Terminal Sliding Mode Based Relative Position And Attitude Control For Spacecraft Rendezvous

With the increasing requirements of exploring and exploiting the universe,space missions are becoming more complicated and diversified.As the key technology in various space missions,like assembly of large-scale space structure,on-orbit service and sapce interception and so on,space rendezvous plays an improtant role in these missions and also determines whether they can success or not.Consequently,the design methods of position and attitude control have always been a hot research aera.Problems that should be taken into consideration include the external disturbances,collision avoidance and actuator faults and so on.Moreover,space rendezvous has high demands on control accuracy and response speed.Both of them pose challenges to the controller design of spacecraft position and attitude.This dissertation conducts research into the controller design of spacecraft position and attitude with space rendezvous as a background.The main contents of this dissertation are listed as follows.For the modelling of the relative position and the relative attitude between the chasing spacecraft and the target spacecraft in rendezvous,the T-H equation and quaternion are utilized to describe the translation and rotation seperately.For the position control of the chasing spacecraft,a nonsingular terminal sliding mode(NTSM)is adopted to design the position tracking control law.In order to avoid the singularity problem,a sinusoidal function is introduced into the controller.Then the NTSM is extended to fixed-time terminal sliding mode(FTSM).The proposed controller which is based on FTSM enables the relative position and the relative velocity to reach the equilibrium within fixed time.The collision avoidance druing rendezvous is considered as well.the FTSM reaching law and the artifical potential function are combined to design a feedback controller.For the attitude control of the chasing spacecraft,an attitude tracking control law based on FTSM is proposed under the circumstance that the target spacecraft is freely tumbling.Then the actuator faults and the external disturbances with unknown upper bound are taken into consideration,an adaptive fixed-time attitude tracking controller is designed.Finally,an auxilary variable containing the scalar part of quaternion is introduced to solve the anti-unwinding problem,and an attitude controller based on integral terminal sliding mode and adaptive technology is developed.