On Actuation and other solutions

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Currently, I think the most frustrating part of this adventure is trying to source the components that I need, only to discover they are in Sweden, or elsewhere in the EU, and they either don't ship to North America or the shipping is horrendous.

Regardless of these setbacks, I think I have settled on an Electric-Hydraulic Actuation solution. It is a beautiful balance of high power and step-motor control... now all I have to do is source them here in North America... getting closer every day.

I have also settled on a I have made some interesting discoveries Exoframe-wise as well:

1. There needs to be a compensation mechanism in place to accommodate the shoulder axis upward shift when the arms are raised to the sky - solved


2. I need to reduce the weight on the distal segments of the extremities to minimize energy cost: I recently came to the conclusion that the knee does not actually have to be actuated! I can get away with a Knee Acceleration Damper called a Dashpot which I can set to have a free swing forward for energy conservation, but proportionally to load, slow the flexion on the way down in order to keep the knees from buckling. Also the ankle assembly is going to be passive and incorporate a sort of mini-McPherson strut system to store and release energy. I will also rig the Exo spine to have the ability to slightly rotate to facilitate the Contra-Postal swing of the shoulders/arms while walking (Which again conserves energy). The arms will only be actuated for shoulder raise and arm curl/press contractions. The forearm will incorporate a rigid rotational coupling for forearm suppination. This will have some mechanical resistance inherent as opposed to a freely rotating assembly.
   

More later...

Creating a HUD

I need some method of projecting an image to the inside surface of - say - a visor. I've been looking at several options including microprojectors, but they just don't seem to fit the way I'd want. If this is going to mount inside a helmet, then I can't deal with any bulk. It has to be able to mount either on the forehead or between the eyes above the eyeline and project (with about an 80 degree FOV) on to the visor, while remaining completely unobtrusive to the human vision.

On top of that, I need to control the focus of the image such that the eye can "see" it from about 4-5 cm away. If you stick your hand in front of your face, you can't focus on it. I'm seeing a lot about focusing on infinity in other forums and such, but I haven't been able to try it yet.

Liquid Crystal on Silicon is another option as well. I need to determine what level of projection these provide, as well as a resolution. This will need to be a fairly wide image, but vertically narrow.

Mission Commences

This project is the result of what happens when you get an Armoursmith working near a Computer Scientist. Between the two of us, the plan is to implement a fully-functioning exoskeleton, capable of lifting extremely heavy objects and other exhausting activities with the human wearing it to exert as little effort as possible. On top of this, we want to design a computer-based system to operate alongside the exo, one that can read data from sensors to determine variables about the environment, for example, or sense the amounts of forces applied to certain parts of the skeleton, and provide all this information on a heads-up display.