V2P prehensor - first look
This is a first comment on features of the new V2P Prehensor designed and built by Bradley Veatch (Physionetics / ADA Technologies). One of the best features is that right out of the box this prehensor looks great - I got compliments for wearing high tech that was consistently valued higher than a human hand shape. And that right out of the box this allows tweaks and improvements such as my winter tyres that I put on.
Previous works to study:
- Hooks are without question important, and Dr Harold Sears' doctoral thesis highlights the use of a hook design with wider claw surfaces. So far, I have not seen this idea put into practice. Until now. The V2P has wide claw surfaces.
- The Trautman hook precedes some of the design elements found here such as a non-curved hook grab part and wide round claws - but the V2P is just so much more beautifully and powerfully done.
General grasping ability
This V2P Prehensor is way past the usual prosthetic bionic review that we tend to get such as "OMG I can hold A BOTTLE" or "OMG I can hold a book". Holding a bottle is nice but if your prosthetic device cannot hold a bottle, for one it may not matter as I get by fine without holding on to most bottles (I place them somewhere on a table or in the car), but secondly, grabbing a bottle - for a prosthetic hook or hand - may just not be so terribly hard. Holding books mostly also does not seem to be a terribly difficult task for most terminal devices. So you are of course free to see whether you can in fact hold a bottle or a book but by and large that may not be so much of a controversial issue.
Particularly when I clean my glasses, I cannot see so well. Obviously. But the prosthetic industry so far failed to implement that into some sensible feature of a prosthetic device. I'd be a real good candidate for a Krukenberg cineplasty just for that reason alone - but for now we will keep trying prosthetics. Now the V2P does this right: when I hold glasses the grip needs to be both soft and gentle and firm. When I polish the lenses the glasses wiggle - and so the prosthetic grip must be metrically forgiving. The V2P elegantly solves this.
I usually type using a steel hook or by grabbing a pen(cil) with a prosthetic hand. With the V2P. using a pen(cil) has just become a lot easier as the grip firmness - high rubber tension and high rubber pad friction - is a lot better than with previous parts. Even better is typing with the hook itself even though that tends to use up my nitrile glove finger tips.
Grip for objects
The V2P has an interesting substructure of the claw inside surfaces beneath the rubber pads. The grip firmness for objects of all varieties is surprisingly good. It is even surprisingly good to pick up stuff from the ground. Or to grab small or thin stuff.
Grip for thin plastic bags
Besides the Becker hand that has a good option to squeeze plastic bags, this is the best grip on garbage bags, shopping bags or thin plastic folders I ever saw happen.
Carrying objects with handles
This is the first terminal device that does not yield when I pull a heavy shopping basket around. The claws stay put, they do not open.
Push functionality for doors
Opening doors has become a lot easier with the rubber covers of the hook claws. There is a low-slip / low-damage contact and the hook feels stable.
Push for lids
Opening and holding lids such as the one of our garbage wagon is very well performed with the V2P. It is not as easy to achieve that with the other terminal devices.
I can hold and operate tweezers!
Cable strength options
The range (very soft to very strong) is extremely well implemented, particularly as the nonlinearity of the force distance relationship increases with increasing force. At the end of the day, many small manipulations are done saving a lot of energy and on the other end, I can benefit of a very strong grip as well. This is a real killer argument for this terminal device.
The rubber padded claws are so wide and yet the grip force can be adjusted in so many small steps that I find the driving comfort of the V2P almost unsurpassed.