichever four happen to be touching the ground 
02-01-2007 22:38
s_forbes
Re: pic: FRC488 - Six Wheel Drive Chassis
Wow, looks light! Do you have an estimated weight for the entire drive base?
And on the subject of omniwheels: It looks like with the setup you have it would be very easy to swap them for traction wheels if they are needed. I guess that would be decided in testing.
02-01-2007 23:07
MikeDubreuil
Re: pic: FRC488 - Six Wheel Drive Chassis
Can you explain why you chose not to have a cross brace? I'm not a mech-e but I would guess you need one.
02-01-2007 23:24
Madison
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by dhoizner
A couple of questions:
Does that have any rocker in it? And is that 25 or 35 chain? |
|
Originally Posted by Joel J.
Why omniwheels on a 6WD?
|
|
Originally Posted by Gdeaver
If the bumpers are back and the design is like 2006, then the next step is to add mounting to this frame that would allow the bumpers to be a structural element. If the rules allow forget home center plywood. Baltic birch "wood" be a good choice.
|
|
Originally Posted by Cody C
Not necessarily more maneuverable, But I bet it is nice to have the 'bot spin around it's center set of wheels instead of whichever four happen to be touching the ground
|
|
Originally Posted by s_forbes
Wow, looks light! Do you have an estimated weight for the entire drive base?
And on the subject of omniwheels: It looks like with the setup you have it would be very easy to swap them for traction wheels if they are needed. I guess that would be decided in testing. |
The omniwheels are riding on 5/8" keyed shaft, while the AndyMark performance wheel is broached for a 1/2" hex shaft. It'd be relatively easy to change out a set of omniwheels for a set of traction wheels with a little bit of forethought. Namely, I'd need to make some shafts that are 5/8" diameter with keyway on one end and 1/2" hex on the other.
|
Originally Posted by MikeDubreuil
Can you explain why you chose not to have a cross brace? I'm not a mech-e but I would guess you need one.
|
02-01-2007 23:33
Gdeaver
Re: pic: FRC488 - Six Wheel Drive Chassis
I noticed that the front and rear c channels are notched for the drive rails on top and bottom. This could be a weak point. Shouldn't the drive rails fit inside the c channel leaving the channel uncut ?
03-01-2007 00:00
dlavery
Re: pic: FRC488 - Six Wheel Drive Chassis
M -
Looks quite nice, and you have obviously put a lot of work and thought into the design. The efforts to minimize the total weight are obvious. The biggest concern you may have is strength in the event of an impact or collision. You might consider making the frame members out of rectangular tube instead of channel. Given the amount of material you are removing, the additional weight from the fourth side of the tube will be minimal, but there will a considerable increase in stiffness of the frame assembly.
Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?
-dave
03-01-2007 00:17
Madison
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by dlavery
Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary? -dave |
03-01-2007 00:22
Jeff K.
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by dlavery
Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary?
-dave |
Any crocs?
CRIKEY!
03-01-2007 07:51
DanDon
Re: pic: FRC488 - Six Wheel Drive Chassis
WATCH OUT!!! WE'VE GOT A DAVE ON THE LOOSE!!! SOS...SOS...SOS
03-01-2007 09:23
Rich Kressly
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by dlavery
M -
Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary? -dave |
I love the simple approach to the 6-wheel drive. I'll be follwing up later if you use this to see what additional stiffening was used/needed. Good luck.
03-01-2007 22:48
Madison
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by Rich Kressly
Who keeps letting him in? Security!!!
I love the simple approach to the 6-wheel drive. I'll be follwing up later if you use this to see what additional stiffening was used/needed. Good luck. |
Because of the holidays primarly, we haven't really done much of anything with our mecanum drive prototype. It still has no feedback system installed and remains difficult to drive. Most of the team agrees that, unless it appears to be a perfect solution for the new game, we'll stick with something more traditional like this drive, so there's a good chance you'll be seeing it somewhere.
04-01-2007 20:34
Andrew Blair
Re: pic: FRC488 - Six Wheel Drive Chassis
Madison, I know that you have no broach capability, so I'm curious- where do you buy your #25 sprockets? I can't find any finished ones online, or in the Browning catalog.
