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How HTC Vive Controllers Work, Feel, And Fail

June 10, 2016 | vive htc controller touch wrist strap break
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Holoball. Expert Mode. I’m down 4-2 in the third round, one slip up away from defeat. The despicable AI is taunting me from across the court even as I angrily shake my large, glowing paddles, which move perfectly in unison with my hand and arm motions like real rackets, at it. I’m a sweaty mess after an hour and a half of just-one-more-match-and-I’ll-take-this-AI-down. Grim determination is setting in. I’ll win, whatever it takes.

Little do I know, I’m seconds away from disaster.

Touch Changes Everything

You’ve probably heard about or even experienced roomscale VR by now, where you can walk around the room with a headset on and look at the VR world from wherever you walk to. This is a really cool bit of technology, but it would be mostly novelty if you couldn’t interact with the world as you moved around it.

This is where the Vive’s approach departed from and scored a definitive, widely acknowledged win over the Rift. It wasn’t the roomscale headset tracking, it was the combination of roomscale headset tracking with the ability to naturally interact with what was in the room using the Vive controllers as you moved around.

What They Are

The Vive controllers are just two separate plastic sticks with some buttons and an open loop on the top of each one. You hold them in your hands similar to the way you would hold a small water bottle with the large open loop pointed up and the top of the loop roughly parallel with the floor when in a neutral position. Let’s get into some pictures.

The facing side.

The side of the controller that faces you. The top of the controller is the open loop. The buttons from the top to the bottom are the menu button, the thumb pad, and the system button.

The other side.

The side of the controller that faces away from you. Again, the bottom is the part away from the large open loop. The trigger near the top is the index finger trigger button and the two buttons further down are the grip buttons that actually act as one single button you can squeeze with your palm.

Let’s talk about what the various parts of the controller do. First, the open loop at top has no purpose other than to create additional surface area for all the sensors. We’ll talk later about how the sensors work.

The sensor loop.

The most important button on the controller is the trigger button. When you have the controller gripped like a small bottle of water, your index finger will naturally curve around the trigger. The trigger is the button you use to indicate that you are grasping an item or pulling a trigger in game.

The trigger button is an analog button. This means it can tell the game or app how far it is depressed from zero to all the way. This data can be used in any number of ways such as for throttling or even controlling the width of paint strokes in a creative app like Tilt Brush.

The next most important button is the system button. It brings up the Steam system menu, even in game, which you can use to change to a different game, change settings like volume, and browse Steam. It is also the button you use to turn the controller on or off. A small LED below it shows green when the controllers are turned on and can also show other colors, such as when charging (orange) or fully charged (white).

Then we move to the thumb pad, the large circular button on the facing side. It functions like a trackpad on a laptop computer, although most games use it as a simple button.

The menu button above the thumb pad if you are holding the controller upright brings up the menu of the app or game you are in. It’s just a simple digital switch like the system button. When you first start, it’s easy to confuse the menu button and the system button. A simple mnemonic is that apps run on top of an operating system, so the button up top is for the app menu and the button on bottom is for the Vive sub-system.

The dual grip buttons can be used in some games to do certain things, like move the world around your fixed location. They are not used very often and are somewhat hard to activate with your palm.

There are two other things to note on the side that faces away from you. First, in the little concave depression at the very bottom, there is a micro-USB port. Second, just above this there is a small channel for the wrist strap connector loop. Reconstruction of my disaster identified this as a key factor in what resulted.

What It Feels Like

You may wonder how having two plastic sticks with some buttons translates into anything useful or better than a gamepad. It does in two important ways:

First, the controllers are fully tracked in three dimensional space, so the app and headset know where they are at all times. This means apps and games know where your hands are in relation to things in the virtual world.

Second, in most apps and games, the controllers are rendered in the app or game in some way. In fact, when you put the headset on in the home environment before launching any apps, the controllers appear exactly as they appear in real life, except that where they say Vive in real life, they say htc in VR. Not that I recommend it, but the controllers are rendered and tracked so well you could yell to a buddy across the room, “Hey, toss me the Vive controllers!” and you could catch them when your buddy tossed them to you. With the headset on.

Once you caught them, they would become your virtual hands. You may feel you would really need gloves to do anything useful in VR with your hands, but you’ll be amazed at how you can do just about anything you can do with your hands in real life in VR with just the trigger button.

Games can figure out what you are trying to interact with by proximity and motion, so they can determine if you are pinching, grasping, or smashing. I’ve been able to juggle coffee mugs and other items in VR, albeit not very well, which is quite an accomplishment, since I can’t juggle in real life.

One last note here is that, in the default VR rendering, the battery status is indicated as a row of LEDs at the bottom of the controllers. These LEDs don’t exist in the real life version of the controller. Games and apps can and do change how the controllers are rendered.

How It Works

I’ve tried to avoid the technical aspects so far because the experience and what it does is more important, but I’ll talk about that here. If you don’t care, skip to the next section regarding the wrist straps.

