Comparison Between Minimum and Near Minimum Time Optimal Control of Flexible Slewing Spacecraft

In this paper. muiitruun and near-minimum time optimal control laws aredeveloped and compared for' a rigid space platforn: with flc:tible links duriru] anorientating nuuieuuer with a im'.gr; angle of rotation. the control conuiuuid«m'e considered as typical l!!lng-bang with muliip!« symmetrical suntclies, thetime optimal control solution for the tigid-body mode is obtained as a bangbangfunction and applied to the .fle:rible system after smoothening the controlinpnt.s to avoid stimulation of the .flexilile modes. this will also reflect practicallimitations in erertuu; bang-i)(lt/,g actuator' jorces/torques due to delays andnon-zero time constants of eiisiiru; actuation elements. the smoothness ofthe uiuut. commasul is obtained by ncshaping its profile based on consuierationof addiiion.a! derioaiiue constraints. the optimal control problem is convertedinto parameter optimization problem. the steps of tlu solution procedure andnumerical algorithm. to obt.aiti the time optinuil control input are discussednext: the developed control law is applied to a given satellite duriiu; aslewing maueuuer. the simulation results show that the couirol input withjust a few switching times can significantly lessen the vibrating motion of thejieribie appendage. which reneols the merits of the developed control law. themodified realistic optimal input compared to the liang-bang solution goes wellwith the practical iiniitations and alleviates the vibrating motion of the flexibleappendage. which reveals therneriis of the new developed control law.