Project Logs

Collapse

• Overview of Passive VR Shoes

  finallyfunctional • 03/23/2022 at 23:51 • 0 comments

  The passive VR shoes are overshoes that have wheels that are meant to be used in combination with one of my VR support rigs (celling mounted or free standing) to keep the user in place while walking in VR. You can find some videos of me using them here.

  Here are some aspects of the VR shoes.
  

  • Has low friction by using wheels with 3mm bearings. Walking with these is much less tiring than my experience walking on a Virtuix Omni.
  • Has a heel flap that allows the user to lift his heels, so he doesn't need to walk flat footed.
  • Simple design that doesn't use motors to reduce cost and weight.
  • Made out of TPU (flexible filament) and metal rods to be durable. I've jumped on them and thrown them on the ground, used them for several months, and they are completely fine.  
  • Weigh about 800 grams each. I haven't found this to be too much. I can easily walk with them for over an hour and not feel very tired.
  • Stoppers on front and back of the shoe. These stoppers go into the ground when the user lifts his heel or toes, which happens at the end of each stride in a natural walk.
  • Removable stopper that fits on the underside of the shoe, in the middle. This stopper allows the user to walk around outside of the VR support rig with the VR shoes one. The stopper should be removed before using the VR shoes in a game.
  • Adjustable length. The middle part of the shoe can be removed and the metal rods can be replaced with shorter ones. The minimum length is 8in.

  If you're interested in building these shoes, you should first read my log going into why you should or should not build them.

  Improvements

  Future improvements to these VR shoes I may make are as follows.

  • Redesign them so that a regular shoe doesn't need to be worn with the VR shoes. This will reduce the size and weight more, but I don't want to sacrifice comfort.
  • Possibly experiment with splitting the shoe in the middle so more bending of the foot is possible.
  • Replace the TPU wheels with neoprene rollers to reduce noise.
  • Add a wheel encoder and IMU for feet tracking.
  • Introduce motors again.
  • Introduce omni-directional wheels.

• Should You Build These VR Shoes and Support Rig?

  finallyfunctional • 03/22/2022 at 22:19 • 0 comments

  This log will be about if you should build my passive VR shoes and one of my support rigs (either the ceiling mounted one or the free standing one). Over the past several months I have had lots of fun using these passive VR shoes to walk around in VR games. However, I don't think everyone would enjoy it. They are not perfect and not completely natural. They work better in some VR games than others.

  Feet Tracking

  First, I do not have feet trackers made yet. I have just been using the joystick on the regular controller. This has worked fine for me because I do not have to think about using the joystick while I'm playing games. It doesn't bother me, but I'm sure this limitation would bother many others. 

  I plan on making custom trackers for these shoes, but if you want trackers now you will need to use a 3rd party tracking solution. Natural Locomotion or Kat Loco are a few options you have. I tried using Natural Locomotion with Nintendo joycons, but found that the joycons constantly disconnected on me.

  Watch My Demos

  Watch some of my demos here (the demos of the passive VR shoes, not motorized ones) to see what the device looks like when being used. Also listen to the noise the device makes and decide if that noise level is fine for you.

  Try a Slidemill

  Before building my device(s), I encourage you to find somewhere you can try a slidemill (like the Virtuix Omni or Kat Walk C). You can find a list of locations where you can try the Virtuix Omni here.  Please note that I have only tried the Virtuix Omni, not the Kat Walk C or any other slidemill.

  Slidemills have a similar sensation to my passive VR shoes, but these are the key differences I noticed between my device and the Virtuix Omni. So I encourage you to try a slidemill while keeping the following differences in mind.

  Effort to Move

  Walking with my VR shoes was much less tiring than walking on the Virtuix Omni. After 10 minutes of using the Virtuix Omni I was tired and winded because of the extra friction. I normally use my VR shoes for at least 45 minutes, sometimes double that, without feeling very tired. However, if you're not used to walking for long periods of time like that, you may still end up being tired after using my VR shoes, but a lot less tired than if you used the Virtuix Omni. 

  When using the Virtuix Omni, I felt like I had to run most of the time, since I needed more force in my legs to overcome the friction. My VR shoes using wheels with 3mm bearings, so they have very low friction (the friction is so low in fact, one of the purposes of the carpet on the platform is to increase friction a little bit).

