Browsing by Subject "Navigation (Astronautics)"
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Item Advanced navigation algorithms for precision landing(2007-12) Zanetti, Renato, 1978-; Bishop, Robert H., 1957-A detailed analysis of autonomous navigation algorithms to achieve autonomous precision landing is presented. The problem of integrated attitude determination and inertial navigation is solved. The theoretical results are applied and tested in three different applications. Optimality conditions for constrained quaternion estimation using the Kalman filter are derived. It is common in spacecraft applications to separate the attitude determination from the inertial navigation system. While this approach has worked in the past, it inevitably degrades the navigation performance when the correlations between the two systems are not correctly accounted for. It is shown how to optimally include an attitude determination algorithm into the Kalman filter. When the conditions to achieve optimality are not met, it is shown how to achieve sub-optimality by properly accounting for the correlation. The traditional approach to inertial navigation is to employ the inertial measurement unit (IMU) outputs to propagate the estimated states forward in time, rather then use them to update the state. A detailed covariance analysis of deadreckoning Mars entry navigation is performed. The contribution of various sources of IMU errors are explicitly accounted for and the filter performance is validated through Monte Carlo analysis. The drawback of dead-reckoning is that this approach prevents the inertial measurements from reducing the uncertainty of the estimated states. While this shortcoming can be compensated by the availability of other measurements, it becomes crucial when the IMU is the only sensor to provide measurements. Such a situation arises, for example, during Mars atmospheric entry. In the second application of this work, IMU measurements from a NASA mission are processed in an extended Kalman filter, and the results are compared to dead-reckoning. It is shown that is possible to reduce the uncertainty of the inertial states by filtering the IMU. The final application is lunar descent to landing navigation. In this example the IMU is filtered and the algorithms to include an attitude estimate into the Kalman filter are tested. The design performance is confirmed by Monte Carlo analysis.Item Generalized approach to navigation of spacecraft formations using multiple sensors(2006) Holt, Greg Nate; Lightsey, E. GlennItem Navigation algorithms and observability analysis for formation flying missions(2006) Huxel, Paul John; Bishop, Robert H., 1957-Item Real-time navigation for Mars final approach using the Mars Network(2007-12) Mogensen, Andreas Enevold, 1976-; Lightsey, E. GlennReal-time navigation during the final approach phase of an interplanetary mission can significantly increase the accuracy of aerocapture and pin-point landing. The Mars Network is a versatile telecommunications network that is ideally situated to provide spacecraft-to-spacecraft radiometric navigation during Mars final approach and entry, descent, and landing via the Electra UHF transceiver, which is capable of providing autonomous, on-orbit, real-time trajectory determination using two-way Doppler measurements between a Mars approach vehicle and a Mars Network orbiter. A detailed dynamic analysis and link analysis of the final approach problem is presented, which seeks to determine the expected operating conditions of the Electra transceiver. In particular, the maximum Doppler shift and Doppler rate, which determine the transceiver tracking loop requirements, and the total received signal power and signal-to-noise ratio, which determine the range at which the communications link can be closed, are investigated for a range of Mars Network orbital geometries. A model of the Electra signal is developed on the basis of the results of the dynamic analysis and link analysis and is used as input to a high-fidelity simulation of the Electra transceiver. A Monte Carlo analysis is performed to determine the performance of the Electra transceiver for a range of signal and tracking loop parameters. In particular, the performance analysis focuses on the maximum range at which the link can be closed and on the acquisition and tracking performance of the second-order tracking loop. The analysis of the tracking performance is used to characterize and model the error in the Doppler measurement of the Electra transceiver. The error model is incorporated into the design of an extended Kalman filter, in order to improve the fidelity of the navigation filter design. The information content in the Doppler measurement and the observability of the estimated states are investigated for various orbital geometries and the accuracy of the navigation solution is analyzed.Item Spacecraft precision entry navigation using an adaptive sigma point Kalman filter bank(2007) Heyne, Martin Cornelius, 1973-; Bishop, Robert H., 1957-