Research On Structure Design And Interactive Control Method Of Elastic Actuator Based On Variable Stiffness

In recent years,the aging of the population has become increasingly serious,and the old people are vulnerable to stroke and other diseases.To enhance the muscle vitality of patients,which needs a large number of repeated rehabilitation training actions.These factors promote the rapid development of rehabilitation robots.The rehabilitation robot can provide help for human movement,the flexibility and adaptability of are particularly important in dealing with complex external environment.Therefore,to build a rehabilitation robot system that is flexible and adaptable,which performs tasks in clinical environment.The variable stiffness elastic driver becomes an important part of the rehabilitation robot.Proving a reliable flexible driving joint.Aiming at the flexible interactive control of the rehabilitation robot,this paper takes the safe and comfortable flexible drive as the research objective,comprehensively considers the driving mechanism of human skeletal muscle system regulating muscle stiffness,designs a stable and comfortable driver structure,and establishes the driver dynamics model.Using PID cascade controller strategy,which establishes accurate trajectory tracking control of the driver.In view of the common problems existing in the research of elastic actuators,this paper focuses on the structure of actuators,human-robot interactive control and other issues,including the following research contents:(1)Aiming at the problem of flexible output of rehabilitation robot,a variable stiffness elastic driver is designed based on worm wheel-worm mechanism.Owing on the bionics theory,the properties of the human skeletal muscle system are analyzed,and the general design goal of the actuators is developed.The combination of motor and elastic element simulates the skeletal muscle system,which provides flexible driving for the joints of the rehabilitation robot.The output stiffness aided with worm wheel-worm of the driver is adjustable,which makes the variable stiffness elastic driver have self-locking function,reduces the motor load and improves the energy utilization rate.(2)The mathematical model of variable stiffness elastic actuator is established based on the analysis of variable stiffness elastic drive dynamics.The structure of the actuator is simplified reasonably according to the principle of biomechanics,which establishes the mechanism diagram of the actuator.To improve the safety of human-robot cooperation,a new algorithm is proposed,based on flexible driving.The experiment of interactive controller is completed to verify the effectiveness,which provides a theoretical basis for the hardware control system.(3)To evaluate the kinematic performance of variable stiffness elastic driver scientifically,which constructs the hardware control system of variable stiffness elastic driver.The hardware platform of variable stiffness elastic driver is designed,including power management unit,acquisition unit,control unit and drive unit.The high stiffness trajectory tracking experiments are carried out to evaluate and test the transmission performance of variable stiffness elastic driver’s flexible structure,which verifies the tracking performance and dynamic response performance of the driver.The tracking experiment of the actuator is carried out,which shows the stiffness of the actuator is continuously adjustable for the variable stiffness mechanism of the actuator.The range of stiffness adjustment is large,which lays a good foundation for the flexible joint of the robot.