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BUILDING EFFICIENT AND FLEXIBLE FEATURE-BASED INDEXES

INFORMATION SYSTEMS 1990年第6期15卷 653-662页

作者： JEA, KFJ LEE, YC Robotics Research Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2122 United States Current affilation: Cell Communications Research United States Current affilation: AT and T Bell Laboratories U.S.A.

If database management systems are to play an important role in CAD/CAM technologies, building engineering indices must be a primary task even though it is beyond conventional database practice. Information regarding design semantics or functionalities is often embedded in the geometric description of design objects, and is therefore not directly available for indexing. Presented in this paper is an efficient and flexible indexing mechanism for retrieving design objects that possess similar design features as described by the user. The underlying database is composed of rotational objects represented by constructive solid geometry (CSG). Although domain-specific representation schemes and algorithms are involved, the main objective of this paper is to emphasize the importance of engineering indices and to illustrate the effort required to build as well as to use such indices.

关键词： engineering DATABASE MANAGEMENT engineering INDEXES FEATURE EXTRACTION CONSTRUCTIVE SOLID GEOMETRY MULTIPLE KEY ACCESS PATTERN MATCHING DESIGN RETRIEVAL

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On reducing compensator bandwidth of LQG/LTR control: an H∞- optimization approach

On reducing compensator bandwidth of LQG/LTR control: an H∞...

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American Control Conference (ACC)

作者： K. C. Han T. C. Hsia Robotics Research Laboratory Department of Electrical Engineering and Computer Science University of California Davis CA 95616 Robotics Research Laboratory Department of Electrical Engineering and Computer Science University of California Davis CA USA

Due to lack of robustness, the Linear Quadratic Gaussian (LQG) approach to the design of control systems is enhanced by Loop Transfer Recovery (LTR) techniques. However, the robustness is recovered with the price paid to the unduly large or infinite bandwidth of the compensator. Such compensators are undesirable because plant output measurement noise is greatly amplified so as to degrade the system performance. A simple method is presented for reducing compensator bandwidth by H ∞ - optimization of a stable function which combines the usual sensitivity function difference with a weighted closed-loop transfer function from noise to plant input. An example is given to show the improvement achievable by this new design method.

关键词： Bandwidth Noise robustness Robust control Control systems Noise measurement Degradation System performance Optimization methods Transfer functions Noise reduction

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AN ADAPTIVE SCHEME FOR ROBOT JOINT TRAJECTORY GENERATION

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JOURNAL OF ROBOTIC SYSTEMS 1990年第6期7卷 881-895页

作者： HSIA, TC GUO, ZY LI, L Robotics Research Laboratory Department of Electrical Engineering and Computer Science University of California Davis Davis CA 95616

It has been shown recently that robot inverse kinematic transformation can be easily carried out by using a nonlinear dynamic system called “joint space command generator.” In this paper, an adaptive version of the command generator is proposed. The main feature of this command generator is that the inverse Jacobian is estimated on-line (using least-squares algorithms), thus the explicit form of the inverse Jacobian is not required. Since the Jacobian is dependent on the end-effector orientation representation, the adaptive command generator is then inherently flexible in accommodating any choice of orientation representation during Cartesian trajectory planning. The only knowledge required is the forward kinematics of the robot. Thus inverse kinematic transformation of robot trajectories can be carried out with a minimum amount of kinematic information. Extensive simulation studies of the proposed scheme have been carried out which showed that the adaptive command generator is computationally feasible and highly accurate. Different orientation representations have been tested with equal success. Some typical simulation results are presented to illustrate the performance of the adaptive command generator.

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Review of the four parameter controller approach for FDI problems

Review of the four parameter controller approach for FDI pro...

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IEEE International Symposium on Intelligent Control (ISIC)

作者： C.A. Jacobson K.P. Valavanis Robotics Laboratory Department of Electrical and Computer Engineering Northeastern University Boston MA USA

A summary of fault detection and isolation methodologies used to accommodate system actuator and sensor failures is given. The four-parameter controller for failure diagnostic problems is described in detail. Applicat... 详细信息

关键词： Fault detection Sensor systems Acoustic sensors Failure analysis Actuators Open loop systems Control systems Jacobian matrices Robot sensing systems Laboratories

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Efficient Plan Formulation and Organization for Robotic Assemblies and Intelligent Robotic Systems

Efficient Plan Formulation and Organization for Robotic Asse...

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American Control Conference (ACC)

作者： Kimon P. Valavanis Socrates J. Carelo Robotics Laboratory Department of Electrical and Computer Engineering Northeastern University Boston MA USA

An efficient planning technique for the organization and formulation of complete plans applicable to both Robotic Assemblies and Intelligent Robotic Systems is proposed. Constraints are introduced to facilitate and optimize the organizer operations. An example demonstrates the feasibility and applicability of the proposed methodology.

关键词： Robotic assembly Intelligent robots Intelligent systems Hierarchical systems Assembly systems Laboratories Constraint optimization Mathematics Reliability engineering Design engineering

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T-buffer: Fast visualization of relativistic effects in spacetime 90

T-buffer: Fast visualization of relativistic effects in spac...

