首页> 中文期刊> 《西北工业大学学报》 >一种改进的非定常气动力模糊逻辑建模方法

一种改进的非定常气动力模糊逻辑建模方法

         

摘要

We aim at the severe nonlinearity, coupling and hysteresis of the aerodynamic forces and moments when an airplane has post⁃stall maneuver. The modeling method is based on large⁃amplitude oscillatory wind tunnel test data analysis results and considers various factors that influence the aerodynamic forces and moments. Then we use the quadratic membership function to transform the angle of attack and its first and second⁃order derivatives, yaw angle and reduced frequency into fuzzy inputs. The aerodynamic forces and moments calculated with fuzzy rules are used as outputs. Compared with other modeling methods, our modeling method can identify the structure and fuzzy logic model in a unitary way and is versatile. The precision of the model satisfies the requirements for given correla⁃tion coefficients. We design the time⁃scale dynamic and inverse control law according to the singular perturbation theory. We also use the Daisy⁃chain method to allocate the actuator′s deflection in an over⁃actuated system. The comparison of simulation results on the “Cobra” typical maneuver under normal and unsteady aerodynamic forces shows the necessity of establishing a precise unsteady aerodynamic model when an airplane has post⁃stall maneuver and verifies the good control effect of the dynamic inversion method on a nonlinear system.%针对飞机过失速机动时气动力和气动力矩出现严重的非线性、耦合性和迟滞性等现象,提出了一种改进的模糊逻辑非定常气动力建模方法。该方法基于大幅振荡风洞实验数据分析结果,充分考虑了影响飞机气动力和气动力矩的不同因素,通过二次型隶属度函数将迎角、迎角导数、迎角二阶导数、侧滑角和缩减频率等转化为模糊输入,将模糊规则计算出的气动力和气动力矩作为模糊输出。与其他方法相比,该方法能够对模糊逻辑模型的结构和参数统一辨识,通用性强,模型精度满足给定的多层相关系数要求。最后,根据奇异摄动理论,设计了时标分离的动态逆控制律,采用了串接链方法实现过驱动系统的舵面偏转分配。通过对比常规气动力和非定常气动力下典型的“眼镜蛇”机动仿真结果,说明了过失速机动时建立精确非定常气动力模型的必要性,也验证了动态逆方法对于非线性系统有良好的控制效果。

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