Over the past 8 months I've been making prototypes of many different VR locomotion devices. I've been trying out many different concepts, but now I'm starting to focus on one setup again.
I'll be expanding upon the leg exoskeleton concept I tried. It will be attached to either a VR shoe with wheels or a floor slider. I will attach the leg exoskeletons to my ceiling mounted support rig first, but then I want to try to make a new free standing support rig.
I'll be making the next leg exoskeleton out of EMT conduit like I did with the last prototype. The joints will be 3D printed and designed to be springy. I first wrote about the idea here, with this quick summary -
When the joints flex, they will store some energy and want to return to their original form, like a spring.
The basic idea is that as the user brings their foot forward, there will be some resistance because the joints will flex, then as they bring their foot back, the joints will help them. The joints store some energy when they bring their foot forward, then release it when they bring their foot back.
- With the mechanism always wanting to bring the foot back to the starting position, it will be harder for slipping to occur.
- The shoe could be taller if needed since the mechanism should make it harder to tip the shoes.
- The weight of the shoe can be negated.
- The mechanism can help the user lift their foot. To lower their foot, they just let the weight of their own legs overcome the force from the joints.
- Springy joints can help reduce impact on knees.
- A taller and/or heavier shoe or floor slider is easier to add more features to, such as something simple like cushioning to reduce impact on ankles or something complicated like simulating stairs.
- Less effort
- Since energy can be stored in the springy joints, once the user gets going, it should be easier to keep going.
- Can be paired with an omnidirectional VR shoe or a floor slider to provide omnidirectional movement.
- Can support sitting in the same way wearable chairs can.
- User can be strapped to the leg mechanism, so a climbing harness, waist harness, or vest is not needed.
- Nothing needs to be strapped to the user's back, reducing the possibility of back pain.
- Less constrained movement.
- Great tracking.
- Potentiometers or encoders can be placed in each joint to track leg and foot movement precisely.
- Turning will still need to be tracked via an IMU or encoder on the support rig.
- Conduit can be telescoping rods making it adjustable to different heights.
- Simple, durable design made of cheap materials (conduit, 3D printer plastic mostly).
- Coupled to a support rig, this still provides safety and keeps user constrained to a small space (around 42in in diameter in my case).
- No electronics except trackers.
- Design is can be adapted to be motorized later if I want.
- Compared to motorized VR shoes by themselves -
- More hardware.
- More storage space.
- More constrained.
- Less convenient to strap into.
- A passive system with springs will probably still not feel as natural as a motorized system.
VR Shoe or Floor Slider
I've been looking into making small omnidirectional wheels, such as the omni-sphere, to use in a VR shoe, as well as looking into if a floor slider could work.
Making small omnidirectional wheels (2in or less in diameter) that are not bumpy, can handle the load, and are not noisy has been a challenge I will write about later. I still have more ideas, including possibly using large omnidirectional wheels in a design similar to these motorized shoes.
Regarding floor sliders, I've made some progress. The issue I've ran into in the past is the friction is too high and they are noisy. Even if I could lower the friction, they are also unstable. However, the leg exoskeleton providing stability means lower friction shouldn't be a problem. With that in mind I've tried various combinations of floor types such as acrylic, wood, HDPE, UHMW, and metal, with various lubricants such as silicon spray, grease, furniture polish, personal lube, vegetable oil, soap, with several different shoes. I may go into more detail later, but I was able to make a very slippery surface that was also quiet by walking on acrylic covered with regular dish soap (no water, just soap). I am now printing different shoe sole designs out of TPU to see which work the best and will also be trying out silicon mats to see how well they slide.
A New Free Standing Rig
My last free standing rig suffered from one problem, which was it was harder to turn than when using my ceiling mounted rig. This was because when I turned there was a lot of mass I had to move, such as the ring that went around the platform and the rig extending up from the ring.
I am going to try to reduce the weight of the support rig to make it easier to turn. I have a few ideas on how to do this I can write about later.