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Old 07-22-2009, 12:57 PM   #2058 (permalink)
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Originally Posted by MPaulHolmes View Post
So, I tried a new throttle idea that Joe had (you know! The guy doing the DIY EV charger!?). It's really a very good idea. It works really really well, too. OK, you basically make throttle proportional to pwmDuty*current, rather than to current or pwm duty! Now, pwmDuty is proportional to the voltage, so basically, this make the throttle proportional to POWER!!! If you want full power, push the pedal down the whole way. If you want only a little power, then only push the pedal down a little. It feels really really good. I tried it out today with Ben's controller. I just did some ramping code so the power chases the throttle rather slowly. I'll also try a PI loop so that the power will chase the throttle like you know who chases a pound of bacon, then I'll have settings for how fast the throttle response is, on a scale of like 1 to about 16, where 16 is the most responsive.

It's one of those ideas that is so simple and so pretty, that you just have to say, WHY DIDN'T I THINK OF THAT!!!!!!!!!!!!!!!!!!!!! MAKES ME MAD!!!!! HAHAHA!
Paul this sounds like it would work really well; enough so that I am re thinking about not using straight PWM for the controller I am working on. I probably will skip the PI loop, but the direct throttle = power formula is just exactly the response I want.

Don't get me wrong though, I am not saying that the PI loop is a waste or bad idea, it's just like I mentioned before we are building different controllers for different intentions. Personally I want that anamalistic aggressiveness, that when I put my foot down I have power that very instant, and the same for letting off. but as you mentioned that can result in a rough and jumpy ride for many drivers who would be better off with a more domesticated code approach.
"Experience is something you get right after you need it !"
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