607 research outputs found
A Massively-Parallel 3D Simulator for Soft and Hybrid Robots
Simulation is an important step in robotics for creating control policies and
testing various physical parameters. Soft robotics is a field that presents
unique physical challenges for simulating its subjects due to the nonlinearity
of deformable material components along with other innovative, and often
complex, physical properties. Because of the computational cost of simulating
soft and heterogeneous objects with traditional techniques, rigid robotics
simulators are not well suited to simulating soft robots. Thus, many engineers
must build their own one-off simulators tailored to their system, or use
existing simulators with reduced performance. In order to facilitate the
development of this exciting technology, this work presents an
interactive-speed, accurate, and versatile simulator for a variety of types of
soft robots. Cronos, our open-source 3D simulation engine, parallelizes a
mass-spring model for ultra-fast performance on both deformable and rigid
objects. Our approach is applicable to a wide array of nonlinear material
configurations, including high deformability, volumetric actuation, or
heterogenous stiffness. This versatility provides the ability to mix materials
and geometric components freely within a single robot simulation. By exploiting
the flexibility and scalability of nonlinear Hookean mass-spring systems, this
framework simulates soft and rigid objects via a highly parallel model for near
real-time speed. We describe an efficient GPU CUDA implementation, which we
demonstrate to achieve computation of over 1 billion elements per second on
consumer-grade GPU cards. Dynamic physical accuracy of the system is validated
by comparing results to Euler-Bernoulli beam theory, natural frequency
predictions, and empirical data of a soft structure under large deformation
Scalable partitioning for parallel position based dynamics
We introduce a practical partitioning technique designed for parallelizing Position Based Dynamics, and exploiting
the ubiquitous multi-core processors present in current commodity GPUs. The input is a set of particles whose
dynamics is influenced by spatial constraints. In the initialization phase, we build a graph in which each node
corresponds to a constraint and two constraints are connected by an edge if they influence at least one common
particle. We introduce a novel greedy algorithm for inserting additional constraints (phantoms) in the graph
such that the resulting topology is q-colourable, where ˆ qˆ ≥ 2 is an arbitrary number. We color the graph, and
the constraints with the same color are assigned to the same partition. Then, the set of constraints belonging to
each partition is solved in parallel during the animation phase. We demonstrate this by using our partitioning
technique; the performance hit caused by the GPU kernel calls is significantly decreased, leaving unaffected the
visual quality, robustness and speed of serial position based dynamics
GPU-based Real-Time Soft Tissue Deformation with Cutting and Haptic Feedback
Special Issue on Biomechanical Modelling of Soft Tissue MotionInternational audienceThis article describes a series of contributions in the field of real-time simulation of soft tissue biomechanics. These contributions address various requirements for interactive simulation of complex surgical procedures. In particular, this article presents results in the areas of soft tissue deformation, contact modelling, simulation of cutting, and haptic rendering, which are all relevant to a variety of medical interventions. The contributions described in this article share a common underlying model of deformation and rely on GPU implementations to significantly improve computation times. This consistency in the modelling technique and computational approach ensures coherent results as well as efficient, robust and flexible solutions
Real-time deformation and fracture in a game environment
This paper describes a simulation system that has been developed to model the deformation and fracture of solid objects in a real-time gaming context. Based around a corotational tetrahedral finite element method, this system has been constructed from components published in the graphics and computational physics literatures. The goal of this paper is to describe how these components can be combined to produce an engine that is robust to unpredictable user interactions, fast enough to model reasonable scenarios at real-time speeds, suitable for use in the design of a game level, and with appropriate controls allowing content creators to match artistic direction. Details concerning parallel implementation, solver design, rendering method, and other aspects of the simulation are elucidated with the intent of providing a guide to others wishing to implement similar systems. Examples from in-game scenes captured on the Xbox 360, PS3, and PC platforms are included. © 2009 ACM
Fast GPU-Based Two-Way Continuous Collision Handling
Step-and-project is a popular way to simulate non-penetrated deformable
bodies in physically-based animation. First integrating the system in time
regardless of contacts and post resolving potential intersections practically
strike a good balance between plausibility and efficiency. However, existing
methods could be defective and unsafe when the time step is large, taking risks
of failures or demands of repetitive collision testing and resolving that
severely degrade performance. In this paper, we propose a novel two-way method
for fast and reliable continuous collision handling. Our method launches the
optimization at both ends of the intermediate time-integrated state and the
previous intersection-free state, progressively generating a piecewise-linear
path and finally reaching a feasible solution for the next time step.
Technically, our method interleaves between a forward step and a backward step
at a low cost, until the result is conditionally converged. Due to a set of
unified volume-based contact constraints, our method can flexibly and reliably
handle a variety of codimensional deformable bodies, including volumetric
bodies, cloth, hair and sand. The experiments show that our method is safe,
robust, physically faithful and numerically efficient, especially suitable for
large deformations or large time steps
Six Degrees-of-Freedom Haptic Interaction with Fluids
International audienceIn this work, we propose a novel approach that allows real-time six Degrees of Freedom (DoF) haptic interaction with fluids of variable viscosity. Our haptic rendering technique, based on a Smoothed-Particle Hydrodynamics physical model, provides a realistic haptic feedback through physically based forces. 6DoF haptic interaction with fluids is made possible thanks to a new coupling scheme and a unified particle model, allowing the use of arbitrary-shaped rigid bodies. Particularly, fluid containers can be created to hold fluid and hence transmit to the user force feedback coming from fluid stirring, pouring, shaking, and scooping, to name a few. In addition, we adapted an existing visual rendering algorithm to meet the frame rate requirements of the haptic algorithms. We evaluate and illustrate the main features of our approach through different scenarios, highlighting the 6DoF haptic feedback and the use of containers
Real-time Knowledge-based Fuzzy Logic Model for Soft Tissue Deformation
In this research, the improved mass spring model is presented to simulate the human liver deformation. The underlying MSM is redesigned where fuzzy knowledge-based approaches are implemented to determine the stiffness values. Results show that fuzzy approaches are in very good agreement to the benchmark model. The novelty of this research is that for liver deformation in particular, no specific contributions in the literature exist reporting on real-time knowledge-based fuzzy MSM for liver deformation
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