04-01-2007 20:45
Dan Petrovic
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by Cody C
Not necessarily more maneuverable, But I bet it is nice to have the 'bot spin around it's center set of wheels instead of whichever four happen to be touching the ground
|
04-01-2007 20:50
Cody Carey
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by InfernoX14
Wouldn't the spinning of the robot automatically lift the front and back wheels up and equal distance from the floor? Kind of like when your arms raise up when you spin around.
|
05-01-2007 03:26
Madison
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by Andrew Blair
Madison, I know that you have no broach capability, so I'm curious- where do you buy your #25 sprockets? I can't find any finished ones online, or in the Browning catalog.
|
05-01-2007 07:23
Andrew Blair
Re: pic: FRC488 - Six Wheel Drive Chassis
Ah, I see. We were going to be using 1/2" bore, and for some reason, no one on earth carries broached 1/2" bore sprockets. Thanks though!
05-01-2007 11:58
Rick TYler
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by InfernoX14
Wouldn't the spinning of the robot automatically lift the front and back wheels up and equal distance from the floor? Kind of like when your arms raise up when you spin around.
|
05-01-2007 12:25
CE Mexican
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by dlavery
M -
Looks quite nice, and you have obviously put a lot of work and thought into the design. The efforts to minimize the total weight are obvious. The biggest concern you may have is strength in the event of an impact or collision. You might consider making the frame members out of rectangular tube instead of channel. Given the amount of material you are removing, the additional weight from the fourth side of the tube will be minimal, but there will a considerable increase in stiffness of the frame assembly. Just out of curiosity, what is the spacing between the wheel sets? Is it sufficient to cross a 20-inch wide, 16-inch deep, water-filled moat, should that capability ever be necessary? -dave |
05-01-2007 12:28
dfukuba
Re: pic: FRC488 - Six Wheel Drive Chassis
That looks very nice and pretty well engineered. My suggestions are that you only use one set of omni wheels. You have to admit that you will be getting in to conflict no matter what you do.
The frame does look pretty sound, but with all that material taken out, are you worried about bending at all? these bots go through some pretty hard hits.
But i am very impressed by your design and i look forward to seeing the end product after the next hectic 6 weeks =)
--Dan
05-01-2007 12:36
CE Mexican
Re: pic: FRC488 - Six Wheel Drive Chassis
team 1783, which is my schools team, used a different drivetrain set up, we had designed a setup where each side had indepent suspension, and two wheels for each side. and this year (depending on the game) i have designed a three speed gear box that would be incorperated into our original design. also i was thinking about trying out a four whee drive design that would be built by me and a local shop. how many of you guys know about the xmods remote control cars at radio shack? well i got one for christmas (god only knows why) but i was looking at upgrades for it and i saw that they have a four wheel drive kit for them. and after hours of configuring, and designing i think that i can build the 4 wheel drive suspension and drivetrain for our robot.
05-01-2007 12:59
Fred Sayre
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by Rick TYler
The last two years I worked on center-drive, 6-wheel robots and both times we purposely loaded one end of the 'bot with a LOT more weight for game reasons. This also had the effect of having the same four wheels on the ground most of the time. We had little fore-and-aft rocking and the robot wasn't tricky to steer at all. Having said that, Madison makes nice chassises -- er, chasses -- er, chassisses -- what IS the plural of chassis anyway? I'd hire her to consult on our chassis, but since I'm now on a VEX-only team, I think we'd be wasting her skills.
|
Stop by if you feel you are missing out on the hectic 6 weeks that is FRC this season!
05-01-2007 13:16
JaneYoung
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by Rick TYler
what IS the plural of chassis anyway?
|
the plural would have a wee different pronunciation though
05-01-2007 13:39
Richard Wallace
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by Jane
chassis, singular = chassis, plural
the plural would have a wee different pronunciation though |
05-01-2007 13:52
Rick TYler
Re: pic: FRC488 - Six Wheel Drive Chassis
Ah, jeez, I know that the plural of chassis is chassis, I was just funnin' around.
For the record, in 2005 our bot had six wheels with 2WD, but last year our very heavy, very strong chassis had six wheels with 6WD. In case anyone cared.
I AM going through FRC withdrawal now that kickoff is near, but I also fell asleep last night thinking about softballs, so maybe I'm becoming a VEXer, too.
I would like to bring our new, nearly-all-rookie team to visit an FRC team during build, so maybe I will take 488 up on their offer. We also have had friendly comments from team members at 1318 and 492. I think the "F" in FIRST really stands for "friendly."
