Double-loop decoupling control for a supercavitating vehicle

Underwater vehicles that travel inside a large continuous gas bubble offer an opportunity for high speed transportation. This type vehicle is referred to as high speed supercavitating vehicle (HSSV). The main challenge of the HSSV control is that dynamics model of HSSV system have strong-coupling and weak damped characteristics. In general, the dynamic response of the system is relatively fast, and the kinematics response is relatively slow. In the control design, the system is divided into fast varying inner loop and slow varying outer loop and this double-loop is used to stabilize the high-frequency and low-frequency mode respectively. Through the design of inner and outer loop, the feedback control law of kinematics and dynamics decoupling is given. Root locus of the system show that weakly damped oscillation of HSSV is inherent, and thus it is inevitable by feedback control. Simulation results verified effective of the designed control method and motion stability of HSSV. This idear of Double-loop Decoupling Control design provide a new method, which could be as a reference for the design of systems with weak damping and strong coupling.