[Oeva-list] Throttle and brake interaction question for Leaf and Think

Paul Wallace ianaudio at aracnet.com
Sat Aug 25 09:19:37 PDT 2012

I'm using the simple, state machine control in provided in the inverter
in my truck.  There is a more sophisticated way to control the inverter,
but that would involve me developing a little CAN bus module.  I have a
pot on the throttle and one on the brake, a mode supported by the simple
state machine.  Both have torque control profiles that allow regen and
coasting depending on the pedal position, which is controlled by
parameters I set.  The problem is that the brake pedal absolutely
overrides the throttle, making start up from a standing stop on any kind
of slope very difficult.  I must fully release the brake pedal and then
apply the throttle to get any drive torque.  No easing off of the brake
while applying the throttle to take up drive train slack and preventing
roll back.

Do the Leaf and Think allow both brake and throttle input with the one
giving the larger command winning out, like a summation of the two?  Do
they have 'creep' mode, like a Prius, where the car will move in the
commanded direction when the brake is released without any throttle
input?  I can't get torque command summation, the state machine won't
allow it. I may be able to program for creep, which would help quite a
bit, but I would lose accelerator pedal up regen and coast.  If I go for
creep, I was thinking that I could adjust the brake pedal and pot so
that I can get coasting and varying regen at the beginning of the brake
pedal travel before the mechanical brakes are engaged.  This would
involve a new driving style.  To coast, foot off accelerator and
slightly depress brake which will turn off creep, add more brake for
regen, add still more brake for mechanical brakes.

Paul Wallace
'94 USElectricar S10 rebuild around the block once and now working on
refinements in control programming

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