Task-Adaptive Admittance Control for Human-Quadrotor Cooperative Load Transportation with Dynamic Cable-Length Regulation

TL;DR

This paper presents a novel task-adaptive admittance control method for human-quadrotor cooperative load transportation, enabling dynamic cable-length regulation and improved responsiveness during load handling tasks.

Contribution

The paper introduces a new admittance controller that accounts for coupled dynamics and allows dynamic cable-length regulation in human-quadrotor load transportation.

Findings

The proposed controller improves system responsiveness during load transportation.

Experimental results show enhanced motion smoothness compared to conventional methods.

The method effectively handles load tasks with variable and fixed cable lengths.

Abstract

The collaboration between humans and robots is critical in many robotic applications, especially in those requiring physical human-robot interaction (pHRI). Previous research in pHRI has largely focused on robotic manipulators, employing impedance or admittance control to maintain operational safety. Conversely, research in human-quadrotor cooperative load transportation (CLT) is still in its infancy. This letter introduces a novel admittance controller designed for safe and effective human-quadrotor CLT using a quadrotor equipped with an actively-controlled winch. The proposed method accounts for the system's coupled dynamics, allowing the quadrotor and its cable to dynamically adapt to contact forces during CLT tasks, thereby enhancing responsiveness. We experimentally validated the task-adaptive capability of the controller across the entire CLT process, including in-place loading/unloading and load transporting tasks. To this end, we compared the system performances against a conventional approach, using both variable and fixed cable lengths under low- and high-stiffness conditions. Results demonstrate that the proposed method outperforms the conventional approach in terms of system responsiveness and motion smoothness, leading to improved CLT capabilities.