3 motor drive train

[oreocookeee]

i think he means three motors per side, totaling six motors. i guess you would add the fisher price motor somehow. i dont think it would be worth the trouble. in that case, you might as well design it from scratch, which most teams are already capable of.

[nuggetsyl]

Originally Posted by oreocookeee

i think he means three motors per side, totaling six motors. i guess you would add the fisher price motor somehow. i dont think it would be worth the trouble. in that case, you might as well design it from scratch, which most teams are already capable of.

yes i mean 6

[phrontist]

You'd need a whole mess o' differentials and torque converters and all sorts of nasty stuff to make an odd number of motors work...

[nuggetsyl]

not really just the right gear ratio

[Cory]

Originally Posted by phrontist

You'd need a whole mess o' differentials and torque converters and all sorts of nasty stuff to make an odd number of motors work...

Says who? all you have to do is match their speeds. Plenty of teams have done it. 45, 494, 188, etc.

And there's definitely an advantage. If you figure out how to keep the FP's cool, and not draw a ton of current with them, you've got a 5th and 6th CIM in your transmission, for all practial purposes

[nuggetsyl]

i think changing gears on the fly is over rated.

[nuggetsyl]

Originally Posted by phrontist

Why would you use an odd number of drive motors?!

why not

[Max Lobovsky]

It's surprisng how many people post without reading the whole thread. Phrontist is talking about an odd number of motors total. The thread starter meant 3 motors per side, 6 motors total. An odd number of motors total in a normal skid steer design would definitley be no easy feat.

As for 6 motors, I do not expect a great increase in the number of them. First of all, I don't think the gain is that great because every 4 motor robot i have seen loses traction before it puts too great of a load on its motors. Also, if you use your FPs, you aren't left with much power for your arms between the remaining motors.

[David Guzman]

In my opinion it will be better to have 3 motors on each side, however that just gives you more stuff to worrie about and more things that can go wrong. I'll rather stay with two reliable ones, also the FP motor burns easily.

David

[JVN]

Decisions concerning the number of motors in a drivetrain (2, 4, 6, 8, 10, 12... whatever!), the number of speeds in a drivetrain, and what speeds to gear at, are engineering design decisions.
These decisions are dependant on a robot's gearing, wheel traction and many other factors.

The output power from the motor must be modified (via gearing) to be "optimized" to achieve desired performance. Sometimes more power must be added (more motors) and sometimes the gearing must be modified for different tasks (multiple speeds). There are many different definitions of "competitive performance". There are also many different combinations of drivetrain components tha can be used to achieve these levels of performance.

Note: for more information on drivetrain physics, shifting gears, or multiple motor drivetrains, please click the *search* button.

To imply that this decision can be universally made for all drivetrains, without showing any calculations
(i.e. "6 Motor drive is stooopid. Long Live 4-motors...") is foolish.

I urge everyone: keep your opinion to yourself; unless you have some calculations to back it up.

Thanks,
John

[Kit Gerhart]

Originally Posted by Max Lobovsky

As for 6 motors, I do not expect a great increase in the number of them. First of all, I don't think the gain is that great because every 4 motor robot i have seen loses traction before it puts too great of a load on its motors. Also, if you use your FPs, you aren't left with much power for your arms between the remaining motors.

If you want to be able to push and do burnouts while using "tall" gearing, using a Fisher-Price on each side along with the CIP's would give you an additional 50% or so in horsepower. Of course, doing this could get you dangerously close to tripping the 120A breaker while doing high speed pushing.