A time suboptimal method for real-time spacecraft attitude agile maneuvering with angular velocity constraint

Abstract

A time suboptimal method for on-orbit rapid attitude maneuver control of agile spacecraft with attitude angular velocity constraint is proposed, which can generate suboptimal control torque command for real-time application. Spacecraft time-optimal slew maneuver has been studied by many researchers, and most of the interest is focused on formulating and resolving the optimization problem of spacecraft attitude maneuver in proper ways. Pseudospectral method, among most of the existing methods, is feasible to figure out the preferred solution satisfying the control precision, which possesses the values of practical application. However, pseudospectral method consumes much time for planning attitude trajectory making it impossible for on-orbit spacecraft real-time control, especially for observation mission with frequent maneuver. After thorough analysis of the time optimal attitude maneuvering results, several patterns with respect to the generation of attitude control command are summarized that result in an interpolation control method, which is time suboptimal and is capable of on-orbit real-time application for spacecraft with small products of inertia. Closed-loop control is implemented to cancel the final pointing error. Several simulations have been performed to validate the performance of the proposed strategy, and have demonstrated the potential application for small agile spacecraft with limited attitude control ability.