Published 5 years ago
How VirZOOM turns exercise into a natural VR experience
In early 2014 we set out to make stationary bikes fun using the awesome power of VR games to provoke emotional and physical reactions and channel that energy into pedaling for exercise. Surprisingly we found that physical effort makes the VR more believable and is a key ingredient in our solution to the VR locomotion problem, along with the intuitiveness of using a bike for control and virtual motion that correlates the balance of your inner ear with the visual stimulus of VR.
It was necessary to solve VR locomotion so regular people could use VirZOOM every day, but we also had to invent games that motivated people to perform interval workouts that don’t grow boring after a week, and wanted to deliver our exercise hardware at a cost that everyone could afford and setup with the VR system of their choice.
The biggest surprise of VirZOOM is that it’s not a simulation of biking, because just doing that would short sell the amazing things you can be in VR. Instead you become a sheriff chasing horse bandits, an F1 race car gunning around the track, and a Pegasus soaring above a beautiful canyon. After that we’ll make games for helicopters, butterflies, tanks, surfboards, jets, submarines, motorcycles, dragons and any other fantasy you can power by pedaling. 

Moving in a Virtual Space

Setting out to make new types of games and hardware for the combination of VR and exercise, we knew our development process had to be agile and checked frequently by external tests. We had the same questions everyone else does about whether VR would be comfortable for exercise and how pedaling and steering a bike would translate into VR. Our first prototype was a step-through bike on a trainer, with an Arduino to feed steering and rear wheel measurements to a Unity simulation of a horse on an island. We hopped on the bike with an Oculus DK1 and proceeded to climb hills, simulate flying, and make turns until we were good and sweaty. We found that the DK isn’t too heavy, isn’t a problem with sweat, and rarely fogs up which is solvable with goggle spray. Thousands of subsequent playtests confirm those findings. Riding and braking in a straight line felt natural, and lifting off and flying was amazing powered by your own effort. But landings felt like a punch in the gut, and turning for more than a few minutes produced nausea because we had done nothing to synchronize your inner ear with the simulation.
Simulation sickness is motion sickness in reverse: your inner ear senses that you aren’t moving in the real world the way your eyes sense you are moving in the virtual world. Through playtests we determined that your inner ear is most sensitive to differences in rotational acceleration and gravitational direction. To understand how we remedy these differences, imagine your virtual body between your virtual avatar and your virtual head. Your virtual head moves the same way as your real head, which in turn follows your virtual body which follows your virtual avatar driven by your actual pedaling and steering through the virtual world.
Our first remedy is to keep your virtual body upright, so the virtual horizon remains level with gravity and you must look up or down along hilly roads. Our second remedy is to only initiate turns of your virtual body at the same time as turning your actual head. This is different than “head steering” because you can look around independently of steering on the exercise bike. Steering without head turning is interpreted as swerving rather than turning, where swerving is a temporary change in direction that only affects the virtual avatar’s rotation while your virtual body remains unchanged. Only when your actual head follows a road around a curve, looking in the direction the avatar is rotated, does your virtual body start turning and stop as you straighten out. Our third remedy is to soften landings from falls or flight by limiting descent speed as a function of your virtual height above the ground, normal to its slope. Our fourth remedy is that virtual collisions should never rotate your virtual body, only your avatar.
Our bike controller is the other half of what makes VirZOOM work. It provides an intuitive and safe way for players to move through virtual worlds, by pedaling to move and leaning to steer with your seat and hands firmly planted.
We learned from our prototype that steering through handlebars without leaning was difficult for many people, and dangerous with a regular bike on a trainer. We also learned that stationary bikes come in all shapes and sizes and we couldn’t fit our sensors to all of them. We settled on a silent, folding bike with adjustable magnetic resistance and seat height, with widened feet to support stable leaning, and our wireless sensors incorporated. The result is easy to assemble, storeable with a 13x24” footprint, and unfolds with a 26”x24” footprint anywhere in sight of your VR tracking system. It turns on with your activity and sleeps automatically with 2AA batteries that last for months.
We designed our sensors to get the most bang-for-the-buck. We wanted the speed of your pedaling, forward and reverse, as responsive as a game controller. We rely on your VR system’s tracking to determine lean and steering from your head position, and being seated means the VR tether never gets in the way. Your heartrate and resistance settings are measured to accurately track and rank your fitness accomplishments. Our initial design had one button on each handlebar grip, but that expanded to  flightstick grips to enable more gameplay actions. We considered a controllable motor for resistance, but it would have made the bike more noisy and expensive, and we discovered our games could trick you into feeling slopes by changing your virtual gearing to go slower or faster.

The Games

Our games complement our motion tech and bike controller to provide interval exercise as a result of reacting to gameplay. VR is a visceral experience, so we thought the games should be intuitive to play but require repetition and learning to master, like an arcade game that gives you fitness rather than taking your quarters.
The first game, called Stampede, pits you against horse thieves that you have to chase and lasso at just the right moments, through waves of difficulty like a spin class that get harder and easier. In this game your virtual body never turns, it only ever swerves, which we found that nearly 100% of testers can enjoy in their first VR outing.
Go Fast Car, our second game, builds on swerving to change lanes and introduces turning around curves, as you sit in the cockpit of an F1 race car to race AI and other online players around multiple courses. VR uniquely improves racing games by allowing you look around, including seeing different angles in mirrors. Pedaling guns or brakes the engine while your head movement provides fast and precise steering. We learned to keep the game HUD attached to your avatar or floating in front of your virtual body, never directly attached to your head.
Our third game is Pegaso, which turns you into a beautiful winged Pegasus with a variety of challenges around a giant canyon. It introduces the mechanics of flying, from anywhere and in any direction, which is incredible for your ability to look down in VR and the feeling of your wings connected to pedaling the bike. Each challenge emphasizes a different combination of the VR skills you’ve learned: there’s a gate race along a mountain road with flying shortcuts, an exploration mode to find gems hidden in the hills, and a continuous flying mode to eat apples out of trees in the valley. Other online players can join you to compete or simply walk and fly beside you, which is a magical social experience in VR.
Tying all these games together is an intuitive VR menu system which supports music streaming, custom and timed workout sequences through the different modes of each game, and visual tracking of the fitness coins you’ve earned with bonuses for playing regularly. We also developed weekly and all-time leaderboards and share telemetry of workout times to help players connect online.

What’s Next

VirZOOM is a completely intuitive experience that nevertheless must be tried to be understood, not only for the VR aspect but also for its unique controls. We’ve travelled non-stop to VR meetups and shows to demonstrate it, and found that families are the most impressed by its effectiveness to keep kids and parents moving and enthralled with VR fantasies. We will keep releasing games and improving our platform for the long haul, and are making it affordable enough for every living room, office, hotel, and gym to keep gamers exercising. 
eric malafeew