
An artificially intelligent, open-source bionic leg - akeck
https://qz.com/1636413/an-open-source-ai-bionic-leg-is-the-future-of-prosthetics/
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Pulletwee12549
This leg uses advanced AI and Machine Learning algorithms with a cloud
Prosthetic as a Service (PaaS) model. Utilizing the latest in state of the art
open source blockchain technology, this leg will bring added value while
synergizing with your efficiency to optimize your bottom line.

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wishrider
The Prosthetic as a Service (PaaS) model uses a pay-as-you-go approach.

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forgone
first 20 miles for free

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devoply
after that, the fall of man.

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thundergolfer
I'm the owner of a very dodgy right leg (fibula hemimelia) that will probably
only last another 10-20 years. 15-yr-old me dreamed of being able to
eventually replace it with something more iRobot than steel-post.

Godspeed to these amazing researchers.

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DigitalTerminal
More than any other field prosthetics MUST be open source. If you do not have
full control of your body do you really have control of anything?

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justinclift
Breakdown of the cost:

* Star Prototype (machined parts) ……………….. ~$15.6 k

* Dephy (actuators and encoders) ……………….. ~$8.7 k

* SDPSI (belts) ……………………………………… ~$0.2 k

* McMaster-Carr (bearings, fasteners, etc.) …….. ~$1.6 k

* Misumi (shafts) …………………………………… ~$0.1 k

* Motion Industries (angular bearings) ………….. ~$0.8 k

* Amazon (batteries and case) …………………… ~$0.5 k

* K&J (magnets) …………………………………… ~$0.0 k

* Shipping charges ……………………………….. ~$0.9 k

* Total Cost ……………………………………….. ~$28.5 k

The greatest cost (~$15.6k) is for the machined pieces.

That seems seriously inflated though.

Wonder how much someone with a well calibrated workshop CNC could get that
down to...?

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robomartin
We have a full CNC shop in house with the latest equipment. I took a quick
look at the design. It really isn't optimized to reduce fabrication cost. The
CNC work on this leg is substantial and very expensive. It simply isn't
designed for low cost manufacturing. I am not being critical, just stating a
fact in response to your question.

In CNC machining cost reduction can be obtained through the reduction of
what's called "setups" (how many sides of a part you have to machine),
judicious selection of feature types (some types of cuts require the machine
to slow down a bunch, special tooling or both) and fixtures.

The last one, fixtures, are custom made tools to hold the raw material and in-
progress machined parts for machining. They can make a significant difference
in cost. Without them a machinist has to spend a lot of time manually managing
what is known as "work-holding" (how you hold the material for machining).

Beyond that, it's a matter of volume. If you are only making one set at a
time, without tooling and without optimization to reduce CNC machine cycle
time and tooling requirements it is going to cost a lot. If, on the other
hand, the design is optimized for the process, part counts are reduced, setups
are reduced and you pay for palletization tooling (allows you to make more
than one part at a time) cost can be reduced substantially.

In addition to this if you can reduce or modify the size and shape of the
parts such that you can fit, say, ten of them within the working envelope of a
machine rather than five, it can make a huge difference in cost. This, again,
requires the design of a palletizing fixture.

Fixturing and workholding for production of a few parts at a time costs money.
Think of it this way: Each part you have to make requires a fixture to be made
for every setup. In other words, if you machine from the top, bottom, left and
right of an aluminum block and want to design a fixture to hold ten of them at
a time, you have to design one fixture for each setup or side you are
machining. There are ways to reduce this by working closely with the designers
and optimizing for work holding.

You can also integrate work-holding such that one pallet can hold the part in
different setups. In other words, you hold four parts in setup 1, four in
setup 2, four in setup 3 and four in setup 4. A pallet designed like this
produces four finished parts per machining cycle. After each run you move the
parts to the next setup location. So, the four parts that were being machined
from the top are moved to the right one position and clamped onto an area of
the fixture designed to hold them for bottom machining. The other parts are
similarly moved one position for the next setup and the parts on the last
setup slots come out of the machine for finishing (clean, debur, inspect,
post-process).

If you do the math on this the scope of the manufacturing problem starts to be
revealed. If you have ten parts to machine, and each part requires, on
average, machining from two sides, you need to design twenty individual
holding fixtures. Some can be integrated into a unified multi-setup fixture
but the design work isn't any different, in fact, it can be more expensive. If
the parts require machining from four sides you need 40 fixtures.

