Research On The Testbed For The Simulated Vertical Separation On The Lunar Surface Of Spacecrafts

To simulate the vertical separation process of the ascender and the lander of Chang’e 5 detector in low gravity environment on the lunar surface,the testbed in the earth’s gravity is required,which could simulate the characteristics of the ascender and compensate the gravity.In this dissertation,the design works are finished,and the separation dynamics and the gravity compensation technology are researched.According to the functional and performance requirements of testbed,various low gravity simulated methods are compared.The suspension gravity compensation scheme is selected. To satisfy the requirements of gravity compensation during the instantaneous separation process,the gravity compensation device and truss structure are designed. Based on APDL, the finite element analysis was carried out on the truss structure,including modal analysis and statics analysis.The adjustable ascender simulators with high precision are designed,such as five round cakes and rectangular blocks-round cakes.To simulate lunar surface,the tilting table and the 2-DOF mobile platform are designed, and the characteristic of the tilting table is studied.To verify the validity of the testbed for separation experiment,separation dynamic models of 5-DOF on the ground and 6-DOF on the lunar surface are established theoretically.The motion process of two kinds of modelsaresimulated with Simulink.The virtual prototype models on the ground and on the lunar surface are built with ADAMS,which verify the results of the theoretical models.Various simulation models with different angles of tilting table are established and simuliated,in order to study the effect of tilting angle on the separation process.To simulate low gravity environment on lunar surface,the gravity compensation technology is researched.According to the the working process of the gravity compensation device,the suspension gravity compensation model is established, and the open-loop system is anlyzed.Then the feedback controller is designed with the symmetric root locus method and pole placement method, which changes the compensation system to the closed-loop control system and improve the stability and quick responsiveness.Interference immunity of system is studied,and the influence of interference is analyzed.