Multi-robot Aerial Soft Manipulator For Floating Litter Collection

TL;DR

This paper introduces a multi-robot aerial soft manipulator system that uses two drones connected by a flexible rope to efficiently collect floating litter, with an optimized rope-shape planner and real-world validation.

Contribution

It presents a novel multi-robot aerial system with an adaptive rope-shape planner for floating litter collection, improving payload, endurance, and success rate over single-robot solutions.

Findings

Successful outdoor litter collection demonstrated

Adaptive rope-shape planner enhances grasping success

System effective in real water channel tests

Abstract

Removing floating litter from water bodies is crucial to preserving aquatic ecosystems and preventing environmental pollution. In this work, we present a multi-robot aerial soft manipulator for floating litter collection, leveraging the capabilities of aerial robots. The proposed system consists of two aerial robots connected by a flexible rope manipulator, which collects floating litter using a hook-based tool. Compared to single-aerial-robot solutions, the use of two aerial robots increases payload capacity and flight endurance while reducing the downwash effect at the manipulation point, located at the midpoint of the rope. Additionally, we employ an optimization-based rope-shape planner to compute the desired rope shape. The planner incorporates an adaptive behavior that maximizes grasping capabilities near the litter while minimizing rope tension when farther away. The computed rope shape trajectory is controlled by a shape visual servoing controller, which approximates the rope as a parabola. The complete system is validated in outdoor experiments, demonstrating successful grasping operations. An ablation study highlights how the planner's adaptive mechanism improves the success rate of the operation. Furthermore, real-world tests in a water channel confirm the effectiveness of our system in floating litter collection. These results demonstrate the potential of aerial robots for autonomous litter removal in aquatic environments.