Dynamics Modeling of a Multi-UAV Slung Load System Using a Discrete-Link Cable Approach
Harvey Merton, Ian Hunter
AI summary
Problem
Existing models often assume massless, always-taut cables, which fails during aggressive maneuvers or tension loss. There is a need for a plug-and-play, computationally efficient dynamics model that integrates with standard rigid-body simulators while capturing realistic cable behavior.
Approach
The authors derive an Euler-Newton dynamical model that represents each flexible cable as a chain of rigid links with distributed inertia, optimized for Featherstone’s articulated body algorithm. They validate the model against real-world flight data and systematically tune link count, joint damping, and friction for optimal fidelity and stability.
Key results
- Mean translation error <132 mm and orientation error <11.4° across maneuvers
- Optimal parameters: 15 links per cable, 2×10⁻³ N·s/rad damping, zero friction
- Near real-time simulation (up to 99% real-time factor) in standard rigid-body engines
- Public release of real-world flight data and simulation code
Why it matters
Provides robotics researchers and control engineers with a validated, plug-and-play simulation framework for accurately testing multi-UAV payload transport systems without custom solvers.
Abstract
A common assumption to simplify the problem of controlling a multi-UAV slung load system (MUSLS) is that the flexible cables can be modeled as massless rigid rods. In this work, we propose an alternative Euler-Newton derived dynamical model which uses a series of rigid links to model the flexible cables. The model is specifically designed to allow efficient simulation using Featherstone’s articulated body algorithm. We perform real-world validation of this model on gentle, aggressive, and tension-engagement maneuvers and run a parameter sweep to determine the number of links, joint damping, and joint friction to achieve the greatest model fidelity. The model closely matches real-world flight data with mean load translation errors below 132 mm (5.5% of the cable length) and orientation errors below 11.4 degrees. We make the real-world flight data publicly available for the development of future cable models. SUPPLEMENTARY MATERIAL Video: https://youtu.be/VATTPYYDwYY Code: https://github.com/hmer101/ musls_cable_modeling/