The authors ask what is the complexity of computing equilibria for physically realizable analog networks like those of J.J. Hopfield (1984) and T.J. Sejnowski (1981) with arbitrary connectivity. It is shown that, if t...
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The authors ask what is the complexity of computing equilibria for physically realizable analog networks like those of J.J. Hopfield (1984) and T.J. Sejnowski (1981) with arbitrary connectivity. It is shown that, if the amplifiers are piecewise-linear, then such networks are instances of a game-theoretic model known as polymatrix games. Equilibria for the latter may be computed by vertex pivoting algorithms similar to the simplex method for linear programming, which are in practice of low order polynomial complexity. These algorithms appear to be the only ones both guaranteed to work and which are polynomial in practice. These results suggest that networks with few nonstable equilibria would be computationally attractive.< >
This paper presents the basic ideas of the theory of stochastic complexity with rigorous asymptotic results in the field of time-series analysis and system identification, which demonstrate the applicability of stocha...
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This paper presents the basic ideas of the theory of stochastic complexity with rigorous asymptotic results in the field of time-series analysis and system identification, which demonstrate the applicability of stochastic complexity to these difficult statistical problems.< >
The authors describe how a surface reconstruction algorithm based on minimizing the variation of surface curvature can be used to stabilize and correct the results of local shading analysis. The approach is viewpoint ...
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The authors describe how a surface reconstruction algorithm based on minimizing the variation of surface curvature can be used to stabilize and correct the results of local shading analysis. The approach is viewpoint independent and applicable to any process that can provide estimates of local surface orientation. The assumptions used in formulating the minimization are derived from standard differential geometry. When applied as a second stage of processing after local shading analysis, the algorithm can recover a close approximation of the true surface orientation under realistic assumptions about image noise. Results are presented that show the performance of the algorithm on synthetic and real data. In particular, they demonstrate how this form of reconstruction can compensate for some of the shape distortion incurred in local shading analysis.< >
The question posed is what can be inferred from ambiguity in processes of visual interpretation? Much emphasis is naturally placed on the form of constraints used to minimize ambiguity, particularly as they pertain to...
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The question posed is what can be inferred from ambiguity in processes of visual interpretation? Much emphasis is naturally placed on the form of constraints used to minimize ambiguity, particularly as they pertain to such issues as perceptual acceptability. The authors feel that it is perhaps more instructive to consider what can be learned from situations where different interpretations of data are possible, i.e., the ambiguity of perception. This immediately raises a number of issues regarding the characterization of ambiguity, communicating it to other visual processes, and using ambiguity to further refine visual interpretation. The context in which the authors discuss these problems is the interpretation of scene geometry in the form of volumetric models. They describe a representation for ambiguity in terms of an ellipsoid of confidence in which there is a finite probability that the true parameters of the model can be found.< >
The authors describe the geometrical criteria which define viewpoint-invariant features to be extracted from 2-D line drawings of 3-D objects. They also discuss the extraction of these features, which forms the initia...
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The authors describe the geometrical criteria which define viewpoint-invariant features to be extracted from 2-D line drawings of 3-D objects. They also discuss the extraction of these features, which forms the initial stage of a generic object recognition system, the Primal Access Recognition of Visual Objects (PARVO) system. In this system, part-based qualitative descriptions are built and matched to coarse 3-D object models for recognition. The segmentation and labeling of the constituent parts of an object rely on the 3-D properties inferred from the presence of its 2-D features. The original motivation for PARVO its recognition by components, a theory of human image understanding from the field of psychology. Definitions of the geometrical criteria defining the viewpoint-invariant features are introduced. Examples of results obtained by applying these criteria to a typical line drawing are shown.< >
A new model is introduced for avoiding accidents where a tugboat capsizes or trips when towing a larger vessel. The development of the Tripping Avoidance Knowledge Base (TAKB) is described in terms of the relevant des...
