This paper describes algorithms for the animation of men and women performing three dynamic athletic behaviors: running, bicycling, and vaulting. We animate these behaviors using control algorithms that cause a physically realistic model to perform the desired maneuver. For example, control algorithms allow the simulated humans to maintain balance while moving their arms, to run or bicycle at a variety of speeds, and to perform a handspring vault. Algorithms for group behaviors allow a number of simulated bicyclists to ride as a group while avoiding simple patterns of obstacles. We add secondarymotion to the animations with springmass simulations of clothing driven by the rigid-body motion of the simulated human. For each simulation, we compare the computed motion to that of humans performing similar maneuvers both qualitatively through the comparison of real and simulated video images and quantitatively through the comparison of simulated and biomechanical data.

Image rendering maps scene parameters to output pixel values; animation maps motion-control parameters to trajectory values. Because these mapping functions are usually multidimensional, nonlinear, and discontinuous, #nding input parameters that yield desirable output values is often a painful process of manual tweaking. Interactiveevolution and inverse design are two general methodologies for computer-assisted parameter setting in which the computer plays a prominent role. In this paper we present another such methodology.

This paper describes an algorithm for automatically adapting existing simulated behaviors to new characters. Animating a new character is difficult because a control system tuned for one character will not, in general, work on a character with different limb lengths, masses, or moments of inertia. The algorithm presented here adapts the control system to a new character in two stages. First, the control system parameters are scaled based on the sizes, masses, and moments of inertia of the new and the original characters. Then a subset of the parameters is fine-tuned using a search process based on simulated annealing. To demonstrate the effectiveness of this approach, we animate the running motion of a woman, child, and imaginary character by modifying the control system for a man. We also animate the bicycling motion of a second imaginary character by modifying the control system for a man. We evaluate the results of this approach by comparing the motion of the simulated human runners...

Birds, fish, and many other animals travel as a flock, school, or herd. Animals in these groups must remain in close proximity while avoiding collisions with neighbors and with obstacles. We would like to reproduce this behavior for groups of artificial creatures with significant dynamics. In this paper we describe an algorithm for creatures that move as a group and evaluate the performance of the algorithm with three simulated systems: legged robots, human-like bicycle riders, and point-mass systems. Both the legged robots and the bicyclists are dynamic simulations that must control balance, facing direction, and forward speed as well as movement with the group. The point-mass systems have minimal dynamics and are included to facilitate our understanding of the effects of the dynamics on the performance of the algorithms. Introduction To run as a group, animals must remain in close proximity while changing direction and velocity and avoiding collisions with other group members and o...

Legged robots can sustain stable dynamic locomotion without sensors or feedback. It is possible to construct a running robot that is inherently stable and needs no sensing to reject minor perturbations; the robot is therefore self-stabilizing. In contrast, most previous attempts to make robots run have used active, high bandwidth feedback control systems. I mathematically analyze the behavior of a simple self-stabilizing monopod, determine a running pattern, and generalize the motion to two and four legs. Using physics-based simulations, I demonstrate the stability of these motions as applied to robots. The quadruped can stably trot, pace, bound, and gallop. I verify the simulations' behavior with a physical monopod robot. Low bandwidth control systems layered on top of the self-stabilizing running motion could allow the robot to respond to the operator's desires or changes in the environment. Thesis Supervisor: Marc Raibert Title: Professor of Electrical Engineering and Computer Scien...

The motion of a human platform diver was simulated using a dynamic model and a control system. The dynamic model has 32 actuated degrees of freedom and dynamic parameters within the range of those reported in the literature for humans. The control system uses algorithms for balance, jumping, and twisting to initiate the dive, sequences of desired values for proportional--derivative servos to perform the aerial portion of the dive, and a state machine to sequence the actions throughout the dive. The motion of the simulated diver closely resembles video footage of dives performed by human athletes. The control and simulation techniques presented in this paper are useful for providing realistic motion for synthetic actors in computer animations and virtual environments and may someday be useful for analysis of sports performance. 1. Introduction In this paper, we explore dynamic simulation as a technique for generating animations of an Olympic sport, platform diving. The simulated diver ...

In this paper we describe an animation of a human platform diver. We simulated the motion of the diver using a dynamic model and a control system. The dynamic model is a 32 degree-of-freedom rigid body model with dynamic parameters similar to those reported in the literature for humans. The control system uses algorithms for balance, jumping, and twisting to initiate the dive, proportionalderivative servos to perform the aerial portion of the dive, and a state machine to sequence the actions throughout the dive. The motion of the simulated diver closely resembles video footage of dives performed by human athletes. The combination of dynamic simulation and a control system allowed us to animate the diver using high level commands. The control and simulation techniques presented in this paper may be useful for analysis of sports performance and for providing realistic motion for synthetic actors in computer animation and virtual environments. Keywords: Human Figure Animation, Simulatio...

Birds, fish, and many other animals are able to move gracefully and efficiently as a herd, flock, or school. We would like to reproduce this behavior for herds of artificial creatures with significant dynamics. This paper develops an algorithm for grouping behaviors and evaluates the performance of the algorithm on two types of systems: a full dynamic simulation of a legged robot that must balance as well as move with the herd and a point mass with minimal dynamics. Robust control algorithms for group behaviors of dynamic systems will allow us to generate realistic motion for animation using high-level controls, to develop synthetic actors for use in virtual environments, mobile robotics, and perhaps to improve our understanding of the behavior of biological systems. 1 Introduction To run as a herd, animals must remain in close proximity while changing direction and velocity and while avoiding collisions with other members of the herd and obstacles in the environment. In this paper, w...

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Many robot applications require legged robots to traverse rough or unmodeled terrain. This paper explores strategies that would enable legged robots to respond to two common types of surface contact error: slipping and tripping. Because of the rapid response required and the difficulty of sensing uneven terrain, we propose a set of reflexes that would permit the robot to react without modeling or analyzing the error condition in detail. These reflexive responses allow robust recovery from a variety of contact errors. We present simulation trials for single-slip tasks with varying coefficients of friction and single-trip tasks with varying obstacle heights. Keywords--- reactive control, reflexes, rough terrain, slipping, tripping, biped locomotion I. Introduction R OUGH terrain occurs not only in natural environments but also in environments that have been constructed or modified for human use. Currently, most legged robots lack the control techniques that would allow them to behave ...