Research On Dynamic Modeling And Terminal Optimal Homing Based On A Kind Of Small Parachute

Parafoil airdrop is an important technique to convey materials and staff from high altitude to the target on the ground. For its high lift-drag ratio, flexible turning performance and flared landing ability, parafoil system has developed as a hot research topic in airdrop and recycle field to achieve precise airdrop and undamaged landing from high latitude. It is widely used for battle replenishment, humane rescue, and what’s more, applied in remote stakeout or helping commando to sliding into the enemy region. In this paper, to fulfill an airdrop emergent rescue mission, a kind of small parafoil’s basic flight character, the relative motion between the parafoil and payload are both under discussed. In order to realize precision airdrop at the desire time, a kind of real time terminal optimal homing method is provided here.First of all, Vortex Lattice Method(VLM) is used to calculate the aerodynamic force and moments on the parafoil gliding state and turn state. Several flight samples are presented here and these results are used to fitting parafoil aerodynamic coefficient by least square method.Then 6DOF rigid model with attached mass matrix are built to analyze parafoil basic flight characters such as flight path and attitude angle in sliding and turning states. Two body model are built to analyze the relative motion between the parafoil and payload when the system is under wind disturbance or when it is making a turn.What’s more, traditional multiphase homing trajectory strategy is used according to the basic dynamic property analyzed above. Adaptive genetic algorithm(AGA) is used to improve the accuracy and efficiency. In addition, this kind of small parafoil is used for rescue and emergent condition, precision airdrop at a certain time is as equal importance. Therefore, a new kind of virtual domain method is introduced into terminal trajectory guidance, it helps to produce new real-time optimal reference trajectories in the final turn phase when the system deviates from the expected route because of outside disturbance. This method only need unilateral trailing edge deflection operation, it can be easily realized in the practical engineering application.This paper can provide references for small parafoil and relative research, and it offers new method to solve homing trajectory problems.