This work serves as a pioneering contribution in the use of QFT (qualitative feedback theory) methodology to the design of a controller for a high speed ship. The authors have improved the design of a multivariable robust controller G so that it will be able to reduce incidences of motion sickness on high speed ferries. Motion sickness is caused by vertical accelerations associated with the heave and pitch motions induced by waves. Testing of the controller in sea behaviour trials using a scaled down replica 1/25 the size of a high-speed ferry in CEHIPAR has shown the validity of the design, since acceptable MSI reduction percentages have been obtained similar to those foreseen in simulation. The designed controller G has been compared with a previous one - a gain scheduling scheme with PD. The comparison has shown that the system controlled with G has got robust performance and presents low saturation of the actuators, while the system controlled with a gain scheduling scheme with PD presents a higher saturation and has not got robust performance. Nevertheless, reductions in MSI were observed as greater at two specific working points with the gain scheduling scheme. Under nominal conditions, they were virtually the same as those obtained with the robust design. This result was to be expected since QFT methodology works with a large family of plants giving rise to a robust control design, which ensures some minimum features for all the family plants. It is a more conservative design than the gain scheduling scheme, which uses classic controllers tuned exclusively at four working points. In theory, the design of a gain scheduling scheme with PD controllers seems simpler than the robust design with QFT. However, the heavy dependence on using a process model to syntonise the PD makes it necessary to resyntonise several times. This in effect make its use more complex than the QFT design.
Design of a multivariable robust controller to decrease the motion sickness incidence in fast ferries
Entwurf eines Mehrgrößenreglers zur Verringerung der Seekrankheit auf einem schnellen Fährschiff
Control Engineering Practice ; 13 , 8 ; 985-999
2005
15 Seiten, 15 Bilder, 4 Tabellen, 16 Quellen
Article (Journal)
English
Motion Sickness Incidence Study on Rottnest Island High Speed Ferries
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