Which hand do I need to grab a ski pole?

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marito
Posts: 2
Joined: Wed May 10, 2017 2:16 pm

Which hand do I need to grab a ski pole?

Postby marito » Wed May 10, 2017 4:16 pm

Hi, my apologies if this is not the right place for asking this. I have a congenital deformation of my right hand, four missed fingers and an underdeveloped thumb. My wrist is completely functional in terms of the general prosthetic hands I read about. My purpose is to use it for grabbing the ski pole as I used to for many years with a home made prothesis that reached to its end of life. I think that with the technologies available today I should get better results with some 3d printed hand.
I guess that the best hand for this task shall have a distributed force over the fingers in order to catch properly the pole grip. The pole need to be well grabbed in order to support some pressure from the arm-hand set when the pole is put into the snow. This task is a brief and gentle movement made mainly with the purpose of marking the beggining of a turn over manouver.
I need your help to select the proper hand among the models available at e-NABLE.
Additonally, there is a subtle movement needed to properly plant the pole: The wrist need to rotate a few degrees in the thumb-kinky finger plane (up-down ). I can do this movement with my incomplete hand but I did not see any 3d printed hand available with such degree of freedom. Maybe I need to customize one of them in a next version.
I will appreciate any comment and suggestion about my question.
Regards

andrew615
Posts: 8
Joined: Thu Apr 13, 2017 12:04 pm

Re: Which hand do I need to grab a ski pole?

Postby andrew615 » Fri May 12, 2017 12:38 pm

Hi marito!

Can you share some pictures of your original prothesis? We have designs for trumpet holding and viola playing so maybe we could create one for ski pole holding.

I currently do not know of any prosthetic that allows for rotation in the thumb-kinky finger plane (if I'm understanding that correctly, it's like a "chopping" motion, right?). Can you design one with us so the entire community can also benefit?

Also, have you tried any of the general purpose hands (like the Raptor Reloaded http://enablingthefuture.org/upper-limb ... -reloaded/ ) to test out what is good/bad about them for skiiing?

marito
Posts: 2
Joined: Wed May 10, 2017 2:16 pm

Re: Which hand do I need to grab a ski pole?

Postby marito » Mon May 15, 2017 12:52 pm

Thanks andrew615 for your answer. Here´s my rapid answer.
My home made hand is nothing more than an aluminum plate cut in the shape of a hand with a prolongation to wrap the wrist . The objective was to fill in a ski glove. Then the "fingers" can be shaped around the handgrio. The aluminum bends more or less easily and remains in that position without problems all the time that is needed. Once my hand is entered in the glove the prolongation acts as support for my forearm (in the same way many of the 3d hands do) and transmits the force to the pole for the pole plant manouver. Later I will upload some photos. The aluminum broke in some postions due to the many bendings along the time.
Regards to the addional motion I wish to have, it is like chopping motion: I attached a schematic picture showing the direction of the motion and the center of the arc. This motion was not possible with my old "prothesis".
I agree with you that maybe it is better to redesign one of the available hands. I thought the following requirements for a hand I need:
1- Instead of forcing my wrist continously for grabbing the pole (I saw this is the most common mechanism in body powered 3d hands), a lock mechanism that leave the hand grabbed to the pole and an "unlock button" can be more suitable for me. Maybe this is a not personal safe design but I don´t see any other solution.
2- A split of the palm+fingers section from the forearm section is needed. But both sections need to be attached with something like a rivet or a hub that allow the rotation between them.

Still I need the community to advise me about which 3d hand it is better to begin with. Maybe the Raptor Reloaded as you mentioned?
Thanks again and regards
Attachments
HandGripMotion.png
HandGripMotion.png (271.33 KiB) Viewed 884 times

andrew615
Posts: 8
Joined: Thu Apr 13, 2017 12:04 pm

Re: Which hand do I need to grab a ski pole?

Postby andrew615 » Thu May 18, 2017 12:33 pm

Got it!

If you're a Autodesk Fusion360 user you can start with the Raptor Reloaded (or at least download a more editable version) from https://myhub.autodesk360.com/ue29da5d6 ... 4d0c151a57 You will definitely need to make some changes but editing a cad file should be easier than editing a bunch of .stls.

What design software are you planning on using? And how can we best support you?


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