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Supercomputing Conference

作者： P.-K. Hsiung R.H. Thibadeau C.B. Cox R.H.P. Dunn Department of Electrical & Computer Engineering Carnegie Mellon University Pittsburgh PA USA Imaging Systems Laboratory The Robotics Institute Carnegie Mellon University Pittsburgh PA USA Department of Physics Carnegie Mellon University Pittsburgh PA USA Department of Art Carnegie Mellon University Pittsburgh PA USA

The authors extend their previous effort in visualizing the spatial aspect of relativistic effects, and treat the phenomenon of time dilation, an inherent temporal effect of special relativity. Here, the authors demonstrate through still-frame images and live animations that, in observing the viewing-independent time dilation, the finite light transit time involved in performing the observation makes the observed time dilation also depend on the viewing condition. As the authors introduce the physics of special relativity into ray-tracing and make time to pass as a ray travels through space, they are able to link the spatial and temporal dimensions in a fundamental and consistent way in their simulations, and generate images that reveal the spatial and temporal properties of the 4D geometry of spacetime. The present exploration highlights the interplay of the imaging process and the imaged physical events in producing the final images.< >

关键词： Visualization Physics Time measurement Ray tracing Space exploration Geometry Clocks Laboratories Orbital robotics Motion measurement

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Evaluation functions for assembly sequence planning

Evaluation functions for assembly sequence planning

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Intelligent Robots and computer Vision VII 1988

作者： Sanderson, Arthur C. De Mello, Luiz S. Hornern Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute TroyNY12180 United States Department of Electrical and Computer Engineering Robotics Institute Carnegie Mellon University PittsburghPA15213 United States

Planning robotic manipulation operations is fundamental to the implementation of systems for assembly, disassembly, and repair of space-based equipment. Both teleoperated and fully-autonomous modes of operation will require the representation of feasible operations sequences which accomplish specified tasks. We have developed the AND/OR graph representation of assembly sequences and shown its completeness and correctness for assembly plan representation. The AND/OR graph partitions the state representation in a manner which facilitates local planning decisions. The use of alternative plan representations is coupled to the need for evaluation functions which guide the choice of desirable actions at any given state. In assembly planning, entropy evaluation functions provide a tool for assessment of the complexity of the current state in terms of the available degrees of freedom of motion of parts. Reducing the degrees of freedom of motion of the parts through the introduction of constraints corresponds to a decrease in entropy measures of the assembly. Assembly steps which couple the accuracy of the positioning device to the constraint clearances of the parts are selected using this measure. The entropy evaluation measure may be computed directly from attributes incorporated into a relational description of the parts geometry. The entropy measures must be coupled with other measures of manipulation complexity, availability of tools and fixtures, and speed and cost requirements for the development of general system planning systems. © 1989 SPIE. All rights reserved.

关键词： Entropy

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Attributed image matching using a minimum representation size criterion

Attributed image matching using a minimum representation siz...

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IEEE International Conference on robotics and Automation (ICRA)

作者： A.C. Sanderson N.J. Foster Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute Troy NY USA Electrical and Computer Engineering and The Robotics Institute Carnegie Mellon University Pittsburgh PA USA

The authors describe a novel approach to image matching which utilizes the minimal representation criterion as a means to obtain robust matching performance, even when image data are extremely noisy. They describe the application of this approach to the problem of matching noisy gray-level images to attributed models. Using the minimum representation criterion, the match between gray-level image features and an attributed graph model incorporates a representation size measure for the modeled points, the data residuals, and the unmodeled points. This structural representation identifies correspondence between a subset of data points and a subset of model points in a manner which minimizes the complexity of the resulting model. The proposed minimum representation matching algorithm is polynomial in complexity, and exhibits robust matching performance on examples where less than 30% of the features are reliable. The minimum representation principle is extensible to related problems using three-dimensional models and multisensor data matching.< >

关键词： Image matching Polynomials Data engineering Sensor systems and applications Robustness Pattern matching systems engineering and theory Sensor phenomena and characterization Robot sensing systems Application software

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A correct and complete algorithm for the generation of mechanical assembly sequences

