Hybrid quad-plane unmanned aerial vehicles (UAVs), also known as dual-system hybrid UAVs, combine the advantages of multicopters and fixed-wing UAVs and have recently been gaining increasing attention. However, quad-planes are characterized by complex structures, high nonlinearity, strong coupling, effector redundancy, and three flight regimes (hover, transition, and fixed-wing flight), posing significant challenges for researching their flight control laws. Classical linear control laws have been widely used for quad-planes, but their limited adaptability can lead to degraded flight performance. To enhance the flight performance of a quad-plane named Scihunter, this thesis aims to design nonlinear flight control laws for it in the three flight regimes. These control laws should enable Scihunter to autonomously follow a predefined path and achieve stable and smooth transition flight. Nonlinear flight control laws, based on incremental nonlinear dynamic inversion (INDI) and linear parameter-varying (LPV) control methods, are proposed in this thesis because they are simple to design, easy to implement, and offer superior control performance. Moreover, due to the distinct flight characteristics in the three flight regimes, the variable structure control technique is employed in the control law design. A brief analysis of Scihunter's mathematical model is first provided, followed by the proposed cascade control structures divided into inner and outer loops. Then, control laws based on INDI control are designed for each control loop in hover and fixed-wing flight. During the control law design for transition flight, an extension of INDI, incremental nonlinear control allocation, is adopted to address effector redundancy and achieve a smooth flight transition. Subsequently, control laws based on LPV control are proposed for the three flight regimes. The loop shaping-based parameter-dependent Lyapunov function method is used to design the inner-loop control law. To reduce the controller order and improve computational efficiency, the proportional-integral-derivative (PID) control method is used to track outer commands. Given the over-actuated property of Scihunter in transition flight, the weighted least square control allocation strategy is utilized to allocate virtual control inputs to actual actuators to fulfill transition requirements. Finally, simulations are conducted in four cases: a nominal case, a measurement noise case, a wind disturbance case, and a model parameter uncertainty case, to evaluate the designed control laws. To provide a benchmark for comparison, the conventional flight control law for quad-planes, designed using the PID control method, is chosen as a comparison group. Simulation results corroborate the performance improvements achieved by the proposed control laws.


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    Title :

    Nonlinear Flight Control Law Design for a Hybrid Quad-Plane Unmanned Aerial Vehicle


    Contributors:
    Zhou, Li (author)

    Publication date :

    2025



    Type of media :

    Miscellaneous


    Type of material :

    Electronic Resource


    Language :

    Unknown






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