The Modular Training Arm

For discussion of arm designs.
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Skip Meetze
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The Modular Training Arm

Postby Skip Meetze » Mon Aug 31, 2015 9:28 pm

The Training Arm is an experimental elbow-actuated assistive device that is being developed by e-NABLE R&D volunteers to be fabricated using 3D printing technology. The modular design will “fast-track” through the testing process in order to quickly develop an arm design (with limited utility) to be provided to recipients by a wide range of qualified e-NABLE volunteer Fabricators and Fitters.
Printed flat Raj arm.JPG
Printed flat Raj arm.JPG (275.09 KiB) Viewed 3934 times

Leading candidates for the modular design include components that are printed flat and then thermoformed for ease of fabrication and strength to weight ratio.

https://drive.google.com/open?id=0B3VhD ... 1lVSVZfMzg video of Printed Flat and Thermoformed Arm

Lusie’s first test drive of the Printed Flat and Thermoformed Arm 17 August 2015
https://drive.google.com/open?id=0B3VhD ... 0o4R0lWM1U

Training Arm Designs https://drive.google.com/folderview?id= ... sp=sharing
is a repository of experimental designs that are potential components of the modular Training Arm
to be presented at the EnableCon2015 http://enablingthefuture.org/2015/08/19 ... a-bothell/

A draft of the modular components being considered for the Training Arm can be found here Training Arm Design Links DRAFT https://drive.google.com/open?id=1piJGT ... Pny2wb1IB4
Lusie Test Drive 1.png
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10 mov pic.png
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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Mon Aug 31, 2015 9:45 pm

A handy draft of the modular components being considered for the Training Arm can be found here https://drive.google.com/open?id=1piJGT ... Pny2wb1IB4

untulis
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Re: The Modular Training Arm

Postby untulis » Wed Sep 02, 2015 7:24 pm

On Monday you mentioned that you thought that the PLA became stronger after being heated and here is an article http://www.sciencedirect.com/science/ar ... 6110001414 that talks about annealing of PLA.

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Tue Sep 15, 2015 12:26 am

Status update on the Training Arm:
The current design plans for printed flat and thermoformed components in 3 sizes that hopefully will accommodate elementary school kids (Small, Lusie size), teenagers and female adults (Medium, Raj size) and adult males (Large, Nate size). I have uploaded assembly parts for test printing here: Small Left Arm https://drive.google.com/folderview?id=0B3VhDqFhSJU9Z3pnRW5aT1NnNnc&usp=drive_web (about 51 hr print time at .1mm layers), Medium Left Arm https://drive.google.com/folderview?id=0B3VhDqFhSJU9VXctQXZpZkFfVkE&usp=drive_web (about 54 hr print time at .1mm layers) , Large Left Arm https://drive.google.com/folderview?id=0B3VhDqFhSJU9TWhleE5OWE94SHM&usp=drive_web(about 67 hr print time at .1mm layers).

Please print a set of parts and report issues. Instructions for assembly will be posted later in the week.

Note that these devices provide the new terminal device the “Gripper Thumb” which will replace the split hook of a conventional arm prosthesis, and only the thumb moves. The fingers are thermoformed to curl to a fixed position. The thumb opposes the first two fingers in the "3-Jawed Chuck" position with power from an elastic ring. Voluntary opening is achieved with a standard arm prosthesis Bowden cable.

The Gripper Thumb design was conceived to provide Lusie with a device for riding her bicycle without training wheels and to provide Raj with a more anthropomorphic hand appearance and Nate with a replacement for his split hook. However, it is believed that the device may provide a large number of functions for use in two-handed tasks.
Attachments
Printed Flat Arm parts.JPG
Printed Flat Arm parts.JPG (367.9 KiB) Viewed 3812 times

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Skip Meetze
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Instructions for assembling and thermoforming the arm

Postby Skip Meetze » Fri Sep 18, 2015 8:16 pm

Some instructional materials have been uploaded to the drive
Gripper Thumb Instructions
https://drive.google.com/folderview?id= ... sp=sharing

Training Arm Instructions
https://drive.google.com/open?id=0B3VhD ... 2tZSnZ3U2c

Daniel Ashbrook Photos of the Training Arm
https://drive.google.com/folderview?id= ... sp=sharing
Attachments
Training Arm Assembly 1.jpg
Training Arm Assembly 1.jpg (107.04 KiB) Viewed 3730 times

Skriver
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Re: The Modular Training Arm

Postby Skriver » Mon Sep 21, 2015 4:04 pm

Hello Skip,

I'm looking for an arm prosthesis for a friend of mine. I'm not e-NABLE volunteer (yet :)) but I'm really impressed by what you are doing. I own a 3D printer and I'm quite good in "making things" (including designing them in CAD). I would like to make an arm using your design. I will be very happy to help in testing and give you some feedback.

