Safe Autonomous Docking Maneuvers for a Floating Platform based on Input Sharing Control Barrier Functions

TL;DR

This paper introduces a control strategy using input sharing control barrier functions for safe autonomous docking of a floating platform, ensuring safety, proper approach, and visual lock while maintaining feasibility and conflict-free control inputs.

Contribution

The paper proposes a novel input sharing control barrier function framework for conflict-free, safe, and efficient autonomous docking of floating platforms, with proven invariance and convergence properties.

Findings

Control inputs are shared conflict-free among barrier functions.

The approach guarantees safety, approach direction, and visual lock constraints.

Simulations validate the effectiveness of the proposed control strategy.

Abstract

In this article, we present a control strategy for the problem of safe autonomous docking for a planar floating platform (Slider) that emulates the movement of a satellite. Employing the proposed strategy, Slider approaches a docking port with the right orientation, maintaining a safe distance, while always keeping a visual lock on the docking port throughout the docking maneuver. Control barrier functions are designed to impose the safety, direction of approach and visual locking constraints. Three control inputs of the Slider are shared among three barrier functions in enforcing the constraints. It is proved that the control inputs are shared in a conflict-free manner in rendering the sets defining safety and visual locking constraints forward invariant and in establishing finite-time convergence to the visual locking mode. The conflict-free input-sharing ensures the feasibility of a quadratic program that generates minimally-invasive corrections for a nominal controller, that is designed to track the docking port, so that the barrier constraints are respected throughout the docking maneuver. The efficacy of the proposed control design approach is validated through various simulations.