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1990 IEEE International Workshop on Intelligent Motion Control, IMC 1990

作者： Luo, Ren C. Pan, T.J. Aras, C.M. Robotics and Intelligent Systems Laboratory Department of Electrical and Computer Engineering North Carolina State University University RaleighNC27695 United States

To improve the performance of autonomous vehicles operating in a factory environment, it is important to develop an intelligent planning system to avoic. vehicle collisions as well as to design a good path network which can minimize the congestion problem. Given a path network, the collision problem can be eliminated by velocity planning for vehicles. To achieve this, we first represent each vehicle as an intersection of time varying half-planes. Then, we use traversability vectors method to predict vehicle collisions along their paths. Once a collision is predicted, time constraints on lower-priority vehicles are registered on a constraint map which shows time instances when the path is obstructed. Velocity planning is then accomplished ty a search on the map. To solve the congestion problem, we must reduce the average waiting time of vehicles. We use a queueing network model to evaluate the average waiting time for different path network configurations. As a result. the network that yields the best performance is selected. © 1991 IEEE.

关键词： Autonomous vehicles

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Surface reconstruction based on descripions of cross-sectional contours

Surface reconstruction based on descripions of cross-section...

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Sensing and Reconstruction of Three-Dimensional Objects and Scenes 1990

作者： Kim, Yonghoon Luo, Ren C. Robotics and Intelligent Systems Laboratory Department of Electrical and Computer Engineering North Carolina State University RaleighNC27695-7911 United States

Surface reconstruction from cross-sectional contours has become increasingly important in medical image applications. In this paper, a method of reconstructing the surface of an object based on the descriptions of cross-sectional contours has been developed. Each cross-sectional contour is first partitioned into convex/concave segments based on the relative locations of points on the contour. Each segment of the contour is then described by a parametric cubic polynomial, and the boundary is recovered based on the description. A matching technique incorporating possible deformations between adjacent cross-sections is used to obtain the correspondence between adjacent cross-sectional contours. Once the correspondence is established, the surface between correspondent segments of adjacent crosssectional contours is reconstructed by a traditional triangulation technique. As the reconstruction is based on the shape of the cross-sections, the reconstructed surfaces are more close to that of the original object. © 1990 SPIE. All rights reserved.

关键词： Surface reconstruction

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An intelligent path planning system for robot navigation in an unknown environment

An intelligent path planning system for robot navigation in ...

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Mobile Robots IV 1989

作者： Luo, Ren C. Pan, Tai-Jee Robotics and Intelligent Systems Laboratory Department of Electrical and Computer Engineering North Carolina State University RaleighNC27695-7911 United States

In this paper, a novel approach to solve the mobile robot path planning problem in an unknown environment is presented. Inherently, the obstacle information from robot perception is contaminated with uncertainties, and thus, the acquired obstacle knowledge for path planning needs to be updated dynamically. Therefore, the development of an adaptive path planning scheme capable of determining a desired path with uncertain, and incomplete obstacle knowledge is necessary. We use the concept of traversability vectors to analyze the spatial-relations between the robot and obstacles in the task environment. Then, these analyzed relations are used to determine the obstacles that must be bypassed by the robot, and the ways to bypass them. Dynamically changing obstacle knowledge can be accommodated by replanning the path at the time when a change is reported. The proposed scheme can work very efficiently since because of the elimination of an exhausted search process that is often required in previous approaches. We implement a computer program to simulated the proposed planning scheme. A graphical representation for robot motions guided by the planned paths is illustrated to show the feature of the presented work. © 1990 SPIE. All rights reserved.

关键词： Motion planning

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3D object recognition using a mobile laser range finder

3D object recognition using a mobile laser range finder

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1990 IEEE International Workshop on Intelligent Robots and Systems, IROS 1990

作者： Luo, Ren C. Scherp, Ralph S. Robotics and Intelligent Systems Laboratory Department of Electrical and Computer Engineering North Carolina State University RaleighNC27695-7911 United States

The objective of this paper is to present a 3D object recognition system with emphasis on an optimum placement strategy for a mobile 3D range sensor. The theoretical aspects leading to the development of the 3D sensor placement paradigm are presented and described. In this paper we use a triangulation type laser range finder in which a CCD based imaging device is utilized to view a plane of laser light bounced from a sweeping mirror. The sensor characteristics are described and modeled. A set of criteria for use in constraining the. possible sensor site location for future scans is presented. These constraint conditions are essential to drive the actual sensor placement algorithm for 3D object recognition. © 1990 Institute of electrical and Electronics Engineers Inc.. All rights reserved.

关键词： Laser mirrors

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BUILDING EFFICIENT AND FLEXIBLE FEATURE-BASED INDEXES

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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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