My friend is 28 years old man. As I seen you already prepared arm files for such person. I've never printed any e-NABLE device and I think I will start from making a hand. I was thinking about Raptor Reloaded or Phoenix Hand - which one would work better with Training Arm? On one video you've shown modified Raptor Reloaded device (with changed thumb angle) - is it possible to download files for it in proper size?

Best Regards,
Skriver

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Wed Sep 30, 2015 4:11 pm

Hello Skriver,

There is a bit of a learning curve to safely and successfully provide a 3D printed arm to an amputee. The wrist-powered hands provided by our volunteers are fairly easy to learn to make and that is the best place to start. http://www.enablecommunityfoundation.org/get-involved/build-a-hand/ The hands have much less clinical risk than arms, and after you demonstrate your proficiency with making a hand, enablematcher will find a recipient for you to work with.

Prosthetic arms normally are provided by prosthetists who have a considerable amount of training. e-NABLE R&D volunteers are working at universities around the world (with the help of prosthetists and other clinical people) to develop arms that might be safe enough for the amputee to use and easy enough to fit safely by someone with less training and skill than a certified prosthetist to provide. We have made good progress in the mechanical designs that can be fabricated with the help of people with 3D printers, but coming up with designs that can be safely provided by our volunteers is still being developed.

Right now, we recommend that people providing arms should be working under the clinical guidance of someone such a prosthetist or occupational therapist when (1) fitting the device and (2) following up with the amputee. We are making rapid progress with our open-source sharing within our community and you are welcome to join in. Please go the the website and follow the process. This forum and the google plus community will help you get up to speed.

We look forward to your contributions!

Cheers,
Skip

EricIsraelson
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Re: The Modular Training Arm

Postby EricIsraelson » Mon Oct 05, 2015 10:13 pm

We're working with a 26 year old male (AnLA). We have built a standard RIT Arm.The forearm receiver is too large in that his residual limb is too short. In the current design the forearm receiver is quite bulky. With these two factors, the residual doesn't catch so he can't gain any leverage to bring the arm up and close the fingers. We believe that the Training Arm design would be a lot more effective for him as the receiver cup is much lighter and can be adjusted using velcro or reworking the thermoplastic.

We have the need for a large right arm. Are there files available we can size and use?

If this is not available we can print a left arm version of the arm and then reverse engineer the parts that need to be changed for a right arm version.

We understand this is a R&D product but would like to participate in the development as well as test it with our client.

Our client is not local, but knows the importance of working with a professional to get the final fit.

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Fri Oct 16, 2015 10:24 am

Hi Eric,

Please contact me at skip dot meetze at gmail dot com for a more extensive conversation. Sounds like you have a good understanding of the printed flat and thermoformed version of the training arm socket that is under development. I agree that the printed flat socket is more likely to fit properly. The fitting involves some fabrication skills as well as clinical experience in concern for the safety and comfort of the recipient.

I would prefer that you wait a few weeks and be a part of the official beta test so the community at large can benefit from your experience. The left and right training arms are identical except for the terminal device. My personal favorite TD at the moment is the Gripper Thumb hand and the design should stabilize within the next week or so. The left and right terminal devices are mirror images.

We hope to get by with 3 sizes, small, medium and large of most of the modular elements, and some elements (like the end plug, quick connect and hinges) should work for all sizes and for both left and right.

Cheers,
Skip

Skriver
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Re: The Modular Training Arm

Postby Skriver » Fri Oct 30, 2015 3:46 pm

Hello,

I will also be happy to become a beta tester for this design. As you advised, I submitted the intake form and made a RR test hand. It's currently waiting for approval. If you are curious about the hand I made, you can see my videos at https://www.youtube.com/channel/UCUj7jY ... Lgcn-rcJZw .

Meanwhile, I also printed parts for Training Arm and assembled it just for trial. It turned out that the prosthesis is too big for the recipient (the components for thermoforming are too wide) so I will try to print a smaller version. You can see all photos at https://drive.google.com/folderview?id= ... F9KZEJsdWc .

Cheers,
Skriver

joecross
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Re: The Modular Training Arm

Postby joecross » Mon Nov 16, 2015 1:20 pm

Has this entered Beta testing yet?

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Tue Nov 17, 2015 11:34 am

Joe,
The training arm will not be ready for beta testing (to see how the training arm works for experienced teams of fabricators/recipients) until after the first of 2016. We are doing alpha testing now to see if people with diverse types of printers and a range of skills can print and assemble the current level of design development. Stay tuned...
Cheers,
Skip

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Tue Nov 17, 2015 12:04 pm

Skriver,
I am very pleased to see your photos. You have done an excellent job of fabrication, so you should feel proud of that! Your work makes you one of our early alpha testers where we see if people with diverse types of printers and a range of skills can print and assemble the current level of design development.

