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On-line system identification for control system applications in particle accelerators
Chowdhary, Mahesh
Chowdhary, Mahesh
Abstract
Particle accelerators require a number of feedback systems in order to stabilize a variety of parameters. The Continuous Electron Beam Accelerator at Thomas Jefferson National Accelerator Facility presents a unique set of control and identification problems. This accelerator produces a continuous electron beam with energies between 0.5 and 4.0 GeV to be delivered to the experimental halls. In order to meet stringent beam quality requirements specified by the experimental halls, the position and the energy of the electron beam needs to stabilized at various locations in the accelerator.;A number of noise measurement tests were conducted at various locations in the accelerator to obtain accurate information about the amplitude and the frequency of disturbances on the beam orbit and energy. Results of these measurements indicate that the line power harmonics were the primary source of disturbance on the beam orbit and energy.;A prototype fast feedback system was implemented in the injector and the East Arc regions of the accelerator to stabilize the beam position and energy at these locations. The scheme of implementation of these systems and measurements of their performance are presented here.;These feedback systems have to operate under conditions of varying noise characteristics and changing dynamics of the systems. For the feedback systems to always perform optimally, the knowledge of time varying noise characteristics and changing system dynamics needs to be incorporated into the feedback strategy. The approach presented in this work is to perform on-line system identification using a formulation of Fast Transversal Filter (FTF) in order to extract the time varying information from input/output data of the feedback system.;A simulation test stand was developed using an analog computer to represent a continuous time system whose noise characteristics and dynamics could be changed in a controlled manner. An on-line system identification algorithm was implemented on a microprocessor similar to the ones used in the accelerator control system. Experience with the hardware-in-loop simulation for various cases of changing system dynamics and noise characteristics and the performance results of the on-line system identification algorithm operating under these conditions are presented in this dissertation.
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1997
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9805155.pdf
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Applied Science
DOI
https://dx.doi.org/doi:10.21220/s2-dem7-wt14