All that is connected to your computer when you use a Vive is the headset. Not the base stations nor the controllers. The only connections from the headset to the computer are HDMI and USB cables. HDMI simply carries the visual signals from the computer to the display panels in the headset. USB reports back the sensor data from the headset as the sensors on the headset pick up infrared laser flashes and sweeps from the base stations.

In the movie Lawnmower Man, there is a scene where the doctor and lead scientist uses VR in his basement. The movie was made 25 years ago, but at least this part of it is eerily prescient because he basically looks like he is wearing a Rift. Also, his hands are tracked, but with gloves. Quaintly, they must have had a discussion on the set and determined the only way hand tracking data could get to the computer was with wires, so the gloves actually have wires going to them in the movie.

Clearly that was before wireless became a major thing, so the Vive controllers don’t have wires. However, they don’t use Bluetooth or Wi-Fi either. Apparently, they use a proprietary protocol to talk with the headset, though it uses similar radio frequency ranges to Wi-Fi.

Through this protocol, the controllers are able to report all the data coming from their sensors and button presses to the headset, which then passes this information along with the headset tracking data to the computer via USB. With this information, the game or app can track the locations of the headset and both controllers in 3D space.

This explanation suffices, but people who are more interested in the technology should know there are also accelerometers in the controllers and headset, so actual tracking is not just based on the sensors reporting the base station infrared laser show, but a combination of all available positional and tracking data. Also, the base station technology deserves its own thorough technical description outside the scope available here.

When Things Go Horribly Wrong

Over the past month or so, various reports have emerged on r/Vive regarding the wrist straps breaking and controllers flying across rooms and getting damaged. I looked at these comments and thought, "Nah, it won't happen to me because I don't swing my controllers around that hard."

Back to down 4-2 in Expert Mode in Holoball. I serve hard. The AI returns like John McEnroe. A furious volley develops with the holoball flying back and forth like a bullet. Left, right, then the AI sends one to the left I have to chase down.

The AI, perhaps detecting I’m left of my usual position, sends the holoball back far to the right. I dive for it with an outstretched, vicious slashing swing as the ball is streaking past, intending a hard return to the upper right corner where the AI won’t be able to get to in time.

Except that the paddle is suddenly flying away from me, slipped from my sweaty grip. As the car I’m supposedly protecting from the holoball explodes behind me in VR (which signals you lost in Holoball), all I hear through the taunts of the AI is the controller crashing around in real life as it rebounds off multiple walls and metal baseboards. This, after colliding with the first wall at somewhere in the vicinity of 50 miles an hour.

I scream “Nooooooo!”, rip off the headset, and go to the aid of the fallen controller. When I reach it, it is lying broken on the floor in a state of obvious distress. Part of the top of the open loop has come away and I can see… wiring.

I immediately start compressions, trying to get it back together again. Fortunately, a plastic tab had just come free of the housing and I am able to push it back together.

Damage to the left sensor extension, note the larger than normal gap where I pushed things back together.
Major scarring to the bottom of the controller. This may have been the impact with the first wall.

To my astonishment, it still works with tracking, haptic feedback, and audio. Then I notice something strange. First, the wrist strap is still on my wrist! Second, where the wrist strap used to be attached to the controller, there are just two very sad little black threads.

The two little threads. The scratches near the Vive logo are further damage, likely from rebounding off the metal baseboard.

And that’s when I saw the most absurd thing about the Vive. All that holds the controller to the first buckle of the wrist strap is a tiny little plastic cord with some cosmetic black threading around it. It’s surprising it doesn’t break just when carrying the controller by the wrist strap, never mind when swinging it around.

That tiny little plastic thread you can barely see? That's all that holds your controllers to your wrist.

Get New Wrist Straps NOW

Buy new wrist straps from Nintendo. It’s less than $6 for two wrist straps with standard shipping, which takes less than a week. Do it now. Do it here (registration during check out is quick and simple, all you need is a credit card):

Nintendo: Wii Remote Wrist Strap (Wii U, Wii mini, Wii

Nintendo carries Vive wrist straps because they released inadequate wrist straps for the Wii controllers, which people swung around for games like Wii Sports tennis. Apparently, the wrist straps broke and people were none too happy with unrestrained Wii controllers flying through expensive televisions, so Nintendo released new and much stronger wrist straps.

The Nintendo wrist straps at top and bottom compared to the original wrist straps in the middle.

The Nintendo wrist straps are much better. They have reinforced attachment lanyards and are of much higher quality. It’s possible to change the size of the loop over your wrist using a small snap and sliding buckle system so you can avoid the wrist strap just sliding off your wrist after the controller. Changing out the wrist straps takes only a couple minutes.

Damaged Vive controller re-secured with a Nintendo wrist strap.

The alternative is a long RMA process with HTC and upwards of $100 in repairs to one of your controllers, plus whatever other damage you do to your environment or people.