Trajectory Tracking Control Of Free-flying Space Robot

In recent years, with the rapid progress and development of science andtechnology, human’s field of vision widened and research areas largening, spacerobotics are attempted to be applied to space.As we all know,the earth’s resourcesare depleting and the environment are worsening so that searching and exploitingthe space resources has become our current mission.Exploring space gives rise to alot of danger confronted by the astronauts currently.Under such a background,it isof great significance to develop space robots for space missions.The research issue in this paper is the trajectory tracking control problems withexternal disturbance and without it,which gives priority to adaptive control and acombination with other methods,resulting in tracking the desired trajectory of spacerobot joints.The paper is extended in turn about the development of the space robot at homeand abroad, and several common control methods applied to the space robots.Multibody dynamics theory and Lagrange equations are used to derive the dynamicsand kinematics equations so that these equations about free-flying and free-floatingmode result.Some theoretical results are in order for concerning us during the study oftrajectory tracking in free flight mode. Firstly, the dynamic model of a two-linkplanar space robot is derived to lay the foundation for the following simulation.Then focusing on the strong coupling and unknown kinectic parameters of the thefree-flying space robot system, the adaptive control method is adopted and thedynamic equation is linearized Sequently,in order to verify the effectiveness of thecontroller, joint space trajectory tracking simulation is designed,having a goodperformance.Lastly in the case of external random disturbance, the trajectory tracking for theunknown and known upper bound of random perturbations is researched,combining the adaptive control method and the variable structure control method.The combination of the two methods has a remarkable advantage that adaptivecontrol can effectively obtain the estimation of unknown kinetic parameters andvariable structure control has strong robustness so that we have a robust adaptivecontroller with the ability of disturbance rejection.