The Experts below are selected from a list of 6867 Experts worldwide ranked by ideXlab platform
Chaoxu Mu - One of the best experts on this subject based on the ideXlab platform.
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adaptive critic based robust trajectory tracking of uncertain dynamics and its application to a spring mass Damper System
IEEE Transactions on Industrial Electronics, 2018Co-Authors: Ding Wang, Chaoxu MuAbstract:In this paper, the robust trajectory tracking design of uncertain nonlinear Systems is investigated by virtue of a self-learning optimal control formulation. The primary novelty lies in that an effective learning based robust tracking control strategy is developed for nonlinear Systems under a general uncertain environment. The augmented System construction is performed by combining the tracking error with the reference trajectory. Then, an improved adaptive critic technique, which does not depend on the initial stabilizing controller, is employed to solve the Hamilton–Jacobi–Bellman (HJB) equation with respect to the nominal augmented System. Using the obtained control law, the closed-loop form of the augmented System is built with stability proof. Moreover, the robust trajectory tracking performance is guaranteed via Lyapunov approach in theory and then through simulation demonstration, where an application to a practical spring–mass–Damper System is included.
M. Hu - One of the best experts on this subject based on the ideXlab platform.
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Measurements and Analysis of Beam Transfer Functions in the Fermilab Recycler Ring Using the Transverse Digital Damper System
arXiv: Accelerator Physics, 2008Co-Authors: N. Eddy, J.l. Crisp, M. HuAbstract:The primary purpose of the Fermilab Recycler Ring Transverse Digital Damper System is to prevent instabilities due to high phase space densities of the cooled antiproton beam. The System was designed to facilitate Beam Transfer Function measurements using a signal analyzer connected to auxiliary System ports for timing and diagnostic purposes. The Digital Damper System has the capability for both open and closed loop measurements. The Beam Transfer Function provides direct measurement of the machine impedance, and beam and lattice parameters such as betatron tune and chromaticity. An overview of the technique is presented along with analysis and results from open and closed loop measurements in the Fermilab Recycler Ring.
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Measurements and Analysis of Beam Transfer Functions in the Fermilab Recycler Ring Using the Transverse Digital Damper System
2008Co-Authors: N. Eddy, J.l. Crisp, M. HuAbstract:The primary purpose of the Fermilab Recycler Ring Transverse Digital Damper System is to prevent instabilities due to high phase space densities of the cooled antiproton beam. The System was designed to facilitate Beam Transfer Function measurements using a signal analyzer connected to auxiliary System ports for timing and diagnostic purposes. The Digital Damper System has the capability for both open and closed loop measurements. The Beam Transfer Function provides direct measurement of the machine impedance, and beam and lattice parameters such as betatron tune and chromaticity. An overview of the technique is presented along with analysis and results from open and closed loop measurements in the Fermilab Recycler Ring. INTRODUCTION The Fermilab Recycler Ring is a permanent-magnet based, 8 GeV anti-proton storage and cooling ring. Both stochastic and electron cooling have been employed to increase the phase space density to meet the collider RunIIb luminosity goal of 2 x 10cms. To meet and exceed this requirement, the maximally allowable chromaticities, constrained by beam lifetime considerations, do not provide adequate Landau damping at the phase-space densities required by the luminosity goal. The transverse stability threshold has been consistently observed and well understood for the Recycler [1]. A transverse Damper System which provides active beam feedback is used to keep the beam stable. The density threshold with operational chromaticities at which instabilities occur has been increased by a factor of greater than 4 with the current broad-band transverse digital Damper System. TRANSVERSE Damper System A basic diagram of the System is shown in Fig. 1. Two pickups in each plane approximately 90° apart in betatron phase are used to simulate the optimum betatron phase advance between pickup and kicker. The feedback System consists of a beam pickup, a filter to reject revolution harmonics, a delay line, power amplifiers, and a kicker. Transverse damping is accomplished by two independent Systems acting in the horizontal and vertical planes. The System provides negative feedback from 15KHz to 70Mhz in each plane which covers the first 780 rotation harmonics. Figure 1: Basic System diagram. Only the vertical plane is shown.
Hiroshi Midorikawa - One of the best experts on this subject based on the ideXlab platform.
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forced vibration test of a building with semi active Damper System
Earthquake Engineering & Structural Dynamics, 2000Co-Authors: Narito Kurata, Takuji Kobori, Motoichi Takahashi, Naoki Niwa, Toshihisa Ishibashi, Jun Tagami, Hiroshi MidorikawaAbstract:The authors developed a semi-active hydraulic Damper (SHD) and installed it in an actual building in 1998. This was the first application of a semi-active structural control System that can control a building's response in a large earthquake by continuously changing the device's damping coefficient. A forced vibration test was carried out by an exciter with a maximum force of 100 kN to investigate the building's vibration characteristics and to determine the System's performance. As a result, the primary resonance frequency and the damping ratio of a building that the SHDs were not jointed to, decreased as the exciting force increased due to the influence of non-linear members such as PC curtain walls. The equivalent damping ratio was estimated by approximating the resonance curves using the steady-state response of the SDOF bilinear hysteretic System. After the eight SHDs were jointed to the building, the System's performance was identified by a response control test for steady-state vibration. The elements that composed the semi-active Damper System demonstrated the specified performance and the whole System operated well. Copyright © 2000 John Wiley & Sons, Ltd.
