Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1714156 | Acta Astronautica | 2016 | 8 Pages |
•Librational motion of TSS is controlled by reel rate through a NMPC controller.•The MPC controller confines the tether length in a given range.•Tethered space robot is controlled by a hybrid CTM-MPC controller.•The method is used for positioning and trajectory tracking of TSR end-effector.•Performance of the method is evaluated numerically for several maneuvers.
Dynamic analysis and trajectory tracking of a Tethered Space Robot (TSR) is investigated in this paper. A hybrid controller is used to perform the control task. It consists of two components, the first one deals with librational motion of the tether, while the second one takes care of the manipulator motion. A Nonlinear Model Predictive Control (NMPC) approach is used to control the tether libration; for this purpose, the libration is described by a single degree of freedom and the tether length rate is employed as the input to suppress the librational motion. A modified Computed Torque Method (CTM) is used to control the manipulator motion. The dynamic interaction between the manipulator motion and the librational motion is considered both in the system dynamics and control of the system. Using numerical simulations, performance of the proposed control system is evaluated for end-effector positioning as well as for trajectory tracking for two cases: a Low Earth Orbit (LEO) and the Geostationary Earth Orbit (GEO).