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Human finger model movements DC activated. Answered

Hello good folk I have been working on some artificial finger extensions and retraction via a DC motor. An H-bridge is used which is connected to a dial switch. The tendons are braided fishing line. It has proven worthy during the prototype stage. The advantage of my design is that a single DC motor of servo can control movement and grasping of the entire finger. This design particularly excels when compared to the most advanced models at the moment.... The Shadow hand would be an example. Extremley capable yet the muscle collection to the rear of the hand makes their model obsoliete even before it was created. Much work needs to be done on their model to make it effective. I apologise for the pics (camera phone) as the detail leaves much to be desired. This is just a functional model of the unit, so it's not ment to look pretty. It only purpose is to serve as the concept base as I was trying to get the tendons/joint configuration worked out... You should notice the holes in each section, the tendon passes within the finger segments within a sheath embedded inside the epoxy segment. The tendon is only exposed at the joints which also need to be finished with a exterior protectant layer. I am posting these as an example of the funtioning finger. However I would like to post videos at a later date.


DC motor and dual tendon bar.


I lost my left index finger three days ago, I found this site through the google search engine. I would like to ask the person above if they ever thought about going to a tools rental store?

What size is the finger, complete with motor, I've been looking at some sophisticated prosthetic fingers, I lost my left index finger three days ago, and I'm getting a be nice warning...but they are very expensive. I look forward to any information regarding this problem.

Finger extension.


Woah... I'm looking at picture 3, I can't do that with my fingers! Adding three more fingers is probably a lot of work and expense for not much gain and it's been shown to be possible many times. I'd suggest, if you already have a thumb, try to connect the two so you can perform "precision", "key" and "power" grips, then you can think about the rest of the fingers. (Key grip is how you would hold a latch key against the side of your index finger, precision grip is how you would hold a very small object between index finger and thumb tips, power grip is like a baseball bat hold or a fist)

It is capable of precision and power grip, key grip would requires at least one universal joint on the thumb and a second servo to operate the "twist" of the thumb. Bu it could be done. Just just 6 servos, so I might look into it.

i've made something like this it's made of that K'nex chain drive thing

You know those roller coaster K'nex sets? they have special pieces for the chain i got the set for free, 1/4th of the pieces are missing, but hey, it's free

Very nice. I will have to look into it... I don't have access to any machinery except my drill etc. So prefab pieces would be great for proto-typing.

lol, me too the only power took i have is a drill my dad isn't into buying stuff, so i bought like half the tools that my family has you can also use bike chain, but you'll have to cut it, ther is an instructable using motor cycle chain, but i can't find it at the moment

The fluid movements allow a much smaller powering device than what is pictured. That large DC , motor only needs to run at 1.5V to actuate the mechanism. At 12v its capable of giving you a nasty little blood blister if the finger retracts and grabs you in the wrong place.

Thankyou! The movements are suprising fluid... I was inspired by the corrugated black tubing animation hand featured on "Ibles a while ago. If only I had a few thousand to blow on servo's and CnC machined parts. I beileve I good design and build a functional prosthesis far surpassing the current models. I have the thumb built also. I'll attach it and post.

So would I!! webcam is on the blink and i'm having issues converting my files from the phone camera... They end up being like 30mb for 10sec at lowest convert quality.. But your right video would be good, it's just a stick of epoxy with no video, sorry.

Retracted finger.


H-bridge dial switch.