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View Full Version : pic: 6 wheel drive with a suspension


joeweber
08-01-2008, 09:30 AM
[cdm-description=photo]31738[/cdm-description]

zachjo
08-01-2008, 09:34 AM
how do you plan on driving the wheel using the CIM motor? Miter Gears?

JesseK
08-01-2008, 09:35 AM
This is an interesting concept, however what happens when the drive train tries to lateral sideways? The mecanum wheel vectors will cancel each other out but the omni vectors will put a rotation on the drive train.

I do like how the motors don't stick out into the middle of the drive train. Are those supposed to be worm, helical, or beveled spur gears?

InfernoX14
08-01-2008, 09:51 AM
how do you plan on driving the wheel using the CIM motor? Miter Gears?

Helical gears. Check them out. They could be worm gears if he didn't have that banebots transmission on there.

If that's going to be $1900 maybe you want to look at your design again. You don't NEED helical gears to get this to work.

Alex Cormier
08-01-2008, 01:10 PM
by is it so much money? Interesting idea though, I would like to see you build on the idea and make it more efficient and cost much less. Good luck. Also what's the point of the omnis?

artdutra04
08-01-2008, 01:18 PM
Is there any particular reason why you need helical gears?

Or in other words, Is there any reason why just face-mounting the Banebot transmission to the inside frame member would not work?

joeweber
08-01-2008, 01:27 PM
The gears are helical type. The secret? There will be a chain from the rear mec to the center omni, there will be another chain from the front mec to the center omni. At the center omni We will build a ball differential that will ride between the sprockets. When they go the same direction they will drive the omni wheels, when they go in opposite directions ( to go side ways) they will cancel each other out and not move. They will also be able to go on angles. Using these we will have 6 wheel drive forward and reverse. Each drive assembly will pivot at the omni location and with a pivoting support to the frame at mid-way of both drive assembly this will give us a suspension so the wheels will always be in contact with the floor when transitioning on ramps. We have the designs down but are just getting it on cad now.

The left drive is a mirror of the right drive. Using helical gears allows the motor to go the same direction thus allowing for the same speed when driving forward. It will not wander right when driving.

Rough drawings of the side veiw http://www.team1322.org/ideas.htm#Omni%20Direction

AdamHeard
08-01-2008, 07:20 PM
The gears are helical type. The secret? There will be a chain from the rear mec to the center omni, there will be another chain from the front mec to the center omni. At the center omni We will build a ball differential that will ride between the sprockets. When they go the same direction they will drive the omni wheels, when they go in opposite directions ( to go side ways) they will cancel each other out and not move. They will also be able to go on angles. Using these we will have 6 wheel drive forward and reverse. Each drive assembly will pivot at the omni location and with a pivoting support to the frame at mid-way of both drive assembly this will give us a suspension so the wheels will always be in contact with the floor when transitioning on ramps. We have the designs down but are just getting it on cad now.

The left drive is a mirror of the right drive. Using helical gears allows the motor to go the same direction thus allowing for the same speed when driving forward. It will not wander right when driving.

Rough drawings of the side veiw http://www.team1322.org/ideas.htm#Omni%20Direction

It's an interesting concept, but is certainly a lot of complexity to pull it off. If I recall correctly teams with mecanums have been able to climb ramps, 40 in 2006 and 1540 in 2007 for example. Have you also given thought to how this would affect any manipulators? The two segments pivot a lot in regards to each other, that looks like it'd be quite a hassle.

=Martin=Taylor=
08-01-2008, 07:36 PM
Rough drawings of the side veiw http://www.team1322.org/ideas.htm#Omni%20Direction

Some of those designs are insane! All wheel drive!!?? 90+ wheels!!??

I really like your idea of slaving the manipulator to the orientation of the crab modules. This way, the driver could easily control BOTH the drive and the manipulator orientation.

joeweber
08-01-2008, 10:12 PM
It's an interesting concept, but is certainly a lot of complexity to pull it off. If I recall correctly teams with mecanums have been able to climb ramps, 40 in 2006 and 1540 in 2007 for example. Have you also given thought to how this would affect any manipulators? The two segments pivot a lot in regards to each other, that looks like it'd be quite a hassle.