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1990 Symposium on Interactive 3D Graphics, I3D 1990

作者： Hsiung, Ping-Kang Thibadeau, Robert H. Wu, Michael Carnegie Mellon University PittsburghPA15213 United States Department of Electrical and Computer Engineering Carnegie Mellon University United States Imaging Systems Laboratory Robotics Institute Carnegie Mellon University United States

ISBN: (纸本)0897913515

Wc have developed an innovative ray-tracing simulation algorithm to describe Welativistic Effects in SpaceTime ("REST"). Our algorithm, called REST-frame, models light rays that have assumed infinite speed in conventional ray-tracing to have a finite speed in spacetime, and uses the non-Newtonian Lorentz Transformation to relate measurements of a single event in different inertial coordinate systems {inertial frames). Our earlier work [5][6][7] explored the power of REST-frame as an experimentation tool to study the rich visual properties in natural world modeled by Special Relativity. Non-intuitive images of the anisotropic deformation ("warping") of space, the intensity concentration/spreading of light sources in spacetime, and the relativistic Doppler shift were visualized from our simulations. REST-frame simulations arc computationally expensive. Several hours of CPU time may be needed to generate one intricate image on a relatively powerful DECStation 3100. This high simulation cost of REST-frame precludes its application in interactive, real-time graphics environments. In this paper, we report a scanline based REST-frame rendering method that provides a faster alternative to the original ray-tracing based REST-frame implementation. This new method operates in the spirit of the classical Z-buffer in computer graphics[2] and the inter-inortial frames point-mapping method investigated in physics in the early 1960's[14][12], and determines the visibility of points in spacetime by their spatial and temporal visibility. Specifically, all spacetime event points that arc potentially visible from the viewpoint at the imaging time are geometrically projected in three dimensional (3D) space to the image plane pixel buffer. Multiple points with a same pixel affiliation arc sorted by their time distance © 1990 ACM.

关键词： Ray tracing

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Tracking in a complex visual environment 1st

Tracking in a complex visual environment

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1st European Conference on computer Vision, ECCV 1990

作者： Aloimonos, John Yiannis Tsakiris, Dimitris P. Computer Vision Laboratory Center for Automation Research and Institute for Advanced Computer Studies and Computer Science Department University of Maryland College ParkMD20742-3411 United States Electrical Engineering Department and Systems Research Center University of Maryland College ParkMD20742-3411 United States

ISBN: (纸本)9783540525226

We examine the tracking of 3-dimensional targets moving in a complex (e.g. highly textured) visual environment, which makes the application of methods relying on static segmentation and feature correspondence very problematic, even under specific assumptions about the trajectory of the target. From the system kinematics and optical flow formalism we derive a general criterion, the Tracking Constraint, which specifies the optimal camera reorientation as the one that minimizes the optical flow in the center of the camera in the sense of an appropriate metric. A correspondence-free scheme is devised which employs dynamic segmentation and linear features of the image in order to capture global information about the scene and bypass numerical differentiation of the image intensity. © Springer-Verlag Berlin Heidelberg 1990.

关键词： Optical flows

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Robot manipulator control using decentralized linear time-invariant time-delayed joint controllers

Robot manipulator control using decentralized linear time-in...

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IEEE International Conference on robotics and automation (ICRA)

作者： T.C. Hsia L.S. Gao Robotics Research Laboratory Department of Electrical Engineering and Computer Science University of California Davis CA USA

It is shown that robot manipulator control can be accomplished using simple decentralized linear time invariant time-delayed joint controllers instead of the complicated computed torque control scheme. This means that all the online computational problems associated with computing robot inverse dynamics can be avoided, and the robot control problem is essentially reduced to that of computing n linear proportional-derivation controls for n joint subsystems. The proposed control technique employs a time-delayed control with a specially designed constant diagonal gain matrix to decouple and linearize the robot joint dynamics so that linear centralized joint control can be achieved. It is shown that the proposed controller is stable, and the value of the special gain matrix can be selected based on a sufficient condition of stability presently developed. However, the establishment of this sufficient condition requires knowledge of the inertial matrix of the robot. It is also shown that the controller is robust in the presence of payload uncertainty. A two-link planar robot is presented to illustrate the controller design procedures and the performance of the controller.< >

关键词： Robot control Torque control Centralized control Transmission line matrix methods Manipulator dynamics Sufficient conditions Proportional control Stability Robust control Payloads

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Joint trajectory generation for redundant robots in an environment with obstacles

Joint trajectory generation for redundant robots in an envir...

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IEEE International Conference on robotics and automation (ICRA)

作者： Z.Y. Guo T.C. Hsia Robotics Research Laboratory Department of Electrical Engineering and Computer Science University of California Davis CA USA

The problem of determining collision-free joint space trajectories for redundant robots is considered, and the command-generator approach is used to generate such trajectories. In this approach, a distance objective function is defined and is optimized along the robot joint trajectories through a vector in a null space. Algorithms for implementing this optimization problem are fully developed. It is shown that the proposed collision-free trajectory generation scheme is efficient and practical. Extensive simulation results of a four-link robot example are presented and analyzed.< >

关键词： Orbital robotics Collision avoidance Robot sensing systems Kinematics Null space Analytical models Path planning Object detection Robot control Servomechanisms

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Survey of the Robust Control of Robots

Survey of the Robust Control of Robots

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American Control Conference (ACC)

作者： C. Abdallah P. Dorato M. Jamshidi CAD Laboratory for Systems and Robotics Electrical and Computer Engineering Department University of New Mexico Albuquerque NM USA

In this survey, we discuss current approaches to the robust control of the motion of robots and summarize the available literature on the subject. The three major designs discussed are the "Linear-Multivariable" Approach, the "Passivity" approach and the "Variable-Structure" approach. The survey is limited to rigid robots and nonadaptive controllers.

关键词： Robust control Robot kinematics Control systems Tellurium Equations Robot control Adaptive control Symmetric matrices Gravity Lagrangian functions

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