1,134 research outputs found
Real-time Error Control for Surgical Simulation
Objective: To present the first real-time a posteriori error-driven adaptive
finite element approach for real-time simulation and to demonstrate the method
on a needle insertion problem. Methods: We use corotational elasticity and a
frictional needle/tissue interaction model. The problem is solved using finite
elements within SOFA. The refinement strategy relies upon a hexahedron-based
finite element method, combined with a posteriori error estimation driven local
-refinement, for simulating soft tissue deformation. Results: We control the
local and global error level in the mechanical fields (e.g. displacement or
stresses) during the simulation. We show the convergence of the algorithm on
academic examples, and demonstrate its practical usability on a percutaneous
procedure involving needle insertion in a liver. For the latter case, we
compare the force displacement curves obtained from the proposed adaptive
algorithm with that obtained from a uniform refinement approach. Conclusions:
Error control guarantees that a tolerable error level is not exceeded during
the simulations. Local mesh refinement accelerates simulations. Significance:
Our work provides a first step to discriminate between discretization error and
modeling error by providing a robust quantification of discretization error
during simulations.Comment: 12 pages, 16 figures, change of the title, submitted to IEEE TBM
Finite Element Analysis for Linear Elastic Solids Based on Subdivision Schemes
Finite element methods are used in various areas ranging from mechanical engineering to computer graphics and bio-medical applications. In engineering, a critical point is the gap between CAD and CAE. This gap results from different representations used for geometric design and physical simulation.
We present two different approaches for using subdivision solids as the only representation for modeling, simulation and visualization. This has the advantage that no data must be converted between the CAD and CAE phases. The first approach is based on an adaptive and feature-preserving tetrahedral subdivision scheme. The second approach is based on Catmull-Clark subdivision solids
Controlling the Error on Target Motion through Real-time Mesh Adaptation: Applications to Deep Brain Stimulation
We present an error-controlled mesh refinement procedure for needle insertion
simulation and apply it to the simulation of electrode implantation for deep
brain stimulation, including brain shift. Our approach enables to control the
error in the computation of the displacement and stress fields around the
needle tip and needle shaft by suitably refining the mesh, whilst maintaining a
coarser mesh in other parts of the domain. We demonstrate through academic and
practical examples that our approach increases the accuracy of the displacement
and stress fields around the needle without increasing the computational
expense. This enables real-time simulations. The proposed methodology has
direct implications to increase the accuracy and control the computational
expense of the simulation of percutaneous procedures such as biopsy,
brachytherapy, regional anesthesia, or cryotherapy and can be essential to the
development of robotic guidance.Comment: 21 pages, 14 figure
VISIO-HAPTIC DEFORMABLE MODEL FOR HAPTIC DOMINANT PALPATION SIMULATOR
Vision and haptic are two most important modalities in a medical simulation. While
visual cues assist one to see his actions when performing a medical procedure, haptic
cues enable feeling the object being manipulated during the interaction. Despite their
importance in a computer simulation, the combination of both modalities has not been
adequately assessed, especially that in a haptic dominant environment. Thus, resulting
in poor emphasis in resource allocation management in terms of effort spent in
rendering the two modalities for simulators with realistic real-time interactions.
Addressing this problem requires an investigation on whether a single modality
(haptic) or a combination of both visual and haptic could be better for learning skills
in a haptic dominant environment such as in a palpation simulator. However, before
such an investigation could take place one main technical implementation issue in
visio-haptic rendering needs to be addresse
Position Based Balloon Angioplasty
Balloon angioplasty is an endovascular procedure to widen narrowed or obstructed blood vessels, typically to treat arterial atherosclerosis. Simulating angioplasty procedure in the complex vascular structures is a challenge task since the balloon and vessels are both flexible bodies. In this paper, we proposed a position based balloon physical model to solve nonlinear physical deformation in the process of balloon inflation. Firstly, the balloon is discrete modeled by the closed triangle mesh, and the hyperelastic membrane material and continuum based formulation are combined to compute the mechanical properties in the process of balloon inflation. Then, an adaptive air mesh generation algorithm is proposed as a preprocessing procedure for accelerating the coming collision process between balloon and blood vessel according to the characteristic of collision area which is relative fixed. The experiment results show that this physical model is feasible, which could simulate the contact and deformation process between the inflation balloon and the diseased blood vessel wall with good robustness and in realtime
Adaptive Physically Based Models in Computer Graphics
International audienceOne of the major challenges in physically-based modeling is making simulations efficient. Adaptive models provide an essential solution to these efficiency goals. These models are able to self-adapt in space and time, attempting to provide the best possible compromise between accuracy and speed. This survey reviews the adaptive solutions proposed so far in computer graphics. Models are classified according to the strategy they use for adaptation, from time-stepping and freezing techniques to geometric adaptivity in the form of structured grids, meshes, and particles. Applications range from fluids, through deformable bodies, to articulated solids
Computational Methods for Crashworthiness
Presentations and discussions from the joint UVA/NASA Workshop on Computational Methods for Crashworthiness held at Langley Research Center on 2-3 Sep. 1992 are included. The presentations addressed activities in the area of impact dynamics. Workshop attendees represented NASA, the Army and Air Force, the Lawrence Livermore and Sandia National Laboratories, the aircraft and automotive industries, and academia. The workshop objectives were to assess the state-of-technology in the numerical simulation of crash and to provide guidelines for future research
- …