Direct Rotor Thrust Sensing and Feedback Control for Disturbance Rejection of Multirotors Using Load-cells

2026-07-10

AI Summary

This study addresses the susceptibility of multirotor aerial vehicles to aerodynamic disturbances such as gusts, downwash, and ground effect, which conventional trajectory-feedback-based control methods struggle to mitigate due to inherent response delays. To overcome this limitation, the authors propose directly integrating low-cost strain-gauge thrust sensors at the rotor level, coupled with custom low-noise hardware and a high-bandwidth thrust-feedback control architecture. For the first time, this approach experimentally demonstrates the feasibility of real-time thrust sensing using such sensors in complex aerodynamic environments, challenging the prevailing assumption that they are too noisy for practical use. Validation on single- and dual-rotor pendulum setups and an actual flying vehicle shows substantial improvements in thrust tracking accuracy and disturbance rejection, enabling rapid suppression of diverse aerodynamic perturbations.

Abstract

Gust disturbances, dynamic vertical inflow and ground effect are key adverse aerodynamic phenomena that induce variations in the forces acting on a multirotor and complicate its flight control. Miniature rotorcraft typically rely on simplified modelling of such effects to compute adjustments in thrust to counteract these forces. In the most basic case, disturbance force estimations are derived from the aircraft's motion and the generated thrust is assumed to exactly match that requested by the controller. However, such systems rely on the aircraft's trajectory to be affected before disturbances can be sensed and compensated. Numerous approaches presented over the last 15-20 years aim to reject external disturbances more quickly, but challenges remain. This paper presents a new approach in this category by measuring the instantaneous force of the rotors directly at the point of generation using load-cells and implementing high-speed control to accurately track the desired thrust. Measurements from load-cells were previously considered too noisy to provide meaningful input, but the experiments presented in the paper using purpose-built hardware from low-cost commodity components in single- and dual rotor see-saw models and a flying aircraft demonstrate both the feasibility and the effectiveness of the approach in the presence of complex aerodynamic phenomena.

Problem

• disturbance rejection
• multirotors
• aerodynamic disturbances
• thrust control
• load-cells

Innovation

• Direct thrust sensing
• Load-cell feedback
• Disturbance rejection
• Multirotor control
• High-speed thrust tracking