Predefined-Time Attitude Tracking Control of a Rigid Spacecraft

A novel predefined-time attitude tracking control method is proposed for a rigid spacecraft. It is required that the attitude tracking error can converge to zero or a small neighborhood of zero in a finite time, whose upper bound is exactly a positive constant parameter that can be set arbitrarily by users. Two definitions about global predefined-time stability and global predefined-time boundedness are given. Time-varying tuning functions are introduced into the backstepping-based attitude control designs. Lyapunov approach proves the system stability and simulation results verify the effectiveness of the controllers.