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IEEE International Conference on robotics and Automation (ICRA)

作者： L.S. Homem de Mello A.C. Sanderson The Robotics Institute Carnegie Mellon University Pittsburgh PA USA Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute Troy NY USA

ISBN: (纸本)0818619384

The authors present an algorithm for the generation of mechanical assembly sequences and a proof of its correctness and completeness. The algorithm uses a relational model which describes the geometry of the assembly and the attachments that bind one part to another. The problem of generating the assembly sequences is transformed into the problem of generating disassembly sequences, in which the disassembly tasks are the reverse of feasible assembly tasks. This transformation leads to a decomposition approach in which the problem of disassembling one assembly is decomposed into distinct subproblems, each involving the disassembly of one subassembly. It is assumed that at each assembly task exactly two subassemblies are mated and that all contacts between the parts in the two subassemblies are established. The algorithm yields an AND/OR graph representation of assembly sequences. The correctness of the algorithm is based on the assumption that it is always possible to decide correctly whether two subassemblies can be joined based on geometrical and physical criteria. An approach to compute this decision is given, and bounds for the amount of computation required are presented.< >

关键词： Robotic assembly Assembly systems Solid modeling Computational geometry Design engineering Automatic programming Concurrent engineering Design automation Process planning

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Two Adaptive Control Structures of Robot Manipulators

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IFAC Proceedings Volumes 1989年第10期22卷 371-377页

作者： B.J. Oh M. Jamshidi H. Seraji Automation Technologies Department Korea Electronics and Telecomm Research Institute Daedog Danji. P.O. Box 8. Daejeon. Korea CAD Laboratory for Systems/Robotics. Department of Electrical and Computer Engineering University of New Mexico. Albuquerque. New Mexico 87131. USA Jet Propulsion Laboratory. California Institute of Technology. 4800 Oak Grove Drive. Pasadena. California 91109. USA

This paper proposes two simple schemes for adaptive control of robot manipulator, to achieve trajectory tracking. The state feedback controller consists of feedforward from the reference position trajectory, feedback from the actual trajectory, and an auxiliary input. The feedforward/feedback controller is different from the state feedback controller in that it consists of feedforward from the reference position, velocity, and acceleration trajectory based on “inverse” dynamics of robot manipulator. The feedforward and feedback gains and the auxiliary input are adapted using adaptive control theory based on Lyapunov's direct method, and using only the local information of the corresponding joint. The proposed control schemes are computationally fast and do not require a priori knowledge of the parameter of the manipulator or the payload. Simulation results are presented in support of the proposed schemes.

关键词： Adaptive Control Decentralized Adaptive Control Robot Manipulator Feedforward Feedback

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The design of an assembly cell task supervisor

The design of an assembly cell task supervisor

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IEEE International Conference on robotics and Automation (ICRA)

作者： M.C. Moed R.B. Kelley Robotics and Automation Laboratories Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute Troy NY USA

To increase task flexibility in a robotic assembly environment, a hierarchical planning and execution system is being developed which will map user-specified, three-dimensional part assembly tasks into various target robotic workcells, and execute these tasks efficiently using manipulators and sensors available in the workcell. One level of this hierarchy, the supervisor, is responsible for assigning subtasks of a system-generated task plan to a set of task specific specialists, and online coordination of the activity of these specialists to accomplish the user-specified assembly. The design of the supervisor is broken down into five major functional blocks: resource management; concurrency detection; task scheduling; error recovery; and interprocess communication. Using concepts from operating systems, the design of each of these supervisor blocks is examined.< >

关键词： Robotic assembly Assembly systems robotics and automation Manipulators Robot sensing systems Resource management Robot kinematics Sensor systems Job shop scheduling Robot programming

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Analytic formulation of intelligent machines as neural nets

Analytic formulation of intelligent machines as neural nets

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IEEE International Symposium on Intelligent Control (ISIC)

作者： G.N. Saridis M.C. Moed Robotics and Automation Laboratories Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute Troy NY USA

