Research On The Hovering And Attitude Control Method Of Lorentz Spacecraft

Lorentz spacecraft,as a kind of conceptional space vehicle,is able to intentionally change the electric charge on its surface so that Lorentz force is induced via interaction with the local magnetic field,which has much research value and application potential in propellantless electromagnetic propulsion to perform orbital maneuvers and spacecraft attitude regulation by Lorentz force.In this dissertation,based on the real engineering mission of spacecraft hovering,the crucial orbit and attitude control technique of Lorentz spacecraft as a concomitant satellite in the whole process of mission,is researched.The main research work and the main results are as follows:1.A nonlinear dynamical model for Lorentz-augmented hovering is established by adding Lorentz force acceleration to the dynamic equations for two-body relative motion of spacecraft.The effect of electric filed and J₂ perturbations on relative motion of spacecraft is researched by numerical simulation.The feasibility of Lorentz-augmented hovering is also analyzed.2.The properties of Lorentz spacecraft and traditional uncharged spacecraft hovering are respectively researched in circle and elliptic reference orbit.An electromagnetic force control method of Lorentz-augmented hovering aiming at minimizing the control energy consumption is derived and ameliorated.The effect of semi-major axis,eccentricity,hovering model and J₂ perturbations on spacecraft hovering velocity increment of orbital period is analyzed,while the effect of saving propellant by Lorentz force is analyzed.3.The optimal orbit control problem before space service missions of Lorentz spacecraft is researched.Based on the Gauss pseudospectral method,the feasibility of propellantless electromagnetic propulsion to perform orbital maneuvers by Lorentz force is analyzed and the optimal trajectories that minimize control energy consumption are designed.Integral sliding mode control and linear quadratic regular methodologies are used to guarantee the robustness against the external perturbations,different kinds of error in orbital maneuvers and hovering.4.Based on the attitude quaternion to describe orientation of target and concomitant satellite,the method for the Lorentz spacecraft to converge to non-cooperative target spacecraft in all statement is researched,and the dynamical model of attitude propagation errors is established.A nonlinear approach is developed to estimate the rate of non-cooperative target vehicle,which could ensure that the angular velocity converges to true value.Then,a new method,called the q-D technique is presented to solve the quadratic optimal control problem.The spacecraft attitude tracking process with disturb of Lorentz moment and model uncertainty is researched.5.The control method of high-precision attitude stabilization and regulation within space service missions of Lorentz spacecraft is researched.Based on the attitude error model and Lyapunov stability theory,a steady backstepping control method is designed.A real-time predictive filter is used to simulate and equalize model errors and external perturbations.Numerical simulations indicate that the control system is able to satisfy the control precision and stability requirement of the Lorentz spacecraft large-angle attitude maneuver mission.