Attitude Coordinated Control for Docked Spacecraft Based on Estimated Coupling Torque

When a service spacecraft docks successfully with its target spacecraft and forms a docked spacecraft, it will cause a large shift in the dynamics of the docked spacecraft. Not only do the mass properties change, but so do the reaction wheels' configuration. Meanwhile, the attitude of the docked spacecraft will inevitably change, under the influence of contact and impact, and it may lead to instability of the entire system. Due to the limited control torque and saturation, the control system of the reaction wheel may not guarantee the system stability, and the thruster can generate large control torque, but it consumes valuable jet fuel. Since the space manipulator may generate a greater coupling torque by movement, this paper proposes an attitude coordinated control method for docked spacecraft based on the estimated coupling torque. The method adopts the chaotic particle swarm optimization (CPSO) algorithm to plan the coordinated motion trajectory of space manipulator, and then designs a coordinated control law based on the estimated coupling torque of space manipulator to achieve the attitude control of docked spacecraft in order to guarantee the system stability. Numerical simulations validate the feasibility of the proposed method. In comparison with the traditional attitude control method, the attitude coordinated control method makes use of the coupling torque of the space manipulator, and overcomes the shortcomings of the limited control torque and saturation of reaction wheel, without consuming expensive jet fuel.