Modeling and Control for UAV with Off-center Slung Load

2026-01-06

arXiv.org

AI Summary

This work addresses the challenging nonlinear control problem arising from strong coupling between a quadrotor and an off-center suspended payload due to offset suspension points. To tackle this issue, the authors propose a novel cascaded control strategy based on suspension-point modeling. In contrast to conventional approaches that model dynamics relative to the vehicle’s center of mass, this method uniquely formulates the system dynamics with respect to the suspension point, effectively decoupling the interactions between the aerial platform and the payload. The controller features a three-layer architecture: the middle layer modulates payload swing by regulating suspension-point acceleration, while the inner layer achieves high-precision attitude tracking within an eccentric reference frame. Local exponential stability of the closed-loop system is rigorously established via Lyapunov theory, and both simulations and experiments demonstrate the effectiveness of the proposed approach in suppressing payload oscillations, enhancing trajectory tracking accuracy, and improving robustness.

Technology Category

• Intelligent Robots: State Estimation
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Planning, Routing, and Scheduling: Mixed Discrete/Continuous Planning

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• User Modeling, Personalization and Recommendation: Federated recommendation systems and personalization
• Economics, Online Markets and Human Computation: LLM based quality controls for crowd work

Abstract

Unmanned aerial vehicle (UAV) with slung load system is a classic air transportation system. In practical applications, the suspension point of the slung load does not always align with the center of mass (CoM) of the UAV due to mission requirements or mechanical interference. This offset creates coupling in the system's nonlinear dynamics which leads to a complicated motion control problem. In existing research, modeling of the system are performed about the UAV's CoM. In this work we use the point of suspension instead. Based on the new model, a cascade control strategy is developed. In the middle-loop controller, the acceleration of the suspension point is used to regulate the swing angle of the slung load without the need for considering the coupling between the slung load and the UAV. An inner-loop controller is designed to track the UAV's attitude without the need of simplification on the coupling effects. We prove local exponential stability of the closed-loop using Lyapunov approach. Finally, simulations and experiments are conducted to validate the proposed control system.

Problem

• UAV
• slung load
• off-center suspension
• nonlinear dynamics
• motion control

Innovation

• off-center slung load
• suspension-point-based modeling
• cascade control
• nonlinear coupling
• Lyapunov stability