pic: 6 Wheel Drive Render

[JamesCH95]

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.

[gallo26]

Originally Posted by JamesCH95

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.

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!

[Vikesrock]

Originally Posted by gallo26

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)

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.

[JamesCH95]

Originally Posted by Vikesrock

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.

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.