Physics-based Animation Research Articles

Automated Synthesis of Numerical Programs for Simulation of Rigid Mechanical Systems in Physics-Based Animation

Physics-based animation programs are important in a variety of contexts, including science, engineering, education and entertainment among others. Manual construction of such programs is expensive, time-consuming and prone to error. We have developed a system for automatically synthesizing physics-based animation programs for a significant class of problems: constrained systems of rigid bodies, subject to driving and dissipative forces, under the control of an interactive user. Our system includes a graphical interface for specifying a physical scenario, including objects, geometry and coordinate systems, along with a symbolic interface for specifying dynamical variables, forces and constraints operating in the scenario. The entities defined in the graphical interface serve as the underlying vocabulary for specifications entered in the symbolic interface. Our system partitions the constraints and dynamical variables into classes and assigns each class to be implemented in a different component of a general simulation program scheme. It generates a numerical C++ simulation program that drives a real-time animation of the specified scenario. Our system is implemented as a collection of rewrite rules in the Mathematica programming language. Our approach provides some of the benefits of formal deductive program synthesis, while keeping the computational costs of program synthesis more in line with conventional program generator technology. We have successfully tested our system on numerous examples.

PHYSICALLY-BASED COMPUTER ANIMATION CONTROLLED BY MOTION FEATURES

This paper presents motion descriptions for physically-based computer animation. Motion features which are symbolic representations of motion with physical procedures and geometric procedures are proposed for stable control of physically-based animation. The animation system executes physical procedures and geometric procedures suitable for the motion features given by animators. Computation of the motion used in motion features is robust compared to solving dynamic equations when objects are under geometric constraints. Since most mechanical parts are under geometric constraints, robust control by motion features is useful. Graphical representations of motion features for comprehension are also stated. A mass-spring-damper system model is used as a physically-based model in the implemented system to deal with mass points, rigid bodies and flexible bodies altogether.

Interactive control of biomechanical animation

Physics-based animation can be generated by performing a complete dynamical simulation of multibody systems. This leads to the solving of a complex system of differential equations in which biomechanical results for the physics of impacts are incorporated. Motion control is achieved by interactively modifying the internal torques. Realtime response requires the distribution of the workload of the computation between a high-speed compute server and the graphics workstation by means of a remote-procedure call mechanism.

Physically-based modeling: past, present, and future

Physically-based modeling: past, present, and future