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${\cal H}_{\infty}$ Estimation for Uncertain Systems With Limited Communication Capacity

IEEE Transactions on Automatic control 2007年第11期52卷 2070-2084页

作者： Huijun Gao Tongwen Chen Space Control and Inertial Technology Research Center Harbin Institute of Technology Harbin China Department of Electrical and Computer Engineering University of Alberta Edmonton AB Canada

This paper investigates the problem of robust H infin estimation for uncertain systems subject to limited communication capacity. The parameter uncertainty belongs to a given convex polytope and the communication limitations include measurement quantization, signal transmission delay, and data packet dropout, which appear typically in a network environment. The problem of H infin filter design is first solved for a nominal system subject to the aforementioned information limitations, which is then extended to the uncertain case based on the notion of quadratic stability. To further reduce the overdesign in the quadratic framework, this paper also proposes a parameter-dependent filter design procedure, which is much less conservative than the quadratic approach. The quadratic and parameter-dependent approaches provide alternatives for designing robust H infin filters with different degrees of conservativeness and computational complexity. Two examples, including a mass-spring system, are utilized to illustrate the design procedures proposed in this paper.

关键词： Filtering Nonlinear filters Uncertain systems Kalman filters Space technology Noise robustness Quantization Delay estimation Equations Aerodynamics

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EEG Effects of Motion Sickness Induced in a Dynamic Virtual Reality Environment

EEG Effects of Motion Sickness Induced in a Dynamic Virtual ...

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29th Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBS 2007), vol.10

作者： Chin-Teng Lin Shang-Wen Chuang Yu-Chieh Chen Li-Wei Ko Sheng-Fu Liang Tzyy-Ping Jung Department of Electrical and Control Engineering the Department of Computer Science Brain Research Center Hsinchu Taiwan The Department of Computer Science Brain Research Center Hsinchu Taiwan Department of Electrical and Control Engineering Brain Research Center Hsinchu Taiwan Department of Computer Science and Information Engineering National Cheng Kung University Tainan Taiwan Institute for Neural Computation University of California San Diego CA USA

The Electroencephalogram (EEG) dynamics which relate to motion sickness are studied in this paper. Instead of providing visual or motion stimuli to the subjects to induce motion sickness, we employed a dynamic virtual-reality (VR) environment in our research. The environment consisted of a 3D surrounding VR scene and a motion platform providing a realistic situation. This environment provided the advantages of safety, low cost, and the realistic stimuli to induce motion sickness. The Motion Sickness Questionnaire (MSQ) was used to assess the sickness level, and the EEG effects on the subjects with high sickness levels were investigated using the independent component analysis (ICA). The fake-epoch extraction was then applied to the nausea-related independent components. Finally we employed the Event-Related Spectral Perturbation (ERSP) technology on the fake-epochs in order to determine the EEG dynamics during motion sickness. The experimental results show that most subjects experienced an 8-10Hz power increase to their motion sickness-related phenomena in the parietal and motor areas. Moreover, some subjects experienced an EEG power increase of 18-20Hz in their synchronized responses recorded in the same areas. The motion sickness-related effects and regions can be successfully obtained from our experimental results.

关键词： Electroencephalography Virtual reality Layout Vehicle dynamics computer science Safety Motion analysis Independent component analysis control engineering Costs

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Cooperative Graph Search Using Fractal Decomposition

Cooperative Graph Search Using Fractal Decomposition

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American control Conference (ACC)

作者： James R. Riehl Joao P. Hespanha Center for Control Dynamical Systems and Computation Electrical and Computer Engineering Department University of California Santa Barbara CA USA

We present an algorithm based on hierarchical decomposition that finds close-to-optimal search paths for a cooperative team of agents searching for one or more targets on a graph. The method partitions the graph to create a high-level problem and several lower-level problems. Since the computations on each level are identical, the lower-level problems can be further decomposed. In this way, the problem becomes fractal in nature. We use best-case and worst-case instances of the decomposed problem to establish upper and lower bounds on the optimal search reward, and the bounds are determined with much less computation than what is required to solve the full problem. We show that as the number of decomposition levels increases, the computational complexity approaches O(n) at the expense of looser bounds on the optimal reward. A large-scale test case shows that this method is computationally fast, produces good results, and achieves true cooperation between agents.

