It's easy to be sucked in!
My thoughts go along the same lines - the potential is enormous for a stand-alone TCU.
To keep these thoughts under control(!), I've decided to keep the solution as three modules, and define the interfaces between them. That way each function can be developed seperately without biting off more that we can deal with. If we don't keep it simple, then the project will die.
Throttle driver servo. The input to this is from the TCU (see below). It expects an input as per the standards layed down in radio-controlled modelling i.e. pulse every 20mS with varying pulse-width. I've now decided on a single Hitec 805BB jumbo servo. It doesn't need two, these things are very rugged, powerful, and bloody-reliable. The output to the TB can be either direct-linked or a Bowden cable.
TCU. The input from this should be a DC voltage referenced to 0v. There can be input-modifier-circuits that e.g. convert a resistive (or inductive, or capacitive) input to the required voltage. The output should be as described for the Throttle-driver-servo above. The TCU should also contain a very stable 5 volt source derived from the car's power. This 5 volt source should be used to power the TCU, servo module, and pedal (if required). The TCU needs to feature reduntant circuits and fail-safes.
Throttle Pedal. Output should be resistive, inductive, or capacitive as per above.
That should cover everything!
I'm waiting for my servo to arrive. When it does, I'll start with a simple 555 timer circuit and the spare VX pedal I've got. That will allow me to focus on the servo part first.
Steve
