I haven't posted an update here in a while, but I have still been busy with this project. I've been posting regular updates on YouTube. Here is my latest demo.

I mentioned in my last build log that I wanted to try a passive system with a rigid support rig. This is what I came up with for my first version and I'm very happy with it.

I've gone into more details in my build logs on YouTube, but to summarize the VR shoes I'm wearing in this video are made mostly out of TPU and metal rods, so they are very durable. How durable? I through them on my cement floor here. I've tossed them on the floor, jumped on them, and have been using them regularly for a few months now and they are fine. 

These passive shoes have wheels that spin freely and stoppers on the front and back. If you think about a typical walking motion, when you are walking and you bring your foot back behind you, you lift your heel up, then lift your foot off the ground. The stoppers take advantage of this. When you lift your heel up the stopper gets pushed into the ground, stopping the shoe right where you want it to stop so you can lift it up without slipping. Walking backwards is a similar situation where you instead lift your toes up first, and this drives the back stopper into the ground. With these simple stoppers you're not just walking around on essentially roller skates. If that was the case it would be very easy to slide and slip. Using the shoes still takes some practice but the stoppers make it much easier.

Additionally I am walking on a platform that has some thin carpet stapled to it. It is just a 4ft square piece of wood, 3/4in thick, with thin carpet stapled to it. This carpet has a few functions. It provides a little bit of resistance so the VR shoes don't roll around quite as easily as they would otherwise. A little bit of resistance is good and the thin carpet strikes a good balance between easily rolling the shoes and stability. The other function of the carpet is that it reduces noise from the wheels by quite a bit.

You'll see that I'm also wearing a rigid support rig. It is bolted to two beams in my ceiling and consists mostly of pipes, pipe fittings, square tubes, and a safety harness around my waist. This support rig is what you push against to bring your feet back. It supports crouching and sitting.

For this setup, I don't have foot trackers yet. I tried Natural Locomotion but was having trouble getting the joycons I was using to stay connected to my computer. For now I'm just pushing on the joystick on the controller whenever I walk. I've been gaming my whole life so using the joystick is 2nd nature to me and I do not have to think about it, so this method is completely acceptable to me for now. Later I will try to make my own feet trackers.

I am going to soon make a video about what I think about this setup after using it for a couple of months. But to summarize my thoughts so far - 

• It takes some practice to get used to the device. It's not completely natural walking obviously. But it's still a ton of fun and very immersive. For me it feels close enough to walking and I'm used to it by now. I'm sure this device isn't for everyone. Some people just seem to not like any devices to don't simulate natural walking either perfectly or close. Some people don't like the idea of a little bit of practice being required. Some people think the support rig will feel too restrictive. Some people just like the joystick. But if you're willing to practice for 30 minutes to a few hours with this device and are okay with learning how to walk a bit differently then you may like this device.
• I picked up walking with this device within a few minutes. My wife was able to walk forward with it after 20 minutes of practice. Being able to walk and turn at the same time took me a few days to be able to do and over a week to be able to feel comfortable doing. Walking backwards took a few days to do but is still awkward.
• It's not noisy with headphones and walking. The carpet really helps with noise reduction. I always where headphones while playing VR for better sound quality and while walking I can hear my footsteps but it's a soft muffled sound. If you don't play with headphones it will be louder, but I don't think it's too bad, especially compared to slidemills. The exception is it's very noisy while running because you are slamming the shoes against the platform much harder and much faster.
• I walk 95% of the time and am good with that. I've used a slidemill in the past (a virtuix omni) and found I ran most of the time with it because it had a lot more resistance. I needed the extra force from running to use the slidemill well. Walking was just too hard and the result was I got tired pretty quickly. With my VR shoes I can easily walk and really don't run with them much at all. Running is a bit hard with these VR shoes and I hope to improve that in the future, but even so I just find walking to be much more pleasant and it works fine. I'm able to walk around for an hour with these VR shoes and not feel very tired. I've used them in Half-Life Alyx and No Man's Sky mostly. These games are super heavy on fast paced combat so keep that in mind. I don't really play multiplayer games and could maybe see myself running in those games or just see myself using a speed multiple to transfer walking in real life to running in game. Going forward, making walking feel really good will be my main focus, with some focus on being able to do a "duck walk" where you squat down a bit and move pretty quickly. Think of how soldiers run while pointing their gun forward, or how the characters in Gears of War ran. I think supporting a duck walk will be fine for faster situations in games, it's a more stable way to run, and is less intense on the VR shoes. Full on sprints are not really going to be a priority for me anytime soon.
• The support rig allows me to turn and walk at the same time and turn quickly while feeling stable, which is now very important to me. When I used the virtuix omni I found it very hard to be able to turn and walk. You push the harness you are strapped into, around your waist, against the ring around your waist. The harness and ring is just plastic rubbing against plastic, so there is a lot of friction. This resulted in me having to turn separately from running while using the slidemill which I did not like. I now consider smooth and quick simultaneous turning to be one of my top priorities going forward.
• I have a very easy time going up and down slopes and stairs while using the VR shoes. I've heard some people say that the inability to simulate stairs and slopes will limit certain VR locomotion devices to games that are completely flat. I have to say I completely disagree. It's not a big deal, a minor limitation at best. Simulating slopes and stairs doesn't seem that important to me, and is a low priority going forward, especially if doing so will add significant complexity and cost to the device.

Here are my pros and cons of this setup.

Pros

• With a bit of practice, it's very immerse and fun to use.
• Walking is easy and not tiring. I normally use it for 1 hour at a time and I am not tired at the end of it, but I may be a little sweaty.
• It's good exercise. The day I got it working I used it for 3 times that day, 1 hour each, so I got 3 hours of walking in (plus another hour of walking that day at the dog park).
• The support rig has crouching (you can adjust the distance), sitting, and really helps with feeling stable and balanced. It also supports turning quickly and at the same time as you are walking.
• It's not noisy, especially with headphones.
• Since it uses a wood platform, it can be used in any room regardless of the flooring material.
• It looks like it doesn't take a lot of practice to use it. I got it in a few minutes, my wife in 20 minutes. I need to test it out with more people and put together a guide.

Cons

• Running feels less stable and balanced than running on the virtuix omni. I just prefer walking most of the time, but if someone wants to run most of the time this is an issue.
• The support rig is slightly restrictive. For me I don't notice it while playing games. It's a constant sensation so my body just tunes it out.
• It requires some practice and isn't completely natural. This will not be good enough for some people that want a more perfect solution.
• The support rig requires bolting to the ceiling and a low ceiling.
• It would be nice to not need a platform, but this setup has it.
• Walking backwards is awkward.
• I don't have my own feet tracking solution yet. Natural Locomotion might work fine if the devices stay connected.

So my next steps are to make these videos - 

• Detailed build tutorials for the support rig and VR shoes for anyone that wants to build them.
• A video where I describe my thoughts of this setup after using it for a couple months and what kind of person would like it.
• A comparison between the virtuix omni and this setup and my overall thoughts of the virtuix omni.
• More build logs.
• More gameplay videos.
• A getting started guide that goes into how to practice using the device.

I'm also working on another support rig that doesn't require any bolting to the ceiling or walls. I will eventually try to add motors back into the VR shoes.