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Old 05-16-2013, 05:08 PM   #28 (permalink)
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Originally Posted by Old Mechanic View Post
A curved piece of clear plastic tubing (could be hose) with a bubble of air in it with a mirror so you could look ahead and see the angle without having to take your eyes off the road would be neat. Just thought of it, maybe I'll build one. Where I live the grades are very mild, with the worst being the Interstate overpasses, but when I get in the mountains my perception of grades is terrible.

That is a good idea, it sounds like a construction level, but again I'm looking for a digital gauge. You should definitely build one, though and let us know how it goes!

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
I'll look into that, thanks. I wonder if I will need it if I can just attach an accelerometer that is designed for an Arduino directly to the Arduino board.

Originally Posted by Xist View Post
I have been coasting down hills in neutral for years and had also wanted an inclinometer. This Sunday was the first time that I drove to my parents' house using pulse and glide. I pulsed up. I glided down. If the hills were not steep enough, I would pulse again, but it was interesting, I was not as concerned with maintaining speed, I was satisfied with a slow deceleration.

I wish that I could say that it was a record trip.

I did forget to check my tire inflation, but when I noticed uneven wear, I stopped over-inflating.
Having a reading of the slope of the road would definitely help you determine what the best time to glide/coast is. After a learning period, knowing a grade of 7% will help you determine how far you can get just by coasting. I have been learning how to maintain a slow deceleration in neutral and slow down to the perfect speed right when I get to a turn into a parking lot or streetlight or whatever. It's kinda a little victory when I can do it right!

Over inflation can definitely be as bad as under inflation. Unfortunately the tire pressure threshold for up or down is really small and that range is different for every car. Good to hear you noticed the uneven wear and made a change.

Originally Posted by Occasionally6 View Post
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.
Build one! Would love to see what everybody comes up with! I'll stick with the digital (hopefully a pre-built module) if I am going to do an Arduino. Thanks for the extra link, that looks like it will be a great resource! I'm still a little lost, so I'm not sure what you mean by integrating the acceleration #s, adding mass and KE and PE. I would like the inclinometer output, but if these numbers can give me other useful information, I would be open to looking into it.

Originally Posted by Nevyn View Post
That is very interesting and I like the price tag, but I would like something with a digital display. A quick glance I know the incline. Also, my dash is not flat, so by default, I think it would be off, unless I make something to force it into level.
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