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利用最优控制方法研究倾转旋翼机的最优动态倾转过渡过程,并得到最优操纵策略,使得由时间、姿态角变化以及驾驶员工作负荷等组成的性能指标达到最小。首先,在基本纵向刚体飞行动力学模型的基础上引入混合操纵方程,并使用杆量位移的一阶导数作为控制量,形成适用于计算倾转旋翼机动态倾转过渡过程的飞行动力学模型,从而能在动态倾转操纵策略优化过程中考虑到操纵系统特性对操纵量变化速度的限制,以及避免操纵量在优化过程中出现跳跃不连续。然后,将倾转旋翼机的最优动态倾转过渡过程转化为非线性动态最优控制问题,建立合理的性能指标,并采用直接转换法和序列二次规划算法进行求解。最后,以XV-15倾转旋翼机为样机,分别计算正向和逆向最优动态倾转过渡过程,并与驾驶员飞行仿真数据进行对比。结果表明:飞行状态量的时间历程与文献吻合地较好,且俯仰姿态角和杆量位移变化更加柔和。最优控制方法可以用于研究倾转旋翼机的最优动态倾转过渡过程。
Optimal control method is used to study the optimal dynamic tilting transition process of tiltrotor rotor and the optimal control strategy is obtained to minimize the performance index composed of time and attitude changes and driver workload. First, based on the basic longitudinal rigid body flight dynamics model, a hybrid governing equation is introduced and the first derivative of displacement is used as the control variable to form a flight dynamics model suitable for calculating the dynamic tilting transition of a tiltrotor. Which can take into account the characteristics of the control system to control the speed of the manipulated variable in the optimization process of the dynamic tilting maneuvering strategy and avoid the jump discontinuity in the optimization process. Then, the optimal dynamic tilting transition process of tiltrot rotorcraft is transformed into the nonlinear dynamic optimal control problem. The reasonable performance index is established and solved by direct conversion method and quadratic programming algorithm. Finally, taking the XV-15 tilting rotorcraft as a prototype, the optimal dynamic tilting transition process of forward and reverse directions was calculated and compared with the pilot flight simulation data. The results show that the time history of the flight state quantity is in good agreement with the literature, and the pitching attitude angle and the displacement of the rod mass are more gentle. The optimal control method can be used to study the optimal dynamic tilting transition of tilting rotorcraft.