Collision Resolutions in Cloth Simulation

We present a new collision resolution scheme for cloth collisions. Our main concern is to find dynamically convincing resolutions, i.e. positions and velocities of cloth elements, for any kinds of collisions occuring in cloth simulation (cloth-cloth, cloth-rigid, and cloth-cloth-rigid). We define our cloth surface as connected faces of mass particles where each particle is controlled by its internal energy functions. Our collision resolution method finds appropriate next positions and velocities of particles by conserving the particles’ momentums as accurately as possible. Cloth-cloth collision resolution is a special case of deformable N-body collision resolution. So to solve deformable N-body collision resolutions, we propose a new collision resolution method, which groups cloth particles into parts and resolves collisions between parts using the law of momentum conservation. To resolve collisions, we solve a system of linear equations derived from the collision relationships. A system of linear equations is built using a scheme adapted from the simultaneous resolution method for rigid N-body collisions [1]. For the special case where we can find cyclic relationships in collisions, we solve a system of linear inequalities derived from the collision relationships

Dynamic Simulation for Zero-Gravity Activities

Working and training for space activities is difficult in terrestrial environments. We approach this crucial aspect of space human factors through 3D computer graphics dynamics simulation of crewmembers, their tasks, and physics-based movement modeling. Such virtual crewmembers may be used to design tasks and analyze their physical workload to maximize success and safety without expensive physical mockups or partially realistic neutral-buoyancy tanks. Among the software tools we have developed are methods for fully articulated 3D human models and dynamic simulation. We are developing a fast recursive dynamics algorithm for dynamically simulating articulated 3D human models, which comprises kinematic chains - serial, closed-loop, and tree-structure - as well as the inertial properties of the segments. Motion planning is done by first solving the inverse kinematic problem to generate possible trajectories, and then by solving the resulting nonlinear optimal control problem. For example, the minimization of the torques during a simulation under certain constraints is usually applied and has its origin in the biomechanics literature. Examples of space activities shown are zero-gravity self orientation and ladder traversal. Energy expenditure is computed for the traversal task

Efforts in Preparation for Jack Validation

This document presents a detailed record of the methodologies, assumptions, limitations, and references used in creating the human figure model in Jack, a program that displays and manipulates articulated geometric figures. This report reflects current efforts to develop and refine Jack software to enable its validation and verification as a tool for performing human engineering analysis. These efforts include human figure model improvements, statistical anthropometric data processing methods, enhanced human figure model construction and measuring methods, and automated accomodation analysis. This report discusses basic details of building human models, model anthropometry, scaling, Jack anthropometry-based human models, statistical data processing, figure generation tools, anthropometric errors, inverse dynamics, smooth skin implementation, guidelines used in estimating landmark locations on the model, and recommendations for validating and verifying the Jack human figure model

Dynamic Simulation for Zero-Gravity Activities

Working and training for space activities is difficult in terrestrial environments. We approach this crucial aspect of space human factors through 3D computer graphics dynamics simulation of crewmembers, their tasks, and physics-based movement modeling. Such virtual crewmembers may be used to design tasks and analyze their physical workload to maximize success and safety without expensive physical mockups or partially realistic neutral-buoyancy tanks. Among the software tools we have developed are methods for fully articulated 3D human models and dynamic simulation. We are developing a fast recursive dynamics algorithm for dynamically simulating articulated 3D human models, which comprises kinematic chains--serial, closed-loop, and tree-structure-- as well as the inertial properties of the segments. Motion planning is done by first solving the inverse kinematic problem to generate possible trajectories, and then by solving the resulting nonlinear optimal control problem. For example, the minimization of the torques during a simulation under certain constraints is usually applied and has its origin in the biomechanics literature. Examples of space activities shown are zero-gravity self orientation and ladder traversal. Energy expenditure is computed for the traversal task

Techniques for Mitigating Lag-Time When Joining Interest Groups in Real-Time Simulations

Distributed virtual environments, which simulate a physical or imaginary world on a network and allow multiple participants to interact simultaneously with one another within it, are becoming increasingly important for both research and practical purposes. As the number of participants and the amount of information exchanged among participants increase, it is crucial to large-scale distributed virtual environments to overcome bandwidth limitations and resolve network latency and synchronization problems. We present..