Commit f9a75fc1 authored by Jake Read's avatar Jake Read

notes for cv experiment

parent 9b6c5c77
......@@ -82,6 +82,20 @@ While the samples fail around the same load, the difference in elongation is ~ 1
This obviously warrants correction. One way to do this is to build a stiffer machine, however, we will be chasing up the cost and complexity if we do this. Rather, we should throw some more control at it. To start, we can circle back to our attempts at [subpixel tracking](https://gitlab.cba.mit.edu/calischs/subpixel_tracking), or attach a small linear stage directly to our fixturing elements. For this, I am imagining something like the [AMS5311](https://ams.com/as5311), which should do some 12 bits inside of a 2mm throw (for 0.4um resolution). Either can be added to existing systems, given network controllers / modular browser code. Since I want to integrate it elsewhere, it's likely that the camera option comes first.
#### Vision in the Loop
We're currently working to build a computer vision based displacement sensing method for the DEX. Since our machine (or, many machines manufactured by novices / in the public domain) are liable to flex (indeed, nothing is infinitely stiff!), the thought is to measure local displacements of the sample, at the sample, rather than measuring open-loop through the machine's structure.
To spin this up, I've written a small / barebones subpixel template tracker in the browser, in cuttlefish. This is conveniently lightweight - the whole cycle (image collection -> analysis) can happen at ~ 10Hz, which is not splendid, but not diabolical either.
![vd](video/2019-11-17_micrometers-cv.mp4)
Here we can see a desktop test - I am reading the X- position from my tracking system on to a chart, and moving the tracker on a linear stage. This system resolves ~ 15um, which is not bad for a proof of concept.
#### Vision on the Machine
To get after this, next step here is to integrate a camera onto the DEX mechanically. The previous work taught me that (1) strong lighting is important, as is clarity of target-against-background. Some prep will be worth it. This is a fitting (haha) time to re-design the fixturing for the DEX, as the targets / camera / fixturing system will all need to agree with one another.
## Testing Notes
The D683 ASTM Dogbones:
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