Attitude and orbit coupled control and simulation of spacecraft formation by using intelligent adaptive control based on characteristic model
Regarding to the relative attitude and orbit of spacecraft formation flying, a nonlinear dynamic model of six degree of freedom coupled with attitude and orbits established, with the help of characteristic model, this paper mainly analyzes the factors of the spatial perturbation and multiple disturbance torques, a kind of intelligent adaptive controller is designed based on the combination of RBF neural network and the golden section adaptive control. Later, the simulation platform Jade is used to simulate and analyze the Multi-Agent system of spacecraft formation. The results show that the spacecraft formation can run along in the ideal orbit, the effect of the control system has good robustness, fault tolerance and intelligence.
Point Targeting of Multisatellites via a Virtual Structure Formation Flight Scheme
This paper proposes a formation flight control scheme for spacecraft based on the virtual structure approach. The virtual structure approach treats the entire formation as a virtual rigid-body structure. With this approach, the geometric relationship among the spacecraft can be maintained during a maneuver. The information on the geometric relationships is used to complete the formation flight mission. Using rotational kinematics and rigid-body dynamics, the virtual structure formation algorithm calculates the reference position and attitude command to perform the synchronized maneuvers required to point to the desired target. The adaptive sliding mode control law is adopted to make the system track the reference command generated by the formation algorithm. An adaptive sliding mode controller, which combines the merits of the adaptive control scheme and the sliding mode control scheme, is proposed and used to make the spacecraft follow the specified position and attitude command. The stability of the proposed controller is analyzed by using the Lyapunov stability theorem, and a numerical simulation is performed to verify the effectiveness of the proposed formation algorithm and the adaptive sliding mode controller.
Chemical constituents and chemotaxonomic study of Glycyrrhiza pallidiflora maxim
Abstract Phytochemical study of Glycyrrhiza pallidiflora Maxim. gave seventeen compounds, including two sterols (3 and 4), four triterpenes (1, 2, 5, 6), ten flavones (7, 9–17), and one pterocarpan (8). The chemotaxonomic significance of G. pallidiflora was discussed, which indicated the close relationship between G. pallidiflora with other species of Glycyrrhiza. Moreover, pallidiflorin can be served as a fingerprint for G. pallidiflora, macedonic acid and echinatin can be recognized as biomarkers for Glycyrrhiza, while formononetin, afrormosin and calycosin may be typical second metabolites for Papilionoideae.