Research On Modeling And Flight Control Of Parafoil Under The Airdrop Mission

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.