What is the best place to mount CIM motors...?

[team2061]

What is the best place to mount the CIM motors when going with a 6 wheel drive terrain?
Directly connect the gearbox shaft into the middle wheel?
^^(wouldnt this make the middle wheel spin faster than the front and back wheels?)
Somewhere between the middle and back wheels?
Help please!!!

[Billfred]

The answer is: It depends. If you do live axles, you can drive the center wheel (which won't spin any faster than the other two; they'll all turn at the same speed). With dead axles, the gearboxes have to go elsewhere. Where you put them depends on your weight distribution; we put them on the front when the heavier part of the robot was in the back, and a problem with our wheel screws on the center wheel bit us in the butt. Hard.

Ideally, you'll make sure your drive system can handle some Irritating Failures without them becoming Paralyzing Failures.

[EricH]

Which type of 6-wheel? Rocker, you should probably put the gearboxes on what you want to be the heavy side. Planar (with or without omnis), doesn't matter. This is assuming a dead-axle setup.
The middle wheel will only turn faster than the front and back wheel if you screwed up your gearing between wheels. (1:1 between wheels; if you connect the gearbox in two places, make sure the ratios are the same on both connection points.)

For a live-axle, the same general guidelines apply, but you get more complicated.

[artdutra04]

Here's a top view diagram of two different chain paths we've (Team 228) used in the past with six wheel drive.

[Qbranch]

REMEMBER! Placing a motor is not just a mechanical consideration!

If you will be using encoders on your drivetrain, be wary of scary electro-magnetic fields created by motors and high currents. Especially if you are using analog encoders (aka limitless potentiometers) keep your motors and their wires as well separated as possible from the motors, and remember to use shielded cable for sensors in high emf areas.

-q

[MrForbes]

Originally Posted by Qbranch

and remember to use shielded cable (like cat5) for sensors in high emf areas.

cat5 is unshielded twisted pair, but yeah, take care with the wiring!

[whytheheckme]

I bought a 4 1000 foot spools of Plenum Cat6 shielded cable (my family recently built a second house, that has almost a mile of Cat6 in it.... minimum of 2 home runs per room, including the bathrooms )

I have about 300 feet left over, so that should be plenty for us. It's beautiful how each pair is separated by plastic.

Jacob

[popo308]

It also makes things nicer when you build this to keep in mind robot up keep. It may look easy to maintain when you don't have your arm or whatever this years manipulator will be on there but once you cover it things become alot more interesting in the long run when something malfunctions and you need to fix it.

[Al Skierkiewicz]

Team 2061,
A couple of things have not been added here on the motor placement. You should consider replacement, so place the motor where it will be easy to replace should it fail. If you use the threaded holes in the end plate to mount it, be sure you can get at the bolts when you need to perform some maintenance. It is also important to note that the bearings in the either of the Chalupa motors are not designed for high side loads and require additional bearings to prevent early failure of the motor.
As to the use of CAT UTP cables...Remember that this family of cable is solid conductor. Solid conductor cables on moving devices spell disaster resulting from fatique breakage. They will require special handling to insure no failures.
And as a side note, could you include a name in your online profile? Team 2061 is so informal, thanks.

[Qbranch]

Originally Posted by Al Skierkiewicz

As to the use of CAT UTP cables...Remember that this family of cable is solid conductor. Solid conductor cables on moving devices spell disaster resulting from fatique breakage. They will require special handling to insure no failures.

We often use CAT5/6 cables where I work to run sensor signals and ethernet communications for Gig-E cameras mounted on moving members of production machines. True, single core has a low flex life. NEVER use single core CAT5/6 wire on moving members or high vibration environments.

At work, we use industrial grade stranded CAT5/6 wiring. Here's a page out of the mouser catalog listing some industrial stranded ethernet cable: http://www.mouser.com/catalog/632/928.pdf

Questions? Need better application example? Post!

-q

[Peter Matteson]

Pete's wise gut answer:
As low as possible. They are fairly heavy and can greatly effect your CG.

Originally Posted by team2061

What is the best place to mount the CIM motors when going with a 6 wheel drive terrain?

Usually on the robot, unless you happen to have found some other method of propulsion...

But yeah, I personally always design my 6 wheels to have the center wheel drive directly. This makes it so we're not entirely grounded in the case of a chain failure. If you mount between wheels, and a chain happens to break, you're stuck for the rest of the match.

[MrForbes]

If you mount the transmission between two wheels, and drive those wheels with separate chains, then drive the furthest wheel with another chain off the center wheel, then chain failure would not be quite so much of a problem. Of course building a reliable chain drive system in the first place is a better idea

What you end up doing will probably depend on your design and fabrication skills, abilities, and equipment. It's really easy to set an Andy Mark shifter trans on top of the frame between wheels and run chains from there to sprockets on wheels that are mounted on dead axles, no fancy machining required.

[Richard Wallace]

I like driving the center wheels with relatively short #35 chains, and placing the motors fairly close to the center -- anywhere from directly above the center axle to offset as much as 5 inches fore or aft, depending on where we need the CG and what scoring mechanisms are required. #35 chain provides a little extra reliability, and re-tensioning is not a problem because it won't stretch much. The corner wheels can be driven with longer #25 chains, one for each wheel, two driven from each center wheel. So center wheels each get one #35 sprocket and two #25 sprockets.

This set-up requires some method of tensioning the corner wheel chains. Several good methods have been discussed in other threads.

We used the set-up described above on our 2007 robot with good results. Drivers reported easy handling. We only had one chain failure all season, and that one was easily repaired -- a few minutes work field-side between elimination matches at Boilermaker.

[+()c|D]

depending on what dive system you are going to use...

chained with a gearbox then probably as close to the center of the robot as possible