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The Effect of Memory in Observer Design for a DP System

[+] Author Affiliations
A. Hajivand, S. H. Mousavizadegan

Amirkabir University of Technology, Tehran, Iran

Paper No. IMECE2010-38040, pp. 53-59; 7 pages
  • ASME 2010 International Mechanical Engineering Congress and Exposition
  • Volume 8: Dynamic Systems and Control, Parts A and B
  • Vancouver, British Columbia, Canada, November 12–18, 2010
  • Conference Sponsors: ASME
  • ISBN: 978-0-7918-4445-8
  • Copyright © 2010 by ASME


The behavior of marine structures is investigated in regular waves using various models in frequency and time domains. In normal practice, the differential form of motion equations are used with constant hydrodynamic coefficients. Those coefficients which are added masses and damping coefficients are frequency dependent due to the memory effect. The memory effect is usually represented by a convolution integral and hence it converts the motion equations into integro-differential forms. The presence of the convolution integral makes the equations complex. However, it is necessary to take into account the memory effect in ship motion control and specially in dynamic positioning system to enhance the accuracy and obtained a more precise controller. The motion equations are solved for a DP system with memory effect and compare with the conventional model. The computations show that memory effect is important as the wave frequency increases. A nonlinear observer has been design to solve the wave filtering and state estimation problems with the memory effect. The performance of the nonlinear observer is demonstrated by computer simulations.

Copyright © 2010 by ASME
Topics: Design



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