Collaborative Research: HCC: Medium: "Unboxing" Haptic Texture Perception: Closing the Loop from Skin Contact Mechanics to Novel Haptic Device

Modern virtual-reality devices attempt to create a realistic sense of touch in the absence of physical surfaces and objects, but as of yet they fall short. Indeed, no existing interfaces for the sense of touch, known as “haptic interfaces," are capable of replicating one of the most fundamental aspects of touch: how a textured surface feels during direct skin contact. Interfaces that simulate contact through a tool eliminate features that are available only from skin contact, but the interfaces that do allow direct skin contact are currently insufficient to convey material and fine-grained structural details of surfaces. Put simply, they do not feel realistic. This project promotes the progress of science and technology by providing a new approach to the design of haptic devices aimed at producing highly realistic virtual textures, and it will take a step towards understanding touch perception that addresses a previously unstudied component: the detailed physical interaction between the skin and the surface it contacts. The development of our proposed haptic technology and further understanding of our sense of touch can benefit applications in human-machine interaction, such as creating more immersive virtual environments and improving the control of remote robots. There are also multiple applications in education and virtual-reality development, especially for blind and visually impaired people, that would benefit from advanced understanding of touch perception and better tools for creating virtual experiences. In addition, as we know from past technological developments in the basic science of perception, such as the study of hearing that led to cutting-edge audio interfaces, it is likely that we underestimate the technological advancements that will result from a better understanding of this powerful sense modality. This project will develop novel haptic technologies based on three complementary objectives: (1) Formulate models of the contact mechanics of human skin using direct imaging by “Optical Coherence Tomography” of the fingerpad sliding over a texture, coupled with Boundary Element and Finite Element Methods that can be used to characterize and model responses within the skin layers during interactions with texture. (2) Fabricate haptic devices that instantiate the model mechanisms and parameters, so as to recreate skin-texture interactions. These devices will include a pin array capable of spatially distributed, high-bandwidth control of normal and lateral excitation, as well as an electromagnetic haptic device that uses elastomers embedded with ferromagnetic particles to transmit perpendicular and shear forces to the user in response to controllable magnetic fields. (3) Validate and extend the models by means of human-user studies with both physical textures and the haptic devices of Objective 2, using psychophysical experimental techniques and broader haptic interface studies. This objective will test whether model-based actuation is sufficient to create rich haptic perceptual experience. Success will establish principles for realistic texture rendering in next generation haptic devices. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.