H_(infinity) robust control technology applied to the design of a combined steering/stabiliser system for warships

摘要

The role of the Navy creates the requirement for modem warships to be able to operate effectively in the most severe of weather and sea conditions. Wave induced roll motions in ship operation can seriously degrade the perofrmance of mechanical and personnel effectiveness. In order to alleviate roll motions, most warships are equipped with fin stabilisers. Rudders can also generate roll motions which can be harnessed to function in congress with the fins to accrue enhanced levels of roll stabilisation. An integrated rudder and fin stabilisation control strategy is proposed. Rudder roll controllers and autopilots are devleoped using the H_(infinity) optimisation technique and their performance compared with the classical counterparts. This integrated control philosophy is simulated to quantify the performance of the designed controllers. The interaction present between the roll and yaw control loops is also quantified. It is concluded that the performance of the H_(infinity) RRS controller and autopilot is superior to that of the classical type. The level of interaction between the two loops can be suitably modified by varying the performance weighting functions. Existing sensors and actuators can be utilised to achieve rudder roll stabilisation. The proposed integrated strategy gives the command the flexibility to choose the mode by which stabilisation is achieved by the selection of the appropriate roll controller.