Bearing-Based Collision-Free Formation Control for Spacecrafts Under Dynamic Event-Triggered Input

This paper investigates a motion planning problem for multiple spacecrafts under dynamic event-triggered input and bearing constraint. As a safety-critical system, collision avoidance plays a key role in endowing the formation system with fully autonomous operating space under obstacle-cluttered environment. Given this fact, a control barrier function (CBF)-based quadratic programming (QP) is developed based on backstepping framework, such that each spacecraft is able to move to its predefined position without collisions among static/moving obstacles and its neighbors. Considering the limited communication and actuation capability, an input-based event-triggered mechanism (ETM) is then introduced with dynamic parameter to schedule the triggering instants. By doing so, the data transmission from the controller to the actuator can be well-regulated with system input only, which offers a more practical solution to limited communication resources. The stability of the system is proved via Lyapunov analysis and the simulations are conducted to show the effectiveness of the proposed strategy. Note to Practitioners - This paper was motivated by the problem of collision-free control for spacecraft formation. Practically, existing formation are commonly localized based on real-time position measurements under global framework. We introduced a bearing-based approach into the formation control of spacecrafts, which enables more natural self-localization using vision measurements. Under bearing-based framework, the collision-avoidance problem is then considered. In both initial stage and steady stage, the safety problem is nonnegligible. We developed the existing CBF-based algorithm to generate a collision-free path for each spacecraft. To minimize redundant actions of actuator, an ETM was incorporated to help improve the control efficiency. In simulation part, we will show how these methods work collaboratively in given tasks.