2,601 research outputs found
Real-Time Numerical Simulation for Accurate Soft Tissues Modeling during Haptic Interaction
The simulation of fabrics physics and its interaction with the human body has been largely studied in recent years to provide realistic-looking garments and wears specifically in the entertainment business. When the purpose of the simulation is to obtain scientific measures and detailed mechanical properties of the interaction, the underlying physical models should be enhanced to obtain better simulation accuracy increasing the modeling complexity and relaxing the simulation timing constraints to properly solve the set of equations under analysis. However, in the specific field of haptic interaction, the desiderata are to have both physical consistency and high frame rate to display stable and coherent stimuli as feedback to the user requiring a tradeoff between accuracy and real-time interaction. This work introduces a haptic system for the evaluation of the fabric hand of specific garments either existing or yet to be produced in a virtual reality simulation. The modeling is based on the co-rotational Finite Element approach that allows for large displacements but the small deformation of the elements. The proposed system can be beneficial for the fabrics industry both in the design phase or in the presentation phase, where a virtual fabric portfolio can be shown to customers around the world. Results exhibit the feasibility of high-frequency real-time simulation for haptic interaction with virtual garments employing realistic mechanical properties of the fabric materials
Virtual Reality Games for Motor Rehabilitation
This paper presents a fuzzy logic based method to track user satisfaction without the need for devices to monitor users physiological conditions. User satisfaction is the key to any product’s acceptance; computer applications and video games provide a unique opportunity to provide a tailored environment for each user to better suit their needs. We have implemented a non-adaptive fuzzy logic model of emotion, based on the emotional component of the Fuzzy Logic Adaptive Model of Emotion (FLAME) proposed by El-Nasr, to estimate player emotion in UnrealTournament 2004. In this paper we describe the implementation of this system and present the results of one of several play tests. Our research contradicts the current literature that suggests physiological measurements are needed. We show that it is possible to use a software only method to estimate user emotion
Investigation of the use of meshfree methods for haptic thermal management of design and simulation of MEMS
This thesis presents a novel approach of using haptic sensing technology combined with virtual environment (VE) for the thermal management of Micro-Electro-Mechanical-Systems (MEMS) design. The goal is to reduce the development cycle by avoiding the costly iterative prototyping procedure. In this regard, we use haptic feedback with virtua lprototyping along with an immersing environment. We also aim to improve the productivity and capability of the designer to better grasp the phenomena operating at the micro-scale level, as well as to augment computational steering through haptic channels. To validate the concept of haptic thermal management, we have implemented a demonstrator with a user friendly interface which allows to intuitively "feel" the temperature field through our concept of haptic texturing. The temperature field in a simple MEMS component is modeled using finite element methods (FEM) or finite difference method (FDM) and the user is able to feel thermal expansion using a combination of different haptic feedback. In haptic application, the force rendering loop needs to be updated at a frequency of 1Khz in order to maintain continuity in the user perception. When using FEM or FDM for our three-dimensional model, the computational cost increases rapidly as the mesh size is reduced to ensure accuracy. Hence, it constrains the complexity of the physical model to approximate temperature or stress field solution. It would also be difficult to generate or refine the mesh in real time for CAD process. In order to circumvent the limitations due to the use of conventional mesh-based techniques and to avoid the bothersome task of generating and refining the mesh, we investigate the potential of meshfree methods in the context of our haptic application. We review and compare the different meshfree formulations against FEM mesh based technique. We have implemented the different methods for benchmarking thermal conduction and elastic problems. The main work of this thesis is to determine the relevance of the meshfree option in terms of flexibility of design and computational charge for haptic physical model
Model reduction for the material point method via an implicit neural representation of the deformation map
This work proposes a model-reduction approach for the material point method
on nonlinear manifolds. Our technique approximates the by
approximating the deformation map using an implicit neural representation that
restricts deformation trajectories to reside on a low-dimensional manifold. By
explicitly approximating the deformation map, its spatiotemporal gradients --
in particular the deformation gradient and the velocity -- can be computed via
analytical differentiation. In contrast to typical model-reduction techniques
that construct a linear or nonlinear manifold to approximate the (finite number
of) degrees of freedom characterizing a given spatial discretization, the use
of an implicit neural representation enables the proposed method to approximate
the deformation map. This allows the kinematic
approximation to remain agnostic to the discretization. Consequently, the
technique supports dynamic discretizations -- including resolution changes --
during the course of the online reduced-order-model simulation.
To generate for the generalized coordinates, we propose a
family of projection techniques. At each time step, these techniques: (1)
Calculate full-space kinematics at quadrature points, (2) Calculate the
full-space dynamics for a subset of `sample' material points, and (3) Calculate
the reduced-space dynamics by projecting the updated full-space position and
velocity onto the low-dimensional manifold and tangent space, respectively. We
achieve significant computational speedup via hyper-reduction that ensures all
three steps execute on only a small subset of the problem's spatial domain.
Large-scale numerical examples with millions of material points illustrate the
method's ability to gain an order of magnitude computational-cost saving --
indeed -- with negligible errors
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