Quote:
Originally posted by Andy Baker
You could be on to something here. Your basic idea of coupling two motors through a differential is good and could be used in a compact manner on a FIRST robot.
Keep designing and good luck.
Andy B.
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Really, the design isn't a whole lot different from the functionality of a planetary system. The output shafts are akin to the sun and ring gears. The housing would be the planet carrier. These similarities are in terms of functionality. If you rotate both the sun and ring gear in the same direction, the carrier will rotate at an average of both speeds. The torque will be combined.
You can't overlook these similarities, because then you will easier understand what will work and what won't. Although the torque with such a system is combined, you have to see that
the maximum torque you can ever exert (for an extended period of time)
is twice that of the weakest motor (stall torque). If you exert more than this, the breakers will trip due to excessive current draw. All torque will be spent on spinning the (now) dead motor, instead of accelerating your robot.
I wish I had my laptop out. A few months back I was talking with a teammate about prototyping a drivetrain with a similar idea of using a differential as a gearbox. Though, I realized these limitations, which is why I went with the idea above (using two similar motors on the housing and side input).
In all practical applications, lego "prototypes" have no usefulness for a FIRST robot beyond design concept. We have various restrictions, both electrical and mechanical, that cannot be modelled accurately. The Thunderchicken's found this out last year - the hard way. They blew motors and tripped breakers like crazy, all using a similar design. You are only doomed to repeat their failures if you fail to heed my warnings.
I do believe such a design would work, and well, but not without substantial thought and time in creating a simple and efficient design.