When we are ready for Beta testing (in a few months), we will have instructions worked out that will help in choosing the right size the first time. Yes, try a smaller size and keep developing your skills. You can (and should) trim the socket and cuff with heavy scissors so that the two sides do not overlap but almost touch as the thermoforming is adjusted to the recipients arm with velcro.

The final adjustments should:
(1) make sure the hinge pivots are located over the epicondyle (bumps on the sides of the elbow)
(2) make sure the padding fits comfortably and that there are no sharp corners or edges
(3) be adjusted by removal from the recipient and trimmed, then further thermoformed (with a heat gun) by bending down tabs at the distal end of the recipients arm (for a snugly comfortable fit) and also tabs slightly around the bottom of the elbow.
(4) make sure that with a sock on the recipient's arm, the training arm fits comfortably without sliding around on the arm as it is used. Compare the fit and feel to a properly fitting shoe.

Keep up the good work and excellent photo documentation and get back to us on this forum. You should consider trying the gripper thumb terminal device and quick connect (to be published soon without complete instructions).

Cheers,
Skip

joecross
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Re: The Modular Training Arm

Postby joecross » Tue Nov 17, 2015 12:47 pm

Thanks Skip. Are we moving away from the RIT arm or Raptor Wing in favor of this design? We've been making RIT arms for awhile now, but wonder if there is a problem that I'm unaware of. To date, none of our recipients or medical advisors have raised any issues with the RIT arm.

Regards,
Joe

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Tue Nov 17, 2015 9:06 pm

Gripper Thumb Hand 2.0.JPG
Gripper Thumb Hand 2.0.JPG (107.02 KiB) Viewed 3017 times

Experimental RIT Gripper Thumb Hand 2.0:
Modular Terminal Device by e-NABLE

The Gripper Thumb Hand is a Voluntary Opening (normally closed) Terminal Device (TD) for a prosthetic arm. It is printed flat and then thermoformed so that the 4 fingers are fixed in a flexed grip. The thumb pivots at the proximal end and is flexed under power of an elastic ring in order to contact the first two fingers in a “three-jawed chuck” grip. The grip is opened by a Bowden cable that is pulled by an elbow or shoulder action.

The Gripper Thumb Hand incorporates a 1/2 inch (or M12) fine-thread bolt for connection at the wrist of a prosthetic arm. It can replace the commonly used split hook of a conventional prosthetic arm or it can attach to the experimental Modular Training Arm system being developed by e-NABLE.

Printing Files can be found here:
https://drive.google.com/folderview?id= ... sp=sharing
Instructions can be found here:
https://docs.google.com/document/d/13BO ... m3mbngj476

Request for alpha testers on new Experimental Terminal Device for prosthetic arms: Request for alpha testers on new Experimental Terminal Device for prosthetic arms:
1. We are looking for experienced hand and arm printers to try printing and fabricating the Experimental RIT Gripper Thumb Hand.
2. We are also looking for current users of prosthetic arms with a split hook and shoulder harness. We are interested in evaluating the Experimental Gripper Thumb Hand as an alternative to the split hook on upper limb prosthetic devices that have been provided by Certified Prosthetists and are currently in use.
3. If you are interested in being involved in either of these tests, please contact me at: skip dot meetze at gmail dot com.

joecross
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Re: The Modular Training Arm

Postby joecross » Wed Nov 18, 2015 8:19 am

Hi Skip - this looks like an amazing initiative. I wish I could help. Unfortunately, the additional parts in this design are near impossible to source in the remote areas I'm focused on (eastern Europe, southeast Asia, northern Africa). I'll keep my fingers crossed for enhancements to the RIT arm, which only requires a few screws and Velcro (if you print the connecting rod). Good luck!

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Sun Nov 22, 2015 6:20 pm

Nate and Lusie 2.JPG
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Lusie and Joe.jpg
Lusie and Joe.jpg (91.1 KiB) Viewed 2924 times
The Mini Maker Faire in Rochester went very well. Lusie and Nate tested the new prototypes there, including the new gripper thumb hand. The terrific news is that Nate can use the new gripper thumb hand with his Hanger prosthetic arm and harness replacing the Hosmer hook. He demonstrated using the device for
writing with a pen, holding a fork

tying his shoe (1 min, 25 sec video)
https://drive.google.com/file/d/0B3VhDqFhSJU9NTZmR0RIejRua0U/view,

zipping his jacket (31 sec video)
https://drive.google.com/file/d/0B3VhDqFhSJU9RnFQT19EaWVXcVU/view,


Lusie tested a prototype variation of the gripper thumb being developed by Joe to grip a handle bar. Joe is going back to the drawing board to work on some safety issues. With a Raptor Reloaded hand and adaptor as a terminal device, Lusie demonstrated stacking cups. Liz, Rebecca, Peregrine, Joe and I enjoyed showing off our wares to the public. Joe and I are already revising the gripper thumb based on Nate’s feedback, and Lusie’s parents were a great help in our understanding of the issues of balance for Lusie’s bike riding.

