31,100 research outputs found
Guidance, flight mechanics and trajectory optimization. Volume 14 - Entry guidance equations
Entry guidance equations, reference trajectories, and guidance system mechanizatio
Advanced Centaur explicit guidance equation study Final report
Generalized equations and in-flight computer requirements for Centaur guidance and control and advanced mission plannin
Guidance, flight mechanics and trajectory optimization. Volume 11 - Guidance equations for orbital operations
Mathematical formulation of guidance equations and solutions for orbital space mission
Astrodynamics-optimization theory and guidance theory Research achievements review series no. 15-16
Review of research achievements in astrodynamics, optimization theory, and guidance theor
Analysis and application of minimum variance discrete time system identification
An on-line minimum variance parameter identifier was developed which embodies both accuracy and computational efficiency. The new formulation resulted in a linear estimation problem with both additive and multiplicative noise. The resulting filter is shown to utilize both the covariance of the parameter vector itself and the covariance of the error in identification. It is proven that the identification filter is mean square covergent and mean square consistent. The MV parameter identification scheme is then used to construct a stable state and parameter estimation algorithm
Guidance and Control strategies for aerospace vehicles
A neighboring optimal guidance scheme was devised for a nonlinear dynamic system with stochastic inputs and perfect measurements as applicable to fuel optimal control of an aeroassisted orbital transfer vehicle. For the deterministic nonlinear dynamic system describing the atmospheric maneuver, a nominal trajectory was determined. Then, a neighboring, optimal guidance scheme was obtained for open loop and closed loop control configurations. Taking modelling uncertainties into account, a linear, stochastic, neighboring optimal guidance scheme was devised. Finally, the optimal trajectory was approximated as the sum of the deterministic nominal trajectory and the stochastic neighboring optimal solution. Numerical results are presented for a typical vehicle. A fuel-optimal control problem in aeroassisted noncoplanar orbital transfer is also addressed. The equations of motion for the atmospheric maneuver are nonlinear and the optimal (nominal) trajectory and control are obtained. In order to follow the nominal trajectory under actual conditions, a neighboring optimum guidance scheme is designed using linear quadratic regulator theory for onboard real-time implementation. One of the state variables is used as the independent variable in reference to the time. The weighting matrices in the performance index are chosen by a combination of a heuristic method and an optimal modal approach. The necessary feedback control law is obtained in order to minimize the deviations from the nominal conditions
Optimal Instruments in Time Series: A Survey
This article surveys estimation in stationary time series models using the approach of optimal instrumentation. We review tools that allow construction and implementation of optimal instrumental variables estimators in various circumstances { in single- and multiperiod models, in the absence and presence of conditional heteroskedasticity, by considering linear and nonlinear instruments. We also discuss issues adjacent to the theme of optimal instruments. The article is directed primarily towards practitioners, but also may be found useful by econometric theorists and teachers of graduate econometrics.Instrumental variables estimation; Moment restrictions; Optimal instrument; Effciency bounds; Stationary time series.
A dynamic programming analysis of multiple guidance corrections of a trajectory /revision no. 1/
Dynamic programming applied to guidance correction for perturbed trajectory of spacecraf
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