关键词： Fractals Search problems Partitioning algorithms Computational complexity Distributed computing Military computing Cities and towns Large-scale systems Testing autonomous agents

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Discrete rotational symmetry and quantum-key-distribution protocols

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Physical Review A 2007年第3期75卷 032341-032341页

作者： David Shirokoff Chi-Hang Fred Fung Hoi-Kwong Lo Center for Quantum Information and Quantum Control Department of Electrical & Computer Engineering and Department of Physics University of Toronto Toronto Ontario Canada M5S 3G4

We study the role of discrete rotational symmetry in the quantum key distribution by generalizing the well-known Bennett-Brassard 1984 and Scarani-Acin-Ribordy-Gisin 2004 protocols. We observe that discrete rotational symmetry results in the protocol’s invariance to continuous rotations, thus leading to a simplified relation between bit and phase error rates and consequently a straightforward security proof.

关键词： UNCONDITIONAL SECURITY CRYPTOGRAPHY

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Random Bipartite Entanglement from W and W-Like States

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Physical Review Letters 2007年第26期98卷 260501-260501页

作者： Ben Fortescue Hoi-Kwong Lo Center for Quantum Information and Quantum Control Department of Electrical and Computer Engineering and Department of Physics University of Toronto Toronto Ontario M5S 3G4 Canada

We describe a protocol for distilling maximally entangled bipartite states between random pairs of parties from those sharing a tripartite W state |W⟩=(1/3)(|100⟩+|010⟩+|001⟩)ABC, and show that the total distillation rate Et∞ [the total number of Einstein-Podolsky-Rosen (EPR) pairs distilled per W, irrespective of who shares them] may be done at a higher rate than EPR distillation between specified pairs of parties. Specifically, the optimal rate for distillation to specified parties has been previously shown to be 0.92 EPR pairs per W, while our protocol can asymptotically distill 1 EPR pair per W between random pairs of parties, which we conjecture to be optimal. We thus demonstrate a tradeoff between overall distillation rate and final distribution of EPR pairs. We further show that there exist states with fixed lower-bounded Et∞, but arbitrarily small distillable entanglement for specified parties.

关键词： Quantum theory

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Quantum key distribution with dual detectors

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Physical Review A 2007年第5期75卷 052304-052304页

作者： Bing Qi Yi Zhao Xiongfeng Ma Hoi-Kwong Lo Li Qian Center for Quantum Information and Quantum Control (CQIQC) Department of Physics and Department of Electrical and Computer Engineering University of Toronto Toronto M5S 3G4 Canada

To improve the performance of a quantum-key-distribution (QKD) system, high speed, low dark count single photon detectors (or low-noise homodyne detectors) are required. However, in practice, a fast detector is usually noisy. Here, we propose a dual-detector method to improve the performance of a practical QKD system with realistic detectors: the legitimate receiver randomly uses either a fast (but noisy) detector or a quiet (but slow) detector to measure the incoming quantum signals. The measurement results from the quiet detector can be used to bound the eavesdropper’s information, while the measurement results from the fast detector are used to generate a secure key. We apply this idea to various QKD protocols. Simulation results demonstrate significant improvements of the secure key rate in the lower loss regime in both Bennett-Brassard 1984 (BB84) protocol with ideal single photon source and Gaussian-modulated coherent states protocol; while for decoy-state BB84 protocol with weak coherent source, the improvement is moderate. We also discuss various practical issues in implementing the dual-detector scheme.

关键词： UNCONDITIONAL SECURITY SINGLE PHOTONS UP-CONVERSION CRYPTOGRAPHY ATTACK STATES CRYPTOSYSTEMS COMMUNICATION GENERATION DEVICES

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A genetic-fuzzy control application to ramp metering and variable speed limit control

A genetic-fuzzy control application to ramp metering and var...

