Based on the singular value decomposition theory,this paper analyzed the mechanism of escaping/avoiding singularity using generalized and weighted singularity-robust steering laws for a spacecraft that uses single gimbal control moment gyros (SGCMGs) as the actuator for the attitude control system.The expression of output-torque error is given at the point of singularity,proving the incompatible relationship between the gimbal rate and the output-torque error.The method of establishing a balance between the gimbal rate and the output-torque error is discussed,and a new steering law is designed.Simulation results show that the proposed steering law can effectively drive SGCMGs to escape away from singularities.
To keep multiple missiles to fly in a formation,a robust controller for missile formation is designed.Based on the leader-follower formation mode,two formation relative motion models in different coordinate frames are established and compared.The three-dimension model built in a follower reference coordinate frame is chosen due to its control inputs decoupling,then this model is decoupled into three subsystems.For each subsystem a robust formation controller is proposed based on the disturbance observer and finite-time control theory when the external disturbance exits.The stability of the closed-loop system adopting the controller is proved theoretically.Simulation results show that the follower can follow the leader and keep the desired formation despite the external disturbance,which validates the effectiveness of the proposed robust formation controller.
