Tactical Haptics Puts Real Force Feedback in a Handheld VR Controller

Tactical Haptics controller
Photo: Evan Ackerman/IEEE Spectrum

In virtual reality games (as in most games), your hands are what you use to interact with your environment, either directly or mediated through some virtual object (like a gun or a sword). But the experience of doing this is almost completely a one-way street: Maybe the controller that you're holding is fancy enough to vibrate a little bit, but that's about the best that you can hope for in terms of the interface physically stimulating you. For a more immersive experience, you want to engage as many of your senses as possible, not just sight and sound.

Besides incorporating motion into VR, adding convincing haptic feedback is the next logical step. It's a difficult step to take, though, because there's no obvious way to exert force on a handheld controller so that it feels like it's responding to the game while it's in your hand. But Tactical Haptics thinks it has the problem licked. It has spent the past few years developing a clever controller that can buck and twist while you're holding it.

Most haptic controllers that are capable of exerting forces on the user are complex, bulky pieces of hardware that are, by necessity, mounted in a fixed location. In order for something to exert a force on you, it has to have some kind of leverage, which usually means it's sitting on your desk or something. The Novint Falcon controller is a good example; it can convincingly replicate a variety of forces and sensations, because it's able to push against your hand.

This doesn't really work for VR games where part of the fun is that you get to stand up and move around. You want your motion to be restricted as little as possible. As stated at its website, Tactical Haptics is solving this freedom-versus-leverage dilemma with “an ungrounded haptic motion controller that utilizes a new form of touch feedback that applies in-hand shear forces to create compelling physical feedback.”

The secret to Tactical Haptics' controller is in the grip. When you hold the controller, your hand is actually wrapped around four individually-actuated smooth plates that can slide up and down the handle’s length. Since you're gripping the plates with your hand, their sliding motions—propelled by small motors insided the controller—cause the device to move in a way that emulates the feeling of friction, force, and torque.

I tried a 3D printed prototype of this controller a couple years ago, and it's one of those haptic experiences that works quite well but is very frustrating to try to describe to someone else. The best way I've come up with is to illustrate the functionality with an example. Let's say that you're playing a VR game that involves shooting a gun. When you pull the trigger, the controller needs to generate the expected feeling of a backwards kick. It does this by rapidly sliding the two plates nearest your palm downward slightly while also sliding the two plates nearest your fingers upward slightly. This causes the entire controller to rotate backwards with a jerk, convincingly emulating the feel of a video game sort of gunshot. The plates recenter themselves more slowly and more smoothly, such that you don't notice that they're returning to zero. This same kind of rotational motion works for things like sword fights, too, where the controller can twist itself as you parry an in-game sword. Besides rotational forces, the controller can also mimic the kinds of stretching forces you'd feel with a slingshot or bow and arrow. It'll also do frictional and shear forces, interactions with passive virtual objects, and make things like in-game lockpicking a lot more immersive. 

Tactical Haptics attempted to Kickstart a consumer controller back in 2013, and made it over halfway to the company’s $175,000 goal. From the sound of things, the team kept working since then; they've just announced some new funding from the U.S. National Science Foundation that should result in “a reference design that can be mass produced” by mid 2018, plus $1.47 million in seed round funding. For more, we spoke with William Provancher, founder and CEO of Tactical Haptics:

The last time we tried the controller was in 2013; can you describe what's new and different now?

Our controllers now use either Oculus or HTC tracking, are fully wireless (communications and battery power), and are much more responsive. We've also been looking at making the devices smaller, simpler, more ergonomic, and lighter, while maintaining a great user performance.

Why is the kind of haptic experience that you're working on so important for VR?

Currently, visual and auditory feedback in VR is significantly more advanced than haptic feedback, which, in consumer gaming, has remained the same “rumble” vibration feedback for 20 years. Our touch feedback can create the sense of elasticity and inertia via a tactile illusion, whereas current rumble is mostly just good at transient information (e.g., gunshots) and texture information (e.g., the rumble of a tank).

What's your vision for a consumer product? 

The consumer product should be able to replace the functionality of standard controllers (e.g., used in place of the HTC Vive, Sony Move, or Oculus Touch). We're trying to design the simplest controller possible, while providing significantly better user experience than rumble. This will allow us to reach a price-point to get this technology in the hands of many more VR enthusiasts and gamers.

While there has yet to be an announcement regarding the timeline or cost for the consumer version of Tactical Haptics' controller, we can safely assume that it won't be ready until the conclusion of the NSF grant in mid-2018. The Kickstarter version of the controller would have sold for $160 (Oculus Touch controllers cost $200 for a pair), but after this government-funded optimization, we're hoping for something a bit more competitive on release.

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