The design of the organization level of the intelligent machine as a Boltzmann machine, as described in current neural network literature, is discussed. Since this level is responsible for planning the actions of the machine, the problem at this tier is formulated as the construction of the right sequence of tasks or events which minimizes the entropy for the desired action. Two search techniques, simulated annealing (SA) and expanding subinterval random search (ESRS), are described. These techniques are used to find the global minimum entropy of a Boltzmann machine. Simulations using these search techniques were conducted using energy as a cost function, and results indicate that ESRS converges faster than SA to a global minimum if the topology contains narrow and deep cost wells.< >

关键词： Machine intelligence Neural networks Intelligent robots Intelligent control Learning systems Artificial intelligence Entropy Control systems Humans Intelligent structures

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An online supervisor for robotic tasks

An online supervisor for robotic tasks

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International Conference on computer Integrated Manufacturing

作者： M.C. Moed R.B. Kelley Robotics and Automation Laboratories Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute Troy NY USA

To increase task flexibility in a robotic assembly environment, a hierarchical planning and execution system is being developed which will map user-specified three-dimensional part assembly tasks into various target robotic workcells, and execute these tasks efficiently using manipulators and sensors available in the workcell. One level of this hierarchy, the supervisor, is responsible for assigning subtasks of a system-generated task plan to a set of task specific specialists, and online coordination of the activity of these specialists to accomplish the user-specified assembly. The design is broken down into five major functional blocks: resource management; concurrency detection; task scheduling; error recovery; and interprocess communication. The overall function of the supervisor is examined in relation to the other levels of the hierarchical system. The theoretical design of each module of the supervisor is presented and a sample assembly is executed under the supervisor's control.< >

关键词： Robotic assembly Robot sensing systems Robot kinematics Assembly systems Manipulators Sensor systems Resource management Concurrent computing Hierarchical systems Communication system control

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Automatic construction of assembly partial-order graphs

Automatic construction of assembly partial-order graphs

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International Conference on computer Integrated Manufacturing

作者： S. Lee Y.G. Shin Department of Electrical Engineering-Systems Institute for Robotics and Intelligent Systems University of Southern California Los Angeles CA USA Computer Science Department University of Southern California Los Angeles CA USA

A system is presented which automatically constructs an assembly partial-order graph from an object-oriented model describing parts and their connections. The construction is based on the principle of assembly by disassembly and on assembly heuristics representing criteria for preferred subassemblies. The system first identifies disassemblable parts and subassemblies by reasoning geometric and physical constraints as well as resource requirements, and then assigns preference to the identified disassembly options based on assembly heuristics. The recursive application of this process to the selected disassemblies results in a hierarchical partial-order graph (HPOG). The HPOG not only specifies the required precedence in part assembly but also provides parallelism for implementing multiple-robot distributed and cooperative assembly. The software is organized under the cooperative-problem-solving paradigm.< >

关键词： Robotic assembly Assembly systems robotics and automation Process planning Job shop scheduling Robot sensing systems Intelligent robots Throughput Parallel robots Motion planning

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Learning expert systems for robot fine motion control

Learning expert systems for robot fine motion control

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IEEE International Symposium on Intelligent Control (ISIC)

作者： S. Lee M.H. Kim Department of Electrical Engineering-Systems Institute for Robotics and Intelligent Systems University of Southern California Los Angeles CA USA Computer Science Department Sung Kyun Kwan University Seoul South Korea

The authors present a learning expert system which enables a robot to acquire fine motion skills automatically. The system follows the paradigm of Expert Assisted Robot Skill Acquisition (EARSA) proposed by the authors (1987). EARSA is mainly concerned with the self-discovery of skills by a robot in conjunction with the transfer of human skills to a robot and emphasizes the distinctive difference in perceptual and physical capabilities between a human and a robot. The authors review the theory and mechanism of EARSA, describe the robot fine motion skill learning algorithm formulated on the basis of EARSA, and present the details of simulation on the robot learning of two-dimensional peg-hole insertion skills. The results of simulation indicate the dramatic improvement of performance as a result of skill learning.< >

关键词： Expert systems Motion control robotics and automation Robot sensing systems Intelligent robots Cognitive robotics Motion planning Robotic assembly Automatic control Humans

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