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      08-24-2008, 06:20 PM   #52
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Originally Posted by southlight View Post
Maybe I'm completely off but I'm not sure about the 35ms shift in D3. What says you that the shift is completed at the point you were drawing the "end of shift" line, swamp? My understanding is that the shift can't be completed as long as the acceleration is higher than it was before the shift and that's some time longer. In case I'm plain wrong here say it in a nice way please.

Attachment 179820

Best regards, south
This is a very good point. Results here have plenty enough signal to noise ratio to be carefully questioned. Particularly in this trace it looks like some significant oscillations (say 4 or so local peaks after the 30 ms) may in fact be part of the clutching operations or some part of the shift dynamics. Quite a few things point to this not being the case though.
  • Look at the size and shape of the oscillations near the beginning of this data. Again these are very similar shape, size and frequency compared to the oscillations I am calling post shift. As I explained to lucid, these are occuring during near WOT acceleration, in 3rd gear well before the shift. They must be noise
  • Examining other shifts in D3 there is almost always this characteristic down spike followed by the up spike and these truly have clear physical meaning/cause related to the clutches.
  • If you examine much longer periods of the raw data you can see a fairly clear drop in the average (average to get rid of all these noise effects) of the acceleration comparing pre and post shift levels. You can see a bit of this in the S4 trace I originially posted. Those pre/post shift acceleration levels are consitent with simulation results as well! Previous work in this domain for MTs could use sampling at only 50 Hz or less to capture a manual shift on the order of 1/4 s. At 50 Hz you would filter the data carefully and almost all of this noise would disappear leaving you a fairly clear indication of pre/during/post shift acceleration levels. Everything is much tougher at 300-500 Hz!
  • The magnitude of the first down spike and following upspike are generally not matched anywhere in else the data set except right at the shifts. This is how I picked them out from the raw data.

These are the very reasons I have provided very large +/- uncertainty values on the actual shift times. Accurate and certain values are a way off and will require quite some additional work.

Below is a fully annotated run. I should have posted this long ago. Not entirely relevant to your question but loosely. I think it will help others see the big picture. The previosuly posted shifts are just serious zooms on both axes but more so on the horitontal/time axis.
Attached Images