H{infinity} synthesis of depth control law for a towed ROV with a weight shift mechanism

The paper treats a design problem of depth control law for a towed ROV with a weight shift mechanism under variations of the towing speed. For the mixed sensitivity problem formulation in applying robust control theory, the parameter perturbations are captured by a norm band of multiplicative perturbations, which is the main contribution of the paper. In order to evaluate a resultant controller obtained by H{infinity} synthesis, the authors investigate nonlinear simulations of the closed-loop system. They can observe that the results of the H{infinity} synthesis are much better than those of LQ synthesis.