  Turning and Walking Simultaneously

  My support rigs allow the user to turn while walking. Being able to do this ended up being one of the most important features for me. For me it's a must have over running, sitting, and crouching. With the Virtuix Omni I had to stop pushing against the waist ring if I wanted to turn. Trying to turn while pushing against the ring resulted in too much friction. The Kat Walk C appears to not have this issue, because I've seen some videos of people walking while turning.

  Crouching, Leaning, Sitting

  My support rigs allow for crouching, leaning, sitting. The Virtuix Omni supports neither. The Kat Walk C has some crouching and leaning support.

  None of these devices (mine included) support laying down.

  Jumping is supported on my device, but keep in mind you'd be jumping on shoes with wheels so it may feel unstable. I never need to jump in VR.

  For sitting, keep in mind that it's possible because the user is strapped into a climbing harness that has straps that go around the waist and legs. Sitting while being held up by the climbing harness is not nearly as comfortable as sitting on a chair, but it's fine for sitting through a loading screen or taking breaks.

  Running

  Running felt more stable and better on the Virtuix Omni, but...

  Read more »

• My Thoughts on my Passive Setup

  finallyfunctional • 11/13/2021 at 19:12 • 0 comments

  I've been using my passive setup for at least 3 months now. My current setup consists of my passive VR shoes and ceiling mounted support rig.

  In this log I'm going to go over my thoughts about this setup. Please keep in mind that these are my personal opinions on how the setup feels. It's going to feel different to everyone. Also keep in mind that I have been using the joystick on the controller to move in-game, I don't have feet tracking set up yet for this setup like I did with my motorized VR shoes. I've been gaming my whole life so using the joystick is 2nd nature and I do not have to think about it. So using the joystick has not been a big deal to me. I plan on adding feet tracking to this setup later.

  It's fun!

  First, I find this setup a lot of fun to use. I've made several demo videos, but I've used this setup a lot more than I show in those videos. I have used it for many hours at this point. I went through the entire Half Life Alyx campaign with it.

  It's not a completely natural walking feeling. These are passive VR shoes, no motors, so you push against the support rig to bring your feet back, similar to a slidemill. That being said, it feels good to use after a little bit of practice. I now have learned how to walk with this setup and it feels good to use.

  I don't notice the harness keeping me in the center. I do not feel constantly restricted. After a few minutes in the device my body tunes it out.

  You can hear how loud this setup is in my demo videos. It's not very loud except while running. Regardless, I always wear headphones when I play VR so I hardly hear the VR shoes. The noise the shoes make is another thing I don't notice after a few minutes.

  Putting the VR shoes on, strapping into the rig, and putting the headset and controllers on takes around 4-5 minutes. If the rig is stored along the ceiling it will take a little longer to set it up. I realize for some people they don't like the idea of it taking several minutes to get setup. I find it completely acceptable, especially since I can then use it for an hour or more once I'm strapped in, without feeling very fatigued while using it.

  In general, I've seen people make the argument that if the VR locomotion system isn't near perfect, your brain will notice the difference and it will not feel natural and be a bad experience as a result. Maybe this is the case for some people but it is certainly not the case for me. With some practice I found it easy to use this setup. Constant sensations are tuned out quickly. The feeling of this device doesn't fall into the uncanny valley, at least for me.

  So I find this device a ton of fun to use. If you're a person who is okay with practicing, learning how to walk with this device, and just in general have an open mind about it, then it may be great for you.

  It takes some practice

  As I said above it take some practice to use this setup. These are the things that I did and had my wife do when she tried it out. I'm going to make a training video going over this in the future. The steps here can probably apply to slidemills as well.

  • Take small steps at first.
  • Learn how the stoppers on the front and back of the shoes work. When you lift your heel or toes, the stoppers will go into the ground, stopping the shoe.
  • Push against the harness to bring your feet back instead of leaning forward. If you find yourself leaning way forward, you will fall over. Push at your hips instead.
  • I found that if I keep my knees very slightly bent that I could take longer steps easily.

  Movement

  Walking forward and turning feel great. Turning while walking took a little bit of practice while playing games but I can do it very easily now.

  Crouching works great without the upper harness. It doesn't work well with the upper harness attached because I can't lean forward, which I go over in this video. I normally don't use the upper harness so this hasn't really been a problem for me.

  I can duck walk pretty easily....

  Read more »

• My Passive VR Shoes and Support Rig Setup

  finallyfunctional • 10/17/2021 at 15:41 • 0 comments

  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...

