Design of Control Law of Post Stall Maneuver under Unsteady Aerodynamics Based on Improved Dynamic Inverse Method

基于改进动态逆方法的非定常气动力下过失速机动控制律设计

School of Automation, Northwestern Polytechnical University, Xi’an, 710072, China

Received: 8 June 2018

Abstract

In this paper, a practical improved dynamic inverse control method is proposed to solve the large control error and control hysteresis of post stall maneuver under unsteady aerodynamics. Firstly, depending on the wind tunnel experimental data of the advanced fighter aircraft model under biaxial coupled large oscillation, an accurate unsteady aerodynamic model is established by using the improved extreme learning machine (ELM) method. Secondly, in terms of the time scale separation, the control error caused by unsteady aerodynamic is reduced by adding integral in the fast loop, and the control delay caused by unsteady aerodynamic is eliminated by applying the lag correction link in the slower loop. The deflections of conventional aerodynamic surface and thrust vector are allocated by the daisy chain method. Finally, the formula of the reduced frequency, which is the key factor in the unsteady aerodynamic modelling process, is derived by analyzing the wind tunnel data. The effectiveness of the present method for the scaled model is verified by herbst post stall maneuver. The present work provides a practical and reliable way for the flight test of post stall maneuver.

摘要

针对非定常气动力作用下基于常规动态逆的过失速机动控制时的误差大和迟滞强的问题，提出了一种实用的改进动态逆控制方法，实现了非定常气动力下过失速机动的精准控制。首先，基于双轴耦合大幅振荡下的先进战斗机缩比飞机模型风洞实验数据，通过改进的极限学习机（ELM）方法建立了准确的非定常气动力模型。其次，基于时标分离的思想，通过在快回路中增加积分环节减小了非定常气动力引起的控制误差；通过在较慢回路中引入滞后校正环节，消除了非定常气动力引起的控制迟滞，并结合串接链方法实现了常规气动舵面和推力矢量喷口的偏转分配。最后，推导了过失速机动时非定常气动力建模过程中关键变量缩减频率的计算公式，并通过该缩比模型"赫伯斯特"过失速机动数字仿真，对比验证了新方法的有效性，为后续过失速机动的试飞验证提供了实用可靠的工程途径。