Asynchronous haptic simulation of contacting deformable objects with variable stiffness

International audienceAbstract--This paper presents a new asynchronous approach for haptic rendering of deformable objects. When stiff nonlinear deformations take place, they introduce important and rapid variations of the force sent to the user. This problem is similar to the stiff virtual wall for which a high refresh rate is required to obtain a stable haptic feedback. However, when dealing with several interacting deformable objects, it is usually impossible to simulate all objects at high rates. To address this problem we propose a quasi-static framework that allows for stable interactions of asynchronously computed deformable objects. In the proposed approach, a deformable object can be computed at high refresh rates, while the remaining deformable virtual objects remain computed at low refresh rates. Moreover, contacts and other constraints between the different objects of the virtual environment are accurately solved using a shared Linear Complementarity Problem (LCP). Finally, we demonstrate our method on two test cases: a snap-in example involving non-linear deformations and a virtual thread interacting with a deformable object

Sensory Communication

Contains table of contents for Section 2 and reports on five research projects.National Institutes of Health Contract 2 R01 DC00117National Institutes of Health Contract 1 R01 DC02032National Institutes of Health Contract 2 P01 DC00361National Institutes of Health Contract N01 DC22402National Institutes of Health Grant R01-DC001001National Institutes of Health Grant R01-DC00270National Institutes of Health Grant 5 R01 DC00126National Institutes of Health Grant R29-DC00625U.S. Navy - Office of Naval Research Grant N00014-88-K-0604U.S. Navy - Office of Naval Research Grant N00014-91-J-1454U.S. Navy - Office of Naval Research Grant N00014-92-J-1814U.S. Navy - Naval Air Warfare Center Training Systems Division Contract N61339-94-C-0087U.S. Navy - Naval Air Warfare Center Training System Division Contract N61339-93-C-0055U.S. Navy - Office of Naval Research Grant N00014-93-1-1198National Aeronautics and Space Administration/Ames Research Center Grant NCC 2-77

A surgical system for automatic registration, stiffness mapping and dynamic image overlay

In this paper we develop a surgical system using the da Vinci research kit (dVRK) that is capable of autonomously searching for tumors and dynamically displaying the tumor location using augmented reality. Such a system has the potential to quickly reveal the location and shape of tumors and visually overlay that information to reduce the cognitive overload of the surgeon. We believe that our approach is one of the first to incorporate state-of-the-art methods in registration, force sensing and tumor localization into a unified surgical system. First, the preoperative model is registered to the intra-operative scene using a Bingham distribution-based filtering approach. An active level set estimation is then used to find the location and the shape of the tumors. We use a recently developed miniature force sensor to perform the palpation. The estimated stiffness map is then dynamically overlaid onto the registered preoperative model of the organ. We demonstrate the efficacy of our system by performing experiments on phantom prostate models with embedded stiff inclusions.Comment: International Symposium on Medical Robotics (ISMR 2018

Use of path planning techniques based on harmonic functions for the haptic guidance of teleoperated assembly tasks

Haptic devices allow the user to feel the reaction forces and torques that arise when the virtual object attached to the user-manipulated probe touches the other objects in the virtual environment. Additionally, the user may feel some guiding constrains and forces that aid him in the completion of a virtual task. Also haptic devices are used as master devices in teleoperation tasks and may include force reflection from the real forces sense by a force sensor located at the robot wrist. Both operation modes can be combined to set up an assisted teleoperation system able to execute assembly tasks. This paper proposes the use of path planning techniques based on harmonic functions to generate a guiding force that aids the user during the teleoperatio

Basel II and developing countries : Sailing through the sea of standards

Despite recently announced delays, Basel II - the new standard for bank capital - is due to be completed this year for implementation in the 13 Basel Committee member countries by the end of 2006. Should the other 170 plus member countries of the World Bank also adopt Basel II? Basel II was not written with developing countries in mind, but that does not necessarily mean that there is nothing in it for developing countries or that it can be ignored. Basels I and II represent a wide Sea of Standards. This paper suggests five alternative island-standards and five navigational tools to help countries choose their preferred island within the sea. It is suggested that for some developing countries the standardized approach will yield little in terms of linking regulatory capital to risk, but that countries may need many years of work to adopt the more advanced internal rating-based approach. The paper then proposes a centralized rating-based approach as a transition measure. The paper also makes proposals regarding a set of largely unresolved cross-border issues.Payment Systems&Infrastructure,Banking Law,Financial Intermediation,Banks&Banking Reform,Settlement of Investment Disputes,Banks&Banking Reform,Banking Law,Financial Intermediation,Financial Crisis Management&Restructuring,Settlement of Investment Disputes

Basel II and Developing Countries: Sailing through the Sea of Standards

Despite recently announced delays, Basel II - the new standard for bank capital - is due to be completed this year for implementation in the 13 Basel Committee member countries by the end of 2006. Should the other 170 or so member countries of the World Bank also adopt Basel II? Basel II was not written with developing countries in mind, but that does not necessarily mean that there is nothing in it for developing countries or that it can be ignored. Basels I and II represent a wide "Sea of Standards", this paper suggests five alternative Island-standards and five navigational tools to help countries choose their preferred Island within the Sea. It is suggested that for some developing countries the Standardized Approach will yield little in terms of linking regulatory capital to risk but that countries may need many years of work to adopt the more advanced Internal Rating Based Approach. The paper then proposes a Centralized Rating Based (CRB) approach as a transition measure. The paper also makes proposals regarding a set of largely unresolved cross-border issues.

Gym-Ignition: Reproducible Robotic Simulations for Reinforcement Learning

This paper presents Gym-Ignition, a new framework to create reproducible robotic environments for reinforcement learning research. It interfaces with the new generation of Gazebo, part of the Ignition Robotics suite, which provides three main improvements for reinforcement learning applications compared to the alternatives: 1) the modular architecture enables using the simulator as a C++ library, simplifying the interconnection with external software; 2) multiple physics and rendering engines are supported as plugins, simplifying their selection during the execution; 3) the new distributed simulation capability allows simulating complex scenarios while sharing the load on multiple workers and machines. The core of Gym-Ignition is a component that contains the Ignition Gazebo simulator and exposes a simple interface for its configuration and execution. We provide a Python package that allows developers to create robotic environments simulated in Ignition Gazebo. Environments expose the common OpenAI Gym interface, making them compatible out-of-the-box with third-party frameworks containing reinforcement learning algorithms. Simulations can be executed in both headless and GUI mode, the physics engine can run in accelerated mode, and instances can be parallelized. Furthermore, the Gym-Ignition software architecture provides abstraction of the Robot and the Task, making environments agnostic on the specific runtime. This abstraction allows their execution also in a real-time setting on actual robotic platforms, even if driven by different middlewares.Comment: Accepted in SII202