The Traject Control Of Flexible Joint Space Manipulator With The Influence Of Gravity

With the rapid development of space technology and the deepening of space exploration,the research of space manipulator has been paid more and more attention.Space manipulator can replace astronauts to carry out a series of dangerous and complex space missions.It has become an important research tool for human to further explore space.Now it is necessary to simulate the space gravity environment on the ground to study the motion behavior of space manipulator and other space mechanisms.But for the current science and technology,such as water tank,suspension,air flotation and other space microgravity simulation methods can not completely eliminate the influence of gravity.Due to the obvious difference between the ground and space gravity environment,the change of gravity leads to the change of the space manipulator model,which affects the control accuracy of the whole system.Therefore,how to ensure that the space manipulator installed on the ground can still meet the desired control requirements after launching into space is a key problem for future research.In addition,there is joint flexibility in the space manipulator system model,which brings high-order harmonic vibration to the system,thus affecting the trajectory tracking accuracy and stability of the manipulator system.Therefore,for the trajectory tracking control problem of space manipulator,this paper mainly considers the change of gravity and joint flexibility to design a high-precision trajectory tracking controller to achieve the control purpose.The main contents of this paper are as follows:Firstly,the kinematic and dynamic models of the flexible joint space manipulator in different gravity environments are established.The influence of gravity change and joint flexibility on the system dynamic model is analyzed.According to the characteristics of the model change,the PD controller based on singular perturbation is designed for control research,and the control effect is analyzed through the simulation results,which provides a reference for the subsequent design of high-precision trajectory tracking control.Then,considering the influence of gravity and joint flexibility on the system,an adaptive iterative learning controller based on singular perturbation is designed for the flexible joint space manipulator fixed on the base.The stability of the control system is verified by Lyapunov method and the simulation is carried out.The simulation results are compared with the control results of PD controller based on singular perturbation,and the effectiveness of the controller is verified.Finally,for the free floating flexible joint space manipulator,considering the influence of gravity change and joint flexibility from the ground to space,a neural network adaptive backstepping controller is designed to study the trajectory tracking control.The stability of the system controlled by the controller is analyzed.The simulation results are compared with PD controller based on singular perturbation and ADRC,and the effectiveness of the design method is verified.