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### Topic: Using accelerometer to detect driving state(s) (Read 13897 times)previous topic - next topic

#### knox

#15
##### Jul 26, 2011, 06:45 pm
Thanks for guiding me through this.
I agree that 1g might be a theoretical value. The actual value will need some empirical foundation, I am afraid. However, I am still thinking about a way to detect an emergency braking (what's the correct expression for that?) state. One thing that came to my mind is if I will see some increasing g (or m/sec2) values due to reduced speed during ongoing braking. The stopping distance increases quadratically in relation to speed (sorry for phrasing it this way, never tried to articulate something in a foreign language). Maybe a very basic quadratic function can help me to express myself: s = (v/10)2. What are your thoughts on this?

I suppose I can neglect aerodynamical downforce since most road cars will rather produce upforce.

#### liuzengqiang

#16
##### Jul 26, 2011, 07:41 pm
That might work. You monitor the time the vehicle is in a deceleration greater than a threshold to tell if a full brake was made.