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作者： Li, Yinan Liu, Jun Ozay, Necmiye Department of Automatic Control and System Engineering University of Sheffield SheffieldS1 3JD United Kingdom Department of Applied Mathematics University of Waterloo WaterlooONN2L 3G1 Canada Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States

This paper proposes a method to compute finite abstractions that can be used for synthesizing robust hybrid control strategies for nonlinear systems. Most existing methods for computing finite abstractions utilize some global, analytical function to provide bounds on the reachable sets of nonlinear systems, which can be conservative and lead to spurious transitions in the abstract systems. This problem is even more pronounced in the presence of imperfect measurements and modelling uncertainties, where control synthesis can easily become infeasible due to added spurious transitions. To mitigate this problem, we propose to compute finite abstractions with robustness margins by over-approximating the local reachable sets of nonlinear systems. We do so by linearizing the nonlinear dynamics into linear affine systems and keeping track of the linearization error. It is shown that this approach provides tighter approximations and several numerical examples are used to illustrate of effectiveness of the proposed methods. © 2015, IFAC (International Federation of automatic control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Nonlinear systems

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Stabilization of a cascaded DC system via adding a virtual impedance in parallel with the load converter

Stabilization of a cascaded DC system via adding a virtual i...

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IEEE International Symposium on Power Electronics for Distributed Generation systems (PEDG)

作者： Xin Zhang Wen-Long Ming Qing-Chang Zhong Xin-Bo Ruan Dept of Automatic Control and Systems Engineering The University of Sheffield UK Dept of Electrical and Computer Engineering Illinois Institute of Technology USA College of Automation Engineering Nanjing University of Aeronautics and Astronautics China

ISBN: (纸本)9781479985876

For cascaded systems, interactions among individually designed power subsystems may cause the instability of the whole system. Regulating the input impedance of the load converter is an effectively way to solve this problem, however, one big challenge of this method is how to consider the stability of cascaded system and the dynamic performance of load converter together. In light of this, this paper proposes a parallel-virtual-impedance (PVI) control strategy to improve the input impedance of the load converter. The proposed virtual impedance is in parallel with the load converter, via the proposed virtual impedances, the magnitude and phase of the input impedance of the load converter is modified only in a small range of frequency. As a result, this method not only solves the instability problem of the cascaded system, but also keeps a good dynamic performance for load converter. This paper discusses the concept, realization and design consideration of the proposed strategy in detail. Finally, a 100 W cascaded system, which consisting of an LC filter and a 48V-12V buck converter, is built to verify the correctness of the proposed methods 1 .

关键词： Impedance Stability criteria Frequency conversion Power system stability Resonant frequency Transfer functions Voltage control

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Improved Path Following for Kites with Input Delay Compensation

Improved Path Following for Kites with Input Delay Compensat...

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IEEE Annual Conference on Decision and control

作者： Nikitas Rontsis Sean Costello Ioannis Lymperopoulos Colin N. Jones Department of Electrical & Computer Engineering Aristotle University of Thessaloniki 54124 Thessaloniki Greece Department of Mechanical Engineering Automatic Control Laboratory EPFL 1015 Lausanne Switzerland

ISBN: (纸本)9781479978878

In kite power systems, substantial input delay between the actuator and the tethered kite can severely hinder the performance of the control algorithm, limiting the capability of the system to track power-optimal loops. We propose a method that deals with this impediment by using a data-based adaptive filter that predicts future states despite variations in wind conditions, other exogenous disturbances and model mismatch. Moreover, we exploit the geometry of the path on a hemisphere to enhance the guidance algorithm for such kites at a fixed length tether. The objective is to improve the automatic crosswind operation of an airborne wind energy system. To test this under realistic conditions, a small-scale prototype was employed for a series of experiments. The robustness to disturbances and the performance of the algorithm in path following was evaluated for a number of different paths.

关键词： Computer algorithms wind power system delay compensation Byways Cerebral Hemispheres actuators

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Object detection and depth estimation of real world objects using single camera

Object detection and depth estimation of real world objects ...

