Position and Attitude Tracking of AUVs: A Quaternion Feedback Approach

: A position and attitude tracking control law for autonomous underwater vehicles (AUVs) in 6 degrees of freedom (DOF) is derived. The 4-parameter unit quaternion (Euler parameters) is used in a singularity-free representation of attitude. Global convergence of the closed-loop system is proven. In addition several 3-parameter representations in terms of the Euler parameters are discussed with application to the same control law. These schemes contain singularities and only local convergence can therefore be proven. The proposed control scheme is simulated with Euler parameters and Euler angles. 1 Introduction For rigid-bodies in 6 DOF the nonlinear dynamic equations of motion have a systematic structure which becomes apparent when applying vector notation. This is exploited in the control literature, particularly in the control of robot manipulators. A convergent nonlinear adaptive tracking control law exploiting the passivity properties of robot manipulators was derived in [19]. Late..