Servomotor actuated worm gear prosthetic knee
I'm an amputee, and not exactly an master engineer, not by a long shot, (I can't even remember how I passed physics back in college) but I'd like to try and take a stab at building my own prosthetic leg. I'm a welder, so fabricating a frame wouldn't be a problem at all.
My problem is a bit of a catch 22, I don't know what servo motor to use, as I don't know what sort of torque is required, and I don't know what torque is required because A. I don't know what worm gear I'm using, and B. I'm not exactly sure what forces are involved.
As it stands, my current prosthetic is essentially a swinging hinge. I can't modify this one, or I'd be voiding the warranty.
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Those are some of the dimensions of my current one
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Thats a 3d model of what I've decided would work best. I've considered nitinol wire working against a spring, but it was too complicated, and SMAs aren't advanced enough or cost effective for this sort of application.
The worm gear would produce the sort of braking I need without consuming any current for holding my weight up at a half-bent position.
As far as controlling this thing, I figure I'll build a battery bank (yes, i know this is going to be heavy) and hook up a rocker switch for forward/backward. At some point, I'd like to try and hook up a more elaborate swith, more of a joystick type deal so I could vary the speed forward/backward for smoother operation.
Anyone got any tips? What servo should I use, and from where? What about the worm gears?
I'm an amputee, and not exactly an master engineer, not by a long shot, (I can't even remember how I passed physics back in college) but I'd like to try and take a stab at building my own prosthetic leg. I'm a welder, so fabricating a frame wouldn't be a problem at all.
My problem is a bit of a catch 22, I don't know what servo motor to use, as I don't know what sort of torque is required, and I don't know what torque is required because A. I don't know what worm gear I'm using, and B. I'm not exactly sure what forces are involved.
As it stands, my current prosthetic is essentially a swinging hinge. I can't modify this one, or I'd be voiding the warranty.
**broken link removed**
Those are some of the dimensions of my current one
**broken link removed**
**broken link removed**
Thats a 3d model of what I've decided would work best. I've considered nitinol wire working against a spring, but it was too complicated, and SMAs aren't advanced enough or cost effective for this sort of application.
The worm gear would produce the sort of braking I need without consuming any current for holding my weight up at a half-bent position.
As far as controlling this thing, I figure I'll build a battery bank (yes, i know this is going to be heavy) and hook up a rocker switch for forward/backward. At some point, I'd like to try and hook up a more elaborate swith, more of a joystick type deal so I could vary the speed forward/backward for smoother operation.
Anyone got any tips? What servo should I use, and from where? What about the worm gears?