  Read more »

• Results from Lots of Testing and the Plan Going Forward

  finallyfunctional • 02/15/2021 at 04:36 • 0 comments

  I've tested and used the shoes a lot in the past 2 weeks. I was able to smooth out the motion of the shoes so that it feels really good to walk with them. I describe some of the algorithm changes I made to smooth out the motion here. I was able to walk around in a couple of games. However, there are some issues with the shoes and it looks like I'll need to make a new version. 

  Wear and Tear

  The biggest issue is wear and tear. In the last week I've had to make several repairs, or just take a portion of the shoe apart to re-align a gear. All the gears are showing wear and I've had to replace 1 of them yesterday because a tooth chipped. I broke part of the platform a couple days ago because I pushed on the metal rods too hard. One of the buttons on the platform also broke today and had to be replaced.

  I want a new more durable design with less parts to resolve some of these issues and to replace the buttons on the platform with capacitive sensors.

  Turning

  As you may have noticed in the video, I struggled a bit with turning. I believe adding an IMU will help resolve some of the issues and will later write a project log that goes into the algorithm changes I'm going to make once I add an IMU. But there are other issues with turning an IMU will not solve.

  I'm going to use X, Y, and Z axes to describe the issues and a few more later in the article. The X axis is forward, Y is sideways, and Z is up. 

  When I turn my foot about the Z axis quickly, I have a tendency to also tilt my foot about the X axis a bit. This causes the whole shoe to tilt about the X axis and cases the electronic box on the side to hit the ground.

  When turning, the point I need to turn around is behind me. Notice how the tethers connecting my safety harness to the ceiling hook go up behind my head. If I back up too much, the tethers hit me in the back of the head. So I need to stand ahead of the tethers and of the ceiling hook. The ceiling hook is my pivot point when turning, so I have to turn around a point that is behind me, making turning more difficult. Naturally, the ideal scenario is to have the pivot point directly above my head.

  Lastly, when I turn my foot, the wheels skid on the ground. The shoe is only capable of going forward and backward, so during turning the wheels are not helping and create resistance. I knew this would be an issue when I designed this version, and it's not that big of a deal for the walking I do in my videos. However, if I want to turn rapidly, like do 180 degree turns rapidly (imagine playing a fast paced shooter), the resistance becomes an issue. I bet that it will also be more of an issue if I use the shoes on carpet or a neoprene mat.

  Speed

  I attempted to increase the speed of the shoes past the walking I was doing in the video. Like when turning my foot rapidly, I seem to have a tendency to tilt my foot about the X axis the faster I try to walk with the VR shoes, causing the shoes to tilting and, again, the electronic box hits the ground.

  Solutions to Wear and Tear

  The biggest problem is wear and tear. I can't have the shoes breaking down after only a few weeks of use, especially if I ever want to sell them or recommend others build the VR shoes. I have several ideas for reducing wear and tear.

  First, I need eliminate the gears as much as possible. I currently have 12 or 13 gears per shoe. A gear train runs along the whole shoe. I need to replace these with a power transfer mechanism that reduces the part count and/or uses stronger materials. I could use a belt with pulleys or chain with sprockets. Both will require a tensioning mechanism. I could also try a coupling rod, like what trains use.

  I will update as many parts as I can to use flexible material, like TPU, instead of rigid material, like PETG. PETG can easily break if pulled too hard. A part made of TPU will just bend under strain, not snap. If I drop a PETG piece on the cement...

  Read more »

• Short Update on Smoothing Motion

  finallyfunctional • 02/11/2021 at 02:17 • 0 comments

  I'm working on smoothing the motion. See my previous project log if you want to know the details. 

  Walking is now pretty smooth and feels pretty good. Turning needs some work and I have some ideas to make it better, and I still need to add an IMU to each shoe.

• Smoother Motion

  finallyfunctional • 02/01/2021 at 00:21 • 0 comments

  This log will go over the ideas I am going to implement to make the motion for my VR shoes as smooth as possible. If you haven't already seen it, check out my walk in No Man's Sky with my VR shoes. The motion I have now is already pretty good, but as you'll read, it can get even better.

  
  

  Note that I will not be going over the return to center algorithm in this article. If you're wonder how the shoes know when to move, you can read about the algorithm here. Essentially, the shoe going forward tells the other shoe to go backwards at the same speed. This article will be going over the additional actions I'll take to smooth the motion. In an ideal world the return to center algorithm on its own would be perfect, but latency for communication between the shoes and start-up time for the motors means that additional actions need to be taken.

