Modeling of frictional forces during bare-finger interactions with solid surfaces

Touching an object with our fingers yields frictional forces that allow us to perceive and explore its texture, shape, and other features, facilitating grasping and manipulation. While the relevance of dynamic frictional forces to sensory and motor function in the hand is well established, the way that they reflect the shape, features, and composition of touched objects is poorly understood. Haptic displays -electronic interfaces for stimulating the sense of touch- often aim to elicit the perceptual experience of touching real surfaces by delivering forces to the fingers that mimic those felt when touching real surfaces. However, the design and applications of such displays have been limited by the lack of knowledge about what forces are felt during real touch interactions. This represents a major gap in current knowledge about tactile function and haptic engineering. This dissertation addresses some aspects that would assist in their understanding. The goal of this research was to measure, characterize, and model frictional forces produced by a bare finger sliding over surfaces of multiple shapes. The major contributions of this work are (1) the design and development of a sensing system for capturing fingertip motion and forces during tactile exploration of real surfaces; (2) measurement and characterization of contact forces and the deformation of finger tissues during sliding over relief surfaces; (3) the development of a low order model of frictional force production based on surface specifications; (4) the analysis and modeling of contact geometry, interfacial mechanics, and their effects in frictional force production during tactile exploration of relief surfaces. This research aims to guide the design of algorithms for the haptic rendering of surface textures and shape. Such algorithms can be used to enhance human-machine interfaces, such as touch-screen displays, by (1) enabling users to feel surface characteristics also presented visually; (2) facilitating interaction with these devices; and (3) reducing the need for visual input to interact with them.Ph.D., Electrical Engineering -- Drexel University, 201

Haptic Rendering of Interacting Dynamic Deformable Objects Simulated in Real-Time at Different Frequencies

International audienceThe dynamic response of deformable bodies varies significantly in dependence on mechanical properties of the objects: while the dynamics of a stiff and light object (e. g. wire or needle) involves high-frequency phenomena such as vibrations, much lower frequencies are sufficient for capturing dynamic response of an object composed of a soft tissue. Yet, when simulating mechanical interactions between soft and stiff deformable models, a single time-step is usually employed to compute the time integration of dynamics of both objects. However, this can be a serious issue when haptic rendering of complex scenes composed of various bodies is considered. In this paper, we present a novel method allowing for dynamic simulation of a scene composed of colliding objects modelled at different frequencies: typically, the dynamics of soft objects are calculated at frequency about 50 Hz, while the dynamics of stiff object is modeled at 1 kHz, being directly connected to the computation of haptic force feedback. The collision response is performed at both low and high frequencies employing data structures which describe the actual constraints and are shared between the high and low frequency loops. During the simulation, the realistic behaviour of the objects according to the mechanical principles (such as non-interpenetration and action-reaction principle) is guaranteed. Examples showing the scenes involving different bodies in interaction are given, demonstrating the benefits of the proposed method

HAPTIC AND VISUAL SIMULATION OF BONE DISSECTION

Marco AgusIn bone dissection virtual simulation, force restitution represents the key to realistically mimicking a patient– specific operating environment. The force is rendered using haptic devices controlled by parametrized mathematical models that represent the bone–burr contact. This dissertation presents and discusses a haptic simulation of a bone cutting burr, that it is being developed as a component of a training system for temporal bone surgery. A physically based model was used to describe the burr– bone interaction, including haptic forces evaluation, bone erosion process and resulting debris. The model was experimentally validated and calibrated by employing a custom experimental set–up consisting of a force–controlled robot arm holding a high–speed rotating tool and a contact force measuring apparatus. Psychophysical testing was also carried out to assess individual reaction to the haptic environment. The results suggest that the simulator is capable of rendering the basic material differences required for bone burring tasks. The current implementation, directly operating on a voxel discretization of patientspecific 3D CT and MR imaging data, is efficient enough to provide real–time haptic and visual feedback on a low–end multi–processing PC platform.

