Optimization-Based wearable tactile rendering

Novel wearable tactile interfaces offer the possibility to simulate tactile interactions with virtual environments directly on our skin. But, unlike kinesthetic interfaces, for which haptic rendering is a well explored problem, they pose new questions about the formulation of the rendering problem. In this work, we propose a formulation of tactile rendering as an optimization problem, which is general for a large family of tactile interfaces. Based on an accurate simulation of contact between a finger model and the virtual environment, we pose tactile rendering as the optimization of the device configuration, such that the contact surface between the device and the actual finger matches as close as possible the contact surface in the virtual environment. We describe the optimization formulation in general terms, and we also demonstrate its implementation on a thimble-like wearable device. We validate the tactile rendering formulation by analyzing its force error, and we show that it outperforms other approaches

손끝 햅틱 장비를 위한 의사 햅틱의 활용

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2016. 2. 이동준.We propose a novel design of cutaneous fingertip haptic device and approach of integrating pseudo-haptics into our cutaneous haptic device. With 2-DoF cutaneous device, angle-force calibration result is presented for its operation. Then, 3-DoF cutaneous haptic device is designed for more realistic contact feedback in virtual reality (VR). Preliminary result of integrating cutaneous device and hand tracking device for complete wearable haptic interface is also demonstrated. Meanwhile, we explore possible utility of pseudo-haptics for cutaneous fingertip haptic device, whose performance is inherently limited due to the lack of kinesthetic feedback. We experimentally demonstrate that: 1) pseudo-haptics can render virtual stiffness to be more rigid or softer only by modulating visual cueand 2) pseudo-haptics can be used to expand the range of the perceived virtual stiffness to be doubled.Chapter 1 Introduction 1 1.1 Motivation and Objectives 1 1.2 Related Works 3 Chapter 2 Cutaneous Fingertip Haptic Device 6 2.1 2-DoF Cutaneous Haptic Device 6 2.1.1 Design and Specification 6 2.1.2 Angle-Force Calibration 8 2.1.3 Application of 2-DoF Cutaneous Haptic Device 10 2.2 3-DoF Cutaneous Haptic Device 11 2.2.1 Design and Specification 11 2.2.2 Control Design 14 2.2.3 IMU Distortion Offset Calibration 17 2.2.4 Device Validation 20 2.2.5 Integration with Wearable Hand Tracking Interface 21 Chapter 3 Pseudo-Haptics with Cutaneous Haptic Feedback 25 3.1 Limitation of Cutaneous Haptic Device 25 3.2 Application of Pseudo-Haptics Effect 26 Chapter 4 Experimental Study 28 4.1 Experimental Settings 28 4.2 Experiment #1 32 4.3 Experiment #2 34 4.4 Experiment #3 36 4.5 Discussion 38 Chapter 5 Conclusion and Future Work 40 5.1 Conclusion 40 5.2 Future Work 41 Bibliography 42 요약 50Maste

Soft finger tactile rendering for wearable haptics

This paper introduces a tactile rendering algorithm for wearable cutaneous devices that stimulate the skin through local contact surface modulation. The first step in the algorithm simulates contact between a skin model and virtual objects, and computes the contact surface to be rendered. The accuracy of this surface is maximized by simulating soft skin with its characteristic nonlinear behavior. The second step takes the desired contact surface as input, and computes the device configuration by solving an optimization problem, i.e., minimizing the deviation between the contact surface in the virtual environment and the contact surface rendered by the device. The method is implemented on a thimble-like wearable device

Delivering Expressive And Personalized Fingertip Tactile Cues

Wearable haptic devices have seen growing interest in recent years, but providing realistic tactile feedback is not a challenge that is soon to be solved. Daily interactions with physical objects elicit complex sensations at the fingertips. Furthermore, human fingertips exhibit a broad range of physical dimensions and perceptive abilities, adding increased complexity to the task of simulating haptic interactions in a compelling manner. However, as the applications of wearable haptic feedback grow, concerns of wearability and generalizability often persuade tactile device designers to simplify the complexities associated with rendering realistic haptic sensations. As such, wearable devices tend to be optimized for particular uses and average users, rendering only the most salient dimensions of tactile feedback for a given task and assuming all users interpret the feedback in a similar fashion. We propose that providing more realistic haptic feedback will require in-depth examinations of higher-dimensional tactile cues and personalization of these cues for individual users. In this thesis, we aim to provide hardware and software-based solutions for rendering more expressive and personalized tactile cues to the fingertip. We first explore the idea of rendering six-degree-of-freedom (6-DOF) tactile fingertip feedback via a wearable device, such that any possible fingertip interaction with a flat surface can be simulated. We highlight the potential of parallel continuum manipulators (PCMs) to meet the requirements of such a device, and we refine the design of a PCM for providing fingertip tactile cues. We construct a manually actuated prototype to validate the concept, and then continue to develop a motorized version, named the Fingertip Puppeteer, or Fuppeteer for short. Various error reduction techniques are presented, and the resulting device is evaluated by analyzing system responses to step inputs, measuring forces rendered to a biomimetic finger sensor, and comparing intended sensations to perceived sensations of twenty-four participants in a human-subject study. Once the functionality of the Fuppeteer is validated, we begin to explore how the device can be used to broaden our understanding of higher-dimensional tactile feedback. One such application is using the 6-DOF device to simulate different lower-dimensional devices. We evaluate 1-, 3-, and 6-DOF tactile feedback during shape discrimination and mass discrimination in a virtual environment, also comparing to interactions with real objects. Results from 20 naive study participants show that higher-dimensional tactile feedback may indeed allow completion of a wider range of virtual tasks, but that feedback dimensionality surprisingly does not greatly affect the exploratory techniques employed by the user. To address alternative approaches to improving tactile rendering in scenarios where low-dimensional tactile feedback is appropriate, we then explore the idea of personalizing feedback for a particular user. We present two generalizable software-based approaches to personalize an existing data-driven haptic rendering algorithm for fingertips of different sizes. We evaluate our algorithms in the rendering of pre-recorded tactile sensations onto rubber casts of six different fingertips as well as onto the real fingertips of 13 human participants, all via a 3-DOF wearable device. Results show that both personalization approaches significantly reduced force error magnitudes and improved realism ratings