<p>Quad-rotor suspension load system (QSLS) has excellent maneuverability and flexibility, and shows significant application potential in material transportation in complex scenarios such as farmland operations. However, the system has high-order degrees of freedom, strong nonlinear dynamic characteristics, and is susceptible to uncertain external interference, which poses a severe challenge to achieving precise control and safe and stable flight. Aiming at the above problems, this paper carries out the design and theoretical analysis of QSLS control strategy: based on Newton–Euler mechanical system and Euler–Lagrange energy equation, the accurate dynamic model of the system is established. On this basis, a fractional proportional–integral-derivative (FOPID) position controller and a super-twisted sliding mode (ST-SMC) attitude controller are designed to accurately adjust the spatial position and attitude angle of the quadrotor. The anti-swing controller is designed by backstepping control method, and the load swing is suppressed by dynamic input compensation mechanism. Aiming at complex mountain agricultural operation scenarios, an adaptive disturbance observer is designed to estimate unknown external disturbances, and a first-order sliding mode differentiator is introduced to suppress sensor noise, thus improving the robustness and dynamic stability of the system. Comparative simulation experiments on MATLAB/Simulink platform show that the proposed control strategy is superior to the single control algorithm in position tracking accuracy and attitude adjustment speed, and the position and attitude errors under different flight trajectories are reduced by 40–55%; The dynamic input compensation mechanism of the anti-swing controller has a significant effect on suppressing load swing, and the swing angle is controlled within <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$30^\circ $</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mn>30</mn> <mo>∘</mo> </msup> </math></EquationSource> </InlineEquation>. Under the common vortex airflow disturbance in mountain scenes, the disturbance observer can accurately estimate about 80% of the disturbance amount, effectively improving the system’s anti-interference ability; The designed first-order sliding mode differentiator can reduce the influence of strong noise on signal output by 79.59%. The introduction of sliding mode differentiator and disturbance observer significantly improves the stability of the system under complex environmental disturbances. Finally, the spectrum analysis experiment further verifies that the system has excellent control performance.</p>

A Trajectory Tracking Control Strategy for a Quadrotor Suspended Load System

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发表日期：

2026年2月11日

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Xu Longyan,
He Zihan,
Ye Ziheng,
Xi Mao,
Huang Liming,
Peng Qiang

摘要

Quad-rotor suspension load system (QSLS) has excellent maneuverability and flexibility, and shows significant application potential in material transportation in complex scenarios such as farmland operations. However, the system has high-order degrees of freedom, strong nonlinear dynamic characteristics, and is susceptible to uncertain external interference, which poses a severe challenge to achieving precise control and safe and stable flight. Aiming at the above problems, this paper carries out the design and theoretical analysis of QSLS control strategy: based on Newton–Euler mechanical system and Euler–Lagrange energy equation, the accurate dynamic model of the system is established. On this basis, a fractional proportional–integral-derivative (FOPID) position controller and a super-twisted sliding mode (ST-SMC) attitude controller are designed to accurately adjust the spatial position and attitude angle of the quadrotor. The anti-swing controller is designed by backstepping control method, and the load swing is suppressed by dynamic input compensation mechanism. Aiming at complex mountain agricultural operation scenarios, an adaptive disturbance observer is designed to estimate unknown external disturbances, and a first-order sliding mode differentiator is introduced to suppress sensor noise, thus improving the robustness and dynamic stability of the system. Comparative simulation experiments on MATLAB/Simulink platform show that the proposed control strategy is superior to the single control algorithm in position tracking accuracy and attitude adjustment speed, and the position and attitude errors under different flight trajectories are reduced by 40–55%; The dynamic input compensation mechanism of the anti-swing controller has a significant effect on suppressing load swing, and the swing angle is controlled within $30^\circ $ $30^{\circ}$ . Under the common vortex airflow disturbance in mountain scenes, the disturbance observer can accurately estimate about 80% of the disturbance amount, effectively improving the system’s anti-interference ability; The designed first-order sliding mode differentiator can reduce the influence of strong noise on signal output by 79.59%. The introduction of sliding mode differentiator and disturbance observer significantly improves the stability of the system under complex environmental disturbances. Finally, the spectrum analysis experiment further verifies that the system has excellent control performance.