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Old 05-17-2013, 07:15 AM   #32 (permalink)
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Originally Posted by Nevyn View Post
Why not get one of these?
Because, like the other suggestions we've come up with, from 5 cent pendulum to $100 Arduino plus accelerometer but minus speed input, it won't measure slope in a moving vehicle. They will all be measuring the slope plus some component or all of whatever acceleration the vehicle is subject to.

It's easiest to describe using the pendulum device. Stop on a slope and the pendulum will be at some angle relative to the car. Accelerate away from rest and the pendulum will swing towards the back of the car, no longer indicating the slope.

What is needed is a way to determine the acceleration of the car relative to the road and subtract that acceleration from the total acceleration (along the slope; x direction) to leave the gravitational component. It will be possible to do that with the Arduino. I expect it would also be possible with the G-Whiz, a speed sensing input and some analog computing but the Arduino will be easier.
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