Dual-Layer-Based Active Disturbance Rejection Decoupling Control for Lateral Stability of Power-Decoupled Agricultural Mobile Platforms Under Complex Operating Conditions

Due to zero emissions of pollutant gases, rapid response capability, and multifunctionality, electric agricultural mobile platforms have gradually become a significant research focus in the field of facility agriculture, especially power-decoupled agricultural mobile platforms with excellent mobility and flexibility. In order to enhance the adaptability of mobile platforms to confined facility spaces and meet high standards of agricultural practices, a four-wheel power-decoupled agricultural mobile platform (FPD-AMP) with independent drive and independent steering is designed in this paper. Furthermore, a dual-layer-based active disturbance rejection decoupling control strategy is proposed to address the lateral instability encountered by FPD-AMPs under complex operating conditions, particularly in turning scenarios. Firstly, the dynamic characteristics of the FPD-AMP, considering both facility agricultural requirements and complex operating conditions, are analyzed. And the corresponding lateral stability state equations are established. Additionally, an S-curve trajectory experiment is conducted to fit the key parameters of the tire model. Then, to tackle the challenges posed by strong nonlinear coupling, time-varying parameters, and external disturbances under complex operating conditions, an upper-layer active disturbance rejection decoupling control method is proposed. This method not only satisfies the requirements for global lateral stability control but transmits clear drive force distribution commands to the lower-layer control system. In the lower-layer control, a torque distribution controller integrating the unscented Kalman filter algorithm is designed to address the multiple constraints under varying soil-road conditions and to further enhance the lateral stability margin. Finally, Experimental results demonstrate that the proposed strategy effectively enhances the lateral stability of the FPD-AMP. Note to Practitioners—In greenhouses, limited space and dense crop planting severely constrain turning areas, while traditional mobile platforms, with poor maneuverability and large turning radii, typically rely on discontinuous and complex forward-reverse maneuvers, significantly reducing efficiency. This paper proposes an FPD-AMP with independent drive and independent steering. Yet, the four wheels still need to undergo large steering angles to complete a continuous U-turn maneuver, which inevitably increases the risk of lateral instability. Furthermore, wide-ranging velocity variations for agronomic requirements, coupled with diverse farmland soil-road conditions, further exacerbate lateral instability during the U-turn maneuver of the FPD-AMP. To address the lateral instability issues, a dual-layer active disturbance rejection decoupling control strategy for lateral stability of the FPD-AMP is proposed. The upper-layer active disturbance rejection decoupling control consists of nonlinear dynamic model decoupling and the design of multi-channel active disturbance rejection controllers for lateral stability. The lower-layer torque allocation control, based on the unscented Kalman filter (UKF), involves farmland soil-road identification using a UKF observer and torque allocation optimization through quadratic programming. The experimental results demonstrate that the proposed control strategy effectively estimates the varying tire-road adhesion coefficients and significantly enhances the lateral stability of the FPD-AMP during U-turn maneuvers and plowing operations under variable farmland conditions.