Automatic installation of underwater elastic structures under unknown currents

This paper deals with the new technique of installation and construction of underwater flexible structures by using learning tracking controller (LTC). The LTC has such potentials on the installation or construction of underwater structures, in deep water under unknown currents, that the structure can be installed precisely on the desired point on seabed. By this method automated construction of very large structure, assembling the onshore fabricated partitioned structures on site is possible. In this paper, the LTC is extended to use for the flexible structural control to avoid spillovers under unknown disturbances. The mathematical convergence condition and design process for the real system is presented. In order to confirm the capability and effectiveness of LTC, basin tests were executed using two types of neutrally buoyant flexible models with ultrasound ranging system and thrusters under unknown currents.