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Old 05-15-2013, 04:33 AM   #23 (permalink)
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Originally Posted by Old Tele man View Post
Maybe you could *revise* this 1968 "G-whiz" idea into an inclinometer SENSOR that provides input to your handheld to read and calculate the road angle from?

source: Popular Electronics Magazine, Sept 1968: Popular Electronics Magazine, September 1968
That's fantastic. Yes, I can see no reason why it could not be modified to feed the output into a digital display (if that is desired). I think it would be cool to build as described though. (I'm tempted to do it but I already have too many other projects I want to build.)

It is still an accelerometer, not (yet?) something capable of measuring an incline in a moving vehicle that is also accelerating. The error due to the slope across the road is also present. That's small in comparison to vehicle acceleration, so can be ignored if that is the intended purpose but not in an inclinometer. An easy way to illustrate the effect is to induce a 90 degree xy "slope" by turning the unit on its side. It then won't work quite as well. For an inclinometer I think digital is required.

I need to correct an error: +z is by convention down not up. (That makes the coordinate system right handed, matching the 3-axis output.)

Another source of Arduino tutorials can be found here:

Getting Started with Arduino!

I picked that page because it is doing exactly the same thing that is required to get 3-axis accelerometer data into an Arduino, process it and ultimately display it. It just uses the single temp. sensor voltage as an input where the 3-axis has 3 voltage inputs.

It occurs to me that maybe measuring an incline isn't necessarily the most useful thing to do with the accelerometer data. I am pretty sure the accelerations can be integrated (in the math sense), the vehicle mass added in and the kinetic and potential energies of the vehicle calculated. I can see those being really useful.

At the very least, setting up a real time lateral and longitudinal g force display is a cool project, however it is done.
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