Safe Aerial Manipulator Maneuvering and Force Exertion via Control Barrier Functions

TL;DR

This paper presents a novel control strategy for safe force application by an aerial robotic arm using Control Barrier Functions within an optimization framework, ensuring safety and stability without environmental compliance models.

Contribution

It introduces a hybrid force-motion control method employing CBF constraints in QP, with formal guarantees and experimental validation for aerial manipulation tasks.

Findings

Guarantees of optimization feasibility

Controller input continuity and stability

Successful experimental demonstrations

Abstract

This article introduces a safe control strategy for application of forces to an external object using a dexterous robotic arm mounted on an unmanned Aerial Vehicle (UAV). A hybrid force-motion controller has been developed for this purpose. This controller employs a Control Barrier Function (CBF) constraint within an optimization framework based on Quadratic Programming (QP). The objective is to enforce a predefined relationship between the end-effector's approach motion and its alignment with the surface, thereby ensuring safe operational dynamics. No compliance model for the environment is necessary to implement the controller, provided end-effector force feedback exists. Furthermore, the paper provides formal results, like guarantees of feasibility for the optimization problem, continuity of the controller input as a function of the configuration, and Lyapunov stability. In addition, it presents experimental results in various situations to demonstrate its practical applicability on an aerial manipulator platform.