HCC: Medium: Collaborative Research: Force Feedback for Fingertips

表面触觉是在触摸屏和触摸板等物理表面上创建可编程触觉效果。 与需要操作者抓住末端执行器的传统力反馈装置不同，表面触觉装置必须直接向指尖提供反馈。 近年来，随着触摸屏界面的急剧崛起，人们已经探索了许多表面触觉的方法，包括振动触觉、形状变形和可变摩擦。 PI和他的团队开创了一种方法，其中表面在每个指尖上产生受控的剪切力。指尖力反馈（F3）使指尖有机会与基于物理的虚拟环境进行交互，就像力反馈设备使整只手能够做的那样。 利用F3，手指可以与具有质量、刚度和阻尼以及更复杂的动力学（例如，碰撞、机制和力场）。 通过协调多个指尖的触觉效果，可以产生更引人注目的幻觉。然而，F3的技术，基础科学和应用仍处于起步阶段。 F3通过将横向振动耦合到某种形式的整流来工作。 例如，一种方法涉及与摩擦减小效应同步的表面的高频横向振动，导致在每次振荡处的滑推过渡。 摩擦力通过静电力或声刺激来调节。 目前的方法在超声波频率下工作，但对指尖在这些频率下的机械或电气行为知之甚少，或者如何优化从表面到手指的能量传递。这项研究将在三个主要领域产生新的知识：F3的物理基础，设备设计和交互设计。 首先，将进行摩擦学和声学测量，以阐明剪切力产生的机制。 高带宽摩擦计和光学成像系统将允许研究摩擦，定制的激励器将允许研究指尖中的声能传播。 激光多普勒振动测量法将用于测量表面波传播，而磁共振弹性成像将用于研究皮下组织内的剪切波传播。 分数阶微积分和有限元技术，然后将被用来建立生物合理的指尖摩擦学和力学模型，匹配的数据。 其次，将开发新一代高性能F3器件。 有了好的模型，就有可能设计出阻抗匹配的装置，使力的产生最大化，能量的浪费最小化。 此外，这些新设备将提供对多个指尖位置中的每一个的力矢量的控制。 第三，将设计新颖的多指交互。 其核心思想是，复杂的感知，如“物体”，可以抓住，感觉好像他们是相对于表面移动，可以从适当协调的指尖力量，由于完形类分组原则出现。更广泛的影响：历史上，PI和他的团队在提供技术，并与同事在人机交互中合作时产生了最大的影响。 受此启发，将开发和共享开源F3套件。 此外，本科生和高中生将参与研究，为开源工具包开发软件例程和示例应用程序。 最后，该工具包将与研究人员已经实施的两项教学创新相结合：翻转教室和便携式实验室。

Surface haptics is the creation of programmable haptic effects on physical surfaces such as touch screens and touch pads. Unlike traditional force feedback devices that require the operator to grasp an end effector, surface haptic devices must provide feedback directly to the fingertips. With the dramatic rise of touch screen interfaces in recent years, many approaches to surface haptics have been explored, including vibrotactile, shape morphing, and variable friction. The PI and his team have pioneered an approach in which the surface generates controlled shear forces on each fingertip. Force Feedback for Fingertips (F3), gives fingertips the opportunity to interact with physics-based virtual environments, much like force feedback devices enable the whole hand to do. With F3, fingers can interact with virtual objects that have mass, stiffness and damping as well as more complicated dynamics (e.g., collisions, mechanisms, and force fields). By coordinating haptic effects at multiple fingertips, even more compelling illusions can be generated.The technology, underlying science, and application of F3 are, however, still in their infancy. F3 works by coupling lateral vibrations to some form of rectification. For example, one approach involves high-frequency lateral vibrations of the surface synchronized with a friction reduction effect, resulting in a slip-push transition at each oscillation. The friction is modulated by means of electrostatic forces or acoustical stimulation. Current approaches work at ultrasonic frequencies, but little is known about the mechanical or electrical behavior of fingertips at these frequencies, or how energy transfer from a surface to the finger can be optimized.This research will produce new knowledge in three main areas: the physical underpinnings of F3, device design and interaction design. First, both tribological and acoustic measurements will be made to elucidate the mechanisms by which shear forces are generated. A high-bandwidth tribometer and optical imaging system will allow friction to be studied, and a custom-built exciter will allow the propagation of acoustic energy in the fingertip to be studied. Laser Doppler vibrometry will be used to measure surface wave propagation while magnetic resonance elastography will be used to study shear wave propagation within the subcutaneous tissues. Fractional calculus and finite element techniques will then be used to build biologically plausible models of fingertip tribology and mechanics that match the data. Second, a new generation of high-performance F3 devices will be developed. Armed with good models, it will be possible to design impedance-matched devices so that force production is maximized and energy wastage is minimized. Additionally, these new devices will provide control over the force vector at each of multiple fingertip locations. Thirdly, novel multi-finger interactions will be designed. The key idea is that sophisticated percepts, such as "objects" that can be grasped and that feel as though they are moving relative to the surface, can emerge from properly coordinated fingertip forces due to Gestalt-like grouping principles.Broader Impacts: Historically, the PI and his team have had greatest impact when providing technology to and collaborating with colleagues in human-computer interaction. Inspired by this, an open source F3 kit will be developed and shared. In addition, undergraduate and high school students will participate in the research, developing software routines and sample applications for the open source kit. Finally, the kit will be integrated with two pedagogical innovations already implemented by the investigators: flipped classrooms and portable laboratories.