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36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2000

作者： Shtessel, Yuri B. Hall, Charles E. Electrical and Computer Engineering Dept University of Alabama Huntsville Al United States Control Systems Group NASA MSFC United States

Ascent flight control of the X-33 is performed using two XRS-2200 linear aerospike engines, in addition to aerosurfaces. The baseline control algorithms are PID with gain scheduling. Flight control using an innovative method, Sliding Mode control, is presented for nominal and engine failed modes of flight. An easy to implement, robust controller, requiring no reconfiguration or gain scheduling is demonstrated through high fidelity flight simulations. The proposed sliding mode controller utilizes a two-loop structure and provides robust, de-coupied tracking of both orientation angle command profiles and angular rate command profiles in the presence of engine failure, bounded external disturbances (wind gusts) and uncertain matrix of inertia. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues. Conditions that restrict engine failures to robustness domain of the sliding mode controller are derived. Simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in the presence of external disturbances and vehicle inertia uncertainties, as well as the single engine failed case. The designed robust controller will significantly reduce the time and cost associated with flying new trajectory profiles or orbits, with new payloads, and with modified vehicles. © 2000 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Sliding mode control

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Sliding mode control of the X-33 with an engine failure

Sliding mode control of the X-33 with an engine failure

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35th Intersociety Energy Conversion engineering Conference and Exhibit 2000

作者： Shtessel, Yuri B. Hall, Charles E. Electrical and Computer Engineering Dept University of Alabama Huntsvilie AL United States Control Systems Group NASA MSFC Huntsvilie AL United States

关键词： Sliding mode control

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X-33 ascent flight control design by trajectory linearization - A singular perturbation approach

X-33 ascent flight control design by trajectory linearizatio...

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AIAA Guidance, Navigation, and control Conference and Exhibit 2000

作者： Jim Zhu, J. Banker, Brad D. Hall, Charles E. Electrical and Computer Engineering Department Louisiana State University Baton Rouge LA 70803 United States Vehicle and Systems Development Department Control Systems Group NASA Marshall Space Flight Center MSFC AL 35812 United States

ISBN: (纸本)9781563479786

The flight control of X-33 poses a challenge to conventional gain-scheduled flight controllers due to its large attitude maneuvers from liftoff to transition and descent. In addition, a wide range of uncertainties in vehicle handling qualities and disturbances must be accommodated by the attitude control system. Nonlinear tracking and decoupling control by trajectory linearization can be viewed as the ideal gain-scheduling controller designed at every point on the flight trajectory. Therefore it provides robust stability and performance at all stages of flight without interpolation of controller gains and eliminates costly controller redesigns due to minor airframe alteration or mission reconfiguration. In this paper, a trajectory linearization design for an X-33 ascent flight controller is presented along with 3-DOF and 6-DOF simulation results. The current design only generates the commanded torque for the vehicle, relying on a gain scheduled control allocation algorithm of the baseline controller developed by NASA MSFC. It is noted that the controller gains for the commanded torque are computed symbolically based on the theoretical derivations and are applicable to any feasible trajectories and airframes with known mass properties. Therefore the design is scalable and mission adaptable. The 3-DOF results were obtained from direct implementation of the symbolic gains, and the 6-DOF results were obtained from the former with only a few days of tuning and refinement. This "plug-and-play" feature demonstrates the simplicity and the inherent robustness of the design technique, which is sought by NASA for the development, test and routine operations of the Reusable Launch Vehicles (RLV's). Plans for further enhancement of the ascent controller and the initial development of the entry and descent controller are also presented. © 2000 by J. J. Zhu. Published by the American Institute of Aeronautics and Astronautics, Inc.

关键词： controllers

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The planning of solution to Istanbul's transportation problem with the coordination of transportation subsystems by the aid of GPS

The planning of solution to Istanbul's transportation proble...

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SICE Annual Conference

作者： A. Demirbilek H. Pastaci College of Electrical and Computer Engineering Electrical Engineering Control and Command Systems Department Turkish State Railways USA College of Electrical and Computer Engineering Electrical Engineering Control and Command Systems Department Yildiz Technical University Turkey

The Istanbul Transportation Information System has been established for the purpose of processing and storing data in a computer environment to arrange, in its most general sense, management service, coordination and planning activities related to transportation. The information system for this objective is one that is composed of a series of hardware and software components including data storage, data processing, data analysis and representation functions. A database called the transportation information system for evaluating the graphical and non-graphical data for the city of Istanbul has been formed. Moreover, some analyses are performed toward design and optimization based on a single intersection. Up-to-date data are accessed with an appropriate interrogation easily and efficiently.

关键词： Transportation Management information systems Environmental management Process planning Hardware Memory Data processing Data analysis Databases Cities and towns

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Algebraic theory of optimal filter banks

Algebraic theory of optimal filter banks

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： O.S. Jahromi B.A. Francis R.H. Kwong Systems Control GroupDepartment of Electrical and Computer Engineering University of Toronto Toronto Canada

We approach the problem of characterizing an optimal FIR filter bank from an algebraic point of view. We introduce the concept of majorization ordering to compare the performance of various filter banks in an admissible set /spl Lscr/. Using the properties of this ordering, we show that a principal component filter bank is associated with the greatest element in /spl Lscr/. A greatest element does not necessarily exist in /spl Lscr/ hence one has to deal with the closely related notion of a maximal element. We show by construction that a maximal element always exist in /spl Lscr/. An interesting result of the presented algebraic theory is that the connection between principal component filter banks and filter banks with maximum coding gain is clearly revealed. In fact, we show that coding gain is a Schur (1973) convex function preserving the order of majorization.

