Spin-Up and Appointed Time Attitude Control of Tethered Spacecraft for Artificial Gravity

This paper investigates an artificial gravity strategy using the spinning tethered spacecraft (STS), which is spun along orbital direction. An appointed-time prescribed performance (ATPP) attitude controller of tethered spacecraft with unknown external disturbance is proposed by backstepping technology. First, the compound thrust control scheme is presented to provide an ideal artificial gravity overload by the centrifugal force on the tether. Then, the novel performance function is devised to ensure the dynamic response of the system but also achieves appointed-time stability. Compared with the traditional disturbance rejection method, an asymmetric barrier function is introduced to suppress unknown disturbances without estimated information. Based on the spin control scheme and the proposed attitude control strategy, the system is proved to be globally uniformly appointed-time stable in the presence of unknown disturbance. Furthermore, applications to the STS are employed to show the effectiveness of the ATPP control approach for artificial gravity.