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Multi-objective trajectory optimization by a hierarchical gradient algorithm with fuzzy decision logic - Application to slew maneuver problems of a flexible space structure

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TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 2004年第155期47卷 66-74页

作者： Kojima, H Nakajima, N Tokyo Metropolitan Inst Technol Dept Aerosp Engn Hino Tokyo 191 Japan

The rest-to-rest maneuver problem of a flexible space structure is a two-point boundary value problem (TPBVP) and is solved by some gradient methods. If TPBVP is strongly restricted by constraints, TBVP becomes an ill-defined problem, and the solution meeting all constraints cannot be obtained. However, reasonable suboptimal solutions are often needed since real plant systems are necessary to be controlled. In order to obtain such suboptimal solutions, we have developed a modified version of the hierarchy gradient method by installing fuzzy decision logic. Constraints are classified into non-fuzzy constraints and fuzzy constraints according to their priorities. Fuzzy constraints having a trade-off relationship with each other are compromised reasonably by fuzzy decision logic. The usefulness of the proposed method is numerically and experimentally verified by applying it to the rest-to-rest slew maneuver problem of a flexible space structure, where fuzzy constraints are final time, sensitivity of residual vibration energy with respect to the structure frequency uncertainty and maximum bending moment at the root of the flexible appendage.

关键词： optimal control gradient algorithm fuzzy decision slew maneuver flexible space structure

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Adaptive wavetable oscillators

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2007年第9期55卷 4382-4392页

作者： Arora, Raman Sethares, William A. Univ Wisconsin Dept Elect & Comp Engn Madison WI 53706 USA

An adaptive oscillator is a system that can lock on to a time-varying input signal, synchronizing its output to both the frequency and phase of the input. A wavetable oscillator generates a periodic output by indexing into a lookup table that stores a single period of the waveform. An adaptive wavetable oscillator (AWO) combines these two ideas in a technique which, separates the periodic output waveform from the parameters that control the adaptation of the frequency and phase of the waveform. This separation is advantageous because it decouples the state of the oscillator from the dynamics of the adaptation, allowing the process of synchronization to be interpreted as a simple gradient optimization on a cost function. The oscillations remain stable over a large and easily described range of parameter values, and analysis of the synchronization can proceed along lines familiar from standard adaptive systems. Key issues in the design of AWOs are: the class of admissible inputs, the shape of the wavetable, the parameters that will be controlled, and the adaptive algorithm that adjusts the parameters. This paper examines these issues through analysis and simulation, focusing on conditions that achieve the desired synchronization between output and input.

关键词： adaptive systems dynamics of adaptation gradient algorithm lookup table mode locking phase-locked loop synchronization

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Parametric identification of input-delay systems with unknown time delay

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26th Chinese Control Conference

作者： Aldin, Najafi Majd Marzieh, Kamali Javad, Askari Isfahan Univ Technol Dept Elect & Comp Engn Esfahan Iran

ISBN: (纸本)9787811240559

In this paper, a method is presented for on-line identification of systems with unknown time delay. This method is based on two parametric models of system that one of them is defined for transfer function parameters estimation and the other one is defined for delay value estimation. gradient algorithm is used for estimating transfer function parameters and a new algorithm is suggested for estimating delay value. The effectiveness of this method has been demonstrated through simulation. Also this method has been used for identifying laboratory CNC system parameters. The delay in this system is due to signal transmission between the CNC and the network.

关键词： identification time delay systems gradient algorithm

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Sensitivity control of a semi-active suspension system equipped with MR-dampers

Sensitivity control of a semi-active suspension system equip...

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International Conference on Control, Automation and Systems

作者： Hong, Keum-Shik Kim, Tae-Shik Kim, Rae-Kwan Pusan Natl Univ Sch Mech Engn San 30 Jangjeon Dong Pusan 609735 South Korea Pusan Natl Univ Dept Mech & Intelligent Syst Engn Pusan 609735 South Korea

ISBN: (纸本)9788995003879

In this paper, numerical aspects of a sensitivity control for the semi-active suspension system with a magneto-rheological (MR) damper are investigated. A 2-dof quarter-car model together with a 6th order polynomial model for the MR damper are considered. For the purpose of suppressing the vertical acceleration of the sprung mass, the square of the vertical acceleration is defined as a cost function and the current input to the MR damper is adjusted in the fashion that the current is updated in the negative gradient of the cost function. Also, for improving the handling performance, a weighted absolute velocity of the sprung mass is added to the control law. The implementation of the proposed algorithm requires only the measurement of the relative displacement of the suspension deflection. The local stability of the equilibrium point of the closed loop nonlinear system is proved by investigating the eigenvalues of the linearized me. Through simulations, the passive suspension, the skyhook control, and the proposed sensitivity control are compared.

关键词： gradient algorithm sensitivity MR damper semi-active polynomial model ride comport

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Parameters identification of continuous system based on hybrid genetic algorithm

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26th Chinese Control Conference

作者： Hou Zhixiang Changsha Univ Sci & Technol Changsha 410076 Peoples R China

ISBN: (纸本)9787811240559

A new hybrid genetic algorithm is provided by adding up the advantages of the genetic algorithm and gradient algorithm, as uses the results of gradient algorithm improving the populations of genetic algorithm, and selects the best point as the start point of gradient algorithm next time by comparing the best point of genetic algorithm with the last results of gradient algorithm. Applying the method to estimating the parameters of continuous system the simulation results show it is more quickly than genetic algorithm and owes better anti-noise ability, and improves the defects of genetic algorithm with slower searching ability near a point and it provides a new method for the parameters estimation of continuous system.

