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Internal force-based impedance control for cooperating manipulators

IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION 1996年第1期12卷 78-89页

作者： Bonitz, RG Hsia, TC Systems Controland Robotics LaboratoryDepartment of Electrical and Computer Engineering University of California Davis CA USA

An internal force-based impedance control scheme for cooperating manipulators is introduced which controls the motion of the objects being manipulated and the internal force on the objects. The controller enforces a relationship between the velocity of each manipulator and the internal force on the manipulated objects. Each manipulator is directly given the properties of an impedance by the controller;thus, eliminating the gain limitation inherent in the structure of previously proposed schemes. The controller uses the forces sensed at the robot end effecters to compensate for the effects of the objects' dynamics and to compute the internal force using only kinematic relationships. Thus, knowledge of the objects' dynamics is not required. Stability of the system is proven using Lyapunov theory and simulation results are presented validating the proposed concepts. The effect of computational delays in digital control implementations is analyzed vis-a-vis stability and a lower bound derived on the size of the desired manipulator inertia relative to the actual manipulator endpoint inertia. The bound is independent of the sample time.

关键词： Impedance Force control Motion control Manipulator dynamics Velocity control Robot sensing systems End effectors Kinematics Stability Computational modeling

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Locally distinguishing inputs for systems on Lie groups and parallelism

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PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND engineering SCIENCES 1997年第1966期453卷 2391-2395页

作者： Apostolou, N Kazakos, D Control Systems Laboratory Department of Electrical and Computer Engineering University of Patras 26500 Patras Greece

This paper is concerned with invariant systems on Lie groups. A sufficient condition for a piecewise constant input to distinguish between any two distinct initial states contained in some open neighbourhood of the state space is given. This condition involves the parallel translation of vectors along curves thus relating observability to parallelism.

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Multimodal Emotion Recognition Based on Multi-Scale Facial Features and Cross-Modal Attention

Multimodal Emotion Recognition Based on Multi-Scale Facial F...

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IEEE International Conference on Industrial Technology (ICIT)

作者： Chengao Bao Luefeng Chen Min Li Min Wu Witold Pedrycz Kaoru Hirota School of Automation China University of Geosciences Wuhan China the Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems School of Automation and the Engineering Research Center of Intelligent Technology for Geo-Exploration Ministry of Education China University of Geosciences Wuhan China Department of Electrical and Computer Engineering University of Alberta Edmonton Canada Tokyo Institute of Technology Yokohama Japan Tokyo Institute of Technology Tokyo Japan

ISBN: (数字)9798331521950

ISBN: (纸本)9798331521967

A multi-modal emotion recognition method based on facial multi-scale features and cross-modal attention (MS-FCA) network is proposed. The MSFCA model improves the traditional single-branch ViT network into a two-branch ViT architecture by using classification tokens in each branch to interact with picture embeddings in the other branch, which facilitates effective interactions between different scales of information. Subsequently, audio features are extracted using ResNet18 network. The cross-modal attention mechanism is used to obtain the weight matrices between different modal features, making full use of inter-modal correlation and effectively fusing visual and audio features for more accurate emotion recognition. Two datasets are used for the experiments: eNTERFACE'05 and REDVESS dataset. The experimental results show that the accuracy of the proposed method on the eNTERFACE'05 and REDVESS datasets is 85.42% and 83.84% respectively, which proves the effectiveness of the proposed method.

关键词： Emotion recognition Visualization Accuracy Service robots Semantics Human-robot interaction Speech recognition Feature extraction Data mining Facial features

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DYNAMIC BEHAVIOR OF SHORTEST-PATH ROUTING ALGORITHMS FOR COMMUNICATION-NETWORKS

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IEEE TRANSACTIONS ON AUTOMATIC control 1982年第1期27卷 60-74页

作者： BERTSEKAS, DP Department of Electrical Engineering and Computer Science Laboratory for Information and Decision Systems Massachusetts Institute of Technology Cambridge MA USA

Several proposed routing algorithms for store and forward communication networks, including one currently in operation in the ARPANET route messages along shortest paths computed by using some set of link lengths. When these lengths depend on current traffic conditions as they must in an adaptive algorithm, dynamic behavior questions such as stability, convergence, and speed of convergence are of interest. This paper is the first attempt to analyze systematically these issues. It is shown that minimum queuing delay path algorithms tend to exhibit violent oscillatory behavior in the absence of a damping mechanism. The oscillations can be damped by means of several types of schemes two of which are analyzed in this paper. In the first scheme a constant bias is added to the queuing delay thereby providing a preference towards paths with a small number of links. In the second scheme the effects of several past routings are averaged as for example when the link lengths are computed and communicated asynchronously throughout the network.

