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空投任务下翼伞建模与飞行控制研究
Research on Modeling and Flight Control of Parafoil under the Airdrop Mission
【作者】 谢亚荣；
【导师】 吴庆宪；
【作者基本信息】 南京航空航天大学 ， 控制理论与控制工程， 2011， 硕士
【摘要】 翼伞系统可用于精确空投和“定点无损”着陆,在军事、航空航天等领域有着广泛的应用前景。目前翼伞系统已成为空投和回收领域研究的热点。本文围绕空投任务下的翼伞空投系统建模、姿态控制、归航控制、航迹规划以及三维动画视景仿真这几个方面展开研究工作:首先,将翼伞和空投物看作刚性连接的整体,忽略空投物与伞体之间的相对运动,对完全张满后的可控翼伞系统建立了六自由度运动模型,并在所建模型的基础上进行了运动特性的仿真分析。其次,利用非线性动态逆控制方法实现翼伞姿态控制系统的设计,考虑到系统建模误差和外界干扰等不确定因素对控制器性能的影响,引入模糊干扰观测器对翼伞飞行过程中所受复合干扰进行逼近和控制,提高整个闭环系统的控制性能。随后,研究了翼伞系统的归航控制,介绍和比较了目前翼伞归航控制的方法,选取分段归航作为本文中翼伞系统归航的方式。在Gockel对翼伞归航设计的基础上,采用内环姿态控制律和外环制导系统设计思路,运用基于模糊干扰观测器的非线性预测控制方法对翼伞归航轨迹进行跟踪控制。实验仿真表明,在存在外界干扰和建模误差的情况下,该控制策略具有良好的鲁棒性和抗干扰性。接着,研究了翼伞系统的航迹规划问题,对地形威胁和火力威胁进行了建模,结合翼伞飞行特性,引入最小威胁曲面生成三维航迹搜索空间,并利用粒子群算法搜索优化翼伞系统的航迹。仿真结果表明,利用粒子群算法规划出的航迹能够躲避威胁,满足航程和高度的要求。最后,进行了基于OpenGL空投系统的三维动画视景仿真,比较生动地演示了空投系统着陆的过程。
【Abstract】 Parafoil system could be widely used in many areas, e.g. military or aviation and aerospace, to realize precise airdrop and precise-undamaged landing. Recently, it has been a hotspot in airdrop and recovery. This thesis focuses on the modeling, attitude control, homing control, route planning, and three-dimensional visual simulation of the airdrop system.Firstly, considering the umbrella body and drop load as a rigid connection, the relative motion between the umbrella body and drop load is ignored. The six-degree-of-freedom model of parafoil system with sails full is established. The movement characteristics of parafoil system are simulated and analyzed for the proposed model.Secondly, based on the nonlinear dynamic inversion technique, the attitude control system of parafoil is designed. Considering the modeling error and external disturbance uncertainties of the controller performance, fuzzy disturbance observer is used to approximate the interference suffered during the flight and to improve the closed-loop control system performance.Thirdly, the parafoil homing flight control system is studied. The current parafoil homing control methods are discussed and compared. The sub-homing method is utilized to design homing flight control sysyem in this thesis. Based on the homing design of parafoil by Gockel and attitude control law and guidance design, the nonlinear model predictive control method using fuzzy disturbance observer is studied for parafoil homing trajectory tracking control. The simulation results that the good robust performance and anti-interference performance of the flight control system are obtained under the condition of external disturbance and dynamic modeling errors.Then, the parafoil flight path planning system is studied, the models of the terrain threat and fire threat are considered. Combining with parafoil flight characteristics, the minimum-risk surface is employed to generate three-dimensional route-searching space. The particle swarm optimization algorithm is used to optimally search the route of parafoil system. The simulation result shows that the planned route can avoid the threats and meet the requirements of range and height.Finally, the three dimension visual simulation of airdrop system based on OpenGL is developed and it shows the process of landing vividly.