Recently, high-agility spacecraft have garnered significant interest in the field of aerospace engineering to satisfy the demands of commercial and reconnaissance space missions. A representative method utilized for this purpose involves mounting high-torque generators (e.g., Control Moment Gyros,CMGs), on spacecraft. However, the utilization of CMGs to generate a control torque input while performing attitude control to reorient a spacecraft may create singularities, including an absence of a specific direction in the control torque.
To avoid this, an analysis chart called the feasible angular momentum chart(FAM chart) is usually utilized to maneuver CMG-equipped spacecraft effectively. This is defined by considering the gimbal angles of the CMG system that correspond to internal or external singularities and superimposing the results corresponding to each CMG, ultimately yielding a single gimbal space where the actuator limit prevents the generation of an accurate command torque input.
Various singularity avoidance/escape and robust steering schemes have been proposed to overcome geometric singularity problems associated with CMG systems. The position of the initial gimbal angle of the CMG system is closely related to the rotational maneuvering performance of the spacecraft. The angular momentum vector along any axis is a function of the gimbal angle, whose value is dependent on the gimbal vector of the spacecraft.
As the value of the gimbal angle must revert to its original value at the end of a maneuver, the angular momentum vector must also revert to its initial value, which eventually leads to a singularity. In turn, this disrupts the generation of a desired torque command by the TPCMG. To recover the angular momentum maneuver, the vector while avoiding a singularity, this paper introduces a steering strategy based on optimal angular momentum vector recovery.
Attitude command generation in high-agility spacecraft, which aims to minimize the total maneuvering duration, also requires the consideration of various other constraints. An analytical attitude command generation technique is also proposed in this paper to improve the maneuvering performance of spacecraft. To this end, a novel scale adjustment and reallocation strategy is introduced to define constraints for attitude command generation and maximize maneuvering capability and the range of attitude reorientation.