关键词： Routing Communication networks computer networks Convergence Delay ARPANET Telecommunication traffic Traffic control Adaptive algorithm Stability

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Implementation of the velocities of the end-effector with the distributed arithmetic architecture

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JOURNAL OF INTELLIGENT & ROBOTIC systems 1996年第4期17卷 387-417页

作者： Grigoriadis, GK Mertzios, BG Automatic Control Systems Laboratory Department of Electrical and Computer Engineering Democritus University of Thrace 67100 Xanthi Greece

The fast implementation of the linear and of the angular velocities of the end-effector of robotic manipulators, using the distributed arithmetic technique is described. The linear and angular velocities of the end-effector as well as the positional and the orientational Jacobian matrices is calculated by a cascade configuration of two pipelined arrays. The building blocks of the arrays are the distributed arithmetic-based circuits that implement the matrix-vector multiplications involved in the calculations. The digit-serial configuration of the proposed implementation of the linear and angular velocities of the end-effector is described, while the serial and the parallel configurations may result as special cases of the digit-serial configuration. The proposed distributed arithmetic computer architecture may be used in the real-time operation of the robot control system that requires the on-line computation of the position, of the linear and angular velocities of the end-effector and of the Jacobian matrix.

关键词： robot kinematics linear velocity angular velocity positional and orientational Jacobian matrices fast implementation pipelining distributed arithmetic and end-effector

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PROJECTED NEWTON METHODS AND OPTIMIZATION OF MULTICOMMODITY FLOWS

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IEEE TRANSACTIONS ON AUTOMATIC control 1983年第12期28卷 1090-1096页

作者： BERTSEKAS, DP GAFNI, EM Department of Electrical Engineering and Computer Science Laboratory for Information and Decision Systems Massachusetts Institute of Technology Cambridge MA USA

A superlinearly convergent Newton like method for linearly constrained optimization problems is adapted for solution of multicommodity network flow problems of the type arising in communication and transportation networks. We show that the method can be implemented approximately by making use of conjugate gradient iterations without the need to compute explicitly the Hessian matrix. Preliminary computational results suggest that this type of method is capable of yielding highly accurate solutions of nonlinear multicommodity flow problems far more efficiently than any of the methods available at present.

关键词： Newton method Optimization methods Constraint optimization Proposals Transportation Quadratic programming Convergence computer science Equations

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AN EIGENSTRUCTURE APPROACH FOR THE RETRIEVAL OF CYLINDRICAL HARMONICS

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SIGNAL PROCESSING 1987年第2期13卷 121-139页

作者： TEWFIK, AH LEVY, BC WILLSKY, AS Laboratory for Information and Decision Systems and The Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 U.S.A.

In this paper, we present a high resolution spectral estimation method for 2-D isotropic random fields with covariance functions equal to weighted sums of cylindrical harmonics. Such fields are often used to model some types of background noises in geophysics and in ocean acoustics. The approach that we present differs from previous 2-D spectral estimation techniques by the fact that we take maximal advantage of the symmetries implied by both the isotropy and the special covariance structure of these fields. Note that isotropy is the natural generalization to several dimensions of the 1-D notion of stationarity. Our approach is similar in spirit to 1-D harmonic retrieval techniques, such as the MUSIC method, which rely on an eigenanalysis of the covariance matrix. In the 2-D isotropic context, we begin with a Fourier series representation of an isotropic field with respect to the angle θ in a polar coordinate representation of the underlying 2-D space. We then obtain a spectral estimate by performing an eigenanalysis of the covariance matrix of samples of the zeroth-order Fourier coefficient process in order to extract the cylindrical harmonics. We also discuss the estimation of this covariance matrix and present examples to illustrate the high resolution and robustness properties of our procedure. Es werden einige neue Abtasttheoreme für isotrope Zufallsfelder und die zugehörigen Fourierprozesse entwickelt. Aufgrund dieser Theoreme wird ein Algorithmus vorgestellt, mit dem sich die zylindrischen Harmonischen eines isotropen Zufallsfeldes aus Werten der zugehörigen Kovarianzfunktion gewinnen lassen. Der vorgeschlagene Algorithmus nutzt die Eigenwertstruktur der Kovarianzmatrix des normalisierten Fourier-Koeffizientenprozesses nullten Grades; dieser Prozeß erweist sich als robust. Cet article propose une méthode d'estimation spectrale à grande resolution pour les champs isotropes aléatoires 2-D dont la fonction de covariance est égale à une somme d'harmoniques cylind

关键词： Isotropic random field Fourier coefficient process cylindrical harmonics eigenstructure analysis harmonic retrieval

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A MULTI-RESOLUTION, PROBABILISTIC APPROACH TO TWO-DIMENSIONAL INVERSE CONDUCTIVITY PROBLEMS

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SIGNAL PROCESSING 1989年第3期18卷 291-311页

作者： CHOU, KC WILLSKY, AS Laboratory for Information and Decision Systems Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 U.S.A.

