Surround Haptics: Tactile Brush Algorithm
Tactile Brush is an algorithm that produces smooth, two-dimensional tactile moving strokes with varying frequency, intensity, velocity and direction of motion. The design of the algorithm is derived from the results of psychophysical investigations tactile illusions such as apparent tactile motion (phi phenomena), phantom sensations (funneling illusion), saltation, etc. Combined together they allow for the design of high-density two-dimensional tactile displays for the body using sparse vibrating arrays. In a series of experimental evaluations we demonstrate that Tactile Brush is robust and can reliably generate a wide variety of moving tactile sensations for a broad range of applications, actuation technology, body sites and embodiments.
See also Immersive Gaming Experience
Tactile illusions are perceptual phenomena that arise when two or more vibrating devices or actuators are placed on human skin. These actuators could be pager motors, speakers, soleniods, militarty-grade voice coils, or any other vibrating device. Indeed, the tactile illusions are fundamental properties of human tactile perception and do not depend on type of tactile actuators.
In Surround Haptics we mainly exploit two tactile illusions:
In Apparent Tactile Motion illusion two vibrotactile stimuli are placed on skin in close proximity and their actuation times are overlapped, as shown in figure on the right. The user would perceive not two actuators, but rather a single virtual actuator moving between physical vibrating points.
In Phantom Tactile Sensation illusion a simultaneous stimulation of two vibrating actuators placed in close proximity would create an illusory vibrating actuator located between the real actuators, as shown in figure on the right. Unlike apparent motion, the phantom illusion is static and no motion is perceived. Note that both phantom and apparent motion illusions are different from saltation or “cutaneous rabbit” illusion that has been often used before.
Drawing on Skin with Tactile Brush.
We designed an algorithm that uses the tactile illusions described above to “draw” smooth moving tactile strokes on sparce actuator grids. The basic idea of the algorythm is to fill empty space between physical actuators with either illusion of motion of static phantom actuators.
The basic principles of the algorythm are shown on the figure on the right. We use apparent tactile motion illusion to produce continuous tactile motion between any two points on the actuator grid. For example, we can draw a tactile stroke by sequentially vibrating actuators along the horizontal row.
The algorythm is universal in that it treats tactile grids as a generic content-rendering platform, independent from the specific mechanical and electrical properties of the tactile actuators used. We named the algorythm a Tactile Brush.
Surround Haptics can be used to enhance movies and rides expereinces. By combining hi-fidelity moving tactile sensations on user body with three-dimensional visuals and sound we can dramatically increases the sense of immersion and realism, create the illusions of being present inside of the story.
In such applications the The Surround Haptics hardware could be embedded inside of chairs in movie theaters or ride vehicles in parks.
Wearable Haptics and Navigation
Surround Haptics displays can be also wearable and by combining them with location-based services, they can provide navigation cues for motorcycle or bicycle riders or persons with limited vision. With just a few light-weight actuators Surround Haptics can provide a rich variety of spatial cues that would increase user awareness in complex navigation scenarios.
In this specific type of application, The Surround Haptics hardware would be embedded in vests, jackets, belts and so on.
Game controllers and accessories can be enahnced with Surround Haptics displays to provide rich tactile feedback in various gaming scenarious. An array of small actuators embedded in hand-held controller can display various dynamic tactile effects when user is interacting with vritual objects. A gaming chaircan provide effect when virtual car is scraping on the side of the road. A gaming west would let user feel when he or she were hit by a bullet or collide with walls in the environment.
The Surround Haptics hardware could be embedded into hand-held controllers, vests or chairs.
Few light-weight actuators can be embedded into handheld computing devices, such as mobile phones, still or video cameras, and provide additional feedback on interaction with the device. The user could feel lists scrolling inside of the device, a game character walking or pictures sliding. A collaborative uses are also possible, where two users could remotely “draw” on each other palms.
The Surround Haptics hardware could be embedded into the back or sides of the handheld device.
- New Scientist: “Illusions to send shivers down a gamer’s spine” 25 May 2011 by Jim Giles, Magazine issue 2813
- Popular Science: “Disney tactile device lets games and movies literally send chills down your spine” 26 May 2011 by Clay Dillow
- Discovery News: “A video game that really gives you the shivers” 28 May 2011 by Emad Hanna
- Wired (UK): “Vibrations create illusion of insects or rainfall on your skin” 27 May 2011 by Olivia Solon
- Engadget: “Tactile Brush uses sensory illusions to let you feel games, movies” 28 May 2011 by Terrence O’Brien
- Gizmodo: “Disney Tactile Device Lets Games and Movies Literally Send Chills Down Your Spine” 27 May 2011 by Clay Dillow
- PC World: “Disney Researches Force Feedback on Your Spine” 31 May 2011 by Kevin Lee
- Pittsburgh Post-Gazette: “CMU group works on movies that reach out and touch you” 8 June 08 2011 by Deborah M. Todd
- New Scientist TV: “Virtual car race lets you feel the swerve” 10 June 2011 by Sandrine Ceurstemont