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      02-16-2011, 10:11 PM   #61

Drives: 2014 Shelby GT500
Join Date: Apr 2008
Location: Vancouver, BC

Posts: 927
iTrader: (4)

Originally Posted by eeghie View Post
Impressive, that you did quite some ground work on data acquisition, but more so that your approach of double integration of an accelerometer signal results in a clean and recognizable position curve (~ an under-damped chassis with dry/stick friction).

I should ask what you mean by 'run out of travel' events because these would cause sharp acceleration spikes, whereas your position curve looks to be within harmonic boundaries. Did you feel/hear the hard bump stops yourself during this measurement? Perhaps you do mean highest/lowest position on the harmonic curve?

Just started a study on a custom EDC controller, but would rather use a u-Ctrl for that. Your PC setup is of course perfect for measurement and calibration, although I had hoped that more turn-key acquisition setups for accelerometers were available (at higher cost no doubt).

Getting the "clean" signal wasn't easy - it's very prone to small offset errors and to noise, so a full second of sensible results takes an hour or so to process by hand.

The run out of travel events are the flattening of the top of the suspension compression curve. I didn't go over the speed bump very quickly and it only just touches, so the "impact" is only really visible in the processed output - in the raw data it's buried in the noise and rumble. I don't recall a "thump", but then it was a year ago.

Best of luck on the EDC controller - the challenge will be knowing how to select the settings, since you don't know where you are, only where you've been. The problem with damper tuning is that it's road-surface dependent, so a rough road benefits from a softer setting than a smooth road. Lateral G's don't really affect how much damping you need - it's all about texture.