Research On Design And Control Of The Humanoid Variable Stiffness Joint Based On Cylinder

The traditional robot has the characteristics of high stiffness,high motion precision and large bearing capacity.Because of the high rigidity of the traditional robot,the application of the robot in the field of service and rehabilitation is restricted.In order to improve the application of the robot in human life,it is necessary for modern robot which can change its stiffness in different environment,to solve the problem of single rigidity of traditional robot.In this paper,we will develop a new humanoid robot arm combining with the technology of mechanical-electronics,control technique,pneumatic technology and biological technology.This arm is not only looked like the shape of the arm,but also can flexibly change the stiffness of the arm.This paper will study this variable stiffness pneumatic joints.In addition,the control means of the variable stiffness joints is studied to improve the adaptability of the robot to the different environment and make the performance of the variable stiffness joints more stable.Raising the variable stiffness manipulator,which has the advantages of safety and reliability,simple structure,easy to control and wide range of stiffness variation,is more widely used.In this paper,the mechanical joints not only can be installed on the manipulator or claw directly,but also can be directly installed on the shoulder joint,with a high imitation of human nature.The main contents of this paper are as follows:(1)Firstly,in this paper,the development of variable stiffness manipulator joints at home and abroad is studied,and the advantages and disadvantages of existing research results are comprehensively analyzed,and the control methods of variable stiffness arm joints are also analyzed and studied at home and abroad.(2)The main mechanisms of changing stiffness are summarized:changing stiffness with mechanical elastic parts and changing stiffness with flexible actuator,and the control method of variable stiffness is studied.Finally,flexible drive is adopted to reach the variable stiffness characteristics of mechanical joints.(3)According to the datum,the design parameters of the pneumatic variable stiffness humanoid manipulator are listed,and the structural design and optimization of the joint are carried out.The main contents include the optimization of the structural layout,the power transfer mode,the dimension and shape,etc.At the same time,the key parts of the strength check.The manipulator model is assembled.(4)The kinematics simulation of the humanoid manipulator with variable stiffness is carried out by using the simulation software,the mathematical model of the structure is established and the variable stiffness simulation is carried out by using MATLAB to verify the variable stiffness characteristic of the humanoid manipulator.(5)The pneumatic circuit and electric control system are designed and the experimental platform is built for the experimental prototype.the motion test and the variable stiffness test are carried out and compared with the simulation results.Finally,we verified the PID control method is fit for this experiment.