Tether length control for orbital transfer of tethered satellite

This study discusses orbital transfer of a tethered satellite system in equatorial plane. By applying a nonlinear control method, this paper proposes a procedure to design a tether length profile which attains the designated states at a specified final position in orbit. The proposed procedure consisting of three steps adjusts the system's three states to the target values with one control input; control for the angular momentum of pitching motion, which leads to control of the tether length, control for the pitch angular rate, and control for the pitch angle. The proposed procedure does not require numerical iterations, and can cope with physical restrictions for the system, such as tether tension or the maximum tether length. Besides, the resulted final states are precisely coincident to the target values.