05-03-2010 09:53 AM

Jared Russell

Re: pic: 6 Wheel Drive Render

Looks good!

* Depending on what scoring functions go on top, you might find yourself wishing you had put the battery somewhere more accessible (just talk to our pit crew about the importance of this ).

* Only 3 Jags?

* Might want to switch the location of the DSC and the main breaker (shorter run of bulky DB37 cable).

05-03-2010 11:09 AM

Andrew Schreiber

Re: pic: 6 Wheel Drive Render

I assume there are more jags near the PD board?

I have to think that you should rearrange the electronics. Keep the distance you have to run the heavy wire to a minimum.

Why did you decide to go with 4 omnis instead of dropping the center? Nothing wrong with it just curious what the reason was.

How are you holding the pieces of angle together?

Looks great, I hope to see more of your work.

05-03-2010 02:18 PM

JamesCH95

Re: pic: 6 Wheel Drive Render

I would drop the center wheels even with the omni wheels. I like the central location of the battery, it keeps your rotational inertia down.

I would draw in all the fasteners you plan to use to make sure everything is going to be accessible and fit well. McMaster has CAD models of almost every fastener they sell, so start there unless you have a 'smart-fastener' type toolbox available in your CAD program.

05-07-2010 03:19 PM

gallo26

Re: pic: 6 Wheel Drive Render

You shouldn't drop the center if you have omni wheels in the corners of a 6 wheel DT. The omni wheels are there to refrain from dropping the center wheel. We've done this setup for 2 years, and the outcome is great. Amazing mobility with the pushing power you need to get the job done.

In theory, with the center wheel dropped, you would lose traction provided by 2 omni wheels. Especially if your CG isn't aligned properly (We also have experience in that)

Very nice cad! Impressive! Keep it up!

05-07-2010 03:47 PM

Vikesrock

Re: pic: 6 Wheel Drive Render

Not sure exactly what you mean by this. The tractive force the robot can exert is the sum of (normal force*coefficient of friction) for each wheel. The total normal force for all the wheels is fixed and is the weight of your robot. By lowering the center wheel you redistribute the normal force from 2 of the wheels (assuming they are entirely off the ground) across the other 4. If your center wheels have a higher coefficient of friction you will gain tractive force by doing this, not lose it.

05-08-2010 11:39 AM

JamesCH95

Re: pic: 6 Wheel Drive Render

Vikesrock beat me to the punch!

Another reason to drop the traction wheels is that their tread is much more compressible than the average omni wheel. If they are at the same height, the traction wheel won't get maximum grip.

One more reason to drop the traction wheels is that their tread will wear faster than the omni wheels, so they will still be able to drive the robot after some use. If they are not dropped then they'll wear out and provide less and less traction.

My team has used dropped-center traction + 4 omni wheels on two robots that won Xerox design awards, clearly it's a valid option.