Position And Attitude Snychronization Planning And Control Of Spacecraft In Close Proximity Based On Dual Quatertion

In the close proximity mission of two spacecraft,the relative position and relative attitude of two spacecraft need to be controlled synchronously.The traditional relative motion dynamics modeling and control methods can not meet the real-time and high-precision requirements of increasingly complex space missions.In this paper,a dual quaternion based coupled dynamic model of relative motion of two spacecraft is established,and then the sequential convex optimization method is used to study the synchronous planning problem of close proximity.On this basis,the model predictive control method is used to track the planned trajectory.Firstly,the basic properties and operation methods of quaternion,quaternion number,dual quaternion and other mathematical concepts are introduced,and the method of using dual quaternion to express six degree of freedom motion of rigid body is given.According to the mission background,the required coordinate system is established,including inertial coordinate system and body coordinate system of two spacecraft.The kinematic and dynamic models of the service spacecraft and the target spacecraft in inertial frame are given respectively,and the relative motion models of the two spacecraft are derived.On this basis,a dual quaternion based integrated kinematics and dynamics model of relative motion and attitude orbit of two spacecraft is presented.Considering that the two spacecraft are affected by various perturbations before the intersection and docking,the relative position and attitude of the two spacecrafts will deviate from the required state.The sliding mode controller and the fast terminal sliding mode controller based on the approach law are designed to eliminate the deviation and stabilize the system.The sliding mode controller based on the approach law selects two kinds of convergence laws,namely exponential and power law,and suppresses the chattering of the control l aw.Finally,the performance of the controllers is compared by simulation under the condition of the same deviation.