Composite Adaptive Control for Safety-Critical Spacecraft Proximity Operations

This paper addresses the relative pose tracking control problem for safety-critical spacecraft proximity operations subject to complex motion constraints, including dynamic obstacle and occlusion avoidance, the sensor’s field-of-view constraint, and the approaching corridor constraint, in the presence of mass and inertia uncertainties. Spacecraft relative motion dynamics and motion constraints are described using dual algebra. In particular, a novel spherocylinder envelope of the pursuer is established, which not only enables us to directly compute the distance between spacecraft and obstacles analytically but also reduces the conservativeness and improves the flexibility compared to the commonly used ellipsoid envelope. Subsequently, a safe composite adaptive controller is proposed by leveraging potential functions and the dynamic regressor extension and mixing (DREM) technique, which enables the pursuer to arrive at the desired anchoring point while complying with complex motion constraints. By incorporating a prescribed time adjustment function into the DREM framework, the composite adaptive law achieves accurate mass and inertia identification within a prescribed finite time, despite the absence of a persistent excitation condition. Lyapunov stability analysis shows the asymptotic stability of the closed-loop system and prescribed-time stability of the parameter estimator. Finally, simulation results are provided to demonstrate the effectiveness of the proposed method.