Switching LPV control for electromagnetic formation flying on highly elliptical orbit

The electromagnetic force generated by the interaction of electromagnetic coils can be used to replace the conventional propellant consumption mode in close relative motion control,thereby promoting the application of formation flight technology for long-term and continuous space missions.Herein,a hysteresis-switching logic-based switching linear parameter varying(LPV)controller synthesis technique with guaranteed performance for electromagnetic formation flying on a highly elliptical orbit is proposed.First,considering that the relative dynamics model of an elliptical orbit is characterized by time-varying uncertainty,the LPV model is described.By introducing switching LPV controllers among different scheduled parameter subsets,conservativeness can be reduced.Second,the system modeling error,the uncertainty caused by a simplified electromagnetic coil model,and external disturbance are considered to derive switching LPV controller synthesis conditions based on the guaranteed H_(∞)performance.Derivation analysis shows that the proposed switching LPV controller not only ensures the robustness of the system against uncertainties,but also realizes the control input constraints.Finally,numerical simulations and comparative analyses are performed to demonstrate the effectiveness and advantages of the proposed control method.

Optimal Release Control of Companion Satellite System Using Electromagnetic Forces

Electromagnetic forces generated by the inter-action of component satellites can be used to release companion satellites. Optimal release trajectories for companion satellite system using inter-electromagnetic forces were investigated. Firstly,nonlinear relative motion dynamic equations of a two-craft electromagnetic companion satellite system were derived in spatial polar coordinates. Then principles of electromagnetic satellite formation flying were introduced. Secondly,the characteristics of the electromagnetic companion satellites release were analyzed and optimal release trajectories of companion satellites using electromagnetic forces were obtained using Gauss pseudospectral method. Three performance criteria were chosen as minimum time,minimum acceleration of the separation distance and minimum control acceleration. Finally,three release examples including expansion along separation distance, rotation in orbital plane and stable formation reconfiguration were given to demonstrate the feasibility of this method. Results indicated that the release trajectories can converge to optimal solutions effectively and the concept of release companion satellites using electromagnetic forces is practicable.