关键词： Channel bank filters Filter bank Finite impulse response filter Signal resolution Gain measurement control systems Explosives Signal processing Bandwidth Distortion

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Linear approximation model network and its formation via evolutionary computation

Linear approximation model network and its formation via evo...

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作者： Tan, K.C. Li, Y. Wang, M.L. Department of Electrical and Computer Engineering National University of Singapore 10 Kent Ridge Crescent Singapore119260 Singapore Centre for Systems and Control Department of Electronics and Electrical Engineering University of Glasgow GlasgowG12 8LT United Kingdom

To overcome the deficiency of local model network (LMN) techniques, an alternative linear approximation model (LAM) network approach is proposed. Such a network models a nonlinear or practical system with multiple linearizing models fitted along operating trajectories, where the individual models are simply networked through output or parameter interpolation. The linearizing models are valid for the entire operating trajectory and hence overcome the local validity of LMN models. LAMs can be evolved from sampled step response data directly, eliminating the need for local linearization upon a pre-model using derivatives of the nonlinear system. Validation results show that the proposed method offers a simple, transparent and accurate multivariable nonlinear modeling technique. © 2000 IEEE.

关键词： Nonlinear systems

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Supervisory control of discrete-event systems: an introduction

Supervisory control of discrete-event systems: an introducti...

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IEEE International Conference on Industrial Technology (ICIT)

作者： W.M. Wonham Systems Control Group Department of Electrical & Computer Engineering University of Toronto Toronto ONT Canada

Discrete-event systems (DES) encompass manufacturing systems, traffic systems, logistic systems, and distributed control and communication networks. The associated processes are discrete (in time and space), asynchronous (event-driven rather than clock-driven) and generative (nondeterministic). In recent years, a theory has emerged of the control of DES, in a setting of finite automata and regular languages; the theory has found application to a range of industrial control processes. This paper provides a tutorial introduction, including an illustrative design problem.

关键词： Supervisory control Discrete event systems Manufacturing systems Communication system traffic control Logistics Distributed control Communication networks Clocks Automatic control Communication system control

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A unified approach for stability robustness computation of quasi-polynomials in a convex set

A unified approach for stability robustness computation of q...

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IEEE Conference on Decision and control

作者： G. Hu E.J. Davison Systems Control Group Department of Electrical and Computer Engineering University of Toronto Toronto ONT Canada

ISBN: (纸本)0780366387

In this paper, the method of approach as used in Qiu and Davison (1992) and Hu and Davison (2000) is extended to the case of delay and neutral type quasi-polynomials. We develop a unified approach to compute the stability robustness measure of quasi-polynomials in a convex set using the framework of convex analysis. The procedure to compute the stability robustness measure which results from this approach is easy to implement. Finally, an example is given to demonstrate the effectiveness of this approach.

关键词： Robust stability Delay Robustness control systems Educational institutions Stability analysis H infinity control Ellipsoids

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Reducing Memory Access Time in the Real-Time Implementation of Signal Processing and control Algorithms

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IFAC Proceedings Volumes 2000年第6期33卷 23-26页

作者： U. Kabir M.A. Hossain M.O. Tokhi Department of Computer Science University of Dhaka Dhaka-1000 Bangladesh Department of Automatic Control and Systems Engineering The University of Sheffield UK

This paper presents a method of enhancing the execution time of a processor in implementing signal processing and control algorithms, through a process of minimisation of memory access time of the processor. The method is based on the design and corresponding software coding of an algorithm, and thus can be adopted for a variety of real-timesignal processing and control applications. The finite difference simulation algorithm ofa flexible beam is considered to demonstrate the effectiveness of the proposed method. The algorithm is implemented on a general-purpose computing platform, and a comparative performance evaluation of the processor with the proposed method is presented and discussed.

关键词： Finite difference method high performance computing memory management real-time signal processing and control simulation of flexible beams

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Hierarchical genetic algorithm based neural network design

Hierarchical genetic algorithm based neural network design

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IEEE Symposium on Combinations of Evolutionary Computation and Neural Networks (CoEN)

作者： G.G. Yen Haiming Lu Intelligent Systems and Control Laboratory School of Electrical and Computer Engineering Oklahoma State University Stillwater OK USA

In this paper, we propose a novel genetic algorithm based design procedure for multi-layer feedforward neural network. Hierarchical genetic algorithm is used to evolve both neural network topology and parameters. Compared with traditional genetic algorithm based designs for neural network, the proposed hierarchical approach addressed several deficiencies highlighted in literature. A multi-objective function is used herein to optimize the performance and topology of the evolved neural network. Two benchmark problems are successfully verified and the proposed algorithm proves to be competitive or even superior to the traditional back-propagation network in Mackey-Glass chaotic time series prediction.

关键词： Neural networks Biological neural networks Algorithm design and analysis Genetic algorithms Neurons Feedforward neural networks Network topology Multi-layer neural network Training data Force measurement

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