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actual seismic response controlled building with semi active Damper System
Earthquake Engineering & Structural Dynamics, 1999Co-Authors: Narito Kurata, Takuji Kobori, Motoichi Takahashi, Naoki Niwa, Hiroshi MidorikawaAbstract:This paper presents the first application of a semi-active Damper System to an actual building. The Semi-active Hydraulic Damper (SHD) can produce a maximum damping force of 1000 kN with an electric power of 70 W. It is compact, so a large number of them can be installed in a single building. It is thus possible to control the building's response during a severe earthquake, because a large control force is obtained in comparison with a conventional active control System. This paper outlines the building, the control System configuration, the SHD, the control method using a Linear Quadratic Regulator, the response analysis results of the controlled building, and the dynamic loading test results of the actual SHD. The simulation analysis shows that damage to buildings can be prevented in a severe earthquake by SHD control. The dynamic loading test results of the SHD are reported, which show that the specified design values were obtained in the basic characteristic test. The control performance test using simulated response time histories, also shows that the damping force agrees well with the command. Finally, it is confirmed that the semi-active Damper System applied to an actual building effectively controls its response in severe earthquakes. Copyright © 1999 John Wiley & Sons Ltd.
Michael Joseph Schulte - One of the best experts on this subject based on the ideXlab platform.
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A digital ring transverse feedback low-level RF control System
Proceedings of the IEEE Particle Accelerator Conference, 2007Co-Authors: Anil Kumar Polisetti, R. C. McCrady, Jeffrey Patterson, Cristian Deibele, S. Assadi, Michael Joseph SchulteAbstract:A digital wide-band System for damping ring instabilities in an accelerator is presented. With increased beam intensity, the losses of an accumulator ring tend to increase due to the onset of various instabilities in the beam. An analog feedback Damper System has been implemented at Los Alamos National Laboratory. This analog System, while functional, has certain limitations and a lack of programmability, which can be overcome by a digital solution. A digital feedback Damper System is being designed through a collaborative effort by researchers at Oakridge National Laboratory, Los Alamos National Laboratory, and the University of Wisconsin. This System, which includes analog-to-digital converters, field programmable gate arrays and digital-to-analog converters can equalize errors inherent to analog Systems, such as dispersion due to amplifiers/cables, gain mismatches, and timing adjustments. The digital System features programmable gains and delays, and programmable equalizers that are implemented using digital FIR and comb filters. The flexibility of the digital System allows it to be customized to implement different configurations and extended to address other diagnostic problems.
Seungbok Choi - One of the best experts on this subject based on the ideXlab platform.
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damping force tracking control of mr Damper System using a new direct adaptive fuzzy controller
Shock and Vibration, 2015Co-Authors: Xuan Phu Do, Kruti Shah, Seungbok ChoiAbstract:This paper presents a new direct adaptive fuzzy controller and its effectiveness is verified by investigating the damping force tracking control of magnetorheological (MR) fluid based Damper (MR Damper in short) System. In the formulation of the proposed controller, a model of interval type 2 fuzzy controller is combined with the direct adaptive control to achieve high performance in vibration control. In addition, (H infinity) tracking technique is used in building a model of the direct adaptive fuzzy controller in which an enhanced iterative algorithm is combined with the fuzzy model. After establishing a closed-loop control structure to achieve high control performance, a cylindrical MR Damper is adopted and damping force tracking results are obtained and discussed. In addition, in order to demonstrate the effectiveness of the proposed control strategy, two existing controllers are modified and tested for comparative work. It has been demonstrated from simulation and experiment that the proposed control scheme provides much better control performance in terms of damping force tracking error. This leads to excellent vibration control performance of the semiactive MR Damper System associated with the proposed controller.
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vibration control of magnetorheological Damper System subjected to parameter variations
International Journal of Vehicle Design, 2008Co-Authors: Seungbok Choi, Kum Gil SungAbstract:This paper presents vibration control of a semi-active magnetorhological (MR) suspension System subjected to parameter variations. After manufacturing the cylindrical MR Damper, the field-dependent damping force and its controllability are experimentally evaluated. The full vehicle model is then derived by considering vertical, pitch and roll motions. A robust H∞ controller is formulated by treating the sprung mass as parameter variation. This is accomplished by adopting the loop shaping design procedure. In order to demonstrate the effectiveness and robustness of the proposed control System, the Hardware-In-The-Loop Simulation (HILS) methodology is adopted by integrating the suspension model with the proposed MR Damper. Vibration control responses of the vehicle suspension System such as vertical acceleration are evaluated under both bump and random road conditions.
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Vibration control of a smart material based Damper System considering temperature variation and time delay
Acta Mechanica, 2005Co-Authors: S-b Choi, Y. M. Han, Sanghyun Han, S S Han, Seungbok Choi, Youngshin HanAbstract:This paper presents vibration control responses of an electrorheological (ER) Damper System subjected to temperature variation and time delay. The field-dependent yield stress of the ER fluid is experimentally evaluated at various temperatures and the dynamic characteristics of the ER Damper are investigated in order to obtain the time constant. These two properties are integrated with the governing model of a quarter car ER suspension System, and a sliding mode controller is formulated. Vibration control responses of a quarter car model installed with the ER Damper System are evaluated under bump excitation.
