Abstract
Efficiency of linear and nonlinear feedback control strategies for the response reduction of the Articulated Leg form (ALP) under random waves is investigated. The linear and nonlinear control laws are derived by minimizing a quadratic and a higher order performance function respectively. The degree of nonlinearity in the latter is regulated by incorporating a 'nonlinearity-weighting-factor' in the control law. The controlled equation of motion (in both control strategies) is solved by an iterative frequency domain technique in which the linear terms are retained on the left hand side, while all nonlinear terms are taken to the right hand side of the equation of motion and treated as loading terms. The solution is essentially obtained by the Newton-Raphson technique. Using the proposed control strategies, the response of a single hinge articulated tower is obtained under a few related parametric variations in order to investigate the performance of both control strategies.