Thanks man :)
It seems to be counter-intuitive the suspension should move a lot slower than a 10 to 13 HZ dominant frequencies in the FFT that would cause motion-sickness I believe
As per friends suggestions, I used the full bandwidth of the accelerometer of 1000HZ since 50HZ LPF might have been cutting off some data and used the maximum sampling rate I could get on the arduino.
FFT UNFILTERED DATA FULL BANDWIDTH of ACCELEROMETER:
here is a sample piece of data of the pothole event and some bumps and road noise around it:
UNFILTERED DATA POTHOLE EVENT
Added the Diode envelope detector circuit, output looks the same... The accelerometer always output 0 to 3.3Volts not negative... I based this idea on filtering and holding the amplitude of the signal like in radio, but the sensor doesn't go negative voltage. the output didn't change much at all. I picked the RC time constant to be around 2mS, I'm sampling at 2mS 500 Samples/ second The accelerometer voltage is always between 0 and 3.3V though... never goes negative so the diode wouldn't work?
I did not see a HUGE different in increasing the sampling from 100HZ to 500HZ, the signals looks almost the same. Also, the FFT suggests anything over 55HZ or so can be cutoff, the pothole event would be a high frequency event though kinda like a step input? I'm not sure how I can reliably filter and detect the peaks of the pothole event form the surrounding road noise