Hello everyone. I’m really not sure the best place to put this, but I’m very interested in beginning a project to build an exoskeleton arm to give much more strength to fingers, forearm and biceps.
You could call it kind of like an ironman type arm. Either way, I’m curious of a few things, and I figured this would be a good place.
- How do the finger joints work in bionic hands? I know there isn’t as much room in an exo suit, but if I can get an idea of exactly how they work, it would make it easier. I assume they use servos in the forearm. If that’s the case, I have a few ideas.
- I have to find a way for a servo to know when torque is being applied. This way, I can program a sketch so when it doesn’t have torque, it knows to pull. This means when you bend your fingers, it knows to pull. Either this, or I could place triggers under each finger tip.
Anyway, I thought I could find some people interested in discussing this here.
There are not too many bionic hands on the market, and there are various different designs.
Inexpensive ones use servos and cables while others use more advanced mechanics.
As you said, exoskeletons are a bit different since you also need feedback, and need to create the program accordingly to have it respond as you’d like.
People have tried many different approaches and there are various ways to get input from fingers / arms.
We suggest trying one approach at a time on one joint and see which you find to be the best.
It could be as simple as a potentiometer or force / pressure sensors to something as complex as muscle sensor input.
As for the actuators themselves, it all comes down to how much additional force you want, and in what size.
A normal (standard) R/C cannot provide anywhere close to the force of a normal hand / finger unless you choose something which offers very high torque in a compact package.
Linear actuators in certain areas might also be a good start.
Feel free to post your ideas / brainstorming here and the community will hopefully provide input / feedback as well.
Wow. I’m clearly getting out of my league on this one, but luckily I’m stubborn. I’ve mostly just done small robotics in the past.
Either way, thank you for the awesome response. If you know of any projects people have worked on (especially using actuators since that seems to be the way to go), I’d really appreciate a link.
Start small and simple: youtube.com/watch?v=F-5-ymKTiMU
Create a simple mechanical structure which has a potentiometer mounted to the side of one of the joints on one of your fingers and rotates the potentiometer.
The potentiometer is connected to the analog input of a microcontroller, and that in turn positions a servo to the same angle.
Do this with five joints and you can control simple fingers.
Next, create a simple robotic finger using a pulley system (lots of designs online), and have that servo pull the string to flex the finger. You now have a basic hand.
