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International Conference on Natural Computation

作者： Wu, Ying Gao, Xiao-Zhi Huang, Xian-Lin Zenger, Kai Department of Control Theory and Engineering Harbin Institute of Technology Harbin China Department of Electrical Engineering Aalto University Espoo Finland Department of Automation and Systems Technology Aalto University Espoo Finland

ISBN: (纸本)9781424459612

A novel hybrid optimization algorithm, PSOCCA, based on the fusion of the Particle Swarm Optimization (PSO) and Cultural Algorithm (CA), is proposed in this paper to enhance the convergence characteristics of the original PSO. In the PSOCCA, the particle swarm is considered to be a population component of the CA, and three knowledge sources are stored in the belief space to update the population space and establish the relationship between the two CA spaces. A unique mutation operator inspired by the Differential Evolution (DE) is used to mutate those particles with unsatisfactory performances in the population space. A new kind of knowledge, average value knowledge, that is stored in the belief space, is also introduced to regulate the variation ratio in the swarm population. The optimization performance of our PSOCCA is investigated using ten high-dimension and multi-peak functions. Simulation results demonstrate that it can be superior to the regular PSO. © 2010 IEEE.

关键词： Particle swarm optimization (PSO)

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Efficiency of steering torque recommendation in limits of driving dynamics: An empirical study

Efficiency of steering torque recommendation in limits of dr...

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作者： Mehrjerdian, E. Gaedke, A. Greul, R. Bertram, T. ZF Lenksysteme GmbH D-73529 Schwaebisch Gmuend Germany Institute of Control Theory and Systems Engineering Faculty of Electrical Engineering and Information Technology Technische Universität Dortmund D-44221 Dortmund Germany

ISBN: (纸本)9783902661722

The potential of controlled torque assistance in safety-related driving situations is investigated in more detail in this paper. For this purpose, a study of test persons was carried out in a real test vehicle in which an oversteer situation was reproducibly induced by activating a kick plate. Driver perception, driver response and vehicle reaction as a result of the activation were evaluated in different types of test with passive and active assistance function in each case. Driver perception was evaluated on the basis of subjective assessments by the test persons. Driver and vehicle response on the other hand were evaluated by analysing vehicle and steering signals. Results in the form of objective criteria are derived which enable the functionality to be evaluated in relation to the level of the assisting torque applied. As well as the holistic consideration of all driver reactions, the benefit of the function to individual drivers is also analysed. A detailed questionnaire was used to classify different driver types from the number of all test drivers, and used as a basis for analysing driver behaviour. Comparison of these responses with journeys carried out by a professional test driver enable conclusions to be drawn relating to the degree of significantly improved driver response to the recommendation. © 2010 IFAC.

关键词： Torque

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A robust stabilization using state feedback with feedforward

A robust stabilization using state feedback with feedforward

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作者： Danapalasingam, Kumeresan A. La Cour-Harbo, Anders Chowdhary, Girish Bisgaard, Morten Department of Electronic Systems Section for Automation and Control Aalborg University 9220 Aalborg Denmark Georgia Institute of Technology Daniel Guggenheim School of Aerospace Engineering Atlanta GA United States

ISBN: (纸本)9781424474264

In a general nonlinear control system a stabilizing control strategy is often possible if complete information on external inputs affecting the system is available. Assuming that measurements of persistent disturbances are available it is shown that the existence of a smooth uniform control Lyapunov function implies the existence of a stabilizing state feedback with feedforward control which is robust with respect to measurement errors and external disturbances. Conversely, using differential inclusions parameterized as nonlinear systems with state and disturbance measurement errors, it is shown that there exists a smooth uniform control Lyapunov function if there is a robustly stabilizing state feedback with feedforward. This paper demonstrates that if there exists a smooth control Lyapunov function for a general nonlinear system with persistent disturbances for which one has previously designed a feedback controller, a feedforward always exists to be augmented for stability. © 2010 AACC.

