H-infinity state feedback design for supercavitating vehicles

This study proposes an H-infinity design for controlling high-speed supercavitating vehicles (HSSV). Because the weight of the body forces the tail of the vehicle into contact with the cavity, the body skips forward on the cavity wall. Therefore, the state variables of the vehicle must be kept within reasonable limits under the consistent planing force acting on the tail. This H-infinity performance requirement is discussed and analyzed in the paper. In addition, the HSSV may respond to perturbation by hitting upwards and downwards against the cavity wall, eventually losing stability. This special stability requirement of an HSSV is also discussed in the paper. The aforementioned requirements lead to the problem of selecting weights for the state variables and control inputs. A comprehensive solution to this weight selection problem is presented, which takes into account solving ill-conditioned Riccati equations, as well as the requirement of a lowfrequency domain and the attitude stabilization problem. The simulation results show the effectiveness of the proposed design. Furthermore, this design methodology can also be used for other H-infinity problems as well.