Safe Inspection Tracking Control for a Tumbling Target Under Full State Constraints and Limited Thrust

Abstract

This article addresses the inspection tracking control problem for a tumbling target with specific safety requirements, incorporating constraints on position, attitude motion, velocity, angular velocity, and thrust limitations. To tackle this issue, methods for representing full state constraints are proposed. Specifically, attitude motion constraints under various fields of view are expressed through the plane projection, while velocity constraints are approximated using superquadratics. Consequently, position, velocity, attitude, and angular velocity constraints can each be described by a single function using the proposed representation methods. In addition, a safety filter integrated with an extended state observer (ESO) is developed, allowing for the generation of safe thrust commands through quadratic programming (QP). The safety filter incorporates estimation information from the ESO and considers the convergence dynamics of the estimation error, thereby enhancing the system's safety and robustness. Moreover, the concept of dynamic safety margin is introduced, and an improved safety filter is proposed to increase the feasibility of the QP problem. Numerical simulations are conducted to validate the effectiveness of the proposed control framework.