Dynamic Modeling And Attitude Control For Dumbbell Configuration Flexible Spacecraft

Due to mission requirements or load constraints,some spacecraft will present a dumbbell configuration,where mass is concentrated at both ends.For example,the gravity-gradient stabilized satellite needs to present a dumbbell configuration because it is supposed to be affected by large gravity gradient moment.Another example is the nuclear-powered spacecraft,for the purpose of isolating the reactor from the payload platform,a nuclear-powered spacecraft is usually composed of a payload platform,a truss,a nuclear reactor,which make it look like a dumbbell.The dumbbell configuration spacecraft is unsual that has no concept of central rigid body and it also has flexibility.In this paper,the dynamics modeling of a flexible spacecraft with a dumbbell configuration is carried out,the attitude control scheme of the dumbbell configuration flexible spacecraft is designed with the flexible vibration suppression as the main consideration point.The content covers several links of the attitude control system.For dumbbell spacecraft has no central rigid body,the dynamic model in the form of virtual power dynamics general equation is established by the recursive method,and then deduced the simplified dynamic model of the flexible spacecraft applicable for control system analysising.Considering that the attitude quaternion has no singularity when describing the attitude of spacecraft,the kinematics equation in the form of attitude quaternion is established.To solve the problem that the constrained mode can not represent the real state of the spacecraft in space,a method to obtain the unconstrained mode frequency of the whole spacecraft is proposed,and the corresponding dynamic response is analyzed.In order to solve the problem that the dynamics model of spacecraft is non-linear and there are errors when analyzing by analytic method,parameters of the input shaper and pulse width pulse frequency modulator are designed by using particle swarm optimization algorithm.The effect of the shaper obtained by optimization algorithm is compared with that obtained by traditional methodIn order to improve the stability of large angle attitude maneuver,a three-stage sinusoidal angular velocity planning scheme was designed to make the spacecraft achieve the goal of smooth maneuver by tracking the desired angular velocity.In the actuator link,aiming at the problem of how to reduce the cost and the proportion of the actuator in the whole star mass and the demand that the output torque of the actuator should be smooth,a new actuator configuration scheme combining the double gimbal scissored-pair control moment gyros and the reaction flywheel is designed.In this scheme,only two control moment gyroscopes can be used to achieve excellent torque output around any Euler axis.In the controller design,the PD controller and the non-singular terminal sliding mode controller were designed respectively in view of the problems of model uncertainty and rigid-flexible coupling of flexible spacecraft,and considering the widespread application of PD controller.The PD controller was combined with the input molding device.The attitude tracking and flexible vibration suppression effect of the control system are verified by simulation.