Research On Multi-dOF Continuum Robot And Motion Planning Based On SMA Actuation

Shape Memory Alloy(SMA),as a new kind of intelligent material,has the functions of driving and sensing.Due to the miniaturization and light weight,it can be conducive to reduce the mass and volume of equipment and broaden the range of motion of the robot when used as the driving device.The continuum robot is highly flexible and capable of continuous bending movement in the workspace.Therefore,it is suitable for medical surgery,disaster relief and other narrow structure,many obstacles in the unstructured environment.In order to solve the problems of large structure and difficult motion control and planning of traditional continuum robot,this thesis is devoted to research the mechanical structure,motion control and motion planning system of continuum robot based on SMA shape memory characteristics.The main research contents are as follows:(1)In order to solve the problems of the large structure and coupling between joints of cable driven continuum robot.In this thesis,the constitutive characteristics,deformation characteristics,superelasticity and resistance characteristics of SMA wire were researched from the perspective of shape memory characteristics of SMA.In this thesis,the internal heating method was used to control the length and shape variables of SMA line,so as to replace the rope driving method to control.the continuum robot.(2)On the basis of SMA line research,the joint mechanism design and the receiving mechanism design of SMA driven continuum robot were carried out in this thesis.In the joint mechanism design of robot,based on the drive characteristics of SMA wire,kinematics model of constant curvature to independently of the SMA line installed in each joint,joint between independent,reduced the continuous joint structure of the robot bulky and joint coupling between phenomenon,and was conducive to continuum multi-joint robot and expand on the length.On the basis of the design of the robot joint mechanism,a storage device for the multi-joint continuum robot was designed in this thesis,which further reduces the structure volume of the robot and makes its application more extensive.(3)As the motion control of continuum robot is complex,SMA is prone to fatigue in the process of heating and loading deformation.In this paper,PD algorithm is combined to control the shape variables of SMA wire and the bending variables of joints,so as to realize the motion control of the continuum robot,and ROS is combined with the design of the control software and hardware of the robot to improve the control efficiency of the robot.Then,from the perspective of fatigue characteristics of SMA,the reliability of the robot is analyzed,and the reliability range of the robot is given,which improves the stability of the continuum robot in the application process.(4)In view of the complex of the motion planning and the obstacle avoidance,the motion planning algorithm is improved based on the motion characteristics of continuum robot in this thesis.On this basis,the motion planning of the continuum robot in Planar space was carried out,and the localization of the continuum robot was combined with monocular visual method.Finally,the continuous robot can accurately complete the motion planning task in multi-obstacle space,which has high practical significance.