I just read through your web page and it's very interesting to see what you have done, and plan to do. I'm rather astounded at the amount of power you are talking about. That 400 kW motor is a beast, but I wonder if you really need that much power. And $250,000 is some sticker shock! I found a 150 HP motor
on eBay for $2500, and I bet it would do the job. If not, there's a 500 HP motor
with VF drive for $30,000.
I went through some approximate calculations for a 30,000 lb vehicle with 400 lb of passengers and a 6000 lb 500 HP motor and a 6000 lb 100 kW-hr battery pack. For a nominal 3% grade it would take about 200 HP to maintain 60 MPH, and for a 12% grade it would take 550 HP to maintain 40 MPH. These are within the capabilities of a 300 HP motor unless you have a very long steep grade. So, maybe the 500 HP (or maybe 4 150 HP motors) would be better, and you get better efficiency if you stay within the conservative ratings.
Thanks for the info on CanBus and FlyByWire. They are overkill for my simple utility vehicle and tractor projects, but they could be good test beds to try some things like that and I can scale up.
As for the joystick control, I found that it does not hold its zero position very well, and I need to incorporate a "deadband" where the motor will stay off. I have just an analog circuit directly producing the DC signal from the joystick, which is just a 150 kOhm variable resistance. So I will probably need to feed the resistance signal to the PIC and produce the control voltage using PWM, although there is still some problem with the +/- output. Maybe I can just disconnect the analog signal until the PIC reads a certain range and then drive the motor controller. I don't really need very slow speeds. Probably 600 to 3600 RPM will be fine.
Also, I might use the trigger buttons for start/stop.