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International Conference on Aerospace Science & engineering (ICASE)

作者： Sana Liaquat Umar S. Khan Ata-Ur-Rehman Department of Mechatronics National University of Sciences and Technology Islamabad Pakistan Department of Automatic Control and Systems Engineering University of Sheffield UK

This research paper proposes a single camera based depth estimation technique. The proposed technique takes images of walls in a room and detects objects of interest in a cluttered environment. Having detected different objects in a room the proposed technique calculates their areas. Based on training data and polynomial curve fitting approach the proposed technique estimates the distance of the camera from the objects. For a real world object one can determine a fixed equation which can then be used to find any random distance. The approach is efficient and can effectively be applied to any indoor navigation or motion planning algorithm. Based on the estimated distances from different objects the proposed algorithm estimates the accurate location of the camera (mounted on a robot) in a room. For detection we have used template matching technique. Algorithm compares the reference template with the objects of interest in a cluttered environment by using SURF (speeded up robust features). The proposed algorithm is tested on real world images and compared with the existing depth estimation techniques.

关键词： Cameras Feature extraction Estimation Curve fitting Clocks Robot kinematics

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Robust set invariance and contractivity of discrete-time systems: The generators approach

Robust set invariance and contractivity of discrete-time sys...

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Mediterranean Conference on control and Automation (MED)

作者： George Bitsoris Marina Vassilaki the Control Systems Laboratory of the Department of Electrical and Computer Engineering University of Patras Patras Greece the Department of Electrical and Electronic Engineering Educators ASPETE Athens Greece

In this paper, the problem of robust set invariance and contractivity with respect to discrete-time dynamical systems is investigated. In contrast to the usual approach consisting in describing regions of system's space by their border surfaces, a dual description of sets in terms of a generator matrix and a, generally nonlinear, generating function is proposed. This leads to the establishment of an associated generated system whose robust set invariance and/or contractivity properties imply corresponding properties for the initial system. This general result is then applied to the development of robust set invariance and/or robust contractivity conditions for linear systems.

关键词： Robustness Generators Linear systems Nonlinear systems Stability analysis Discrete-time systems Convergence

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A bioinspired mathematical model for a robotic swarm to discriminate between self and nonself robots

A bioinspired mathematical model for a robotic swarm to disc...

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International Conference on System Theory, control, and Computing (ICSTCC)

作者： Simona Mihaela Bibic Elena Corina Cipu Cătălin Buiu Department of Applied Mathematics Politehnica University of Bucharest Romania Department of Automatic Control and Systems Engineering Politehnica University of Bucharest Romania

A robotic swarm is a self-organizing multi-robot system characterized by simplicity of individual agents, local sensing and communication capabilities, parallelism in task execution, robustness, scalability, flexibility and decentralized control. Security of robotic swarms has been largely overlooked and the main contribution of this paper is to propose a bioinspired formalism based on membrane computing and P colonies in order to provide the robotic swarm with a way to discern between own and foreign (self and nonself) robots.

关键词： Yttrium Automata Robot sensing systems Biomembranes Actuators

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Active Fault Diagnosis in Sampled-data systems

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IFAC-PapersOnLine 2015年第21期48卷 883-888页

作者： Niemann, Henrik Poulsen, Niels Kjolstad Department of Electrical Engineering Automation and Control Technical University of Denmark Building 326 DK-2800 Kgs. Lyngby Denmark Dept. of Applied Mathematics and Computer Science Section for Dynamical Systems Technical University of Denmark DK-2800 Kgs. Lyngby Denmark

The focus in this paper is on active fault diagnosis (AFD) in closed-loop sampleddata systems. Applying the same AFD architecture as for continuous-time systems does not directly result in the same set of closed-loop matrix transfer functions. For continuous-time systems, the LFT (linear fractional transformation) structure in the connection between the parametric faults and the matrix transfer function (also known as the fault signature matrix) applied for AFD is not directly preserved for sampled-data system. As a consequence of this, the AFD methods cannot directly be applied for sampled-data systems. Two methods are considered in this paper to handle the fault signature matrix for sampled-data systems such that standard AFD methods can be applied. The first method is based on a discretization of the system such that the LFT structure is preserved resulting in the same LFT structure in the fault signature matrix as obtained for continuous-time systems. The other method is an approximation method, where the same structure is obtained for small parametric faults. © 2015

关键词： Continuous time systems

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Robust set invariance and contractivity of continuous-time systems

Robust set invariance and contractivity of continuous-time s...

