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Nonlinear and adaptive estimation techniques in reentry (1972)

Flanagan, P. ; Jazwinski, A. H. ; Pines, S. ; [et al.]

In: CASI

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Publication Date: 2019-06-27

Description: The development and testing of nonlinear and adaptive estimators for reentry (e.g. space shuttle) navigation and model parameter estimation or identification are reported. Of particular interest is the identifcation of vehicle lift and drag characteristics in real time. Several nonlinear filters were developed and simulated. Adaptive filters for the real time identification of vehicle lift and drag characteristics, and unmodelable acceleration, were also developed and tested by simulation. The simulations feature an uncertain system environment with rather arbitrary model errors, thus providing a definitive test of estimator performance. It was found that nonlinear effects are indeed significant in reentry trajectory estimation and a nonlinear filter is demonstrated which successfully tracks through nonlinearities without degrading the information content of the data. Under the same conditions the usual extended Kalman filter diverges and is useless. The J-adaptive filter is shown to successfully track errors in the modeled vehicle lift and drag characteristics. The same filter concept is also shown to track successfully through rather arbitrary model errors, including lift and drag errors, vehicle mass errors, atmospheric density errors, and wind gust errors.

Keywords: SPACE SCIENCES

Type: NASA-CR-123540 , REPT-72-6

Format: application/pdf

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Adaptive filtering Interim report (1967)

Jazwinski, A. H. ; Bailie, A. E.

In: CASI

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Publication Date: 2019-06-27

Description: Adaptive filter with inaccuracies approximated by Gaussian white noise input and determination of covariance for most probable residual sequence

Keywords: SPACE SCIENCES

Type: NASA-CR-84794 , REPT.-67-6

Format: application/pdf

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Nonlinear and adaptive estimation in reentry. (1972)

Jazwinski, A. H.

In: Other Sources

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Publication Date: 2019-07-13

Description: The problem of real-time estimation of a lifting reentry vehicle trajectory of the shuttle orbiter type is considered. Simulations feature large position and velocity uncertainties at radar acquisition and realistic model errors in lift, drag and other model parameters. Radar tracking and accelerometer data are simulated. Significant nonlinearities are found to exist on spacecraft acquisition. An iterated nonlinear filter is shown to perform optimally during the radar acquisition phase. An adaptive filter is shown to track time-varying model errors, such as errors in the lift and drag coefficients, down to the noise level. Such real-time model tracking (identification) is frequently required for guidance and control implementation.

Keywords: SPACE SCIENCES

Type: AIAA PAPER 72-874 , American Institute of Aeronautics and Astronautics, Guidance and Control Conference; Aug 14, 1972 - Aug 16, 1972; Stanford, CA

Format: text

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