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IEEE International Conference on Systems, Man and Cybernetics

作者： Amir Hosein Ghods Ashkan Rahimi Kian Masoud Tabibi Control and Intelligent Processing Center of Excellence Department of Electrical and Computer Engineering University of Tehran Tehran Iran Department of Civil Engineering University of Amir-Kabir Tehran Iran

This paper proposes a fuzzy control approach for the traffic-responsive ramp metering and variable speed limits control, in order to reduce the peak-hour congestion on freeways. The objective of control is to minimize the total time spent in the traffic network. To ease the calibration process of fuzzy controller and improve the overall performance of ramp metering and variable speed limits, genetic algorithm is applied for tuning the fuzzy sets parameters. In order to evaluate the controller's efficiency and applicability, a comparison is made with traditional ALINEA based controller and the fuzzy ramp metering only case by a case-study. The macroscopic traffic model METANET and its extension for dynamic speed limits are used for optimization procedure and presenting the simulation results. The paper concludes that genetic fuzzy control of ramp metering and speed limits is expected to enhance the performance of the freeway traffic network.

关键词： Traffic control Fuzzy control Communication system traffic control Electric breakdown Fuzzy logic Fuzzy sets Nonlinear control systems Velocity control Safety Fuzzy systems

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Experimental study on the Gaussian-modulated coherent-state quantum key distribution over standard telecommunication fibers

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Physical Review A 2007年第5期76卷 052323-052323页

作者： Bing Qi Lei-Lei Huang Li Qian Hoi-Kwong Lo Center for Quantum Information and Quantum Control (CQIQC) Department of Physics and Department of Electrical and Computer Engineering University of Toronto Toronto Ontario Canada M5S 3G4

In this paper, we present a fully fiber-based one-way quantum-key-distribution (QKD) system implementing the Gaussian-modulated coherent-state (GMCS) protocol. The system employs a double Mach-Zehnder interferometer (MZI) configuration in which the weak quantum signal and the strong local oscillator (LO) go through the same fiber between Alice and Bob, and are separated into two paths inside Bob’s terminal. To suppress the LO leakage into the signal path, which is an important contribution to the excess noise, we implemented a scheme combining polarization and frequency multiplexing, achieving an extinction ratio of 70 dB. To further minimize the system excess noise due to phase drift of the double MZI, we propose that, instead of employing phase feedback control, one simply let Alice remap her data by performing a rotation operation. We further present noise analysis both theoretically and experimentally. Our calculation shows that the combined polarization and frequency multiplexing scheme can achieve better stability in practice than the time-multiplexing scheme, because it allows one to use matched fiber lengths for the signal and the LO paths on both sides of the double MZI, greatly reducing the phase instability caused by unmatched fiber lengths. Our experimental noise analysis quantifies the three main contributions to the excess noise, which will be instructive to future studies of the GMCS QKD systems. Finally, we demonstrate, under the “realistic model” in which Eve cannot control the system within Bob’s terminal, a secure key rate of 0.3bit∕pulse over a 5km fiber link. This key rate is about two orders of magnitude higher than that of a practical Bennett-Brassard 1984 protocol QKD system.

关键词： UNCONDITIONAL SECURITY CRYPTOGRAPHY PROOF

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The Mimo Predictive Pid controller Design

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Asian Journal of control 2008年第4期4卷

