Spiderclaw Mechanics
William Croft wrote to me:
"With the headset, am I correct in assuming that all the tensioning is sourced in the back at the octagon? (Via your rubber band loaded arms.)
Wouldn't it be possible to have more tensioning applied from the front of the headset, for example pulling all the arms inwards towards the forehead? That way you have kind of a "hat band" effect gripping the circumference of the head. Then also pulling the arms down to the head, from both the front of the headset and the back.
Or maybe I'm just missing how the headset holds itself down, not seeing any photo of it on your head."
"With the headset, am I correct in assuming that all the tensioning is sourced in the back at the octagon? (Via your rubber band loaded arms.)
Wouldn't it be possible to have more tensioning applied from the front of the headset, for example pulling all the arms inwards towards the forehead? That way you have kind of a "hat band" effect gripping the circumference of the head. Then also pulling the arms down to the head, from both the front of the headset and the back.
Or maybe I'm just missing how the headset holds itself down, not seeing any photo of it on your head."
Comments
"You are correct. There is no tensile force pulling the arms together at the front of the head. It's not a bad idea. I'd like to start a new forum thread regarding the new designs of the Spiderclaw. There are a lot of mechanical improvements that can be made to the current design. The challenge of designing a 3D-printable system that applies a uniform and comfortable pressure along the entire scalp is a tough one.
One idea I've considered is mimicking the mechanical system of the human hand. The hand has ligaments (or tendons?) that run from close to the elbow to the tips of the fingers. Because it is a single chord that creates a tensile force through each joint, the skeletal system deforms to the shape of whatever is grasped by the hand. I think a similar mechanical system would work well for the spiderclaw, with the source of tension originating at the "body". That combined with something providing extra stability at the front of the head might be the trick.
I think Not Impossible Labs used a similar system for <a href="http://www.notimpossiblelabs.com/#!project-daniel/c1imu"; target="_blank">Project Daniel</a> where they 3D-printed prosthetic limbs for amputees in south Sudan."
Let's start the conversation here about improving the mechanical design of the Spiderclaw in future iterations.
The front tensioner could be something as simple as a loose elastic band that threads thru a hole at the front of each arm. Then using a gripper-closure like you see on small camping "stuff bags" (spring-loaded plastic cord closure <a href="https://www.google.com/search?q=+spring-loaded+plastic+cord+closure">link</a>; ) could allow the front band to be easily tightened or loosened. You might have it loose for putting the claw on, then tighten it until comfortable once in place.
I view the rubber bands on each arm as "holding the bowl shape" so the claw does not simply collapse when no one is wearing it. Thus making it easier to put on, take off, since everything stays oriented in a spherical shape. This also lets you see / adjust the regularity of the 10-20 spacing when the claw is off the head.
William, can you share the DIY velcro band sensor system that you sent over email a while ago? I think aspects of it could be incorporated into a future iteration the Spiderclaw that has a combination of both rigid and elastic components.
OK, well this is all speculation, but it seems like ease of taking the headset off and on, would argue for the spiderclaw "holding a hemi-spherical-like head shape" on it's own.