Singularity-free tracking of unmanned underwater vehicles in 6 DOF

Abstract

Nonlinear tracking control of unmanned underwater vehicles (UUVs) in 6 degrees of freedom (DOF) is discussed. The 4-parameter unit quaternion is used in a singularity-free representation of attitude. Several control laws based on a generalized Lyapunov function for the attitude dynamics are derived, including feedback from the vector quaternion, the Euler rotation vector and the Rodrigues parameter vector. A new feedback gain matrix for translational motion is also proposed. Lyapunov analysis is used in the tracking error convergence analysis. Extensions to adaptive control are made. The control laws are tested in a simulation study.<>