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Research On Autonomous Navigation And Configuration Control Technology Of Satellite Formation Flying In The Proximity Of Near Earth Asteroid

Posted on:2015-12-23Degree:DoctorType:Dissertation
Country:ChinaCandidate:H X YangFull Text:PDF
GTID:1222330509961060Subject:Aeronautical and Astronautical Science and Technology
Abstract/Summary:PDF Full Text Request
Near-Earth asteroid(NEA) exploration refers to those deep space exploration activities which reveal the origin, evolution and composition of the solar system. There exits a class of asteroids among the NEAs which have a potential security threat to the Earth. Therefore, the asteroid detection and deflection becomes a hot topic. In the implementation of such missions, orbit determination of the asteroids and autonomous navigation and control of the satellites are the key issues. Due to the uncertainty of the physical properties of asteroids, big challenges were brought to the navigation and control system design. Precise autonomous navigation and control strategies play a vital role for the success of the program. This thesis focused on the autonomous navigation and control method of the satellite formation flying in the proximity of NEA. The main research and conclusions are summarized as follows:The work presented a multi-sensor autonomous navigation method with the inter-satellite measurements included in the measurement model. The relative dynamics model of asteroid/satellite formation was established. An improved "asteroid imaging / range + inter-satellite range" measurement model was built up. The inter-satellite range measurement was combined to the observations with respect to the asteroid. The filter algorithm was designed based on EKF to estimate the relative position and velocity of the satellite to the asteroid. The results showed that this method can achieve a relatively autonomous navigation by adding the inter-satellite range measurement to improve navigation performance.The autonomous navigation strategies were designed in the application of the satellite formation flying around the asteroid. The collaborative navigation schemes were put forward by adding the inter-satellite position vector to the measurement model. At the meanwhile, the three-dimensional position vector between the two satellites is introdued into the measurement model. Then four different combinations of the observable navigation information were constituted, including: two non-cooperative navigation schemes without the inter-satellite measurements and two collaborative navigation schemes which considered the inter-satellite measurements. Comparative analysis of simulation results were shown based on UKF filtering algorithm and proved to be high navigation accuracy for the collaborative navigation scheme. Moreover, sensitivity and robustness of the navigation system were analyzed to the process noise and the observation error. The collaborative navigation schemes were verified to improve the robustness of the navigation system and reduce the sensitivity to noise.Orbit determination and control methods were presented for satellite formation flying in the proximity of the slowly rotating asteroid. Various disturbing factors such as solar gravity and solar radiation pressure were taken into consideration to form a complex dynamic model. Lyapunov stability theory was applied to design the control law, and the estimated states were included in the filtering to realize the real-time control. Simulations verified the validity and correctness of the proposed method based on UKF algorithm. The number of satellites in formation was extended to four. Information redundancy problem was solved by the proposed semi-collaborative navigation schemes, higher navigation accuracy was achieved. The semi-collaborative navigation schemes also proved to be effective methods to solve the problem of sensor failure.The method of absolute orbit determination of NEA was studied. The thesis combined the onboard measurments with the measurements based on ground station to estimate the absolute orbits of asteroid and satellite formation simutanously and obtained high-precision estimations. Considering the failure of ground-based observations due to the Earth’s rotation, Doppler velocimetry measurement was used to obtain the satellite velocity along the line of sight vector relative to the Sun. Simulation results verified the correction of the method.Research on the satellite formation control method based on cyclic pursuit algorithm and its applications to the asteroid exploration. For circular reference orbit formation reconfiguration, the nonlinear cyclic pursuit control law was designed in the flying surface combined with the proportional differential control based on fuzzy adjusting in the direction of the normal surface. For elliptical reference orbit satellite formation control problems, the research focused on the satellite formation flying around Eros, and designed a cyclic pursuit collaborative control strategy. This method avoided satellite orbit drift cause by the asteroid irregular perturbations and made the formation fly under the desired configuration.This thesis presented the autonomous navigation and configuration control method for the satellite formation flying in the proximity of the NEAs for different missions. The designed autonomous navigation system had the high reliability and accuracy, while the control method structure was simple but effective. The work made a great contribution for the satellite formation navigation and control technology and its application in NEA exploration.
Keywords/Search Tags:Satellite Formation Flying in the proximity of Near Earth Asteroid, Relative Navigation, Inter-spacecraft Measurement, Lyapunov Control Theory, UKF, Collaborative Navigation, Absolute Orbit Determination, Cyclic Pursuit, Formation Reconfiguration
PDF Full Text Request
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