Optimal stabilization of small spacecraft angular motion in the process of deployment of an orbital tether system

The problem of stabilizing the motion of small spacecraft relative to the center of mass in the process of deploying an orbital tether system is presented in the paper. Stabilization is carried out with respect to the direction of the tether and is characterized by the classical Euler angles (precession, nutation and proper rotation). The proposed method of suboptimal control is based on the joint application of the principle of Bellman's dynamic programming and the averaging method. The integral quadratic optimality criterion that depends on operating deviations and low control inputs is used. Control synthesis is accomplished using the model of angular motion recorded for small angles of nutation. An example of calculating optimal control of an orbital tether system deployed for the purpose of de-orbiting small satellites to the Earth is given. The efficiency of the optimal control arrived at is confirmed by numerical calculations for the basic nonlinear model of motion of an orbital tether system.