The usual procedure for the optimal design of ship's steering system is to minimize a chosen quadratic performance index, which isdetermined from the view point of economic run. However, the optimal control synthesized in such a straightforward fashion is unsatisfactory because ship's parameters differ from their nominal values due to uncertainties and errors in measurement and/or simplifications in mathematical modelling, and/or the variation of the ship's loading condition. In an attempt to resolve this difficulty, this paper presents a method for designing a low sensitive optimal steering system in a way as to minimize not only given performance index but also the sensitivity of the performance index and trajectory sensitivity. It is also shown that the optimal control so obtained will result in a system whose performance index and transient response are low sensitive to small varation in ship's time constant.

• 이철영