Angle Finder

KenM

I am soliciting ideas on how you might construct a circuit/device that will automatically read measure an incline, with one seemingly difficult requirement.

It cannot be affected by acceleration, as it will be in an automobile.

http://www.quickcar.net/chassis/ch_angle.html

http://www.speedpartz.com/smarttool.htm

http://www.geodetic.com.au/category668_1.htm



Post Edited (KenM) : 4/9/2005 4:44:18 AM GMT

pjv

Ken,

There are a number of possibilities, but it strikes me that some more information is required in trying to determine a plausible solution. Can you tell us what you are trying to accomplish?

Some obvius questions:

You indicate that acceleration may not affect the reading. This implies the device will be in motion. Is it a fixed location you are wanting to measure?

Can a "horizon" be always visible from the device?

Can a differential system be used nulling out acceleration?

Will the device move up/down the plane?

How fast must it operate?

Is a single reading required or a continuous readout?

Are temperatures an issue?

Is cost an issue?

You see, when one is working blindfolded, it is very difficult to home-in on an answer, and it becomes a waste of time. A short description will seriously aid all those who wish to help you find an appropriate solution.

Peter (pjv)

kelvin james

You can try an inclometer like these ones.
www.msiusa.com/sensors/tilt.asp

kelvin

LoopyByteloose

Parallax sells the Mesmic device. It can be positioned vertically to cover a full circle on one axis. two of them, you have two axis, and three of them provides the whole sphere.

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G. Herzog in Taiwan

KenM

Peter and others,

More specific information.

This device will be used in a moving automobile. A horizon is not always visible.
The devices I provided links for work well as long as the vehicle is at a constant speed (not accelereating or decelerating).

Nulling accleration is a possibility

The output needs to be continuos (analog), With an update rate of about·0.5 Hz.

Temperature is not an issue.

Cost is a "so so" issue, as I want build it myself. I am willing to spend $300 ~ $500 to make it work.

There is already a way to do this with a thing called a Vbox. Vbox is a GPS device that tracks distance, acceleration and altitude. From the distance and altitude alone the information can be had, but currently, that requires post processing the information.

I am hoping to get real time information into my data logger while driving.

pjv

Ken;

At the moment, about the only thing that comes to mind that does not somehow use an acceleration sensitive mass is an orthogonal set of 2 gyroscopes. Each one could be made compact; a derivation of some fast spinning brushless motor, and rather than building a low friction gymbal system, use force measuring techniques at each of the gyroscope's bearing points. This could be a bit tricky. I have no idea as to the facilities you have at hand, or your skill in mechanical fabrication. I'm sure you have the electronics end covered.

This concept would use the twisting force to derive both, the pitch and roll angles; you don't need yaw. The pitch is what I believe you are looking for, but the roll is required to correct the pitch measurement. The accuracy would be subject to a slow integration error, depending on the precision of the mechanics, electronics and computation, so the duration after "zero" that it needs to be accurate for could be an issue.

If this approach interests you, then I would be prepared to give it some more thought; it sounds like a fun project.

Peter (pjv)