| In recent years,robot technology has been gradually applied to various fields that need human interaction,so it is very important to ensure the safety of human-computer interaction;In addition,some researches on bionic robots also put forward higher requirements for the environmental adaptability of robots.Therefore,the research on the structure of flexible driving joint is of great significance.Its compliant characteristics are suitable for applications requiring human-computer interaction,and are very beneficial to the elasticity and cushioning of robot in bionic research.As the main module driving the motion of the robot system,the introduction of flexible driver has greater advantages than the traditional electromechanical system,increases the man-machine compatibility of the system,ensures the safety,expands the adaptability of the system and improves the robustness of the system.This paper designs the variable stiffness driving structure in the flexible driving mode,and studies the control in the scenario of elbow rehabilitation,which is also a typical application scenario of human-computer interaction.The specific work contents are as follows:（1）By comparing other flexible actuators and referring to the actual elbow rehabilitation needs,the design indexes and specifications are given.According to the principle of variable stiffness structure,the mechanical structure is designed,and the structural strength of key parts is checked to ensure that the designed mechanical structure has considerable strength while meeting the given performance indexes.（2）For the designed variable stiffness flexible mechanism,the output torque is analyzed when the system is stable,and the relationship between the output torque and the joint deformation angle and the relative angle of the surface is obtained.By calculating the gradient value of the above output torque with respect to the joint deformation angle,the output stiffness characteristics are obtained.The output characteristics are analyzed,and the torque characteristic relationship is verified by experiments.（3）Considering the actual motor and reducer,and referring to the dynamic model of traditional sea,the joint structure and actual operation are analyzed,and the dynamic model of variable stiffness flexible joint based on speed / position source is established.The established dynamic equations are built and simulated in MATLAB Simulink.（4）According to the nonlinear characteristics of the flexible link in the dynamic model and considering the influence of the human body on the joint module when using the joint module,an adaptive backstepping controller is designed for position control to eliminate the disturbance of the equivalent stiffness of the human joint at the output end;A backstepping robust controller is designed for torque control.Firstly,the backstepping control is used to track the output deformation angle（angle difference between input and output）,then the obtained output torque characteristics can be transformed into torque control,and the gravity term can be compensated.Finally,the robust control is used to reduce the influence of disturbance. |
