Modeling And Control Of Three Degree Of Freedom Medical Assistant Robot

With the development of robotics and medical science,medical assistant robots have been widely used.Medical assistant robot has the advantages of less pain,smaller incision,more delicate,less time in hospital and faster recovery.But there are uncertainties in operation,In order to improve uncertainties,it is of great significance and practical value to study the control of medical assistant robot.In this thesis,a three-degree-of-freedom medical-assistance robot is modeled and analyzed for its various basic motions during surgery,and a trajectory tracking control method and terminal link hardware system are designed.Firstly,a kinematics of the medical-aid robot is analyzed,the forward kinematics analytical solution of the robot is solved by D-H method,and the inverse kinematics analytical solution of the robot is solved by algebraic method.Stance arm joint angle at the end of the robot is given and the conversion relationship between the homogeneous transformation matrix expression is obtained by cartesian coordinates and spherical coordinates conversion tool posture at the end of the relational expression,with the established kinematic model,simulation by Matlab robot toolbox,built by kinematics is proved to be correct.When the dynamic characteristics of the three-degree-of-freedom medical-assisted robot need to be considered in percutaneous needle surgery,a dynamic model of the three-degree-of-freedom robot is established by the Lagrange method in this thesis.Secondly,based on the dynamic model of the three-degree-of-freedom robot,in view of the parameter uncertainties and external interference of the system,a robust control strategy is adopted to complete the controller design,and the stability of the system is proved by the stability principle of Lyapunov.By using Matlab simulation toolbox,the trajectory tracking robust control simulation researches are carried out,and the tracking trajectory curve and tracking error curve of each joint are obtained.Simulation results show that the proposed algorithm has good tracking accuracy and dynamic performance.Finally,a terminal subsystem of the motion control hardware system of the medical robot is designed.STM32 series is adopted as the embedded core controller to complete the design of the drive circuit,rectifier circuit,CAN bus,position detection and other related circuits.Thedesign results meet the requirements of positioning accuracy.