Automatic reentry of deepsea riser by adaptive control

J. Ocean Eng. Technol. 1996;10(1):108-118.

적응제어에 의한 대수심 라이저의 리엔트리

남동호

시립인천전문대학 기계설계과

Keywords: Adaptive control, Riser, Reentry, Persistenely exiting input, Unmodeled dynamics, parameter identification

핵심용어: 적응제어, 라이저, 양광관, 리엔트리, 지속적 가진압력, PE특성, 비모델화된 동특성, 파라미터 추정

Abstract

This paper presents automatic reentry of a deepsea reser by adaptive control. Reentry is one of the major pro blems regarding a deepsea riser. In the reentry operation, the lower end of riser must be accurately positioned over the tarket point on the seabed. But the deepsea riser shows complex elastic response due to flexibility and nonlinearity of the riser dynamics and the required positioning accuracy is high. Moreover, elastic deformation must by controlled for securing structural integrity. In adaptive control, uncertainly known parameters like added mass and drag coefficient in the riser dynamics are identified and control forces at the floating body and the riser are calculated simultaneously. An Adaptive algorithm for MIMO linear discrete time system without requiring a persistent excitation is adopted in this study. The effectiveness of adaptive control logic is tested by numerical simulation and model experiment. The designed control system shows good overall performances, so that the present study can be applied to the control of the deepsea riser.