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 13th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2022, held in Hamburg, Germany, in May 2022. The 36 regular papers included in this book were carefully reviewed and selected from 129 submissions. They were organized in topical sections as follows: haptic science; haptic technology; and haptic applications

Realistic tool-tissue interaction models for surgical simulation and planning

Surgical simulators present a safe and potentially effective method for surgical training, and can also be used in pre- and intra-operative surgical planning. Realistic modeling of medical interventions involving tool-tissue interactions has been considered to be a key requirement in the development of high-fidelity simulators and planners. The soft-tissue constitutive laws, organ geometry and boundary conditions imposed by the connective tissues surrounding the organ, and the shape of the surgical tool interacting with the organ are some of the factors that govern the accuracy of medical intervention planning.\ud \ud This thesis is divided into three parts. First, we compare the accuracy of linear and nonlinear constitutive laws for tissue. An important consequence of nonlinear models is the Poynting effect, in which shearing of tissue results in normal force; this effect is not seen in a linear elastic model. The magnitude of the normal force for myocardial tissue is shown to be larger than the human contact force discrimination threshold. Further, in order to investigate and quantify the role of the Poynting effect on material discrimination, we perform a multidimensional scaling study. Second, we consider the effects of organ geometry and boundary constraints in needle path planning. Using medical images and tissue mechanical properties, we develop a model of the prostate and surrounding organs. We show that, for needle procedures such as biopsy or brachytherapy, organ geometry and boundary constraints have more impact on target motion than tissue material parameters. Finally, we investigate the effects surgical tool shape on the accuracy of medical intervention planning. We consider the specific case of robotic needle steering, in which asymmetry of a bevel-tip needle results in the needle naturally bending when it is inserted into soft tissue. We present an analytical and finite element (FE) model for the loads developed at the bevel tip during needle-tissue interaction. The analytical model explains trends observed in the experiments. We incorporated physical parameters (rupture toughness and nonlinear material elasticity) into the FE model that included both contact and cohesive zone models to simulate tissue cleavage. The model shows that the tip forces are sensitive to the rupture toughness. In order to model the mechanics of deflection of the needle, we use an energy-based formulation that incorporates tissue-specific parameters such as rupture toughness, nonlinear material elasticity, and interaction stiffness, and needle geometric and material properties. Simulation results follow similar trends (deflection and radius of curvature) to those observed in macroscopic experimental studies of a robot-driven needle interacting with gels

空中ジェスチャ・インタラクションにおける触覚提示の高臨場感化および安定化に関する研究

Tohoku University昆陽雅司課

Image-Based Force Estimation and Haptic Rendering For Robot-Assisted Cardiovascular Intervention

Clinical studies have indicated that the loss of haptic perception is the prime limitation of robot-assisted cardiovascular intervention technology, hindering its global adoption. It causes compromised situational awareness for the surgeon during the intervention and may lead to health risks for the patients. This doctoral research was aimed at developing technology for addressing the limitation of the robot-assisted intervention technology in the provision of haptic feedback. The literature review showed that sensor-free force estimation (haptic cue) on endovascular devices, intuitive surgeon interface design, and haptic rendering within the surgeon interface were the major knowledge gaps. For sensor-free force estimation, first, an image-based force estimation methods based on inverse finite-element methods (iFEM) was developed and validated. Next, to address the limitation of the iFEM method in real-time performance, an inverse Cosserat rod model (iCORD) with a computationally efficient solution for endovascular devices was developed and validated. Afterward, the iCORD was adopted for analytical tip force estimation on steerable catheters. The experimental studies confirmed the accuracy and real-time performance of the iCORD for sensor-free force estimation. Afterward, a wearable drift-free rotation measurement device (MiCarp) was developed to facilitate the design of an intuitive surgeon interface by decoupling the rotation measurement from the insertion measurement. The validation studies showed that MiCarp had a superior performance for spatial rotation measurement compared to other modalities. In the end, a novel haptic feedback system based on smart magnetoelastic elastomers was developed, analytically modeled, and experimentally validated. The proposed haptics-enabled surgeon module had an unbounded workspace for interventional tasks and provided an intuitive interface. Experimental validation, at component and system levels, confirmed the usability of the proposed methods for robot-assisted intervention systems

Haptic and visual simulation of bone dissection

Tesi di dottorato: Università degli Studi di Cagliari, Facoltà di Ingegneria, Dipartiemnto di Ingegneria Meccanica, XV Ciclo di Dottorato in Progettazione Meccanica.In bone dissection virtual simulation, force restitution represents the key to realistically mimicking a patient--specific operating environment. The force is rendered using haptic devices controlled by parametrized mathematical models that represent the bone--burr contact. This dissertation presents and discusses a haptic simulation of a bone cutting burr, that it is being developed as a component of a training system for temporal bone surgery. A physically based model was used to describe the burr--bone interaction, including haptic forces evaluation, bone erosion process and resulting debris. The model was experimentally validated and calibrated by employing a custom experimental set--up consisting of a force--controlled robot arm holding a high--speed rotating tool and a contact force measuring apparatus. Psychophysical testing was also carried out to assess individual reaction to the haptic environment. The results suggest that the simulator is capable of rendering the basic material differences required for bone burring tasks. The current implementation, directly operating on a voxel discretization of patient-specific 3D CT and MR imaging data, is efficient enough to provide real--time haptic and visual feedback on a low--end multi--processing PC platformInedit

