| With the development of space technology,the requirements of lightweight in the aerospace industry continue to increase,the technology of space robot on-orbit assembly technology has been extensively researched and applied.The space robot has the characteristics of light weight,low rigidity,and strong dynamic coupling,it is easy to induce the vibration of flexible parts during work,cause it cannot be positioned quickly and accurately.This thesis researched on the dynamic modeling and control of the space on-orbit assembly robot with double flexible joints and arms(SRDF).The relationship between the vibration of flexible parts and the motion of space robot is analyzed,and the control methods that can be used to improve the motion control accuracy of space robot while suppress the vibration of flexible parts are explored and verified.The main research contents are as follows:1.Considering the deflection angle caused by the vibration of the flexible arm,the dynamic modeling and analysis of SRDF is carried out.The modeling method of the flexible arm which based on the hypothetical mode method and the modeling method of the flexible joint are presented.And the influence of the modal truncation order on the dynamic characteristics of the flexible arm is analyzed.Then,based on the second type of Lagrange equation,the dynamics model of SRDF is derived,and its dynamics characteristics is analyzed.2.Aiming at the underactuated problem of the flexible arm,the dynamic control of SRDF is researched based on the singular perturbation method.Combined with the flexible compensator,the singular perturbation method is used to decompose the system of SRDF to the fast and slow subsystems,and proposed to use the LQR controller and the computed torque controller to control the fast subsystem and the slow subsystem respectively.This control strategy ensures SRDF can track the target trajectory quickly and stably,and restrain the vibration of flexible parts at the same time.Simulation results confirm that the combined controller can accurately track the target trajectory while suppressing the vibration of flexible parts.3.In order to solve the problem of poor control accuracy caused by uncertain external disturbance,the dual-loop integral sliding mode control is used for the controller design of SRDF.Based on the Coulomb friction model,the uncertain disturbance in on-orbit work is analyzed,and an uncertain external disturbance model is proposed.Then,the controller is designed using double-loop integral sliding mode control on the slow subsystem.Simulation results confirms that the controller can effectively overcome uncertain interference and has great control performance.4.Based on the virtual prototype technology,the dynamic model and control strategies of SRDF are verified.The virtual physical prototype of SRDF was established using Solidworks and Adams software,and the Co-simulation platform was built with Matlab/Simulink.On this basis,the differences between simulation results and theoretical simulations in various situations are analyzed.Simulation results confirms the effectiveness of the dynamic model and control strategies. |
