Research On Structure And Motion Characteristics Of Soft Crawling Robot Driven By SMA

Mollusks with infinite degrees of freedom and continuous deformation ability can arbitrarily change their shape and size in a wide range,and show strong adaptability in nature.The soft robot developed with soft organism as bionic object,through the combination of its own active deformation and passive deformation,breaks through the functional limitations caused by the structural constraints of traditional robots,and has the advantages of strong environmental adaptability and high safety of human-computer interaction,showing great application potential in the fields of exploration,medical treatment and so on.It has become a hot research direction in the field of robotics.With the continuous development of intelligent materials,soft robots driven by intelligent materials similar to soft biological muscles have the advantages of simple structure,more natural and more stable movement,and gradually become the development trend of soft robots in the future.In this paper,based on the analysis of the motion mechanism of Inchworm and the research of the application performance of shape memory alloy(SMA)intelligent material,a soft crawling robot driven by SMA spring is designed and manufactured.The theoretical and Experimental Research on the motion characteristics of the robot is carried out,and the crawling performance of the robot under different "feet" under different contact surfaces is analyzed,Thus,the optimal gait of the soft robot can be achieved through the "feet" structure optimization.The main contents of this paper are as follows:(1)Deformation mechanism modeling and experiment of SMA intelligent actuator.The basic characteristics and deformation mechanism of SMA smart material are studied.The driving model of SMA spring is established.The nonlinear relationship between deformation and load of SMA spring is described and verified by experiments.Furthermore,based on the experimental study of the driving performance of SMA spring actuator,the heating and cooling models of SMA spring actuator under electric heating are established,which provides data support for the kinematic analysis of the soft crawling robot.(2)Structure design and deformation motion analysis of bionic inchworm soft crawling robot.Based on the analysis of the motion characteristics and body structure of the inchworm,a bionic soft crawling robot driven by SMA spring is designed.By using the friction difference between the front and rear "feet" of the robot and the crawling surface,the step motion of the inchworm like robot is realized.The flexible hinge structure is further introduced into the elastic body structure to ensure that the "foot" and the contact surface always keep the surface contact state in the crawling process of the soft robot,which increases the stability of crawling and provides the feasibility for realizing variable friction.Furthermore,based on the bending theory of elastic beam,the deformation principle of the designed soft crawling robot is studied,the motion model of the soft crawling robot driven by SMA spring is established,and the influence of the change of front and back friction on the motion characteristics of the robot is analyzed.(3)Experimental study on motion characteristics of soft crawling robot.The soft body and feet with different structures of the crawling robot were prepared by soft rubber replica technology and 3D printing technology.The experimental platform of the crawling robot was built.The motion characteristics of the soft robot under different moving surfaces,different foot structures and different friction were studied.The experimental results show that the optimization of the motion characteristics of the soft crawling robot under different surfaces can be effectively realized by the design of variable positive pressure and variable "feet".