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A new model is introduced for avoiding accidents where a tugboat capsizes or trips when towing a larger vessel. The development of the Tripping Avoidance Knowledge Base (TAKB) is described in terms of the relevant descriptive parameters, the graphical representation of the knowledge base and its conversion to a decision matrix is also shown. As with any AI application in a new and promising area, there are many unclear points which this paper highlights. The paper closes with the authors' recommendations for future development and refinement of the knowledge base.
Intelligent robotic workcell activities have come to require a database framework for arranging, storing and accessing information in real-time about the workcell environment in a standard way. After a brief introduct...
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Intelligent robotic workcell activities have come to require a database framework for arranging, storing and accessing information in real-time about the workcell environment in a standard way. After a brief introduction to the theory of databases (DB), we examine the general topic of robotic workcells, identify characteristics typical of robotic applications, and then present a survey of DB-related work in the robotics domain. We then construct a set of design constraints based on our analysis of robotic applications, and describe a suitable software architecture. The paper concludes with a discussion of experience gained with two generations of DB implementations.
AbstractThe complexity of modern robotic workcells, consisting of many cooperating elements (e.g., robots, sensing systems) makes programming applications enormously difficult. Even when the application can be easily ...
AbstractThe complexity of modern robotic workcells, consisting of many cooperating elements (e.g., robots, sensing systems) makes programming applications enormously difficult. Even when the application can be easily decomposed into workcelll operations, the tight coupling among these operations due to constraints on precedence and resource sharing makes it difficult to identify and take advantage of possible concurrency. Since robotic workcells are typically configured to repetitively perform an application, we seek to minimize the ‘cycle’ time required, by optimizing the order in which operations take place. Eventually, a sequential program must be written for each workcell element, and they must then execute concurrently. Commercial robot languages and systems provide neither the necessary tools for programming such a distributed collection of elements nor a mechanism for inter‐element communication. In this article the authors propose a two‐part solution to this workcell programming problem: SAGE/WRAP. A graphics interface is provided to the user in order to define the application. Then, from the user's input, SAGE builds a Petri Net description of the workcell application; this is used to obtain a time‐optimal sequence of operations for each workcell element. The time‐optimal sequence then becomes the basis of the runtime program that performs the application. This program is interpreted and executed by the hierarchical workcell runtime environment called WRAP. An example is provided to illustrate t
We consider the problem of aggregating the information provided by sensors such as range finders and its applications to scene modelling. This information consists of collections of three-dimensional points which form...
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ISBN:
(纸本)9780819400383
We consider the problem of aggregating the information provided by sensors such as range finders and its applications to scene modelling. This information consists of collections of three-dimensional points which form a discrete subspace of the objects-to-free-space boundaries within the world to be modelled. The ultimate goal is to obtain a valid surface model which can in turn be transformed into an efficient volumetric representation for solid interference detection algorithms. We first relate our work to that of other researchers, and we then show that surface connectivity is a non-trivial but essential element of a valid representation. To that end, we introduce a formal definition for model validity which we use to guide the process of aggregating the different views and we provide a proof of its correctness under stated assumptions. We eventually suggest heuristic methods for extending our approach when the strict validity conditions do not suffice to construct a perceptually consistent model. Finally, we quickly introduce the topological problems posed by objects non-homeomorphic to spheres, such as multi-holed tori. The methods we develop do not depend on the physical nature of the sensing technique. For example, our results can also be used from data obtained by stereo analysis and to some extent by haptic sensing.
The basic operating principles of ELsim, a timing simulator for digital CMOS circuits, are discussed. ELsim uses the electrical-logic, or ELogic, method where time is solved for rather than voltage and an event-driven...
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The basic operating principles of ELsim, a timing simulator for digital CMOS circuits, are discussed. ELsim uses the electrical-logic, or ELogic, method where time is solved for rather than voltage and an event-driven, selective trace approach is used which exploits circuit latency to improve simulation speed. Voltage levels at the circuit nodes are descretized, and the size of the voltage steps can be increased to trade accuracy for simulation speed. Results of a comparison of the ELsim simulator performance to that of SPICE for sample CMOS circuits are featured. In general, the delay times and waveforms calculated with ELsim show satisfactorily agreement with those obtained using SPICE.< >
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