关键词： system identification genetic algorithm gradient algorithm parameters estimation optimization

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An upper bound of the step size for the gradient Constant Modulus algorithm

An upper bound of the step size for the gradient Constant Mo...

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Conference on Photonics, Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments IV

作者： Dziwoki, G Silesian Tech Univ Inst Elect PL-44100 Gliwice Poland

The paper presents the theoretical derivation of an upper bound of the step size for the CM blind equalization algorithm. The analysis is performed under following assumptions, among other things: SISO (Single Input S... 详细信息

ISBN: (纸本)081946211X

关键词： CM algorithm gradient algorithm step size whitening filtering

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Sensitivity Control of a Semi-Active Suspension System Equipped with MR-Dampers

Sensitivity Control of a Semi-Active Suspension System Equip...

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2007 International Conference on Control, Automation and Systems (ICCAS 2007), vol.5

作者： Keum-Shik Hong Tae-Shik Kim Rae-Kwan Kim School of Mechanical Engineering Pusan National University Busan South Korea Department of Mechanical and Intelligent Systems Engineering Pusan National University Busan South Korea

In this paper, numerical aspects of a sensitivity control for the semi-active suspension system with a magneto-rheological (MR) damper are investigated. A 2-dof quarter-car model together with a 6th order polynomial model for the MR damper are considered. For the purpose of suppressing the vertical acceleration of the sprung mass, the square of the vertical acceleration is defined as a cost function and the current input to the MR damper is adjusted in the fashion that the current is updated in the negative gradient of the cost function. Also, for improving the handling performance, a weighted absolute velocity of the sprung mass is added to the control law. The implementation of the proposed algorithm requires only the measurement of the relative displacement of the suspension deflection. The local stability of the equilibrium point of the closed loop nonlinear system is proved by investigating the eigenvalues of the linearized one. Through simulations, the passive suspension, the skyhook control, and the proposed sensitivity control are compared.

关键词： gradient algorithm Sensitivity MR Damper Semi-Active Polynomial Model Ride Comport

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Adaptive synchronization of discrete-time T-S fuzzy chaotic systems using output tracking control

Adaptive synchronization of discrete-time T-S fuzzy chaotic ...

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SICE-ICASE International Joint Conference

作者： Lee, Won-Ki Hyun, Chang-Ho Kim, Euntai Park, Mignon Yonsei Univ Dept Elect & Elect Engn Seoul 120749 South Korea

ISBN: (纸本)9788995003848

This paper presents a model reference adaptive control approach for the synchronization of a discrete-time chaotic systems using output tracking control. Takagi-Sugeno (T-S) fuzzy model is employed to represent the discrete-time chaotic system. Then, the reference model system is chosen using the output of master system and design the control input so that the controlled slave system achieves asymptotic synchronization with the reference system given that two systems start from different initial conditions, different parameters and/or different type of model. Using a gradient algorithm, the ideal controller gains which can stabilize the error equation are estimated. Simulation examples of two cases are given to demonstrate the validity of our proposed adaptive method.

关键词： synchronization output tracking control T-S fuzzy model reference model system gradient algorithm

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Optimisation of springback in bending processes using FEM simulation and response surface method

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2005年第1-2期27卷 40-47页

作者： Lepadatu, D Hambli, R Kobi, A Barreau, A ISTIA LASQUO UPRES EA 3858 F-49000 Angers France

The aim of this work includes the springback optimisation of bending processes using the concept of experimental design and response surface methodology (RSM). The optimisation method includes two phases. The first involves the objective function prediction using design of experiments and response surface method, while the second is an optimisation process using a FORTRAN gradient algorithm. Springback of sheet parts during bending processes is simulated using finite element model (FEM) including damage evolution effects within the sheet. The numerical simulation of the damage evolution has been modelled by means of continuum damage approach. The Lemaitre damage model, taking into account the influence of triaxiality, has been implemented into ABAQUS/Standard code in order to predict the external fibres rupture evolution during the process and the material characteristics changes after bending. The simulation included die corner radius and punch-die clearance as the main variables.

关键词： bending FEM gradient algorithm optimisation response surface springback

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Optimal utility based multi-user throughput allocation subject to throughput constraints

Optimal utility based multi-user throughput allocation subje...

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24th Annual Joint Conference of the IEEE Computer and Communications Societies

作者： Andrews, M Qian, LJ Stolyar, A Lucent Technol Bell Labs Murray Hill NJ 07974 USA

ISBN: (纸本)0780389689

We consider the problem of scheduling multiple users sharing a time-varying wireless channel. (As an example, this is a model of scheduling in 3G wireless technologies, such as CDMA2000 3G1xEV-DO downlink scheduling.) We introduce an algorithm which seeks to optimize a concave utility function Sigma(i) H-i (R-i) of the user throughputs Ri, subject to certain lower and upper throughput bounds: R-i(min) <= Ri <= R-i(max). The algorithm, which we call the gradient algorithm with Minimum/Maximum Rate constraints (GMR) uses a token counter mechanism, which modifies an algorithm solving the corresponding unconstrained problem, to produce the algorithm solving the problem with throughput constraints. Two important special cases of the utility functions are Sigma(i) log Ri and Sigma R-i, corresponding to the common Proportional Fairness and Throughput Maximization objectives. We study the dynamics of user throughputs under GMR algorithm, and show that GMR is asymptotically optimal in the following sense. If, under an appropriate scaling, the throughput vector R(t) converges to a fixed vector R* as time t -> infinity then R* is an optimal solution to the optimization problem described above. We also present simulation results showing the algorithm performance.

关键词： scheduling wireless CDMA 3G time varying channel QoS gradient algorithm proportional fair maximum throughput rate constraints guaranteed fate

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