D. Bara, \Fast Contact Force Computation for Nonpenetrating Rigid Bodies", Computer Graphics Proceedings, July 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....also be useful in robotic motion planning. Such a system could plan movements by considering large numbers of possible motions looking for some desired outcome (similar to the way Deep Blue plays chess [1] 2 Background A wide range of techniques exist for physical modeling of solid objects [2, 3, 4, 5, 6]. Rigid body techniques [2, 5] tend to be computationally ecient on general purpose CPUs. Since the object is not allowed to deform, collision detection is the only signi cant computational challenge. The disadvantages of this approach include collision detection performance and inability to model ....

.... Such a system could plan movements by considering large numbers of possible motions looking for some desired outcome (similar to the way Deep Blue plays chess [1] 2 Background A wide range of techniques exist for physical modeling of solid objects [2, 3, 4, 5, 6] Rigid body techniques [2, 5] tend to be computationally ecient on general purpose CPUs. Since the object is not allowed to deform, collision detection is the only signi cant computational challenge. The disadvantages of this approach include collision detection performance and inability to model object deformations. More ....

D. Bara, \Fast Contact Force Computation for Nonpenetrating Rigid Bodies ", Computer Graphics Proceedings, July 1994.

....describes two di erent mathematical approaches to determine the reaction forces for colliding rigid bodies. 2 Calculation of contact forces Physically accurate models for the determination of contact forces use a complementarity formulation, which re ects the unilateral nature of the contacts [2, 5, 1, 3, 4]. These methods are well suited for situations with multiple contact points and can be extended to handle friction. Let us consider a multi body system consisting of n rigid bodies in mutual contact at K contact points. Suppose that body B i k touches body B j k at the k th contact point p k . ....

.... 0, b 0 and ab = 0. We de ne the function : IR 2K IR K by (f) f1 ; 1 ( f) fK ; K ( f) T Now we can transform the NCP into the non linear equation system (f) 0; 5) which can again be solved by the Newton Raphson method. In contrast to the classical method [2] this approach uses the contact distances instead of the contact accelerations as variables complementary to the contact forces. In this way the integration of the motion equations can be performed in a stable way with respect to the geometric constraints. The classical method however has to face ....

D. Bara. Fast contact force computation for nonpenetrating rigid bodies. In SIGGRAPH, pages 174-203, July 1994.

....in using springs. If two objects are going to interpenetrate, a spring force depending on the penetration depth pushes them apart. Physically more correct models for the determination of contact forces use a complementarity formulation, which re ects the unilateral nature of the contacts [L ot82, Bar94, BS98, SS98] These methods are well suited to cope with situations in which the bodies mutually touch at many contact points. Even the consideration of friction is possible. An alternative method, called impulse based simulation [Mir96] also takes plastic and elastic impacts between the bodies ....

....In the course of the algorithm the proximity information is continuously improved so that a lower bound of distance can be provided when its execution is suspended. a new method for the determination of contact forces, which is based on a complementarity formulation. In contrast to [Bar94] the contact forces and the contact distances are the complementary variables and not any derivatives thereof. This avoids an accumulation of numerical inaccuracies and ensures that the geometric contact conditions are satis ed quite exactly. 2 THE ARCHITECTURE OF SIlVIA Our fundamental data ....

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D. Bara. Fast contact force computation for nonpenetrating rigid bodies. In SIGGRAPH, pages 174-203, July 1994.

....of the objects. Notice that the LCP approach is not the well known standard LCP formulation with all its drawbacks based on a complementarity relation between the conditions imposed on the normal accelerations of the contact points and the resulting contact forces as described e.g. by Bara [Ba94] and others. We have a complicated complementarity relation between two types of initially nonlinear constraints that have to be enforced for every contact point: 1. the Coulomb friction constraint and 2. the geometrical contact condition. The simulations are energy consistent and do not have the ....

D. Bara, 1994, "Fast contact force computation for nonpenetrating rigid bodies", Proceedings of the ACM Computer Graphics Conference

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D. Bara, \Fast Contact Force Computation for Nonpenetrating Rigid Bodies", Computer Graphics Proceedings, July 1994.

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