Pitch Control Design for Tandem Lifting Body Catamaran by Aft Lifting Body Actuation

We design an adaptive controller to stabilize the pitch of the tandem lifting body catamaran with actuation of the aft lifting body for the case where the hydrodynamic and other parameters are not known a priori. We consider two scenarios: 1) we assume the pitch and the pitch rate to be available for feedback and 2) we use only the pitch rate and the pitch acceleration in the adaptive control design. Our designs are based on three steps: 1) parametrization of the unknown sinusoidal wave disturbance as the output of a known feedback system with an unknown output vector that depends on unknown disturbance parameters; 2) design of an adaptive disturbance observer for the wave disturbance; and 3) design of an adaptive controller. We demonstrate the effect of our control designs in simulations, using a time-domain seakeeping code, named AEGIR.