Control over the deployment of an orbital tether system of great length

Control of deploying an extended tether system into the vertical position is considered in the paper. It is assumed that in the initial state the system consisting of two space vehicles moves in a circular Earth orbit. We propose nominal control programs ensuring the deployment of the system to a predetermined length and taking into account the restrictions on the speed of tether and force in the control mechanism. To construct nominal deployment programs a mathematical model of the systems motion in the orbital moving coordinate system is used. The model takes into account the peculiarities of the problem. We assess the operability of the proposed programs of deployment according to the mathematical model of controlled motion of the orbital tether system with distributed parameters recorded in the geocentric coordinate system. To perform test calculations a linear regulator that provides feedback on the length and speed of the tether deployment is used

Optimizing the process of changing spacecraft orbital parameters by using a spinning electrodynamic tether sytem

The paper considers parametric optimization of the process of changing orbital parameters by using a spinning electrodynamic tether system. Changes in the semi-major axis and eccentricity are taken as the two major goals, and two control laws are proposed accordingly. Current is regulated according to the instantaneous position of the conductive tether, which allows ensuring the calculated direction of the Lorentz force produced by the interaction of the conductive tether with the Earths magnetic field. A combined control scheme for simultaneous changes in the semi-major axis and eccentricity is proposed. The parameters of control laws are optimized on the basis of the Nelder-Mead method by using different objective functions and constraints. It is also shown that, by using the criteria of quick response and minimum impulse, we obtain optimal solutions corresponding to the boundary values of the selected parameters. Therefore, a convolution of these criteria is proposed as a compromise, which ensures a specified change in the orbital parameters of the system mass center