Year: 2017
Type: dissertation
Abstract: vison sensor.The effect of measurement geometry can be different for vision-only, inertial and vision-based TRN camera, and that with star tracker, thus the geometric effect is investigated for each cases by analytic derivation of vision DOP and covariance analysis of integrated navigation system.It is shown that the vision DOP is a function of distance and line of sight angle from sensor to matched features and the number of features.Also, covariance analysis results show that the navigation accuracy can be improved and its dependency on line of sight angle can be reduced if accurate attitude information is provided by star tracker.EKF underweighting is known to be used extensively for practical applications to prevent filter divergence when the magnitude of state uncertainty is large compared to the nonlinear measurement accuracy by adding additional term proportional to the a priori state estimation error covariance to the residual covariance.Generally, constant value of underweighting coefficient is applied which is determined by complicated tuning process for the system under consideration.The underweighting for inertial and vision-based TRN camera integrated navigation of lunar lander using vision DOP is proposed to adaptively determine its coefficient and condition whether to apply or not.The underweighting coefficient is defined as the percentage of decrease of the state estimation error covariance and the predicted accuracy of vision-based navigation using vision DOP is used as the a posteriori covariance.The performance of the proposed EKF underweighting is demonstrated through Monte Carlo analysis.
Author: 박영범
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2784550482