In this paper a method of estimating the conductivity in a bounded 2-D domain at multiple spatial resolutions given boundary excitations and measurements is presented. The problem is formulated as a maximum-likelihood estimation problem and an algorithm that consists of a sequence of estimates at successively finer scales is presented. By exploiting the structure of the physics, the problem at each scale is divided into two linear subproblems, each of which is solved using parallelizable relaxation schemes. The success of our algorithm on synthetic data is demonstrated and numerical results based on using the algorithm as a tool for exploring estimation performance is presented, as well as results based on using the algorithm to study the well-posedness of the problem, and the effects of fine-scale variations on coarse scale estimates. Examples based on analytical results that further the understanding of these issues are also presented. The results suggest the use of inhomogeneous spatial scales as a possible way of overcoming ill-posedness at points far away from the boundary. In dieser Arbeit stellen wir ein Verfahren zum Schätzen der Leitfähigkeit in einem abgeschlossenen zweidimensionalen Gebiet mit verschiedenen räumlichen Auflösungen bei gegebenen Randerregungen und -messungen vor. Wir formulieren das Problem als Maximum-Likelihood-Schätzproblem und geben einen Algorithmus an, der aus einer Folge von Schätzern auf immer kleiner werdenden Gittern besteht. Unter Ausnutzung der physikalischen Struktur haben wir das Problem auf jedem Gitter in zwei lineare Teilprobleme aufgeteilt, die jeweils mit Hilfe von parallelisierbaren Relaxationsverfahren gelöst werden. Wir wenden unseren Algorithmus erfolgreich auf synthetische Daten an und präsentieren numerische Ergebnisse, die auf dem Einsatz des Algorithmus als Hilfsmittel zur Untersuchung der Güte der Schätzung, der Gutartigkeit des Problems und der Auswirkungen von Variationen auf einem feineren Gitter auf den Schät

关键词： Multi-resolution maximum likelihood estimation partial differential equations Gauss-Seidel relaxation schemes Cramer-Rao bound

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A UNIFIED FRAMEWORK FOR PRIMAL-DUAL METHODS IN MINIMUM COST NETWORK FLOW PROBLEMS

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MATHEMATICAL PROGRAMMING 1985年第2期32卷 125-145页

作者： BERTSEKAS, DP 1.Department of Electrical Engineering and Computer Science Laboratory for Information and Decision Systems Massachusetts Institute of Technology 02139 Cambridge MA USA

We introduce a broad class of algorithms for finding a minimum cost flow in a capacitated network. The algorithms are of the primal-dual type. They maintain primal feasibility with respect to capacity constraints, while trying to satisfy the conservation of flow equation at each node by means of a wide variety of procedures based on flow augmentation, price adjustment, and ascent of a dual functional. The manner in which these procedures are combined is flexible thereby allowing the construction of algorithms that can be tailored to the problem at hand for maximum effectiveness. Particular attention is given to methods that incorporate features from classical relaxation procedures. Experimental codes based on these methods outperform by a substantial margin the fastest available primal-dual and primal simplex codes on standard benchmark problems.

关键词： Primal-Dual Out-of-Kilter Relaxation Network Flow

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Guest Editorial - Optical communications and networking series

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2005年第8期23卷 1441-1443页

作者： Chan, VWS Department of Electrical Engineering and Computer Science and Aeronautics and Astronautics United States Laboratory for Information and Decision Systems (LIDS) MIT United States

Why is the optical network to date not as successful commercially as many previously thought it would be and what can the research community do to help? The author offers his opinion on this question. When one gives the first part of this question some thought, several possibilities naturally come to mind: has the cause been substandard optical network performance? Have venture capitalists and entrepreneurs killed the market with glut by miscalculating and overbuilding the core? In my view, both contributed to the problem, but mostly, it is that optical networks have been engineered with insufficient attention given to the cost incurred by the end-user.

关键词： Optical fiber networks Costs Wavelength division multiplexing Optical packet switching Logic gates Optical fiber communication Reliability engineering computer network reliability Home computing HDTV

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