Implicit contact handling for deformable objects (original) (raw)
Efficient Simulation of Contact Between Rigid and Deformable Objects
To appear in Proc. of Multibody Dynamics, 2011
Contact coupling between deformable and rigid bodies often induces situations where the surfaces of both types of bodies collide over a large area. This situation introduces serious difficulties in LCP-type contact solvers, because a large amount of contact constraints are inertially coupled through the rigid body. In this paper, we present an algorithm for efficiently simulating contact between rigid and deformable bodies. The solution to the LCP involves two steps: building the system matrix, which tends to be large and dense due to the coupling between the rigid and deformable bodies in contact, and solving the resulting problem. We efficiently handle both steps by reformulating the large LCP and separating constraint sets acting on rigid bodies alone, on deformable bodies alone, and on both rigid and deformable bodies. A modified projected Gauss-Seidel solver handles the partitioned sets of constraints in an efficient manner. We demonstrate our algorithm on several complex and contact-intensive scenarios, such as those involving cloth simulations, or contact between bone and soft-tissue.
Dynamic Interaction between Deformable Surfaces and Nonsmooth Objects
IEEE Transactions on Visualization and Computer Graphics, 2005
In this paper, we introduce new techniques that enhance the computational performance for the interactions between sharp objects and deformable surfaces. The new formulation is based on a time-domain predictor-corrector model. For this purpose, we define a new kind of (π, β, I)-surface. The partitioning of a deformable surface into a finite set of (π, β, I)-surfaces allows us to prune a large number of noncolliding feature pairs. This leads to a significant performance improvement in the collision detection process. The intrinsic collision detection is performed in the time domain. Although it is more expensive compared to the static interference test, it avoids portions of the surfaces passing through each other in a single time step. In order to resolve all the possible collision events at a given time, a penetration-free motion space is constructed for each colliding particle. By keeping the velocity of each particle inside the motion space, we guarantee that the current colliding feature pairs will not penetrate each other in the subsequent motion. A static analysis approach is adopted to handle friction by considering the forces acting on the particles and their velocities. In our formulation, we further reduce the computational complexity by eliminating the need to compute repulsive forces.
An Efficient Implicit Scheme for the Treatment of Frictional Contact between Deformable Bodies
1998
Newly interpolated implicit schemes are presented for the transient response of highly nonlinear problems of large deformation analysis presenting important material dissipation. Surprisingly these schemes exhibit excellent convergence properties that make them a cost efficient alternative to explicit schemes generally advocated as the best choice for these problems. Three problems of dynamical contact between deformable bodies illustrate this efficiency.
A collision model for deformable bodies
Proceedings. 1998 IEEE/RSJ International Conference on Intelligent Robots and Systems. Innovations in Theory, Practice and Applications (Cat. No.98CH36190), 1998
| In this paper, we describe models and algorithms designed to produce e cient and physically consistent dynamic simulations. These models and algorithms have been implemented in a unique framework, modeling both deformations and contacts through visco-elastic relations. Since this model of interaction (known as \penalty based") is much debated, we present a detailed study of this model. Indeed, the \penalty" based model is supposed to have two major drawbacks : -determining the visco-elastic parameters and -choosing the computation time step. We present a solution for both problems based on physical concepts. Finally, we will present results comparing real data, \impulse" based simulation and \penalty" based simulation.
A Kinematic Model for Collision Response
One aspect of traditional 3D animation using clay or plasticine is the ease with which the object can be deformed. Animators take for granted the ability to interactively press complex objects together. In 3D computer animation, this ability is severly restricted and any improvement would drastically increase the range and style of animations that can be created within a production environment. This paper presents a simple, fast, geometric approach to controlling the nature, extent and timing of the surface deformations arising from the interpenetration of kinematically controlled animated objects. Rather than using dynamic simulations, which are difficult to configure, code, and control, the algorithm presented here formulates collision response kinematically by moving points on a multiresolution surface towards goals points at a certain rate. This new multi-resolution approach to deformations provides control over the response of the surface using a small number of paramete...
Modeling and Simulation of Collision Response Between Deformable Objects
1 abd-lah@fsksm.utm.my, 2 saandilian@hotmail.com, 3 daut@fsksm.utm.my, 4 haida@fsksm.utm.my } Abstract Many simulation and modelling depict two or more objects interacting and potentially colliding. Collision response is a complex process if the objects are intended to respond like soft bodies or deformation bodies and to exhibit the properties of real objects. The main problem in collision response between deformable objects is interpenetration. The goal of this research is to develop an algorithm that provides a realistic, accurate, stable and fast collision response between deformable objects. So, an algorithm will be introduced to solve the problem in collision response between deformable objects. We have developed a technique we call Penalty Impulse Hybrid Method (PIHM). The PIHM method combines two known approaches, the Impulse Based Method and the Force Based Penalty Method which both are commonly applied for simulation and real-time animation of deformable objects.