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IEEE Conference on Cybernetics and Intelligent systems

作者： George Bitsoris Marina Vassilaki Control Systems Laboratory of the Department of Electrical and Computer Engineering University of Patras Patras Greece Department of Electrical and Electronic Engineering Educators ASPETE Athens Greece

In this paper, the problem of set invariance and contractivity with respect to continuous-time dynamical systems is investigated. In contrast to the usual approach consisting in describing regions of system's state space by their border surfaces, a dual description of sets in terms of a generator matrix and a, generally nonlinear, generator function is proposed. This leads to the establishment of an associated generated system whose set invariance and/or contractivity properties imply corresponding properties for the initial system. This general result is then applied to the development of robust set invariance and/or contractivity conditions for linear and nonlinear systems.

关键词： Robustness Generators Linear systems Nonlinear systems Convergence Conferences Random access memory

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Experiment Time Minimisation under Parameter Accuracy Constraints and Time-Domain Signal Amplitude Bounds

Experiment Time Minimisation under Parameter Accuracy Constr...

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European control Conference

作者： M.G. Potters X. Bombois Paul M.J. Van den Hof Delft Center for Systems and Control Delft University of Technology 2628 CD Delft The Netherlands Laboratoire Ampère UMR CNRS 5005 Ecole Centrale de Lyon 36 avenue Guy de Collongue 69134 Ecully Cedex France the Department of Electrical Engineering Eindhoven University of Technology Postbus 513 5600 MB Eindhoven The Netherlands

ISBN: (纸本)9781509025923

We consider the input design problem of finding the minimal required experiment time such that accuracy constraints on the parameter estimate of an identification experiment are satisfied, while also respecting signal amplitude bounds. The input signal is parameterized as a multi-sine. We first show how multiple linear matrix inequalities from the least-costly and applications-oriented experiment design frameworks can be transformed into a generalised E-optimality constraint. Then, the solution to our problem is found by: (i) designing a multi-sine of one period with the Guillaume-Manchester algorithm [12], [10] that minimises the generalised E-optimality criterion under signal amplitude bounds, and (ii) utilising periodicity and an optimality condition to scale the experiment time such that the imposed accuracy constraints are also respected. An example shows an experiment time reduction of 50% compared with a traditional least-costly experiment design approach.

关键词： Experiment Time Minimisation Parameter Accuracy Constraints Time-Domain Signal Amplitude Bounds

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Robust fault tolerant manoeuvring and rudder control of marine vehicles with state saturation

Robust fault tolerant manoeuvring and rudder control of mari...

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IEEE International Conference on Industrial Technology (ICIT)

作者： Xiaozheng Jin Qiuhong Liu Yu Kang Jiahu Qin School of Electrical Engineering and Automation HeFei University of Technology HeFei AnHui China Research Institute of Intelligent Control and Systems Harbin Institute of Technology Harbin China Department of Automation University of Science and Technology of China Hefei China Key Laboratory of Technology in Geo-Spatial Information Processing and Application System Chinese Academy of Sciences Beijing China

ISBN: (纸本)9781467380768

In this paper, the problem of rudder-roll damping control for a class of cruise keeping ships subject to both actuator fault and state saturation is investigated. A manoeuvring and rudder control model of marine vessels is firstly reviewed based on the existing literature. Actuator faults which including partial loss of rudder effectiveness and actuator-bias faults are considered in the model. Then a switching control strategy is developed to compensate for the actuator faults and to guarantee the stability of the rudder-roll damping control system. Moreover, some relationship regarding state saturation bounds, actuator fault limits and control parameters are analyzed in this paper. Finally, simulation results are given to illustrate the proposed procedures and their effectiveness.

关键词： Actuators Vehicles Damping Mathematical model Marine vehicles Vehicle dynamics

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