The Research On Soft Continuum Manipulator Based On Thin McKibben Pneumatic Artificial Muscle

With the development of technology,the robots have been applied in a wide of the fields.As an important branch of the robots,manipulators play an important role in human work and life.Among them,continuum manipulators have attracted extensive attention of researchers due to its own compliance,adaptability and flexibility in recent years.This type of manipulator is inspired by natural biological soft tissues such as snakes,elephant trunks and octopus tentacles.This kind of biological tissue has no specific skeleton structure,but it has flexible movable ability and excellent operation ability.It can work in unstructured environment and adapt to the shape and size of the target,and has a broad research prospects.In this study,a multi-joint continuum manipulator based on thin Mc Kibben pneumatic artificial muscle is developed,which has the characteristics of light,good compliance and strong robustness.Firstly,to overcome the limitations of the existing pneumatic muscles,a new type of Mc Kibben pneumatic actuators with diameter of 2.0mm is fabricated,and its mechanical properties including contraction force and contraction rate are tested by the experiments.Based on the principle of the anatomical and physiological structure of octopus tentacles and other soft organisms,a new type of continuum manipulator configuration is designed.The manipulator is 372 mm in length and consists of five flanges with a thickness of 5 mm and two double-layer module flanges,which the double-layer module can integrate the connected joints.The light flange connection structure is designed and manufactured by 3D printing technology,and a prototype is assembled by combining Mc Kibben actuator and spring.The mass of the prototype is less than 0.35 kg,which is much lighter than the traditional rigid manipulator with the same size.Then,based on the basic theory of kinematics,the kinematics model of the manipulator is established by D-H method and geometric analysis method.The mathematical mapping relationship between input pressure of the pneumatic muscle and the end position of the manipulator is established.The working space and posture space of the manipulator are simulated and analyzed.In addition,the inverse kinematics model of the continuum manipulator is established,and the air pressure value of the pneumatic artificial muscle in the driving space can be solved by the coordinate value of the end position of the soft manipulator in Cartesian space.Finally,the experimental platform was established,and the manipulator performance and model validity were verified.The experimental results showed that the manipulator developed in this study can realize complex three-dimensional motions such as stretching,bending and torsion,and the maximum error of the model is less than 7 mm.The compliance impact test results demonstrated that the continuum manipulator has good compliance and robustness.After being hit,the manipulator can rely on its own compliance to avoid damage caused by external impact,and recover to its original position after the impact is removed,with a maximum recovery error of 5.08 mm.Moreover,the application example of the continuum manipulator indicated that the continuum manipulator can be used in industrial application,medical treatment,military detection,emergency rescue and disaster relief and etc.