Here are some pictures and videos that I took. https://drive.google.com/folderview?id=0B3VhDqFhSJU9MXYyVHZQUzdhNVU&usp=sharing

Nicholas Hall
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Re: The Modular Training Arm

Postby Nicholas Hall » Wed Jan 13, 2016 7:39 pm

This is a simply astonishing piece of work Skip. I think I've probably said it before, but I'm a huge fan of your work. I particularly love that it's a normally closed hand. :) It's simple, elegant, but effective.

I'm very curious as to how constant the force required to open the thumb remains over it's range of motion. Does it get noticeably harder to fully open the thumb vs opening just a little bit?

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Wed Jan 13, 2016 11:17 pm

Thanks for the kind words Nick. It is nice to hear from you again and we welcome your contributions. The mechanical action of the gripper thumb is almost identical to the functioning of the industry standard Hosmer Hook as demonstrated in Nate's first test (see the video above). Therefore, the force is acceptable over the range of motion of the thumb.

I'm excited by the potential of Doug B's KISS Hand http://forums.e-nable.me/viewtopic.php?f=6&t=365 which is a motorized remix that works in his proof-of-concept video https://plus.google.com/u/0/103262303572054348874/posts/GPtMfmVCFQa?pid=6236815823581384866&oid=103262303572054348874 without an elastic. It is voluntary opening AND voluntary closing with successive actuations of a mechanical switch or a myoelectric sensor. So we now have evolving technologies for an elbow powered and a motorized terminal device with a moving thumb against fixed (but adjustable) finger positions. Notice the adjustable finger positions in Doug B's demo!

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Wed Jan 13, 2016 11:30 pm

Joe Cross, we hope to address your concern about sourcing parts. Right now, we are heading toward a design that requires only printed parts, two kinds of screws and nuts, nylon monofilament, velcro and padding to create the training arm. You have me thinking about a version that eliminates the screws. There may also be optional alternatives for the monofilament, velcro and padding. Stay tuned and share your ideas with us.

droomurray
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Re: The Modular Training Arm

Postby droomurray » Thu Jan 14, 2016 8:18 pm

Skip,

To eliminate screws and rivets you might want to check out this idea that myself and stephen have used in the arm we developed.
Basic idea came from scale electric toy tracks and how that joins.

Reality is these printed sections with tabs in can be secured with gorilla glue and the whole section can be thermo-formed - gorilla glue has enough flex in it to not snap during forming.

Hope this is something you can re-cycle into your design !

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Drew.

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Skip Meetze
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Re: The Modular Training Arm

Postby Skip Meetze » Thu Jan 14, 2016 9:04 pm

Thanks Drew.
That looks terrific! I will experiment with that next week if all goes well. I haven't had much experience with gorilla glue. We are always going to need to fabricate devices that are too big for the printer bed and developing some processes to deal with that is vital.

Here's a little challenge:
There are things (such as food containers with tamper-evident openings) that snap together and don't unsnap. Perhaps someone in the community has design experience with that and understands the critical parameters. Eliminating glue and fasteners altogether would be very nice.

Gruber
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Re: The Modular Training Arm

Postby Gruber » Thu Mar 17, 2016 9:10 am

This looks very cool Skip, it's amazing what these 3d printers can do. Will the finished product be made to look more human like? An update on this would be great. Thanks for posting about this.
I got the Jes Extender from https://dudehung.com/my-jes-extender-review-and-results and it's great.

emmajons
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Re: The Modular Training Arm

Postby emmajons » Mon Feb 06, 2017 3:02 pm

Skip Meetze wrote:Status update on the Training Arm:
The current design plans for printed flat and thermoformed components in 3 sizes that hopefully will accommodate elementary school kids (Small, Lusie size), teenagers and female adults (Medium, Raj size) and adult males (Large, Nate size). I have uploaded assembly parts for test printing here:
Please print a set of parts and report issues. Instructions for assembly will be posted later in the week.

Note that these devices provide the new terminal device the “Gripper Thumb” which will replace the split hook of a conventional arm prosthesis, and only the thumb moves. The fingers are thermoformed to curl to a fixed position. The thumb opposes the first two fingers in the "3-Jawed Chuck" position with power from an elastic ring. Voluntary opening is achieved with a standard arm prosthesis Bowden cable.

The Gripper Thumb design was conceived to provide Lusie with a device for riding her bicycle without training wheels and to provide Raj with a more anthropomorphic hand appearance and Nate with a replacement for his split hook. However, it is believed that the device may provide a large number of functions for use in two-handed tasks.


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