Attitude Maneuver Control For The Disturbance-free Payload Spacecraft

Space science is one of the hot topics about natural science.The realization of space science missions requires the effective payloads which are installed on the scientific satellites.The high precision and high stability of the payload are needed to get high quality spatial probe data.At present,energy systems of satellites still include flexible components such as solar panels,which cause the vibration,greatly affecting the accuracy of the payloads.The Disturbance-Free payload(DFP)architecture involves no mechanical contact between the payload and the supporting spacecraft in the physical structure.The vibration of the supporting spacecraft will not affect the pointing accuracy of the payload which provides the possibility of high-precision and high-stability space observation.This paper mainly focuses on the attitude maneuver and relative position control of the spacecraft with the DFP architecture.The main research contents are as follows.To realize the attitude maneuver of the spacecraft with the DFP architecture,the structural characteristics of the DFP architecture and the working principle of the noncontact maglev devices are analyzed.The work pattern of the spacecraft is classified.The reference coordinate systems and the body coordinate systems of the payload cabin and the platform cabin are established.On this basis,the mathematical model of the payload cabin and the platform cabin are established.For the requirement of collision avoidance of the spacecraft with DFP architecture,the relative position equation between the center of the payload and the center of the platform is established.The relative position dynamics model of the coils and the magnetic steels of the maglev devices is deduced.The relative position dynamics equation of the center of the two cabins and the relative position dynamics of the coils and magnetic steels are analyzed.The integrated dynamic equation of the payload attitude and the relative position of the coils and the magnetic steels of the maglev devices is established.Aiming at the constraints of maximum angular acceleration and maximum angular velocity existing in the attitude maneuver,a continuous sinusoidal angular acceleration curve slew path is designed.Taking the designed sinusoidal angular acceleration curve slew path as the desired target,the PD control law for the attitude tracking of the payload cabin and the platform cabin and the relative position of the two cabins are designed.According to configuration of the maglev devices,a control allocation strategy based on zero space is designed and the actual output force model of maglev devices is established.Further more,according to the relative position dynamic model of the coils and magnetic steels of the maglev devices,a sliding mode control law for two-cabins relative position based on exponential reaching law is designed.The mathematical simulations is provided to illustrate the performance of the sinusoidal angular acceleration curve and the effectiveness of the proposed control schemes.Considering the input constraints of the payload cabin,a nonlinear back-stepping attitude controller based on the arc tangent function is designed.The upper bound of the control torque can be obtained by the appropriate control gain.The proposed control law guarantees that the actual control torque never exceeds the bound.Considering the input constraints and the coupling of the relative position and relative attitude of the two cabins,an adaptive sliding mode control law based on the integrated dynamic equation is designed.The mathematical simulations is provided to illustrate the performance of the proposed control law.