Orbital Transfer of a Tethered Satellite System Using Pitching Motion Control through Tether Length Variation

This study deals with orbital transfer of a tethered satellite system in equatorial plane through its tether length control. Since tether length variation generates diversely different pitching motion on an elliptic orbit, appropriately designed tether length profiles can give the satellites a desired velocity-vector-increment at a prescribed position in orbit. This paper proposes a procedure to get an adequate control input profile which attains the designated states at the final position by applying nonlinear control method. Also the procedure can directly cope with physical restrictions for the system, such as the maximum tether length or tether tension. The proposed procedure consists of three steps associated with control for its angular momentum of pitching motion, which finally leads to control of tether length, pitch angular rate, and pitch angle at the final position, respectively.