how to measure the relative movement of two body

[tonyche]

I am trying to figure out what is the best way to measure the relative movement of two body.

Here is the confguration:

1. the normal distance is about 20mm.
2. the relative movement can be +/- 10mm.
3. those two body are made of steel and their shape are irregular.
4. the temperature is about 1000F.
5. The movement of each body could be in 3 dimensions.

Any brillant ideas? What technology / sensor to use?

 

[ScottyUK]

Can you measure the position of each body relative to some datum (one that isn't at 1000[°]F!) and calculate relative motion from the two absolute measurements? 3 laser devices per item might do it, but may have a problem if the item is emitting light itself. 1000[°]F must be just below red heat.

What accuracy do you need? Without that information it is kinda pointless to speculate too much.

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I don't suffer from insanity. I enjoy it...

 

[sreid]

I would think you would need a Vision Sysyem.

 

[tonyche]

Thanks! the optical system seems not ok for such high temp environment.

The accuracy I need is less than 0.5mm.

 

[sreid]

Optical systems can be protected from high temperatures using "Cold Plates" (IR Filter Windows).

 

[IRstuff]

You would need two cameras for the vision approach. Lenses with 12º FOV would give you about 0.1mm resolution at 1 ft, if you use sreid's suggestion of a IR filter glass.



TTFN

 

[Ashereng]

I don't have an answer for you, but I do have some questions:

1) What is used to move the 2 bodies, or are they moving by themselves?
2) What is the effect of 1000°F on steel expansion? And, does this have to be taken into account?


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[tonyche]

actually, these two bodies were connected by seals. I would like to find out how these two parts are moving in order to figure out why there are seal problems.

We can consider the steady state of thermal expansion.

Thanks!