Design And Research Of A Variable Stiffness Actuator Based On Spring Leaf

It is well known that the competitiveness of German machinery in the world plays an important role.The implementation of industrial 4.0 strategy will promote its development in the field of machinery again.Which is associated with China-made 2025,industry 4.0 is characterized as an intelligent era."Intelligent production",one of the three major theme items,mainly involves human-computer interaction.Intelligent production is not only limited to the improvement of intelligent control,but also includes sharing the difficulty of optimizing the control system from the aspects of structural design and application.The two complement each other to realize its intelligence.In the process of production and operation,industrial robots come into contact with human beings.With the improvement of human living standards,service robots also appear in the field of vision.However,before its popularization and application,there are several important problems,that is,the safety in the process of human-computer interaction,the adaptability to the surrounding environment and the problem of energy consumption.As the main functional module of robot motion,the adjustable output stiffness of the actuator is the key to solve the above problems.The application of flexible components and compliant mechanisms has many advantages in this respect.In this paper,based on elastic spring and combined with crank-slider bistable mechanism,a variable stiffness actuator is designed from the aspects of improving the safety of human-computer interaction and reducing energy consumption,and the stiffness characteristics of the actuator are analyzed and studied.The main work is as follows:(1)Aiming at the problems of human-computer interaction security,unknown environmental adaptability and energy consumption caused by the lack of flexibility of traditional rigid actuators,variable stiffness actuators are introduced,which can solve the above problems.And its concept is briefly described.Based on the realization principle of variable stiffness,the existing variable stiffness actuators at home and abroad are studied.However,there are still some problems such as small stiffness range,complex structure,difficult control and large energy consumption in the existing variable stiffness actuators.(2)The design indexes and requirements of the variable stiffness actuator designed in this paper are determined.Based on the elastic leaf combined with the crank-slider bistable mechanism,the preliminary scheme to realize the variable stiffness of the actuator is determined,and then the mathematical model of the actuator is established.The stiffness characteristics of the actuator are analyzed theoretically,and the size parameters of each module are optimized,thus the structural design of the actuator is improved.(3)The dynamic model of the actuator is established and the torque and position tracking characteristics are analyzed by visual block diagram simulation in Simulink.A simple prototype of the variable stiffness module of the actuator was fabricated,and a series of tests such as static load stiffness experiment,position step test,ball hitting experiment and safe collision test were carried out.The results of static load stiffness test verify that the actuator can achieve the variable stiffness characteristics,but there is a certain error with the theoretical analysis results.The position step test results verify that the actuator has certain compliance characteristics.The results of batting test show that the variable stiffness actuator has good energy storage characteristics.The results of safety collision test show that the automatic stiffness conversion can be realized efficiently and conveniently in the event of accidental collision,which indicates that it has certain safety when it works.The design of the variable stiffness actuator can meet the initial design requirements.