Commenced in January 2007
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Optimal Controllers with Actuator Saturation for Nonlinear Structures

Authors: M. Mohebbi, K. Shakeri


Since the actuator capacity is limited, in the real application of active control systems under sever earthquakes it is conceivable that the actuators saturate, hence the actuator saturation should be considered as a constraint in design of optimal controllers. In this paper optimal design of active controllers for nonlinear structures by considering actuator saturation, has been studied. The proposed method for designing optimal controllers is based on defining an optimization problem which the objective has been to minimize the maximum displacement of structure when a limited capacity for actuator has been used. To this end a single degree of freedom (SDF) structure with a bilinear hysteretic behavior has been simulated under a white noise ground acceleration of different amplitudes. Active tendon control mechanism, comprised of prestressed tendons and an actuator, and extended nonlinear Newmark method based instantaneous optimal control algorithm have been used. To achieve the best results, the weights corresponding to displacement, velocity, acceleration and control force in the performance index have been optimized by the Distributed Genetic Algorithm (DGA). Results show the effectiveness of the proposed method in considering actuator saturation. Also based on the numerical simulations it can be concluded that the actuator capacity and the average value of required control force are two important factors in designing nonlinear controllers which consider the actuator saturation.

Keywords: Nonlinear, Active Control, Actuator Saturation, Distributedgeneticalgorithms

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[1] B.F. Spencer and Nagarajaiah S., "State of the art of structural control," ASCE, J. Struct. Eng., vol.129, no.7, pp.845-856, 2003.
[2] T. Kobori, N. Koshika, K. Yamada and Y. Ikeda, "Seismic-responsecontrolled structure with active mass driver system .part 1: Design" Earthquake Eng. Struct. Dynamics, vol. 20, pp.133-149, 1991.
[3] T. Kobori, N. Koshika, K. Yamada and Y. Ikeda, "Seismic-responsecontrolled structure with active mass driver system .part2: Verification,"Earthquake Eng. Struct. Dynamics, vol.20, pp.151-166, 1991.
[4] T. T. Soong, Active structural control: theory and practice. Longman Scientific & Technical, New York, 1990.
[5] J. Ghaboussi and A. Joghataie, "Active control of structures using neural networks," ASCE, J. Eng. Mech., 121(4):555-567, 1995.
[6] A. Joghataie and A. Vahidi, "Designing a general neuro controller for water towers," ASCE, J.Eng. Mech, 126(6): 582-587, 2000.
[7] A. Reinhorn, M. Manolis G. D. and C. Y. Wen, "Active control of inelastic structures,"ASCE, J. Eng. Mech., 113(3):315-333, 1987.
[8] S.F. Masri, G.A. Bekey and T.K. Caughey, "Optimal pulse control of flexible structures," ASME, J. App. Mech., 48(4):619-626, 1981.
[9] J. N. Yang, F. X Long and D. Wong. , "Optimal control of nonlinear structures," Applied Mech., vol. 55, pp. 931-938, 1988.
[10] J. N. Yang, Z. Li, A. Danielians and S. C. Liu, "A seismic hybrid control of nonlinear and hysteretic structures," ASCE, J. Eng. Mech., 118(7):1423-1440, 1992.
[11] C. C. Chang and H. T., Yang Y., "Instantaneous optimal control of building frames," ASCE, J. Struct. Eng., vol.120, no. 4, pp.1307-1326, 1994.
[12] O.Bahar, M. R Banan, M. Mahzoon and Y.Kitagawa, "Instantaneous optimal Wilson-╬© control method,"ASCE, J. Eng. Mech., vol.129, no.11, pp.1268-1276, 2003.
[13] A. Joghataie and M. Mohebbi, "Optimal control of nonlinear frames by Newmark and distributed genetic algorithms," Struct. Design Tall Spec. Build., published online, 2009.
[14] K. J. Bathe Finite element procedures. Prentice-Hall, Inc., New Gersey, 1996.
[15] J.H. Holland, Adaptation in natural and artificial systems. Ann Arbor: The University of Michigan Press, 1975.
[16] D. E. Goldberg, Genetic algorithms in search, optimization and machine Learning. Addison -Wesley Publishing Co., Inc. Reading, Mass, 1989.
[17] Z. Michalewicz, Genetic algorithms + data structures=evolution programs, New York: Springer-Verlag, 1996.
[18] H. M├╝hlenbein, M.Schomisch and J. Born, "Parallel genetic algorithms as a function optimizer," Parallel Computing, no.17, pp.619-632, 1991.
[19] T. Starkweather, D. Whitley and K. Mathias, "Optimization using distributed genetic algorithms," Springer - Verlag Lecture Notes in Computer Science, no.496, pp.176-185, 1990.