Surface Haptics, or the creation of virtual haptic effects on physical surfaces, is a topic of rapidly growing importance in human?]computer interaction because of the increasingly widespread use of touch screens. Touch is at once an elegant and maddening interface modality. It is elegant in its simplicity: one can make a selection or tap a button or key with no intervening mouse or joystick. Moreover, touch (especially multi?]finger touch) supports gestures, such as swiping and expanding, which are satisfyingly natural. It is maddening, however, due to the lack of tactile and kinesthetic feedback that are so critical to natural touch. Typing on a virtual keyboard, for instance, is typically an experience of visually guided hunt?]and?]peck with liberal use of the back?]space key.
In this research the PIs will further develop a new class of surface haptic devices, called xPaDs, that promise to enrich the use of touch screen and touchpad interfaces for sighted as well as blind users. xPaDs are notable because they provide controllable shear forces between the fingertips and an ordinary sheet of glass. By controlling shear force in response to a measure of fingertip position (which may be obtained using a variety of existing technologies), it is possible to simulate a huge array of virtual effects; examples include toggle switches that flip from one state to another (each state is a "potential well" on the glass surface that pulls the finger to a given location), and contours that can be easily traced.
The heart of the current project lies in the systems engineering that will lead to practical and effective devices capable of controlling a force at one or more fingertips, and in the psychophysical and application?]based studies that will teach us how these capabilities may best be used. xPaDs are sophisticated dynamic systems that employ ultrasonic vibrations to modulate friction synchronized with in?]plane vibrations to produce controllable force vectors. The PIs will address the challenges of controlling force individually at each fingertip, of producing xPaDs with large surface area, and of minimizing energy consumption and audible noise generation. They will use the idea and methodology of "pop?]out" experiments to find haptic primitives, that is to say features the human perceptual system can extract with minimal or no perceptual load. The PIs will measure the information transmission capacity of surface haptic devices treated as symbolic channels. And they will explore the ability of the perceptual system to "bind" surface haptic features presented to different fingertips into a meaningful, coherent whole. These studies will position the PIs for investigating a set of applications for the blind.
Broader Impacts: Computer interfaces for the blind often rely heavily on speech, which necessarily presents information serially. The PIs argue that a haptic surface can augment a speech?]based interface with critical spatial information. They will study the editing and reading of mathematical expressions, of locating key content on a web page, of navigating intersections, and of planning routes with tools such as Google Maps. In addition, the PIs will develop a low?]cost xPaD development kit, make the plans and code available on the Internet, and develop a high school enrichment unit based upon these materials.
