ADAPTIVE PI-BASED SLIDING-MODE CONTROL FOR PLANT PROTECTION QUADROTORS WITH VARIABLE MASS AND SLOSHING

Shibbir Ahmed, Muhammad Yousaf Nadeem, Muhammad Zain, Zubair Iqbal, Issac Tawiah, Chengming Sun

Keywords

Agricultural sprayer UAVs, variable mass, liquid slosh, PID, sliding-mode controller, attitude tracking

Abstract

The stability of autonomous liquid transporter unmanned aerial vehicles (UAVs) is crucial for precision in agricultural field spraying. This paper proposes an adaptive robust control scheme designed to stabilise agricultural quadrotor UAVs affected by variable mass and liquid sloshing dynamics during pesticide application. A comprehensive nonlinear mathematical model is developed to explicitly represent UAV–liquid interactions, accounting for both liquid sloshing and time-dependent mass variations. An adaptive PI- based sliding-mode controller is proposed, featuring a neural network identifier to estimate unknown sloshing forces and a nonlinear disturbance observer to mitigate external disturbances. Theoretical analysis through designed Lyapunov functions confirms the closed- loop system’s robustness, stability, and bounded estimation errors, even despite varying liquid mass conditions. Simulation experiments validate the effectiveness of the proposed method, achieving approximately 41.4% and 53.8% in trajectory tracking accuracy, stabilisation, and disturbance rejection along the x- and y-axes, respectively, compared to the conventional proportional integral derivative (PID) counterpart. Overall, this research enhances UAV control methodologies by effectivelymanaging sloshing-induced ∗ Key Laboratory of Crop Genetics and Physiology of Jiangsu Province, Key Laboratory of Crop Cultivation and Physiology of Jiangsu Province, College of Agriculture, Yangzhou University, Yangzhou 225009, China; e-mail: [email protected]; [email protected]; [email protected] ∗∗ College of Water Conservancy, North China University of Water Resources and Electric Power, Zhengzhou 450046, China; e-mail: [email protected] ∗∗∗ School of Science and the Environment, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; e-mail: [email protected] ∗∗∗∗ Department of Automation, Shanghai Jiao Tong University, Shanghai 200240, China; e-mail: isaac k [email protected] † Shibbir Ahmed and Muhammad Yousaf Nadeem contributed equally to the work. Corresponding author: Chengming Sun Recommended by Min Xia

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