  The first action I have already taken is to update that algorithm so that a single stride can only have one speed. Previously, as I would bring my foot forward, the speed at which I did so would vary a bit. This caused the other shoe to try to move backwards and vary it's speed similarly. The variable speed made the motion feel choppy and hard to balance. So, I updated the code so that once the shoe starts moving backwards, it stays at one speed to create a smooth motion. Drift can be compensated by the next stride. In the future I may update the code so that a single stride as one speed or can only accelerate or deaccelerate from there, but I'm not going to do that for now.

  That is the action I have already taken. The rest of the things are actions I plan on implementing.

  Part of the motion algorithm can be described using a state machine diagram.

  The shoes can be in the following states.

  * Stopped - The shoes are not moving.
  * First Step - The user has started to move. The first step is being taken.
  * Walking - The user is beyond the first step and is walking.

  I will have different code for going from stopped to the first step, and from going to the first step to walking. Stopped to the first step will prioritize a smooth, slower startup. The shoes will more gradually gain speed in the first step to make going from stopped to walking feel smoother. Starting up the motors too fast when starting from 0 RPM will feel like a jolt of speed and may through the user's balance off.

  Going from the first step to walking will prioritize maintaining speed and eliminating drift. During walking, the shoes will start up faster. Since the user is already moving the jolts of speed that the motors provide will be less jarring.

  In addition to the state machine I've already shown, the shoes will be in different additional states depending on where they are in the stride. This state machine will apply when the shoes are in the walking state.

  The shoe will be in the following states.

  * Front of stride - The shoe is in front of the user and the user has just put is foot down.
  * Middle of stride - The shoe has been moved (by the motors) to the middle of the stride. The shoe is directly under the user or close to it.
  * Back of stride - The shoe is behind the user and the user is lifting his foot again to start another stride.

  These additional states will be used to increase the responsiveness of the shoes. As the user walks, the user is constantly alternating his legs back and forth. When the legs change direction there is a moment when the speed of the shoe will decelerate, be zero, then accelerate again. During this moment, according to my return to center algorithm, the shoe in front of the user is waiting until the other foot lifts up off the platform and starts to move forward. Once the other shoe has done that, it sends a message to the front shoe that it's good to start actuating the motor and moving backwards. All of this creates a delay.

  How can we get rid of the delay, or minimize it as much as possible? One option is for the front shoe to not wait for a signal from the back shoe. The front shoe will...

  Read more »

• The Return to Center Algorithm

  finallyfunctional • 01/31/2021 at 23:52 • 0 comments

  In this log I'll explain the algorithm I use to the control my VR shoes. Please refer to the following image.

  When the rectangle is solid, that means that the user’s foot is on the motorized shoe. When a rectangle is dotted, that signifies that the user’s foot is in the air and the user is bringing the shoe forward (or to the side) along with their foot.

  Step 1 is the starting position of the user, where they are standing still, shoulder-width apart. In step 2, the user starts taking a step forward. The right foot is in the air, and the motorized shoe is being brought forward along with the user’s foot. The sensor in the right shoe will detect an acceleration in the positive Y direction. The acceleration in the positive Y direction in the right shoe will trigger the left shoe’s main motor to turn on. The left shoe will be start moving backwards at the same speed the right shoe is moving forwards. The speed to use can be calculated by using the accelerometer data (integrating to get the velocity) or by using motor encoders. So put in other words, When the user takes a step forward with his right foot, the left foot is moved at the same speed in the opposite direction.

  In step 3, the user has put their right foot down on the motorized shoe again. In step 4, the user lifts their left foot and begins moving it forward. Just like in step 2, when motion is detected in the left foot, the right foot’s shoe will start bring the right foot back at equal speed in the opposite direction.

  In step 5, the user has brought their left foot down. Now the user decides to take one last shorter step, and then to stop. The shorter step is shown in step 6. In step 7, when the user brings their right foot down, she does not start to move their left foot. Since she doesn’t move their left foot, no motion in the left foot is detected, so the motors in the right foot’s shoe do not start up.

  Let’s now imagine that in step 5, instead of the user taking another step forward, she decides to take a step to the side, as shown in below.

  Shown in step 6, the user will lift their right foot and start moving it in the positive X direction. In step 7, the user has put their right foot down. In step 8, she continues their strafing to the right. She brings their left foot up and starts moving it I the positive X direction. Since motion in the left shoe is detected, the right shoe will start moving sideways in the opposite direction. In step 9, the user brings their left foot down.

  An additional thing to consider with strafing and that I think I’ll need to incorporate into the algorithm is that, with strafing, the user’s feet should not crisscross. If the user lifts his right foot and moves it X distance to the right, the right foot’s shoe should not move back a distance greater than X.

