Fast Reconstruction of 6- and 7-Degree-of-Freedom Trajectories Using Analytic Aerodynamic Sensitivities
Abstract
To estimate the aerodynamic coefficients of a projectile in free flight, a high-fidelity model must be propagated forward in time. The coefficients within the model are adjusted to improve the match between measured data and predicted measurements from the model. When a gradient-based method is used to adjust the model coefficients, the sensitivities of the measurements with respect to the coefficients must be estimated. This can be done through finite differencing, or parametric differentiation. Parametric differentiation has historically been used only for sensitivities with respect to initial conditions and aerodynamic parameters in 6-degree-of-freedom models. Here we present a comprehensive review of the 6-degree-of-freedom formulation and extend the method to a 7-degree-of-freedom projectile, and one with four independent control surfaces. We show that this type of analysis is both possible and worthwhile, resulting in a threefold or greater speed increase in gradient-based algorithms. Several simple examples precede the full projectile model. Results are shown using simulations of a 7-degree-of-freedom projectile and a 6-degree-of-freedom one with active control surfaces.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2020
- Accession Number
- AD1113440
Entities
People
- Bradley T. Burchett
Organizations
- United States Army Research Laboratory