3D Multimodal Interaction with Physically-based Virtual Environments

The virtual has become a huge field of exploration for researchers: it could assist the surgeon, help the prototyping of industrial objects, simulate natural phenomena, be a fantastic time machine or entertain users through games or movies. Far beyond the only visual rendering of the virtual environment, the Virtual Reality aims at -literally- immersing the user in the virtual world. VR technologies simulate digital environments with which users can interact and, as a result, perceive through different modalities the effects of their actions in real time. The challenges are huge: the user's motions need to be perceived and to have an immediate impact on the virtual world by modifying the objects in real-time. In addition, the targeted immersion of the user is not only visual: auditory or haptic feedback needs to be taken into account, merging all the sensory modalities of the user into a multimodal answer. The global objective of my research activities is to improve 3D interaction with complex virtual environments by proposing novel approaches for physically-based and multimodal interaction. I have laid the foundations of my work on designing the interactions with complex virtual worlds, referring to a higher demand in the characteristics of the virtual environments. My research could be described within three main research axes inherent to the 3D interaction loop: (1) the physically-based modeling of the virtual world to take into account the complexity of the virtual object behavior, their topology modifications as well as their interactions, (2) the multimodal feedback for combining the sensory modalities into a global answer from the virtual world to the user and (3) the design of body-based 3D interaction techniques and devices for establishing the interfaces between the user and the virtual world. All these contributions could be gathered in a general framework within the 3D interaction loop. By improving all the components of this framework, I aim at proposing approaches that could be used in future virtual reality applications but also more generally in other areas such as medical simulation, gesture training, robotics, virtual prototyping for the industry or web contents.Le virtuel est devenu un vaste champ d'exploration pour la recherche et offre de nos jours de nombreuses possibilités : assister le chirurgien, réaliser des prototypes de pièces industrielles, simuler des phénomènes naturels, remonter dans le temps ou proposer des applications ludiques aux utilisateurs au travers de jeux ou de films. Bien plus que le rendu purement visuel d'environnement virtuel, la réalité virtuelle aspire à -littéralement- immerger l'utilisateur dans le monde virtuel. L'utilisateur peut ainsi interagir avec le contenu numérique et percevoir les effets de ses actions au travers de différents retours sensoriels. Permettre une véritable immersion de l'utilisateur dans des environnements virtuels de plus en plus complexes confronte la recherche en réalité virtuelle à des défis importants: les gestes de l'utilisateur doivent être capturés puis directement transmis au monde virtuel afin de le modifier en temps-réel. Les retours sensoriels ne sont pas uniquement visuels mais doivent être combinés avec les retours auditifs ou haptiques dans une réponse globale multimodale. L'objectif principal de mes activités de recherche consiste à améliorer l'interaction 3D avec des environnements virtuels complexes en proposant de nouvelles approches utilisant la simulation physique et exploitant au mieux les différentes modalités sensorielles. Dans mes travaux, je m'intéresse tout particulièrement à concevoir des interactions avec des mondes virtuels complexes. Mon approche peut être décrite au travers de trois axes principaux de recherche: (1) la modélisation dans les mondes virtuels d'environnements physiques plausibles où les objets réagissent de manière naturelle, même lorsque leur topologie est modifiée ou lorsqu'ils sont en interaction avec d'autres objets, (2) la mise en place de retours sensoriels multimodaux vers l'utilisateur intégrant des composantes visuelles, haptiques et/ou sonores, (3) la prise en compte de l'interaction physique de l'utilisateur avec le monde virtuel dans toute sa richesse : mouvements de la tête, des deux mains, des doigts, des jambes, voire de tout le corps, en concevant de nouveaux dispositifs ou de nouvelles techniques d'interactions 3D. Les différentes contributions que j'ai proposées dans chacun de ces trois axes peuvent être regroupées au sein d'un cadre plus général englobant toute la boucle d'interaction 3D avec les environnements virtuels. Elles ouvrent des perspectives pour de futures applications en réalité virtuelle mais également plus généralement dans d'autres domaines tels que la simulation médicale, l'apprentissage de gestes, la robotique, le prototypage virtuel pour l'industrie ou bien les contenus web