larger servo questions

I am looking for a way to control vehicles somewhat larger than
typical hobby stuff. Say the size of a small lawn tractor.

This would be for steering so I am thinking about using something
like a more muscular servo motor.

I'm aware of hobby style giant servos. They might work but not
sure if they would be beefy enough.

Industrial servo motors seem to be quite different from hobby stuff.
I have one that's rated 128 VDC, has 5 wires running to the motor and
a bunch more off the attached encoder. No real idea what's going on
here.

Searches on servo motor control bring up mostly hobby information
which I am familiar with.

There is the open servo project which might provide part of
a solution. If I can beef up the control so that it can handle
something
like a cordless drill motor.

I recenly built a remote control tricycle. I handled the steering
using a regular DC motor controller (Victor 883) and got around the
limit switch problem by building a small spring loaded clutch. (Some
details
on my web site under "builders log".)

But I don't really like this solution as there is no automatic
centering
feature.

Any other ideas? What do those guys like Mythbusters do for remote
control full size cars?

Thanks for any help.

DOC

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