Whole-Body Stabilization of a Cable-Suspended Multirotor Platform Carrying a Slung Load
Hemjyoti Das, Grazia Zambella, Christian Ott
AI summary
Problem
Stabilizing a cable-suspended multirotor carrying a slung load is challenging due to its complex seven-degree-of-freedom dynamics and three distinct time scales, while existing control methods often require full actuation or lack practical validation for safety-critical heavy-load transport.
Approach
The authors model the system as a triple pendulum and design a model-based composite controller that exploits the system's three distinct time scales to compute the necessary underactuated wrench for stabilization, alongside a shared control alternative and an operational space controller for crane-specific cases.
Key results
- Novel singular perturbation-based composite controller stabilizes the 7-DoF system using only a 3-DoF underactuated wrench
- Superposition-based shared controller developed and compared for stabilization response and energy consumption
- Numerical robustness and stability analysis confirms effectiveness across varying payload masses and wind disturbances
- Extensive simulations and real-world experiments validate stabilization performance using only onboard sensors
Why it matters
This work enables safe, energy-efficient heavy-load transport in construction and industrial settings by preventing dangerous load oscillations using only onboard sensors and underactuated hardware.
Abstract
Suspended multirotor platforms are fascinating sys- tems that can be employed in construction applications to provide safe transportation of heavy loads. Such a system comprising a cable-suspended platform with attached load features seven degrees of freedom (DoF) motion for the whole system. In this paper, we propose a composite whole-body control framework for the stabilization of the suspended multirotor platform system, leveraging singular perturbation theory to exploit the inherent three time-scale dynamics of the system. The control strategy computes the underactuated 3-DoF wrench space generated by the platform’s actuation units for the stabilization of the complete system. Building upon this, we develop a superposition-based shared control approach and then compare the two controllers. Moreover, to address specific cases where the time-scale sepa- ration between two dynamics of the triple-spherical pendulum becomes negligible, we design an operational space controller. The control approaches are validated using both extensive numerical simulations and experiments in different scenarios. We also carried out numerical robustness and stability analysis of the whole system. Note that our system relies on only onboard sensors for state estimation, which makes it effective for real-life outdoor applications. Note to Practitioners—This paper is motivated by the trans- portation of heavy loads using overhead cranes in construction sites. Due to the safety criticality of such applications, it has to be ensured that no oscillations of the attached load arise during the whole process. These oscillations can result from wind disturbances or due to the motion of the crane. In this work, we ensure that the proposed control approaches stabilize the attached load by utilizing the actuation power of an aerial platform suspended from the crane, and thus ensure safety in the involved construction sites. The practical implications of this work are validated using extensive simulation studies and experi- mental tests in two different lab settings, while demonstrating the numerical stability and robustness of the proposed framework to tackle the different uncertainties and external disturbances that can arise in construction sites.