作者： M.H. Moradi M.R. Katebi M.A. Johnson Department of Electronic and Electrical Engineering University of Strath-clyde Glasgow GI 1QE UK. Dr. Moradi is a Lecturer in the Department of Electronic and Electrical Engineering University of Bu-Ali Sina in Iran. He obtained the BSc and MSc in 1991 and 1993 from the Sharif University of Technology and Tarbiat Modarres University respectively. Dr. Moradi joined the Bu-Ali Sina University in 1993. In 2002 he obtained his PhD degree from the University of Strath-clyde Glasgow Scotland. His theoretical research interests include predictive PID control advanced classical control generalised predictive control system identification and fault monitoring robust control design computer networks and more recently control through networks. His industrial interests are in the areas of large-scale systems especially power systems and power plant modelling and control supervisory control and process control. Dr. Moradi has published a number of Journal and Conference papers. Dr. Katebi is a senior lecturer in the Department of Electronic and Electrical Engineering University of Strathclyde. His theoretical research interests are currently focused on Non-linear Control and Filtering for Complex Systems Autonomous Control Design System integration and Fault monitoring and Reconfiguration Plant Monitoring through the Internet Discrete Event Simulation Process Optimisation and Robust Control Design. The industrial research interests are in the area of Hot and Rolling for Steel and Aluminium Power Plant Modelling and Control Marine Control Systems Process Control and Wastewater Treatment Control. Dr Katebi is the author/co-author of four books and more than 150 papers and industrial reports. Professor Johnson's academic education began at Coventry University (1969) and continued under the supervision of Professor Greyham Bryant in the field of Control Systems at Imperial College London. He obtained the DIC MSc and PhD from Imperial College leaving for industry in 1978. Subsequent experience was in the

This paper is concerned with the design of Multi-Inputs and Multi-Outputs (MIMO) predictive PID controllers, which have similar performance to that obtainable from model-based predictive controllers. A new PID control structure is defined which incorporates the prediction of future outputs and uses future set point. A method is proposed to calculate the optimal values of the PID gains from generalised predictive control results. A decentralized version of the predictive PID controllers is presented and the stability of the closed loop system is studied. Simulation studies demonstrate the superior performance of the proposed controller compared with a conventional PID controller. The results are also compared with generalised predictive control solutions.

关键词： PID control design predictive PID MIMO controller optimisation

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TRACKING control IN THE PRESENCE OF NONLINEAR DYNAMIC FRICTIONAL EFFECTS: ROBOT EXTENSION

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Asian Journal of control 2008年第3期1卷

作者： M. Feemster D.M. Dawson A. Behal W. Dixon Matthew Feemster received the B.S degree in Electrical Engineering from Clemson University Clemson South Carolina in December 1994. Upon graduation he remained at Clemson University and received the M.S. degree in Electrical Engineering in 1997. During this time he also served as a research/teaching assistant. His research work focused on the design and implementation of various nonlinear control algorithms with emphasis on the induction motor and mechanical systems with friction present. He is currently working toward his Ph.D. degree in Electrical Engineering at Clemson University. Darren M. Dawson was born in 1962 in Macon Georgia. He received an Associate Degree in Mathematics from Macon Junior College in 1982 and a B.S. Degree in Electrical Engineering from the Georgia Institute of Technology in 1984. He then worked for Westinghouse as a control engineer from 1985 to 1987. In 1987 he returned to the Georgia Institute of Technology where he received the Ph.D. Degree in Electrical Engineering in March 1990. During this time he also served as a research/teaching assistant. In July 1990 he joined the Electrical and Computer Engineering Department and the Center for Advanced Manufacturing (CAM) at Clemson University where he currently holds the position of Professor. Under the CAM director's supervision he currently leads the Robotics and Manufacturing Automation Laboratory which is jointly operated by the Electrical and Mechanical Engineering departments. His main research interests are in the fields of nonlinear based robust adaptive and learning control with application to electro-mechanical systems including robot manipulators motor drives magnetic bearings flexible cables flexible beams and high-speed transport systems. Aman Behal was born in India in 1973. He received his Masters Degree in Electrical Engineering from Indian Institute of Technology Bombay in 1996. He is currently working towards a Ph.D in Controls and Robotics at Clemson University. His research focuses on the control of no

In this paper, we extend the observer/control strategies previously published in [25] to an n -link, serially connected, direct drive, rigid link, revolute robot operating in the presence of nonlinear friction effects modeled by the Lu-Gre model. In addition, we also present a new adaptive control technique for compensating for the nonlinear parameterizable Stribeck effects. Specifically, an adaptive observer/controller scheme is developed which contains a feedforward approximation of the Stribeck effects. This feedforward approximation is used in a composite controller/observer strategy which forces the average square integral of the position tracking error to an arbitrarily small value. Experimental results are included to illustrate the performance of the proposed controllers.

关键词： Friction compensation nonlinear control

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