05-01-2007 16:55
artdutra04
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by Rick TYler
Having said that, Madison makes nice chassises -- er, chasses -- er, chassisses -- what IS the plural of chassis anyway?
|
21-01-2007 21:41
foundbobby
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by M. Krass
The wheels are all in line -- there's no 'rock' at all. The chain is #25.
Because the center wheel is not lowered at all, at least one outside set of wheels should be omniwheels to alleviate friction while turning. I chose to put a set on each end because there's no penalty to in line pushing force, generally, and I like to subtley encourage our drivers to avoid conflict. I'm now looking at a mounting scheme that will accept bumpers and protect the wheels from impact. I've never put bumpers on a robot before, so I'm looking at examples of others' work to get an idea how to best accomodate the additional weight of the bumper assembly. Our 2005 robot had a lowered center wheel and the tipping action drove me and our drivers crazy. It's an impact to the system each time the robot's inertia shifts and that starts to lead to annoying things like loosened bolts and the like. Practically, it's cheaper and easier for me to make omniwheels than it is to make traction wheels and it's certainly cheaper than buying them. As shown -- which includes everything but stiffening gussets and a base upon which to mount electronics, it's 29.5 lbs. The omniwheels are riding on 5/8" keyed shaft, while the AndyMark performance wheel is broached for a 1/2" hex shaft. It'd be relatively easy to change out a set of omniwheels for a set of traction wheels with a little bit of forethought. Namely, I'd need to make some shafts that are 5/8" diameter with keyway on one end and 1/2" hex on the other. I'm waiting on the game before adding cross-bracing since I'm not sure if I'll need a scoop or something on one or both ends. I'd like to, if weight allows, put an aluminum plate (1/16" or so) across the bottom to add rigidity. |
21-01-2007 21:48
foundbobby
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by M. Krass
Thread created automatically to discuss this image in CD-Media.
 |
21-01-2007 21:52
Richard Wallace
Re: pic: FRC488 - Six Wheel Drive Chassis
Based on pictures in another thread I think this is probably FRC Team 488's robot. Madison is a member of that team, and her team role is mentor.
Maybe I didn't understand your question?
21-01-2007 22:01
Dominicano0519
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by CE Mexican
team 1783, which is my schools team, used a different drivetrain set up, we had designed a setup where each side had indepent suspension, and two wheels for each side. and this year (depending on the game) i have designed a three speed gear box that would be incorperated into our original design. also i was thinking about trying out a four whee drive design that would be built by me and a local shop. how many of you guys know about the xmods remote control cars at radio shack? well i got one for christmas (god only knows why) but i was looking at upgrades for it and i saw that they have a four wheel drive kit for them. and after hours of configuring, and designing i think that i can build the 4 wheel drive suspension and drivetrain for our robot.
|
this is a carpeted field were talking about
21-01-2007 23:36
VEN
Re: pic: FRC488 - Six Wheel Drive Chassis
Do you guys have a shaft coming out of the tranny for the middle wheel as well as 2 sprockets on the inside leading to the front and rear wheels? Are the sprockets inline? Wouldn't you need gears on the same axle as the sprocket to drive the sprockets in that case? Are the sprockets on the same axle? In that case how can your wheels be inline? Are the sprockets on the wheels on an offset?
Alright no more questions 
just curious.
21-01-2007 23:55
Madison
Re: pic: FRC488 - Six Wheel Drive Chassis
|
Originally Posted by foundbobby
Nice design. What about having the wheels on the outside? Don't they need be protected some to avoid bent shafts and broken wheels?
|
|
Originally Posted by foundbobby
Nice picture! We'll see you at SVR
|
|
Originally Posted by VEN
Do you guys have a shaft coming out of the tranny for the middle wheel as well as 2 sprockets on the inside leading to the front and rear wheels? Are the sprockets inline? Wouldn't you need gears on the same axle as the sprocket to drive the sprockets in that case? Are the sprockets on the same axle? In that case how can your wheels be inline? Are the sprockets on the wheels on an offset?
Alright no more questions just curious. |
Attached to this post is a cross-section of the gearbox that may help make the gearing arrangement a bit more clear. Excuse that the gears aren't meshed properly, please.
23-01-2007 10:58
Brian Mocci
Re: pic: FRC488 - Six Wheel Drive Chassis
My favorite part about this design, something that no one has mentioned yet supprisingly, is the way that you extended your front and rear rails in order to protect the cantilevered wheels. Excellent design all around!
view entire thread
Tags
loading ...