关键词： Lyapunov functions

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Stability analysis of periodically time-varying systems using periodic Lyapunov functions *

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IFAC Proceedings Volumes 2010年第11期43卷 57-62页

作者： Christoph Böhm Mircea Lazar Frank Allgöwer Institute of Systems Theory and Automatic Control University of Stuttgart Germany Department of Electrical Engineering Eindhoven University of Technology The Netherlands

This paper proposes a novel approach to stability analysis of discrete-time nonlinear periodically time-varying systems. The contributions are as follows. Firstly, a relaxation of standard Lyapunov conditions is derived. This leads to a less conservative Lyapunov function that is required to decrease at every period rather than at each time instant. Secondly, for linear periodic systems with constraints, we show that compared to standard Lyapunov theory, the novel stability concept yields a larger estimate of the region of attraction. An example illustrates the effectiveness of the developed theory.

关键词： Periodic systems stability region of attraction

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Optimal control over Unreliable Networks with Uncertain Loss Rates

Optimal Control over Unreliable Networks with Uncertain Loss...

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American control Conference

作者： Markus J. Kogel Rainer Blind Frank Allgower Laboratory for Systems Theory and Automatic Control Institute for Automation Engineering Otto-von-Guericke University Magdeburg Magdeburg Germany Institute for Systems Theory and Automatic Control University of Stuttgart Stuttgart Germany

ISBN: (纸本)9781424474264

In this work, we consider an optimal control problem for Networked control systems (NCS), where the loop is closed via an unreliable network. In order to inform the controller about the fates of the control packets, the actuator sends acknowledgements to the controller. In this work, different types of acknowledgements are considered. Since all packets are send over a network, we consequently assume, that all packets can get lost, i.e. the measurement packets, the control packets as well as the acknowledgement packets. The loss of these packets is modeled by independent and identically distributed (iid) Bernoulli processes. Finally, we assume that the parameters of these loss processes are not known exactly. Using this setup, we derive bounds for the uncertainty in the loss rates. Moreover, we present an algorithm to design a sub-optimal controller which can tolerate a given amount of network uncertainties.

关键词： Communication Networks Optimal control Networked control systems TCP/UDP Unreliable Parameters Optimal control Packet Networked control systems networks(communications) controllers

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Floor segmentation of omnidirectional images for mobile robot visual navigation

Floor segmentation of omnidirectional images for mobile robo...

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2010 IEEE/RSJ International Conference on Intelligent Robots and systems

作者： Luis Felipe Posada Krishna Kumar Narayanan Frank Hoffmann Torsten Bertram Institute of Control Theory and Systems Engineering Technische Universität Dortmund Dortmund Germany

This paper describes a novel approach for purely vision based mobile robot navigation. The visual obstacle avoidance and corridor following behavior rely on the segmentation of the traversable floor region in the omnidirectional robocentric view. The image processing employs a supervised approach in which the segmentation optimal with respect to the appearance of the local environment is determined by cross validation over 3D scans captured by a photonic mixer device (PMD) camera. The range data in the front view provides the seeds and validation data to supervise the appearance based segmentation in the omniview. Segmentation relies on histogram backprojection which maintains separate appearance models for floor, obstacles and background. A naive Bayes classifier predicts the occupancy of the robots local environment by fusing the evidence provided by different segmentations and models. The classification error is analyzed on ground truth data generated by a PMD camera and manually segmented scenes. The scheme is highly robust with respect to ambiguous and misleading visual appearances of obstacles and floor, thus enabling the robot to navigate safely in unstructured environments of diverse appearance, texture and illumination. The proposed vision algorithm and the navigation behavior demonstrate a robust performance in extensive robotic experiments across several hours of autonomous operation.

关键词： Histograms Image segmentation Image color analysis Pixel Visualization Navigation Three dimensional displays

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Friction model with elasto-plasticity for advanced control applications

Friction model with elasto-plasticity for advanced control a...

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IEEE/ASME (AIM) International Conference on Advanced Intelligent Mechatronics

作者： Michael Ruderman Torsten Bertram Institute of Control Theory and Systems Engineering Technische Universität Dortmund Dortmund Germany

A novel nonlinear friction model with elasto-plasticity is proposed. Being in accordance with state-of-the-art friction properties the model provides a compact set of concentrated parameters and offers a complexity reduction when describing the hysteretic and the transient response of dynamic friction. Considering the first-order dynamic system with friction, both the pre-sliding and the gross sliding regimes are analyzed and identified from experiments. Intended for control applications the proposed model is used in feed-forwarding in order to improve the tracking performance of a standard linear control, above all at frequently velocity reversals.

