Research Of Parafoil Aerodynamic Parameter Identification Based On Flight Data

Due to the excellent handling performance of the parafoil,the precision airdrop technique has been used more and more in military,rescue,disaster relief,civil and other fields.In China,the theoretical research results of the precision airdrop technology of the parafoil are hardly applied to the actual airdrop process,due to the accurate aerodynamic parameters of the parafoil are difficult to obtain.In this paper,the parafoil flight test data is used to study the aerodynamic parameter identification of the parafoil.Firstly,the 6-DOF motion model of the parafoil is established.Based on this model,the influence of the aerodynamic parameters' value on the flight performance of the model is further analyzed.Then,a parafoil CFD simulation model is established in FLUENT,in order to simulate the influence of external wind field and angle of attack on the aerodynamic coefficient and stability of the parafoil.Secondly,the objective function for solving the aerodynamic parameters is constructed according to the 6-DOF motion model of the parafoil.The algorithmic structure and characteristics of several optimization algorithms are anslyzed,such as maximum likelihood estimate,genetic algorithm,particle swarm optimization algorithm and ecosystem particle swarm optimization algorithm.And then,in order to enhance optimum speed and accuracy,the ecosystem particle swarm optimization is improved.Several standard optimization algorithms are used to detect and compare several optimization algorithms,the ecosystem particle swarm optimization algorithm with the highest precision is selected as the parameter identification optimization algorithm.Thirdly,in order to obtain the data of the parafoil flight test,the parafoil flight test system is designed and established.and the hardware structure and sensor selection of the flight test system are introduced.The flight experiment is designed according to the performance of the system,and the flight data preprocessing algorithm is prepared to correct the wild value in the flight data and reduce the noise interference.Finally,for the flight data of the parafoil six-degree-of-freedom model,the ecosystem particle swarm optimization algorithm is used to minimize the parafoil identification target function.The average relative error of the identification results is small.The aerodynamic parameters with large deviation have little influence on the flight performance of the parafoil model,which verifies the feasibility of the identification scheme.The parafoil flight test was carried out by the parafoil flight test system.By comparing the output data of parafoil model based on the identification aerodynamic parameters and the measured flight data,the identification results are acceptable.