Efficient Attitude Planning for Momentum-Wheel-Controlled Spacecraft with Attitude Forbidden Zones Using Convex Projection Method

The spacecraft needs to consider attitude forbidden zones (AFZs) constraints during attitude maneuvers to ensure the safety of the carried optical or infrared payloads. This paper proposes an efficient attitude planning method for momentum wheel-controlled spacecrafts that takes into account AFZs constraints. Firstly, the attitude kinematics s and dynamics, attitude forbidden zones constraints, momentum wheel control constraints, and boundary conditions are constructed. Considering the minimum energy index, the spacecraft attitude planning problem is formulated as an optimal control problem. Then, for AFZs constraints, a convex projection method is proposed in combination with the trapezoidal attitude maneuver strategy to construct an initial trajectory that satisfies the AFZs constraints. Further, the original optimal control problem is convexified using iterative approximation and relaxation methods, and the initial trajectory using convex projection is used for sequential iteration to ultimately obtain the optimal solution to the original problem. Compared to the sequential convex optimization method without convex projection, the proposed method constructs an initial trajectory that satisfies the AFZs constraints but does not satisfy the dynamics constraints, significantly enhancing the convergence of the iterative solution process.