This paper proposes an efficient collision detection method which is compatible with time-stepping methods in the sense that it enables the robust simulation non-smooth contact between rigid bodies with complex shapes, including industrial CAD models of various topology and in presence of conforming contact situations. It introduces a discrete representation of rigid body shapes based on dilated simplicial complexes, which generalizes the notion of triangulation to domains of arbitrary topological dimension. It also defines finite collections of point contacts between those shapes thanks to quasi-LMDs, which are defined as an extension of local minimum distances with respect to small relative rotations, between the base complexes. Smooth gap functions associated to these point contacts are defined, as well as complete and smooth generalized contact kinematics, enabling the use of non-smooth contact laws like Signorini or Coulomb. Quasi-LMDs also lead to the stable treatment of conforming contact cases. An efficient method based on 5D+1 bounding volume hierarchies for computing quasi-LMDs is presented. Finally, robustness and performance benchmarks show that our method combined with a fast time-stepping-based solver allows interactive-time simulations of complex and possibly conforming contact situations.
APPLICATION OF A RESPONSE SCHEME FOR COLLISION HANDLING AMONG DEFORMABLE OBJECTS
Collision response schemes and deformable models have been recently an important subject of research, since many medical and entertainment applications require the simulation of real environments with deformable objects. Early research in this area comes from the field of Engineering, which propose very exact models but at a very high computational cost. New models propose plausible techniques which study the discrete nature of object representations in order to reduce the time required by these simulations. This paper presents the implementation of a very efficient collision response scheme which calculates the depth and direction of the penetration in the contact region, as well as the deformable model applied to the surface of the object. Furthermore, we present the application of the new collision detection scheme for the simulation of the interaction between a human abdominal organ and a surgery instrument.
An automatic collision response algorithm
1998
Many animations depict two or more objects interacting and potentially colliding. Collision response is a complex process if the objects are intended to respond like soft bodies and to exhibit the properties of real objects. Physically-based models calculate contact forces to incorporate into the calculation of velocities and positions of the control mesh. Some physically-based models, for example those that model cloth, strive for visually realistic results. Until recently the magnitude of the calculations required for physically-based modeling have precluded real-time interaction. A complaint with physically-based models is the correlation between the parameters, such as forces and torques, and the resulting 'look' of the response are sometimes di cult for the user to understand. The work presented in this thesis does not strive for the simulation of real object properties. Instead it tries to remove the interpenetration between two objects while providing a set of control...
A Contact Dynamics Simulation Framework for Robotics
2008
An object-oriented framework that facilitates the creation of contact models based on compliance is introduced. Contact models are created by adding contact model components to a standard container class. The geometric components can readily be implemented for objects with simple geometries. The volumetric contact model is then proposed to handle complex objects. It can be used as a general-purpose tool to model contact between objects of any shapes. Numerical simulation results are presented.
Continuous collision detection for non-rigid contact computations using local advancement
Proceedings - IEEE International Conference on Robotics and Automation, 2010
We present a novel algorithm to perform continuous collision detection(CCD) between non-rigid, deformable models using local advancement. Given the initial and final configurations of a deformable model, our algorithm computes linear deformation by interpolating the vertices from the initial to the final configurations with a straight line path and checks for collision along that path. Our approach is applicable to polygon-soup models with arbitrary topology, handles selfcollisions and makes no assumption about the underlying nonrigid motion. We accelerate the algorithm by computing motion bounds on the primitives and their bounding volumes. These bounds are combined with hierarchical culling techniques and used for fast collision checking. In practice, we have observed up to four times improvement in running time because of local advancement.
Adaptive Dynamics with Efficient Contact Handling for Articulated Robots
2006
We present a novel adaptive dynamics algorithm with efficient contact handling for articulated robots. Our algorithm automatically computes a fraction of the joints whose motion provides a good approximation to overall robot dynamics. We extend Featherstone's Divide-and-Conquer algorithm and are able to efficiently handle all contacts and collisions with the obstacles in the environment. Overall, our approach provides a time-critical collision detection and resolution algorithm for highly articulated bodies and its complexity is sub-linear in the number of degrees-of-freedom. We demonstrate our algorithm on several complex articulated robots consisting of hundreds of joints. Modeling and simulation of multi-body dynamical systems has been well-studied due to its wide applications in robotics and automation, molecular modeling, computer animation, medical simulations, and engineering analysis. Examples of highly articulated robots include snake or serpentine robots, reconfigurable robots [3], , and long mechanical chains. In molecular modeling, long series of atoms typically represented by hundreds or thousands of links are commonly used . Catheters [10], cables , and ropes can also be modeled as articulated robots with a very high number of joints. One of the key components of multi-body dynamical systems is forward dynamics computation, which determines the acceleration and resulting motion of each link, given a set of joint forces and external forces. The optimal algorithms have a linear runtime complexity in the number of degrees of freedom (DOFs). However, these algorithms may still not be sufficiently fast for complex systems that have a very high number of degrees of freedom. Furthermore, if the environment consists of many obstacles or multiple articulated robots, dynamic simulation with robust contact or collision handling can become a major bottleneck for real-time applications. In this paper, we address the problem of handling complex interactions between articulated rigid bodies with a high number of DOFs. Our solution incorporates static or dynamic friction states, resting states, as well as separating contacts. Many different methods have been proposed to detect such interactions and handle them robustly. Some of the commonly used approaches include constraint-based, penaltybased, impulsed-based methods, or via analytical constraints. We present a novel and fast contact handling algorithm with adaptive dynamics computation for highly articulated robots. We exploit the structure of the hybrid tree representation introduced by the adaptive dynamics algorithm and show that we can also efficiently compute collision response for all contacts in a similar manner. We use impulsebased dynamics computation along with analytical constraint solving techniques. To improve the runtime performance, we derive a new formulation for the "hybrid-body Jacobian", which exploits the structure of the hybrid tree to reduce the overall computational complexity. Our algorithm has a sublinear runtime complexity in the number of DOFs and can be used to efficiently simulate the dynamics of snake-like or deformable robots with a very high number of DOFs.
