Haptic Rendering of Hyperelastic Models with Friction

International audience— This paper presents an original method for inter-actions' haptic rendering when treating hyperelastic materials. Such simulations are known to be difficult due to the non-linear behavior of hyperelastic bodies; furthermore, haptic constraints enjoin contact forces to be refreshed at least at 1000 updates per second. To enforce the stability of simulations of generic objects of any range of stiffness, this method relies on implicit time integration. Soft tissues dynamics is simulated in real time (20 to 100 Hz) using the Multiplicative Jacobian Energy Decomposition (MJED) method. An asynchronous preconditioner, updated at low rates (1 to 10 Hz), is used to obtain a close approximation of the mechanical coupling of interactions. Finally, the contact problem is linearized and, using a specific-loop, it is updated at typical haptic rates (around 1000 Hz) allowing this way new simulations of prompt stiff-contacts and providing a continuous haptic feedback as well

RoboHive: A Unified Framework for Robot Learning

We present RoboHive, a comprehensive software platform and ecosystem for research in the field of Robot Learning and Embodied Artificial Intelligence. Our platform encompasses a diverse range of pre-existing and novel environments, including dexterous manipulation with the Shadow Hand, whole-arm manipulation tasks with Franka and Fetch robots, quadruped locomotion, among others. Included environments are organized within and cover multiple domains such as hand manipulation, locomotion, multi-task, multi-agent, muscles, etc. In comparison to prior works, RoboHive offers a streamlined and unified task interface taking dependency on only a minimal set of well-maintained packages, features tasks with high physics fidelity and rich visual diversity, and supports common hardware drivers for real-world deployment. The unified interface of RoboHive offers a convenient and accessible abstraction for algorithmic research in imitation, reinforcement, multi-task, and hierarchical learning. Furthermore, RoboHive includes expert demonstrations and baseline results for most environments, providing a standard for benchmarking and comparisons. Details: https://sites.google.com/view/robohiveComment: Accepted at 37th Conference on Neural Information Processing Systems (NeurIPS 2023) Track on Datasets and Benchmark

Unified processing of constraints for interactive simulation

International audienceThis paper introduces a generic way of dealing with a set of different constraints (bilateral, unilateral, dry friction) in the context of interactive simulation. We show that all the mentioned constraints can be handled within a unified framework: we define the notion of generalized constraints, which can be derived into most classical constraints types. The solving method is based on an implicit treatment of constraints that provides good stability for interactive applications using deformable models and rigid bodies. Each constraint law is expressed in constraint subspace, making constraint evaluation much easier. A global solution is calculated using an iterative process that takes into account the mechanical coupling between the constraints. Various examples, from basic to more complex, show the practical advantage of using generalized constraints, as a way of creating heterogeneously constrained systems, as well as the scalability of the proposed method

Real-time hybrid cutting with dynamic fluid visualization for virtual surgery

It is widely accepted that a reform in medical teaching must be made to meet today's high volume training requirements. Virtual simulation offers a potential method of providing such trainings and some current medical training simulations integrate haptic and visual feedback to enhance procedure learning. The purpose of this project is to explore the capability of Virtual Reality (VR) technology to develop a training simulator for surgical cutting and bleeding in a general surgery

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

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

Granular Gym: High Performance Simulation for Robotic Tasks with Granular Materials

Granular materials are of critical interest to many robotic tasks in planetary science, construction, and manufacturing. However, the dynamics of granular materials are complex and often computationally very expensive to simulate. We propose a set of methodologies and a system for the fast simulation of granular materials on Graphics Processing Units (GPUs), and show that this simulation is fast enough for basic training with Reinforcement Learning algorithms, which currently require many dynamics samples to achieve acceptable performance. Our method models granular material dynamics using implicit timestepping methods for multibody rigid contacts, as well as algorithmic techniques for efficient parallel collision detection between pairs of particles and between particle and arbitrarily shaped rigid bodies, and programming techniques for minimizing warp divergence on Single-Instruction, Multiple-Thread (SIMT) chip architectures. We showcase our simulation system on several environments targeted toward robotic tasks, and release our simulator as an open-source tool