Autopilot control synthesis for path tracking maneuvers of underwater vehicles

Abstract

This paper is concerned with the robust control synthesis of autonomous underwater vehicle (AUV) for general path following maneuvers. First, we present maneuvering kinematics and vehicle dynamics in a unified framework. Based on H ∞ loop-shaping procedure, the 2-DOF autopilot controller has been presented to enhance stability and path tracking. By use of model reduction, the high-order control system is reduced to one with reasonable order, and further the scaled low-order controller has been analyzed in both the frequency and the time domains. Finally, it is shown that the autopilot control system provides robust performance and stability against prescribed levels of uncertainty. Notation (Others are defined in the text) I identity matrix; z J yaw moment of inertia about z-axis; m vehicle mass; 0 U vehicle speed; ϕ yaw angle; ρ path curvature; r δ rudder steer angle; ( ) σ o , ( ) σ o maximum and minimum singular value of element, respectively; ( ) G s ∞ H ∞ norm of ( ) G s or sup ( ( )) ω G σ G jω ∞ = ; Δ uncertainty (or perturbation) matrix; T ( ) o , o transpose and absolute value of element, respectively.