Estimation of the Lateral Aerodynamic Coefficients for Skywalker X8 Flying Wing From Real Flight-Test Data

Abstract

Stability and control derivatives of Skywalker X8 flying wing from flight-test data are estimated by using the combination of the output error and least square methods in the presence of the wind. Data is collected from closed loop flight tests with a proportional-integral-derivative (PID) controller that caused data co-linearity problems for the identification of the unmanned aerial vehicle (UAV) dynamic system. The data co-linearity problem is solved with a biased estimation via priori information, parameter fixing and constrained optimization, which uses analytical values of aerodynamic parameters, the level of the identifiability and sensitivity of the measurement vector to the parameters. Estimated aerodynamic parameters are compared with the theoretically calculated coefficients of the UAV, moreover, the dynamic model is validated with additional flight-test data and small covariances of the estimated parameters.

Modeling of the Skywalker X8 Fixed-Wing UAV: Flight Tests and System Identification

“…In addition to [1], which is a continuation of [5], several publications consider this popular airframe. Farhadi et al [6] identify a lateral model of the X8 using flight data, in a combination of the output-error method and ordinary least squares regression. Gan et al [7] identify the static aerodynamic coefficients from a Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) program.…”

“…The parameters of the other coefficients are identified in the same way by parameterizing the regressor matrix and measurement vector according to the model structure in (6).…”