Gallery, Projects and General => The Design Shop => Topic started by: sparky961 on April 14, 2018, 11:05:22 AM

Title: Research Help Needed - Foot Scanner
Post by: sparky961 on April 14, 2018, 11:05:22 AM
I'm interested in the technology behind the "pin scanners" used by podiatrists.  Any keywords, links, or other information you may know or speculate would be appreciated.  Of particular interest is how each individual pin is locked and it's height value obtained.  Does each pin have it's own electronics (unlikely) or are they scanned in a matrix (more likely).  If they're scanned in a matrix, how?  I'd think anything optical would be obscured by surrounding pins.

Here's a video showing one example of what I'm talking about:

Title: Re: Research Help Needed - Foot Scanner
Post by: awemawson on April 14, 2018, 11:36:34 AM
Suppose that the pins are a firm but conductive rubber passing through two plates each with a matrix of holes. If the plates are laterally displaced slightly relative to each other the pins will marginally distort and lock.

Now the length of protruding rubber can be measured by measuring it's electrical resistance but the detail of that I've not quite got sorted in my head
Title: Re: Research Help Needed - Foot Scanner
Post by: Joules on April 14, 2018, 11:55:11 AM
Well quite some years back I got called into a company that did foot scanning.  They used optical scanners and they were fast.  I could well see this pin scanner being like a whole bunch of motorised calipers and each one sending serial data back about its position.  The trick is getting constant force on whatever tip each pin has, alot of contact/needle scanners ring the pin with a piezo element, this gets damped the moment it contacts producing a very repeatable result.

The company I did the work for had two very expensive machines to make specialist insoles, the two companies who made the equipment had fallen out and made the equipment unusable.  I solved the problem with Rhino allowing the scanned data to be manipulated and converted to a format the milling machine could handle.  In the process I also improved the quality of their scans.  Example below, one on the right has noise reduction via Rhino that had been present in all the scans and insoles upto that point.  The solution was also 4 figure fix than the 5-6 figure number they got quoted.  That was some 15yrs ago.