  Braking must also be considered in this algorithm. When the user is standing still, the motors should lock the wheels in place so that the user feels like he has stable footing. When the user is walking, for example, straight forward, the motor in charge of moving side to side will hold its position so that the shoe does not move to either side when it’s supposed to only move straight backwards. To detect the user lifting his feet, buttons will be on the top of the platform. When the buttons are compressed, the user’s foot is on the platform.

  The algorithm, step by step, is as follows.

  1. When the user is standing still with both feet on the platforms, the motors should resist any motion.
  2. When the user lifts one of his feet to start walking, his foot will come off the platform. That will be detected by the buttons on the platform. This will cause that shoe’s motors to stop holding their position.
  3. A 2D vector will be constructed that indicates the direction and speed the user is moving his foot and the shoe in.
  4. The other shoe, where motion is not detected and the user has not lifted his foot, will have its motors activated so that the motorized shoe starts to move. It will move at the...

  Read more »

• Introduction - The Problem and my Solution

  finallyfunctional • 01/31/2021 at 22:57 • 0 comments

  A problem with current virtual reality set ups is that you have to stand in one spot. If you walk forward, you will run into whatever is in front of you (a wall or physical object). To make the virtual reality experience more immersive, it would be ideal to be able to walk infinitely in the virtual world, in any direction, but stay in the same spot in the real world.

  Solutions for this problem already exist; they are called omni-treadmills. Below are examples of omni-treadmills.

  • http://www.virtuix.com/
  • http://katvr.com/
  • https://www.infinadeck.com/

  You can see that the first two consist of a platform that is slippery so that the user can slide her feet. The Infinadeck relies on conveyors. All of the treadmills are bulky and heavy. I also wonder how natural it feels to walk on a slippery surface and slide your feet back.

  My Solution

  At a high level, my idea is a motorized shoe that allows a person to walk while staying in the same physical location. Using this device and other VR equipment, a user can walk infinitely in a video game while staying in the same physical location in the real world.

  Omni-treadmills are large and heavy contraptions, making them hard to move and store. My motorized shoes are lightweight and can easily be stored in a closet. My design will also have of a safety harness connected to a support structure or a hook in the ceiling to make sure the user does not fall over.

  My Design

  I have gone through many designs at this point. My current design is explained in this video.

  My current design can go forward and backward, but doesn't have sideways motion. It utilizes one motor, speed control, and an ESP32 as the microcontroller. It communicates over bluetooth.
  

  The most notable difference with my VR shoes when comparing them with others is the flexible binding. A common issue with VR shoes is weight. All the components to make a motorized shoe, especially one that can go fast and can handle heavier people, adds weight to the shoe and makes it heavy to lift and use. My design gets around that problem by making it so the user never actually lifts the shoe off of the ground. Instead, the user's foot is strapped to the flexible binding and the binding can move up and down the 2 guide rods, but is still coupled to the shoe. The user can still lift his foot like he normally would when walking and the shoe gets moved by the user. The shoe is on wheels, so the resistance is negligible. Having to lift a 10 pound shoe would feel very heavy. Rolling a 10 pound shoe on wheels is easy.

  Safety Rig

  In addition to the shoes, a safety rig is required. The rig is there in case the user falls. Even if I could make the shoes so perfect so that the user doesn't fall 99% of the time, there is still the 1% chance that they will. Edge cases like that include if the shoes break, run out of power, or the user falls over for some reason unrelated to the VR shoes (don't drink and use VR shoes without a harness). Given that a user will likely use the shoes for many hours, hopefully over many years, the 1% event will happen. Think of it like a seat belt. I personally have technically never needed one, but it's still smart to wear one.

  My current safety rig consists of a hook in the ceiling, a safety harness, and a tether connecting the two. This was the simplest setup to get going, as all I had to do was buy off the shelf parts. It's also very easy to store when I'm not using the VR shoes. Right now I'm also using a couple of bungee cords to help me balance while using the shoes. I'm hoping I can eventually get rid of them. Additionally I have two additional hooks within reach that I hang the headset and controllers on.

  My current setup makes it so that it only takes a few minutes (or less) to strap in and start playing.

  1. Put the harness on. You can do this where ever.
  2. Strap the shoes on.
  3. Hook the tether to the ceiling hook.
  4. Grab the controllers and headset.

  Of course, there are many safety rigs that...

  Read more »

View all 9 project logs