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Re: [Electronics_101] Re: More moto ECU tricks

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  • Aaron Turner
    ... The pot/butterflies are calibrated to be certain values at full open / closed. From what I ve seen, it just jams the motor in one direction when the pot
    Message 1 of 12 , Jan 28, 2013
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      On Mon, Jan 28, 2013 at 5:13 PM, rtstofer <rstofer@...> wrote:

      > **
      > --- In Electronics_101@yahoogroups.com, Aaron Turner wrote:
      > >
      > >
      > > One thing that probably simplifies things a bit is that based on the
      > little
      > > information I have, I don't think the motor is PWM driven- it's just
      > given
      > > a solid 12V in either direction. I just ordered a Rigol 1052E, so I'll
      > > be able to find out soon.
      > >
      > You might be able to find out if PWM is in use if you can force a small
      > position error by manually pushing on the mechanism. For a small and
      > unsustained error, the output of the PID -> PWM would be a series of narrow
      > pulses getting wider as the error remains longer.
      > As the error gets larger or remains longer, the pulse width will increase.
      > As the error goes to zero, the pulses will get narrower and eventually
      > cease.
      > At least that my current guess - knowing, as I do, absolutely NOTHING
      > about ECUs.
      > Lacking limit switches, I wonder how the ECU knows when the throttle has
      > reached the end of its mechanical motion. If it is based on the value of
      > the potentiometer, that implies that the ECU knows a LOT about how the pot
      > is rigged to the mechanism. Perhaps it just jams the motor in one direction
      > until the pot quits moving and calls that one end. Then it tries the other
      > end. Perhaps it is guaranteed to run out of potentiometer before it runs
      > out of mechanical space.

      The pot/butterflies are calibrated to be certain values at full open /
      closed. From what I've seen, it just jams the motor in one direction when
      the pot is disconnected.

      > Do these throttle plates modulate as the engine is running under load? Do
      > they override the grip throttle? Boy, I would hate to have a disagreement
      > with the computer when I was laid over in a corner. I learned something new
      > about shaft drive the first time I got in too deep and then backed off the
      > throttle. OOPS!

      Override? yes and no. there are two sets of butterflies in series. So if
      I was giving full throttle and the ECU decided 0%, it could close it's
      butterflies and the effective airflow would be 0% throttle. My
      understanding is that the ECU controlled butterflies are only used in low
      RPM situations so the risk is a lot lower for bad things to happen. Either
      way, there's really no reason for them to be installed on a race bike and
      since they're in the way, off they go!

      Aaron Turner
      http://synfin.net/ Twitter: @synfinatic
      http://tcpreplay.synfin.net/ - Pcap editing and replay tools for Unix &
      Those who would give up essential Liberty, to purchase a little temporary
      Safety, deserve neither Liberty nor Safety.
      -- Benjamin Franklin
      "carpe diem quam minimum credula postero"

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