关键词： Friction Force Hysteresis Modeling Current measurement Trajectory Dynamics

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Discrete Dynamic Preisach Model for Robust Inverse control of Hysteresis systems

Discrete Dynamic Preisach Model for Robust Inverse Control o...

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2010 49th IEEE Conference on Decision and control

作者： Michael Ruderman Torsten Bertram Institute of Control Theory and Systems Engineering (RST) Technische Universitat Dortmund 44227-Dortmund Germany

ISBN: (纸本)9781424477456

Hysteresis effects are present in diverse systems including structural mechanics, tribology, and electromagnetism. Hysteresis systems are generally known as exhibiting a memory effect which aggravates their accurate prediction and control. The classical Preisach model provides powerful means to describe arbitrary hysteresis with rate-independent behavior. In this paper, we address the problem of the robust inverse control of hysteresis systems while presenting a novel formulation of the discrete dynamic Preisach model and its inverse. The control-oriented features, among the advanced computational efficiency and the handling of hysteresis uncertainties are shown and discussed. The properly developed inverse hysteresis control is augmented by an auxiliary disturbance observer which captures uncertainties of the modeled hysteresis and its time-variant behavior. The performance of the proposed observer based control strategy is compared with a standard feedback of the controlled hysteretic value. The proposed approach is experimentally evaluated for linearizing the torsional hysteresis compliance. Providing an universal character the method is suitable for a broad class of hysteresis systems independent of the source and form of underlying hysteresis.

关键词： Hysteresis hysteresis control disturbance observer Inverse Memory effect hysteresis effect control strategy

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Flatness-based trajectory planning for the shallow water equations

Flatness-based trajectory planning for the shallow water equ...

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2010 49th IEEE Conference on Decision and control

作者： Torsten Knuppel Frank Woittennek Joachim Rudolph Faculty of Electrical and Computer Engineering Institute of Control Theory Technische Universitat Dresden 01062 Dresden Germany Chair of Systems Theory and Control Engineering Saarland University 66123 Saarbrucken Germany

ISBN: (纸本)9781424477456

A flatness-based feed-forward control design approach for an open channel flow modelled by the shallow water equations is discussed. The control input consists of the adjustable height of opening of a delimiting sluice gate. In order to compute the trajectory of the control input, the physical boundaries containing the control input are neglected and the problem is reduced to an initial value problem w.r.t. the spatial coordinate. The solution to this problem can be obtained with the method of characteristics.

关键词： control input shallow water equations Physical boundaries LOCK GATE Open channel flow trajectory planning method of characteristics design approach Initial value problems trajectory FEEDFORWARD control

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Enhanced Frameworks for Safety Verification of Autonomous Rendezvous systems

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IFAC Proceedings Volumes 2010年第15期43卷 333-338页

作者： Christoph Maier Antonis Papachristodoulou Institute for Systems Theory and Automatic Control University of Stuttgart Stuttgart Germany Department of Engineering Science University of Oxford Oxford United Kingdom

Abstract We consider the safety of a V-bar hopping manoeuvre which forms part of the final stage in autonomous space rendezvous. This manoeuvre is controlled by thrusters: we assume these inputs are perfect impulses and model the system in a hybrid automaton framework. We consider the operation of the system under bounded parametric uncertainties, e.g. thruster misalignment, and use the concept of Barrier function certificates to assess system safety. This methodology provides an efficient tool for the systematic investigation of the safety property and does not rely on Monte-Carlo simulations. In particular, the existence of a Barrier function certificate guarantees that all trajectories of the system starting from a given initial set do not enter a predefined unsafe region under any possible combination of parameter deviations. Such a Barrier function certificate can be constructed efficiently using the Sum of Squares (SOS) decomposition and semi-definite programming (SDP).

关键词： Satellite control spacecraft autonomy safety analysis hybrid automaton Lyapunov methods Barrier function certificate Sum of Squares semidefinite programming

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