Uncertainty Propagation in Hypersonic Flight Dynamics and Comparison of Different Methods

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Title: Uncertainty Propagation in Hypersonic Flight Dynamics and Comparison of Different Methods
Author: Prabhakar, Avinash
Abstract: In this work we present a novel computational framework for analyzing evolution of uncertainty in state trajectories of a hypersonic air vehicle due to uncertainty in initial conditions and other system parameters . The framework is built on the so called generalized Polynomial Chaos expansions . In this framework , stochastic dynamical systems are transformed into equivalent deterministic dynamical systems in higher dimensional space . In the research presented here we study evolution of uncertainty due to initial condition , ballistic coefficient , lift over drag ratio and atmospheric density . We compute the statistics using the continuous linearization (CL ) approach . This approach computes the jacobian of the perturbational variables about the nominal trajectory . The covariance is then propagated using the riccati equation and the statistics is compared with the Polynomial Chaos method . The latter gives better accuracy as compared to the CL method . The simulation is carried out assuming uniform distribution on the parameters (initial condition , density , ballistic coefficient and lift over drag ratio ) . The method is then extended for Gaussian distribution on the parameters and the statistics , mean and variance of the states are matched with the standard Monte Carlo methods . The problem studied here is related to the Mars entry descent landing problem .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2008 -12 -194
Date: 2010-01-16

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Uncertainty Propagation in Hypersonic Flight Dynamics and Comparison of Different Methods. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -2008 -12 -194 .

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