This paper presents the modeling, system identification, simulation and flight testing of the airbrake of an unmanned experimental aircraft in frame of the FLEXOP H2020 EU project. As the aircraft is equipped with a jet engine with slow response an airbrake is required to increase deceleration after speeding up the aircraft for flutter testing in order to remain inside the limited airspace granted by authorities for flight testing. The airbrake consists of a servo motor, an opening mechanism and the airbrake control surface itself. After briefly introducing the demonstrator aircraft, the airbrake design and the experimental test benches the article gives in depth description of the modeling and system identification referencing also previous work. System identification consists of the determination of the highly nonlinear (saturated and load dependent) servo actuator dynamics and the nonlinear aerodynamic and mechanical characteristics including stiffness and inertia effects. New contributions relative to the previous work are a unified servo angular velocity limit model considering opening against the load or closing with it, the detailed construction and evaluation of airbrake normal and drag force models considering the whole deflection and aircraft airspeed range, the presentation of a unified aerodynamic - mechanic nonlinearity model giving direct relation between airbrake angle, dynamic pressure and servo torque and the transfer function-based modeling of stiffness and inertial effects in the mechanism. The identified servo dynamical model includes system delay, inner saturation, the aforementioned load dependent angular velocity limit model and a transfer function model. The servo model was verified based-on test bench measurements considering the whole opening angle and dynamic load range of the airbrake. New, unpublished measurements with gradually increasing servo load as the servo moves are also considered to verify the model in more realistic circumstances. Then the full airbrake model is constructed and tested in simulation to check realistic behavior. In the next step the airbrake model integrated into the nonlinear simulation model of the FLEXOP aircraft is tested by flying simulated test trajectories with the baseline controller of the aircraft in software-in-the-loop (SIL) Matlab simulation. First, the standalone airbrake simulation is compared to the SIL results to verify flawless integration of airbrake model into the nonlinear aircraft simulation. Then deceleration times with and without airbrake are compared underlining the usefulness of the airbrake in the test mission. Finally, real flight data is used to verify and update the airbrake model and show the effectiveness of the airbrake.

本文介绍了FLEXOP H2020 EU项目框架下的无人实验飞机的空气制动器的建模，系统识别，仿真和飞行测试。由于飞机配备了响应速度较慢的喷气发动机，因此在加速飞机进行颤振测试后，为了保持在当局为飞行测试提供的有限空域内，需要刹车以增加减速度。空气制动器由伺服电机，打开机构和空气制动器控制表面本身组成。在简要介绍了示范飞机，空气制动设计和试验台之后，本文对建模和系统识别进行了深入的描述，并参考了以前的工作。系统识别包括确定高度非线性（饱和且与负载有关）的伺服执行器动力学以及非线性空气动力学和机械特性，包括刚度和惯性效应。与以前的工作有关的新贡献包括考虑负载打开或关闭时的统一伺服角速度极限模型，考虑整个挠度和飞机空速范围的气闸法向力和阻力模型的详细构造和评估，统一的气动-机械非线性模型，给出了制动角，动压力和伺服转矩之间的直接关系，以及基于传递函数的机构刚度和惯性效应建模。确定的伺服动力学模型包括系统延迟，内部饱和度，前述取决于负载的角速度极限模型和传递函数模型。根据试验台的测量结果对伺服模型进行了验证，其中考虑了整个制动器的打开角度和动态载荷范围。随着伺服移动，随着伺服负载逐渐增加的新的，未公开的测量也被认为可以在更实际的情况下验证模型。然后，构建完整的空气制动模型并在仿真中进行测试，以检查实际行为。在下一步中，通过在飞机软件的环内（SIL）Matlab仿真中使用飞机的基线控制器飞行模拟的测试轨迹来测试集成到FLEXOP飞机的非线性仿真模型中的空气制动模型。第一，将独立的空气制动器仿真与SIL结果进行比较，以验证空气制动器模型是否完美集成到非线性飞机仿真中。然后比较了有和没有空气制动的减速时间，强调了空气制动在测试任务中的有用性。最后，真实的飞行数据用于验证和更新空气制动模型并显示空气制动的有效性。