We introduce a promising new approach to rigid body dynamic simulation called impulse-based simulation. The method is well suited to modeling physical systems with large numbers of collisions, or with contact modes that change frequently. All types of contact (colliding, rolling, sliding, and resting) are modeled through a series of collision impulses between the objects in contact, hence the method is simpler and faster than constraint-based simulation. We have implemented an impulse-based simulator that can currently achieve interactive simulation times, and real time simulation seems within reach. In addition, the simulator has produced physically accurate results in several qualitative and quantitative experiments. After giving an overview of impulse-based dynamic simulation, we discuss collision detection and collision response in this context, and present

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We consider the simulation of nonconvex rigid bodies focusing on interactions such as collision, contact, friction (kinetic, static, rolling and spinning) and stacking. We advocate representing the geometry with both a triangulated surface and a signed distance function defined on a grid, and this dual representation is shown to have many advantages. We propose a novel approach to time integration merging it with the collision and contact processing algorithms in a fashion that obviates the need for ad hoc threshold velocities. We show that this approach matches the theoretical solution for blocks sliding and stopping on inclined planes with friction. We also present a new shock propagation algorithm that allows for efficient use of the propagation (as opposed to the simultaneous) method for treating contact. These new techniques are demonstrated on a variety of problems ranging from simple test cases to stacking problems with as many as 1000 nonconvex rigid bodies with friction as shown in Figure 1.

Many applications in Computer Graphics require fast and robust 3D collision detection algorithms. These algorithms can be grouped into four approaches: space-time volume intersection, swept volume interference, multiple interference detection and trajectory parameterization. While some approaches are linked to a particular object representation scheme (e.g., space-time volume intersection is particularly suited to a CSG representation), others do not. The multiple interference detection approach has been the most widely used under a variety of sampling strategies, reducing the collision detection problem to multiple calls to static interference tests. In most cases, these tests boil down to detecting intersections between simple geometric entities, such as spheres, boxes aligned with the coordinate axes, or polygons and segments. The computational cost of a collision detection algorithm depends not only on the complexity of the basic interference test used, but also on the ...

this paper we describe the first complete algorithm to design such sequences for a given convex polygonal part. The algorithm is complete in the sense that it is guaranteed to find a design if one exists and to terminate with a negative report otherwise. Based on an exact breadth-first search of the design space, the algorithm is also guaranteed to find the design requiring the fewest fences. We describe the algorithm and compare results with those previously reported. We conjecture that a fence design exists to orient any convex polygonal part.

We consider the problem of designing traditional (e.g. vibratory bowl) feeders for singulating and orienting industrial parts. Our ultimate goal is to prototype new designs using analytically- and geometrically-based methods. We have developed a tool for designing industrial parts feeders based on dynamic simulation. Our tool allows us to automatically perform multiple feeder design experiments, and to evaluate their outcomes. These results can then be used to compute the probabilities of a Markov model for the feeder. To demonstrate our technique, we present preliminary results for the design of two simple feeders. Our findings suggest that using dynamic simulation is a promising approach for designing parts feeders. 1 Introduction Vibratory bowl feeders and hopper feeders have proliferated industry as a cost-effective means for reliably orienting parts. These feeders and their transfer conveyorsaccount for nearly one-third of the cost and failure risk of an assembly system [8] . H...

The GALILEO-system is a developmental state-of-the-art rigid body simulation tool with a strong bias to the simulation of unilateral contacts for virtual reality applications. On the one hand the system is aimed at closing the gap between the ‘paradigms of impulse-based simulation ’ and of ‘constraint-based simulation’. On the other hand the chosen simulation techniques enable a balancing of the trade-off between the real-time demands of virtual environments (i.e. 15-25 visualizations per second) and the degree of physical correctness of the simulation. The focus of this paper lies on the constraint-based simulation approach to threedimensional multibody systems including a scalable friction model. This is only one of the two main components of the GALILEO-software-module. A nonlinear complementarity problem (NCP) describes the equations of motion, the contact conditions of the objects and the Coulomb friction model. Further on we show, as an interesting evaluation example from the field of ‘classical mechanics’, the first rigid body simulation of the tippe-top. 1

In this paper we examine the constraint equations developed for two general dynamic simulation systems from a new perspective. A contact space framework, similar to the operational space framework used for robotic control, is developed which allows the constraint equations for contact and collision to be easily specified. This framework also allows us to scrutinize the multiple relations that exist between the dynamic models used in simulation and the models originally developed for robotic control and analysis. This framework has been used to develop a simulator that can model complex interaction between generalized articulated mechanical systems at interactive rates. 1 Introduction In recent years, there have been many efforts to accurately simulate physical environments in both robotics and computer graphics. A physically accurate simulation can be used to obtain insight into the real-world behavior of a robotic, fabrication or other dynamic environment. Two recent simulator syste...

Force feedback coupled with a real-time physically realistic graphic display provides a human operator with an artificial sense of presence in a virtual environment. Furthermore, it allows a human operator to interact with the virtual environment through "touch". In this paper, we describe a haptic simulation system that allows a human operator to perform real-time interaction with soft 3D objects that go through large global deformations. We model and simulate such a global deformation using geometrically nonlinear finite element methods (FEM). We also introduce an efficient method that computes the force feedback, in real-time, by simulating the collision between the virtual "proxy"andthedeformable object. To perceptually satisfy a human operator, haptics requires a much higher update frequency (at least 1000Hz) than graphics. We update the graphics using full simulation and interpolate the fully simulated states at a higher frequency to render haptics. The interpolation is made possible by intentionally delaying the display (both graphics and haptics) by one full simulation cycle.

In this paper, we present the results of our experimental effort in one form of impulsive manipulation: tapping. Our previous work studied the mechanics of tapping a planar object which then slides on a support surface, coming to rest due to friction. This work addresses the practical issues in creating a system which uses this mode of manipulation. We begin with the design of tapping devices---end effectors designed to deliver an impulse to an object, and report some of the issues we have found to be important in their design. Our next step was to perform single-tap experiments in order to fit and evaluate the models of impact and sliding. These experiments have shown that objects rotate less than predicted; we have found that the addition of a scaling factor for the torque due to friction enables the models to predict object motion reasonably well. In order to do positioning experiments, we developed a number of planning methods (or feedback control strategies) to compensate for erro...