The only complexity is the ball differential. The rest is off the shelf items. The ball differential must have an adjuster to tension the slippage. I have some ideas on how to do it. For the suspension I am not sure at this time how much movement to allow or to add springs to help control the movement. I have to build it first to find out.

Mike Nawrot
08-03-2008, 01:58 PM
We were tossing this idea around just for kicks at some point this year. We never had any intentions to go through with it, or to even take the time to draw it up. I'm glad somebody did though. But, as awesome as it is, I'm not sure there's not much of an advantage to it. We did a mecanum drive this year, and though we had some problems with strafing, it turned just as well as, if not better than a six wheel drive. In general, the addition of an omni wheel won't help the maneuverability of the drive train. The traction provided by the omni wheel might improve the pushing ability of the drive train, but only if you use soft rubber rollers and an overlapping roller design so you have constant contact between the rollers and the ground. IMHO, the complexity, and thus increased probability of failure of the system outweighs the few performance benefits such a design provides. Though, to quote a friend, "if it looks good, it is good". And this design looks pretty awesome.

joeweber
08-03-2008, 04:40 PM
We have plans on using two omni wheels on both sides for the traction. Many have said how complex it is to build, but from the drawings that we have made there are only 5 parts that we have to make multiple times and the design for these parts are straight forward flat pieces with hole and slots. Very easy to C & C and only requires assembly. When we complete the drawings we will post them. The drawing that we have posted is only missing two parts but is pretty much completed. We will take that assembly and make four units and connect them at the omni wheel with an axel. To attach them to the robot we will have two steel tubes that a drive side will slide onto and then the bumper bolts will slide into the tube and two cotter pins will hold it all together. We have tried to make it simple so the student can understand what they are assembling and can make repairs when needed.

JesseK
08-04-2008, 02:36 PM
After studying a bit of vector analysis with this design I still believe there is a fundamental design flaw in this concept; however I suppose that depends on the functionality that is intended for the final product. Is the final design supposed to be fully holonomic or is it only supposed to be a tank drive-style drive train that has the capability to do a 90 degree sideways lateral?

Dowjonesbotics
08-04-2008, 02:55 PM
I don't really understand where the suspended part is. Coudl someone explain it for me?:confused: :confused: :confused: :confused: :confused:

joeweber
08-04-2008, 03:08 PM
You may be correct, but from what I have observed from the ball differential it should work. The omni wheels will be attached to the shaft that is attached to the disc holding the balls. The balls will be pressed on each side by the sprockets. If the sprockets are going the same direction than the wheels must be moving the same speed. If the sprockets are going in opposite directions (equal full speed) than the omni should be stationary. Correct? Now if one sprocket is not moving while the other is moving at full speed than the omni wheel should be moving one direction at half speed. Thus allowing for a 45% angle run of the robot. Any other difference should be also of the same ratio. On paper the ratios work out but in practice I may be wrong. We will be building a test system this fall to find out.

I don't really understand where the suspended part is. Coudl someone explain it for me?

Go to our site http://www.team1322.org/ideas.htm and scrol down to see a drawing of the suspention movement. The robot will be attached (with a pivot) to the drives in two places center of each moving drive.

Dowjonesbotics
08-04-2008, 03:33 PM
Go to our site http://www.team1322.org/ideas.htm and scrol down to see a drawing of the suspention movement. The robot will be attached (with a pivot) to the drives in two places center of each moving drive.

Ohh, I see. Thanks.

That's seems like a very logical and feasible idea.

AdamHeard
08-04-2008, 11:32 PM
We have plans on using two omni wheels on both sides for the traction. Many have said how complex it is to build, but from the drawings that we have made there are only 5 parts that we have to make multiple times and the design for these parts are straight forward flat pieces with hole and slots. Very easy to C & C and only requires assembly. When we complete the drawings we will post them. The drawing that we have posted is only missing two parts but is pretty much completed. We will take that assembly and make four units and connect them at the omni wheel with an axel. To attach them to the robot we will have two steel tubes that a drive side will slide onto and then the bumper bolts will slide into the tube and two cotter pins will hold it all together. We have tried to make it simple so the student can understand what they are assembling and can make repairs when needed.

Complexity isn't just how many parts have to be made. You could use all COTS components and still have the most complex robot out there. This design is inherently more complex than a 6wd or a 4 wheel mecanum (the two most similar designs). Also, the pivoting frame throws a huge curveball when considering mounting manipulators.