Autopilot design for highly maneuverable multipurpose underwater vehicles

We report innovative results in nonlinear autopilot design for highly maneuverable underwater vehicles. Mathematical model developments and closed-loop system design problems are addressed and solved. Robust linear and nonlinear tracking control algorithms are designed using the tracking errors and state feedback. To control underwater vehicles, control surfaces are used. These control surfaces are actuated by high-performance servos. Mechanical limits, imposed on the deflection of control surfaces, as well as backlash lead to serious degradation of vehicle performance. These nonlinear phenomena are addressed augmenting the 9-DOF rigid-body vehicle dynamics with servo-actuator dynamics. The permanent-magnet synchronous motor drives the propeller, and the propulsion dynamics is studied. A nonlinear mathematical model of the vehicle is found, and nonlinear differential equations are used in nonlinear analysis and design. To solve the motion control problem, control algorithms are designed using states and tracking errors. The flexible simulation platform is developed to study the vehicle performance. For multipurpose underwater vehicles, different control algorithms are tested and verified for a wide spectrum of operating conditions, scenarios, and objectives