Once a human enters the microgravity (weightless) environment, it begins to lose muscle and bone mass. The losses worsen with longer exposure to the environment with little to no exercise. This is mitigated now by various exercise routines on the ISS, but these activities are limited and frankly, dull. The drudgery of these workouts is not limited to space and should be combated here on earth.
To do this, I'm designing an exoskeleton that will interact with a VR environment that can be anything it needs to be. Lift weights on the surface of Mars? Use those pecs to pull a bow? Try your hand at Ninja Warrior? All of these things to provide the positive benefits of exercise with the limitless nature of VR.
I'm using Unity to build up the virtual environment and the HTC Vive to represent the environment itself. I'm also using Blender to create the 3D files and texture mapping. Overall, it's more involved than I had originally thought it would be. Luckily, I'm stubborn and have somehow made it work.
It may not look like much, but it's a working environment. It's still a work-in-progress, but I wanted to show it off. The barbell in the upper left on the rack is interactable with the handheld controllers of the Vive. Each barbell that will be used is coded with the variable representing its weight. This will allow the PC to do the required math for the torque values and send the associated brake positions.
In future iterations, I would like to have background individuals walking around, but at this point in time, that is not happening. For now, I'll finish populating the dumbbells in the gym and optimize for rapid calculations.
With everything finally designed (at this point) I thought it a good idea to make it available for others. Finding an open source exoskeleton is near impossible, let alone one that has a solution for scapular movement. So look for the link below. (119 MB zip file on GoogleDrive)
The hardware used for the joints are 1/4" nuts with associated bolts. The cables to be used are 0.3mm in diameter and will fit a standard brake sheath from a bowden cable. I also used ball bearings found here.
Today was planned to test the PETG components with the new collar to verify strength. That did not happen. What did happen was a frustrating series of failed prints even though no configurations had changed between the two print times. After struggling with it for a couple hours, I decided to return to PLA prints. While not ideal in strength, it does actually print.
Once this component has finished printing (80% infill this time) I will run tests to verify strength and find its limit. Once I find that, I can determine the prototype's limits for experimentation.
Today I'm trying to focus on t,he strength of the elbow. I printed the original elbow in PLA and then used it to test the strength of my braking setup. Things were going well until *snap*, the joint mount delaminated and I was left with a useless plastic. Since then I've been spinning wheels trying to enhance the part.
All this to say I'm now looking at testing PETG as the elbow. The first test didn't survive first contact with the aluminum bar I'm using as an arm bar.
The reinforced one I printed also delaminated in the same manner. In frustration I took a break.
I've since developed a collar that will be printed separately and goes around the top of the mount. It is printed perpendicular to the rest of joint and will also have a mount for the velcro straps to hold the arm in place. Now to bake the PETG to work out any water and get to printing.