| At present,in the most research on control of parafoil systems in homing progress,parafoils possess only lateral control,which achieved by right or left brake deflection.The dissertation focuses on analyzing influence of wind on parafoils' movement performance in their homing phases.And a control method is designed to achieve parafoils' longitudinal control.The main works are as follows:Considering structural particularity of the parafoil,its apparent mass and aerodynamics force are introduced in detail.Then a 6DOF rigid-connected model is established for parafoils' simulation.The parafoil's kinetic characteristics are analyzed.The influence of wind on parafoil systems is obtained and summarized through qualitative analysis and quantitative calculation.And relationship between the system's glide ratio and wind velovity is computed.The effects of incidence angle,right and left brake control on parafoil systems are computed and analyzed,so that appropriable controlled quantities of parafoils are obtained.The controller is designed for the parafoil's homing phase.The fuzzy PD controller is mainly introduced.In allusion to the parafoil's gliding trajectory,a fuzzy PD controller and a proportional controller are designed,and another method is used,in which the controlled quantity's variation is kept unchanged.Besides,a fuzzy PD controller is also designed for studing the parafoil's lateral control.All the controllers are simulated in the system's 6DOF model.The simulation results show the controllers' feasibility and effectiveness for both the parafoil's trajectory and landing point.Finally,the designed longitudinal controller and lateral controller are used in combination to control the parafoil,which is emulationally verified to make the parafoil land precisely in turbulent wind field.These works on parafoils' control in the paper can provide thoughts to engineering application and have great theoretical significance and application values. |
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