View Single Post
Old 07-21-2009, 04:39 PM   #3 (permalink)
MPaulHolmes's Avatar
Join Date: Feb 2008
Location: Maricopa, AZ (sort of. Actually outside of town)
Posts: 3,832

Michael's Electric Beetle - '71 Volkswagen Superbeetle 500000
Thanks: 1,368
Thanked 1,202 Times in 765 Posts
Hey Joe! Do you have the 6 ISP wires accessible even with the enclosure on? I think my 6.7" diameter motor behaves pretty different from your 9" motor. It seems to me that something that feels smooth to me feels pretty jerky to you. I think your motor is lower inductance.

I think it's going to take several variations on the throttle to get it to what feels good to you. It would be nice if the ISP wires were already out with the other wires, so you could just hook up your laptop (and stk500) and program the chip without taking off the case each time.

I'm not sure if a tuned loop for me will behave the same for you. I'll send you code for the PI version with a conservative throttle ramp. I may be using too large of P and I values for your motor, though, but we can try it and see what happens. If it is still jerky or oscillating, I'll know to make the P and I smaller. I'll also send you just a basic ramping code program, that takes both pwmDuty AND current into account, so it might feel more similar to the Curtis. Also, I'll make sure the overtemp is set to about 75 degC to start.

One reason it might feel like you have to push a lot on the gas to get going is that I have a pretty conservative dead zone for the throttle. Maybe it's too big? I just didn't want to risk having the car take off because the pedal was SLIGHTLY above 0 throttle.
kits and boards
  Reply With Quote