Graceful Degradation of Collision Handling in Physically Based Animation
Interactive simulation is made possible in many applications by simplifying or culling the finer details that would make real-time performance impossible. This paper examines detail simplification in the specific problem of collision handling for rigid body animation. We present an automated method for calculating consistent collision response at different levels of detail. The mechanism works closely with a system which uses a pre-computed hierarchical volume model for collision detection.
Abstract A Collision Detection Framework for Deformable Objects
2009
Many collision detection methods have been proposed. Most of them can only be applied to rigid objects. In general, these methods precompute some geometric information of each object, such as bounding boxes, to be used for run-time collision detection. However, if the object deforms, the precomputed information may not be valid anymore and hence needs to be recomputed in every frame while the object is deforming. In this paper, we presents an efficient collision detection framework for deformable objects, which considers both inter-collisions and self-collisions of deformable objects modeled by NURBS surfaces. Towards the end of the paper, we show some experimental results to demonstrate the performance of the new method. Categories and Subject Descriptors I.3.5 [Computer Graphics]: Computational Geometry and Object
Graceful Degradation of Collision Handling Physically Based Animation
Computer Graphics Forum, 2000
Interactive simulation is made possible in many applications by simplifying or culling the finer details that would make real-time performance impossible. This paper examines detail simplification in the specific problem of collision handling for rigid body animation. We present an automated method for calculating consistent collision response at different levels of detail. The mechanism works closely with a system which uses a pre-computed hierarchical volume model for collision detection.
A Convex Formulation of Frictional Contact between Rigid and Deformable Bodies
arXiv (Cornell University), 2023
We present a novel convex formulation that models rigid and deformable bodies coupled through frictional contact. The formulation incorporates a new corotational material model with positive semi-definite Hessian, which allows us to extend our previous work on the convex formulation of compliant contact to model large body deformations. We rigorously characterize our approximations and present implementation details. With proven global convergence, effective warm-start, the ability to take large time steps, and specialized sparse algebra, our method runs robustly at interactive rates. We provide validation results and performance metrics on challenging simulations relevant to robotics applications. Our method is made available in the opensource robotics toolkit Drake.
1995
We present an efficient algorithm for detecting self collisions, as well as some techniques for evaluating collision inside-outside orientation in a robust way. As presented in (VOL 94), we detect collisions using a hierarchical algorithm that takes advantage of curvature properties giving us full power of hierarchical algorithms for self-collision situations. Determining the collision orientation may become a complex problem
Complex contact interactions between a robot and its environment (the contact between a dextrous hand and the grasped object, the contact between an allterrain vehicle and the terrain, ..) depend on physical properties such as mass, mass distribution, stiffness /elasticity factors, viscosity, and collision forces. Classical geometrical models (representing the spatial properties of an object) are obviously not helpful to study such interactions. So, we need another model, which represent not only the shape of the object but also its motion, its deformation, and its interaction with the environment. Such a model is called "physical model". This paper talks about RobotPhi system, which enables to physically represent robots and to study their physical behaviour. This system enables us to calculate the next position of each object and the interactions between them in linear time. It uses an adaptative time step based on the mechanical energy notion, which enables to avoid the...
Dynamic Simulation of Articulated Rigid Bodies with Contact and Collision
IEEE Transactions on Visualization and Computer Graphics, 2006
We propose a novel approach for dynamically simulating articulated rigid bodies undergoing frequent and unpredictable contact and collision. In order to leverage existing algorithms for nonconvex bodies, multiple collisions, large contact groups, stacking, etc., we use maximal rather than generalized coordinates and take an impulse-based approach that allows us to treat articulation, contact, and collision in a unified manner. Traditional constraint handling methods are subject to drift, and we propose a novel prestabilization method that does not require tunable potentially stiff parameters as does Baumgarte stabilization. This differs from poststabilization in that we compute allowable trajectories before moving the rigid bodies to their new positions, instead of correcting them after the fact when it can be difficult to incorporate the effects of contact and collision. A poststabilization technique is used for momentum and angular momentum. Our approach works with any black box method for specifying valid joint constraints and no special considerations are required for arbitrary closed loops or branching. Moreover, our implementation is linear both in the number of bodies and in the number of auxiliary contact and collision constraints, unlike many other methods that are linear in the number of bodies, but not in the number of auxiliary constraints.