Quasi-Symmetrical Variable Inertia Solar Sail with Underactuated Triaxial Control Strategy

Underactuated control is an effective method for fault management and structural weight reduction of spacecraft. However, existing underactuated attitude control methods rely on fixed and unequal principal moments of inertia assumption. In other words, the spacecraft must be an asymmetric gyroscope. This situation makes it difficult for symmetrical solar sails, which are highly sensitive to weight, to benefit from underactuated control. In this paper, an underactuated triaxial control strategy for quasi-symmetrical variable inertia solar sail, is presented from the kinematics perspective. By analyzing the system coupling characteristics and transforming the control problem into an optimal route planning problem, an angular velocity path method with its homotopy initial value determination method is proposed, offering an efficient control approach for quasi-symmetrical variable inertia spacecraft. Numerical findings validate the feasibility of the presented underactuated control strategy, while also indicating that the optimization algorithm readily converges. Additionally, the strategy still works well in the environment with low solar radiation pressure, which suggests the potential for interplanetary missions.