AWD fatbike (first build, first draft..)

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Toorbough ULL-Zeveigh   10 MW

10 MW
Posts: 2362
Joined: Feb 09 2007 3:02am
Location: Marlboro

Re: AWD fatbike (first build, first draft..)

Post by Toorbough ULL-Zeveigh » Apr 30 2018 6:39pm

time for the (sorta) annual motivational poke.
the AWD deniers are casting aspersions.

but 4get the bike, how u doin?
have you fully recovered?
Kick down the barricades Listen what the kids say.
From time to time people change their minds But the Frock is here to stay.
I've seen it all from the bottom to the top Everywhere I go the kids wanna Frock.
Around the world or around the block Everywhere I go the kids wanna Frock.

sgds23   10 mW

10 mW
Posts: 34
Joined: Sep 19 2012 4:13am

Re: AWD fatbike (first build, first draft..)

Post by sgds23 » May 02 2018 12:01pm

Ha-- thanks for asking. I miss my knee stroller (allowed me to travel through airports very quickly), but I'll admit the metal plate in my ankle has limited motion a tiny bit when playing basketball or tennis. Fortunately, I already kinda sucked at both.

I ended up rebuilding the ebike since I turned out to enjoy using the Pinion based fat bike so much, manually.

I'm super happy with the way I have 2wd working currently. I saw someone else on here mention that by using a torque throttle for both wheels, you don't need to worry about synchronizing speed of two different kinds of motors. (Remember, I have a TC3065 in back, and a BMC v2 in front). I've found it a little more complicated than that.

Because my Roboteq controller measures battery amps rather than phase amps, I use the current speed (from halls and knowledge of unloaded RPMs at 50% power) to compute back emf and figure out how much more power needs to be applied. (This is in some ways better than measuring phase amps because you don't need to use PID.) But it gets tricky when the front motor is geared and so doesn't give speed measurements when unengaged. I only use the front motor when I'm accelerating, to save power and wear.

I finally got logging on my phone to work, and everything looks pretty good. I need to study a little more before posting actual results.


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Alan B   100 GW

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Joined: Sep 11 2010 7:43am
Location: San Francisco Bay Area, USA

Re: AWD fatbike (first build, first draft..)

Post by Alan B » May 02 2018 3:23pm

I use a pair of PhaseRunners, so no code to write. The PID loops are built in, and are tweaked as part of the motor setup. Have separate parameters for battery current and motor current for each motor of course. Works out well. Controllers are very small, also. See the Bonanza thread linked in my sig.

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