To separate Real Men from Quiche Eaters, a range of observations can be useful howevermuch one needs to know them before being able to apply them. In the context of prosthetic arms, quite obviously, the ability to discriminate shit from shinola does not grow on trees either.
If you are now even the mildest bit offended by me using clear language, bear in mind that no self respecting quiche eating "bionic" aficionado ever avoids to equate prosthetic hooks with "arcane" technology or fairytale figures such as Captain Hook. And as long as we all accept that the first stone has been cast, and that (if you are part of that group) you might be part of a problem (rather than a solution), we are all super cool, particularly when now we are going to call the cards.
Real tests do grow on trees, actually, in the real world. Already so far, it should have become sky clear to you that wearing a prosthetic arm to do lesser acts than storing a sofa on the attic is mostly (but not quite) pansy boy (not girly!) territory. If your prosthetic arm does not fully assist in solving these bimanual tasks, revise its concept before it is too late. Because if anything, real life does not change because of you suggesting amputees wear 3 kg material that cannot even open a bag of pop corn. I write this because I know that that was what you were (secretly) hoping.
So here is the task.
The tag holder of my Northface bag came off due to travel and strain.
The damage can be seen in the following picture. The other side of the tag holder had come undone more extensively.
Here is me stitching it back on.
For that, I use a thick strong needle and thick strong black string.
In order to push the needle through the dense fabric of the bag, lots of force must be applied to the needle, and to make sure the (gray, see following image) plastic of the tag holder stays in place, the prosthetic hook is used to exert precise ultra hard counter pressure. This works extremely well. I tried sewing with the Becker hand - that works. But sewing with the i-Limb was a disaster. The fingers are too weak, cannot reliably grip, definitely do not push hard enough and the controls are not useful when using the elbow and forearm muscles of the stump to actually push hard with the prosthetic device.
Here is a view on the needle penetrating bag and tag holder:
In order to allow for needle maneuvering from outside to the inside, the inside lid bag inset - the gray net that you see - must be kept away from the needle. So, doing that with the hook is extremely fast and effective as the hook's grip and precision as well as its immediate speed make for a fast progress.
Do not get me wrong here. It is nice and sweet to see fluffy ideas of what a prosthetic hand should do in the imagination of some academics. But it is immensely nicer and sweeter to actually have and be able to use a prosthetic that allows me, here and there and now, to really solve hard bi-manual tasks no researcher, in all years of prosthetic hand research, has EVER thought of, but that I anticipated when we were putting together my prosthetic arm. Not even 15 minutes later after I had started was my bag stitched up and fixed and ready to fly.
Remember. Real men stitch stuff up and get it ready in no time.
[Bimanual task benchmark activities]