Student-computer interface on an intelligent tutoring system for Japanese language instruction, The

Includes bibliographical references.This work describes the human-computer interaction of an intelligent tutoring system designed to mediate some of the difficulties of acquiring proficiency in reading technical Japanese material.This material is based upon work supported by the National Science Foundation under Grant No. INT8818039

Kinetic limitations on the use of redundancy in robotic manipulators

Includes bibliographical references (page 210).The kinematic specification of motion for redundant manipulators has relied primarily on a formulation that decomposes joint velocity solutions into a pseudoinverse component and a homogeneous solution component. While such a formulation is conceptually appealing, since it treats the redundant degrees of freedom as independent from those required to maintain a desired end effector trajectory, it has been shown to be physically inaccurate when applied to the kinetic behavior of redundant manipulators. In this work, the kinetic behavior of the homogeneous solution component is analyzed in order to specify realistic limitations on the use of redundancy. It is shown that the equations that govern these limitations are related to the conditions for guaranteeing stability of the local torque minimization formulation

Computationally efficient ray tracing of parametric surfaces

Includes bibliographical references (page 9).Abstract also in Japanese.Algorithms for ray tracing parametric surfaces are in general too computationally expensive to be widely applicable. The algorithm presented here combines well-known graphics procedures with a modified Newton iteration to provide a computationally efficient means of including parametric surfaces in a ray traced image. By allowing only planar surfaces to be reflective and/or refractive the resulting high degree of ray coherence is utilized to make the algorithm incremental and results in an order of magnitude improvement in computation speed over existing algorithms

Virtual manufacturing workcell for automated assembly, A

Includes bibliographical references (pages 12-13).This work describes the implementation of a novel robot workcell programming interface that allows an assembly designer to obtain immediate feedback regarding the manufacturability of his/her design. The interface allows the user to manipulate the three-dimensional CAD/CAM models of the components and "assemble" them into the final product. The computer then analyzes the relevant assembly operations and translates them into low-level commands for the robots in the specific workcell under consideration. This work is motivated by the complexity and time-consuming nature of manually programming flexible assembly cells for the manufacture of different products, particularly when they involve the cooperation of multiple robot manipulators

Numerical filtering for the operation of robotic manipulators through kinematically singular configurations

Includes bibliographical references (pages 551-552).Abstract also in Japanese.The loss of independent degrees of freedom at singular configurations is an inherent characteristic of robotic manipulators. Due to the unavoidable singularity of mechanical wrists, singular configurations cannot be avoided by simply restricting the bounds of the workspace. Techniques for operating at singular configurations without inducing unacceptably high joint velocities or end effector tracking errors are presented. Extensions to the damped least-squares formulation which incorporate estimates of the proximity to singularities and selective filtering of singular components are illustrated. The generality of the technique presented is illustrated in a computer simulation of a commercially available manipulator operating through singular configurations

Simulators, graphic

Includes bibliographical references (pages 1607-1608).There are many situations in which a computer simulation with a graphic display can be very useful in the design of a robotic system. First of all, when a robot is planned for an industrial application, there are many commercially available arms that can be selected. A graphics-based simulation would allow the manufacturing engineer to evaluate alternative choices quickly and easily. The engineer can also use such a simulation tool to design interactively the workcell in which the robot operates and integrate the robot with other systems, such as part feeders and conveyors with which it must closely work. Even before the workcell is assembled or the arm first arrives, the engineer can optimize the placement of the robot with respect to the fixtures it must reach and ensure that the arm is not blocked by supports. By being able to evaluate workcell designs off-line and away from the factory floor, changes can be made without hindering factory production and thus the net productivity of the design effort can be increased

Simulation of attempts to influence crowd dynamics, A

Includes bibliographical references.An understanding of how to alter crowd dynamics would have a significant impact in a number of scenarios, e.g., during riots or evacuations. The social force model, where individuals are self-driven particles interacting through social and physical forces, is one approach that has been used to describe crowd dynamics. This work uses the framework of the social force model to study the effects of introducing autonomous robots into crowds. Two simple pedestrian flow problems are used as illustrative examples, namely flow in varying width hallways and lane formation in bidirectional pedestrian flow. Preliminary results indicate that robots capable of inducing an attractive social force are effective at improving pedestrian flow in both of these scenarios.This work was supported by the Non-lethal Technology Innovation Center, University of New Hampshire

Parallel algorithm and architecture for the control of kinematically redundant manipulators, A

Includes bibliographical references (pages 413-414).Kinematically redundant manipulators are inherently capable of more dexterous manipulation due to their additional degrees of freedom. To achieve this dexterity, however, one must be able to efficiently calculate the most desirable configuration from the infinite number of possible configurations that satisfy the end-effector constraint. It has been previously shown that the singular value decomposition (SVD) plays a crucial role in doing such calculations. In this work, a parallel algorithm for calculating the SVD is incorporated into a computational scheme for solving the equations of motion for kinematically redundant systems. This algorithm, which generalizes the damped least squares formulation to include solutions that utilize null-space projections and task prioritization as well as augmented or extended Jacobians, is then implemented on a simple linear array of processing elements. By taking advantage of the error bounds on the perturbation of the SVD, it is shown that an array of only four AT&T DSP chips can result in control cycle times of less than 3 ms for a seven degree-of-freedom manipulator

Computing the topology of configuration space

Includes bibliographical references.In this work, an algorithm is developed for generating the connectivity graph for a class of articulated manipulators. The algorithm is based upon the ability to determine whether two distinct obstacles in configuration space intersect. The efficiency of the test which is developed lies in the ability to determine the intersection relation by evaluating the curves which describe the configuration space obstacles at only a small number of points.This work was supported by the National Science Foundation under grant CDR 8803017 to the Engineering Research Center for Intelligent Manufacturing Systems