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71.
72.
《中国航空学报》2020,33(2):561-571
In order to reach a compromise between fast response control and torques matching control in double turboshaft engines, research on nonlinear model predictive control for turboshaft engines based on double engines torques matching is conducted. Meanwhile, a Nonlinear Model Predictive Control (NMPC) method is proposed, which combines the control index of the power turbine speed with torques matching of double engines creatively. In addition to the control index, the difference of output torques between each engine is also incorporated in the objective function as a penalty term to ensure constant speed control and short torques matching time. Simulation results demonstrate that relative to unilateral torques matching, the settling time of the bidirectional matching method can be reduced by nearly 30.8%. Nevertheless, compared with the bidirectional torques matching method under the cascade PID controller, the NMPC method can decrease the overshoot of the power turbine speed by 65% and reduce the matching time by 15.5% synchronously. Besides fast response control of turboshaft engines, fast torques matching control of double engines is accomplished as well. 相似文献
73.
为实现微型共轴无人直升机(MCUH)的航迹跟踪,考虑系统的状态和输入约束,利用非线性模型预测控制(NMPC)技术设计一种快速在线的控制器。首先,简化MCUH的非线性模型,利用系统的微分平坦特性生成满足直升机动力学的可行航迹,沿着该航迹对系统进行线性化,得到近似直升机非线性动力学的线性时变(LTV)模型。然后,将传统输出航迹跟踪NMPC问题转化为LTV-MPC优化问题,降低问题的复杂度,为确保航迹跟踪误差系统的指数渐近稳定,分别设计终端域和终端罚值。最后,通过数值仿真,验证快速在线NMPC策略的可行性。结果表明:设计的预测控制器误差控制精度高、求解速度快,可实现对有约束的时变航迹的跟踪。 相似文献
75.
中心铰式旋翼不产生桨毂力矩,当这类直升机由于急推杆或减小桨距而进入失重状态时,会丧失横向操纵功效及角速度阻尼。如果操纵失当,直升机会陷入急剧横滚并导致旋翼浆叶冲撞挥舞下限动器,造成旋翼破坏以及砍打尾梁、空中解体的灾难。为避免这类事故应防止进入低g或失重状态,保持足够的操纵功效。万一进入失重并发生自发的横滚,必须首先向后拉杆以改出失重状态,待恢复操纵功效后才可施加横向操纵以纠正横滚。 相似文献
76.
77.
A full-span free-wake method is coupled with an unsteady panel method to accurately predict the unsteady aerodynamics of helicopter rotor blades in hover and forward flight. The unsteady potential-based panel method is used to consider aerodynamics of finite thickness multi-bladed rotors, and the full-span free-wake method is applied to simulating dynamics of rotor wake. These methods are tightly coupled through trailing-edge Kutta condition and by converting doublet-wake panels to full-span vortex filaments. A velocity-field integration technique is also adopted to overcome singularity problem during the interaction between the rotor wake and blades. Helicopter rotors including Caradonna-Tung, UH-60A, and AH-1G rotors, are simulated in hover and forward flight to validate the accuracy of this approach. The predicted aerodynamic loads of rotor blades agree well with available measured data and computational fluid dynamics (CFD) results, and the unsteady dynamics of rotor wake is also well simulated. Compared to CFD, the present method obtains accurate results more efficiently and is suitable to rotorcraft aeroelastic analysis. 相似文献
78.
提出了常规试飞应把握的三个环节(做好试飞准备、掌握试飞方法、严格试飞标准)和常规试飞的主要项目(测试和调整旋翼与尾桨震动度、检查和调整旋翼自转转速、检查和调整操纵系统间隙与摩擦力、检查和校验发动机功率)及方法,为直升机试飞员和有关工程技术人员提供参考。 相似文献
79.
主要研究舰载飞机在进场下滑着舰过程中的飞行动力学问题。着重讨论了舰载飞机在进场下滑过程中的轨迹保持及其纵向控制,同时给出了此时飞机的飞行自动控制系统和进场功率补偿器系统反馈控制参数的计算方法。 相似文献
80.
Aerodynamic design optimization of helicopter rotor blades including airfoil shape for hover performance 总被引:1,自引:1,他引:0
This study proposes a process to obtain an optimal helicopter rotor blade shape for aerodynamic performance in hover flight. A new geometry representation algorithm which uses the class function/shape function transformation (CST) is employed to generate airfoil coordinates. With this approach, airfoil shape is considered in terms of design variables. The optimization process is constructed by integrating several programs developed by author. The design variables include twist, taper ratio, point of taper initiation, blade root chord, and coefficients of the airfoil distribution function. Aerodynamic constraints consist of limits on power available in hover and forward flight. The trim condition must be attainable. This paper considers rotor blade configuration for the hover flight condition only, so that the required power in hover is chosen as the objective function of the optimization problem. Sensitivity analysis of each design variable shows that airfoil shape has an important role in rotor performance. The optimum rotor blade reduces the required hover power by 7.4% and increases the figure of merit by 6.5%, which is a good improvement for rotor blade design. 相似文献