Research On A 4-SPS/S Parallel Mechanism Driven By Group Of Four Pneumatic Muscles

Pneumatic muscle is a new type of flexible pneumatic actuator with the same output characteristics as human muscle,and is designed according to motion principle of human muscle.It has not only the advantages of cleanliness,lightweight,cheapness and easy maintenance possessed by pneumatic actuators,but also the special feature of higher power/weight ratio and power/volume ratio as well as good compliance owing to its forcelength characteristics similar to human muscle when compared with the pneumatic cylinder.The parallel manipulator has the characteristics of high loading capability,no accumulative errors,high accuracy and fast response.The parallel manipulator driven by pneumatic muscles proposed in this dissertation is a new application of pneumatic muscle,which consists of group of four pneumatic muscles connecting the moving platform to its base platform.Multiple degrees-of-freedom(DOF)rotation motion of the parallel manipulator can be realized by using cheap pneumatic proportional valves to regulate the pressure inside each pneumatic muscle.Integrating the advantages of both pneumatic muscle and lower-mobility parallel mechanisms,such a test rig has the characteristics of compact structure,easy assembly,cheapness,smooth movement,good natural compliance and safety operation,higher power/weight ratio and power/volume ratio,which will have promising wide applications in robotics,industrial automation,and bionic devices.The main research content of this paper includes five chapters.They are as follows.In chapter 1,the origin of the task,the actuality of research,the research and development on parallel mechanism driven by pneumatic muscles in or out of our country are stated.In chapter 2,based on Stewart platform,according to the configuration evolution method a4-SPS/S parallel mechanism driven by group of four pneumatic artificial muscles is built by adding constrain branch.The DOF of the 4-SPS/S parallel mechanism built are analyzed according to theory of constraint screw.The posture of the moving platform is achieved in type of Z-Y-X Euler Angle.And the dominant type of inverse solution is obtained.Based on the BP neural network algorithm,the forward solution of the parallel mechanism is obtained.And verification shows that error completely meet the requirements.In chapter 3,the test rig of the 4-SPS/S parallel mechanism driven by group of pneumatic artificial muscles is built.The max angle of ordinary spherical pair is too small to meet the requirement of test rig.Therefore a novel connector for pneumatic artificial muscle is designed.Current sensor is difficult to measure the posture of the moving platform.The measurement mechanism constitute of three displacement sensors is designed.And the principle of the measurement mechanism is explained.In chapter 4,the mathematical model of the moving platform position control system is obtained and simulation is carried out by Simulink.The results show that the moving platform of the mechanism can realize three rotational DOFs.In chapter 5,the model of the work space of the 4-SPS/S parallel mechanism is obtained and the work space is obtained through MATLAB.The influences of the max angles of spherical pairs on work space are analyzed,which shows the advantages of the new connector for pneumatic artificial muscles.And the relation between the four inputs and three outputs is analyzed and finally determined in the work space.