Once you are done with mechanical design of the fixtures and setups each one
of them requires CNC programming and tool selection. This is a detailed
process that requires time, expertise and testing, lots of all of them. In a
design like that of this leg the design, fabrication, programming and testing
of fixtures can easily cost much more than what the posted cost for machining
one set of parts.

In short, cost reduction for something like this requires detailed and intense
engagement with the manufacturing process, which would lead to design changes
necessary in order to reduce manufacturing complexity, machine cycle time,
fixture count and complexity, material waste, etc.

One way they could have reduced the cost to manufacture these for other people
could have been to, for example, pay for manufacturing fixtures to make four
to ten of these at a time. Customer #2 would then benefit from this and
possibly cut their cost by a substantial amount (25% to 50%). At the limit the
cost of machined parts become asymptotic with material cost + hours on the
machine + aggregated costs-per-hour for the shop (people, wear and tear,
power, etc.).

It's an interesting project. If the market is large enough it might make sense
for someone to pay for the design and fabrication of the tooling to offer
these parts at a lower price.

At a larger scale you'd have to design the parts for a casting + machining
process, which will make them far less costly.

Metal 3D printing might be another option but that's not as cheap as one might
think and has its own design requirements.

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justinclift
Thanks for looking at it. :)

My experience thus far is using a (somewhat modified) Shapeoko 3, so
personally I only have a very basic practical understanding of using fixtures.

Most of my stuff was cutting MDF, for engineering prototypes though. Haven't
done much with alum or anything tougher (yet), thus the limited fixturing
experience. ;)

> It's an interesting project. If the market is large enough it might make
> sense for someone to pay for the design and fabrication of the tooling to
> offer these parts at a lower price.

Yeah, similar thought. They look to have added a forum (without any posts
yet):

[https://opensourceleg.com/forums/forum/ankle-knee-control-
sy...](https://opensourceleg.com/forums/forum/ankle-knee-control-systems/)

Asking the above there (eg have they considered potential changes to reduce
manufacturing cost?), would _probably_ get it in front of the right people.

Any interest in pinging them? If not, I'll can do it and share the response
(etc). :)

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justinclift
Pinged them manually via email, as their forums don't have a functional log in
yet (being working on apparently).

Discussion around improving the manufacturability seem welcome: :)

    
    
      **********************************************
    
        We'd definitely love to have some DFM help!  You're right that we weren't really
        thinking too much about that when we designed it; mostly, we wanted it to be as
        lightweight and high performance as possible.  But it'd be great to have you or others
        help on the DFM side of things, especially if you're more familiar with how exactly
        machining costs are calculated, and what steps / features can be modified for
        the greatest improvement in cost.
    
        -Elliott
    
        Elliott J Rouse PhD
    
        Assistant Professor
        Director, Neurobionics Lab
        Department of Mechanical Engineering
        Core Faculty, Robotics Institute
        University of Michigan
    
      **********************************************

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justinclift
Their forum is working now:

[https://opensourceleg.com/forums/topic/reducing-the-cost-
of-...](https://opensourceleg.com/forums/topic/reducing-the-cost-of-
manufacturing-for-the-mechanical-structure/)

~~~
robomartin
Just posted offering to help.

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whymauri
Very cool. I think the more open and available this technology is, the quicker
we'll be able to optimize and iterate on it. I'm hoping the price of current
generation prostheses plummet over the next decade as a result.

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debatem1
Is there a link to the source? I can't seem to find it from their website or
github.

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katsura
I'm guessing this is what you are looking for:
[http://dephy.com/wiki/flexsea/doku.php?id=sourcecode](http://dephy.com/wiki/flexsea/doku.php?id=sourcecode)

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dejaime
Transhumanists are coming. As are bionic cyberterrorists. The future is both
amazing and scary!

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blacksmith_tb
Hmm, in both cases I think we'd need to have developed an (open-source or
proprietary) prosthesis that was superior to the limb it replaces, which seems
like it's a ways off still. Then you could imagine people voluntarily
replacing their old-fashioned biological limbs; right now the replacement
process is a lot less voluntary, and the recipients would be excited just to
achieve parity...

