Velocity-free finite-time relative 6-DOF control for rigid spacecraft

This paper addresses the problem of spacecraft's finite-time six-degree-of-freedom(6-DOF) tracking control without velocity measurements. To estimate the unavailable incorporating angular and translational velocities (called the dual angular velocity), a novel observer with a simple structure and finite-time stability is presented in the dual quaternion frame. Then, combining with the estimated dual angular velocity, a continuous velocity-free 6-DOF control law based on the terminal sliding mode theory is presented to achieve the relative pose tracking objective within finite time, where the specially designed parameter ensures its non-singularity. In addition, by designing the desired reference frame, the proposed control law can be employed to various missions. With consideration of the observation errors, a rigorous proof is provided to demonstrate the finite-time stability of the observer-alone and the observer-based control law. Two typical numerical simulations, hovering and circumnavigation, are carried out to verify the effectiveness of the proposed method. (c) 2023 COSPAR. Published by Elsevier B.V. All rights reserved.

Automated summary

This paper addresses the problem of finite-time six-degree-of-freedom tracking control of spacecraft without velocity measurements. A novel observer with a simple structure and finite-time stability is presented in the dual quaternion frame to estimate the unavailable dual angular velocity. The proposed continuous velocity-free 6-DOF control law based on the terminal sliding mode theory, combined with the estimated dual angular velocity, achieves the relative pose tracking objective within finite time. Rigorous proof is provided to demonstrate the finite-time stability of the observer-alone and the observer-based control law, considering observation errors. Two typical numerical simulations, hovering and circumnavigation, verify the effectiveness of the proposed method.