Motion Space Analysis And Trajectory Planning Of The End-effector Of Urinary Minimally Invasive Surgery Robot

With the robot technology is widely used in medical field,minimally invasive surgery robot has gradually become the hot topic of research in recent years.Compared with the traditional minimally invasive surgery,the intervention of the robotic system improves the precision,flexibility and stability of the whole operation process.The robot system not only saves the doctor's physical strength,but also reduces the pain of the surgery for patients.Although the research of all kinds of minimally invasive surgical robots has made a lot of achievements,but there are very few robots specially used in urinary minimally invasive surgery.Traditional urinary minimally invasive surgery are performed independently by the doctors with medical instruments for a long period of time,doctor's physical exertion is large and there are certain operating errors,which may cause secondary injury to the patients and increase the risk of surgery.In order to solve this situation,this paper proposes a new design scheme of urological minimally invasive surgery robot,which combined mechanical arm and the traditional ureteroscope.In order to make the robot complete all kinds of surgical actions in a limited workspace and meet the requirements of practical operation,the motion space of robot end-effector is analyzed and researched.At the same time,different methods are used to plan the trajectory of robot end-effector,and the optimal trajectory planning method is selected to meet the requirements.The main contents of the research are as following:(1)According to the requirements of urinary minimally invasive surgery,a six-dof urinary minimally invasive surgery robot configuration is proposed.The forward and inverse kinematic problems are solved and the correctness of the solution is verified by several groups of joint variables randomly selected.It is convenient to select random points in motion space analysis and to solve the joint variables corresponding to each point in the motion trajectory.(2)Based on forward kinematics analysis,Monte Carlo method is used to realize the simulation analysis of the motion space and limited working space of urinary minimally invasive surgery robot in MATLAB,and the rationality of the robot configuration design is verified.The Jacobian matrix of the urinary minimally invasive surgery robot areestablished,mapping relationship between joint spatial velocity and operating spatial velocity is described.The dynamic equation is constructed,which provides a reference basis for the study of the motion relationship between robot and joint.(3)In order to select the optimal trajectory planning method which can meet the practical operation requirements of urinary minimally invasive surgery,different interpolation methods are used in Joint space and Cartesian space respectively to plan the whole motion trajectory of urinary minimally invasive surgery robot,and compared the advantages and disadvantages of each method.The method of quintic polynomial interpolation is used to plan the trajectory of the end-effector of the urinary minimally invasive robot.(4)The virtual prototype model is established by MATLAB software.and the motion trajectory of the robot was simulated by using different functions.The trajectory simulation of the end-effector planning of urinary minimally invasive robot is carried out by using cubic or quintic polynomial difference method and linear interpolation method.The trajectory curves of the angles,angular velocities and angular accelerations of the six joints of the urinary minimally invasive surgery robot are obtained.By analyzing and comparing the simulation results,it is more intuitive to verify that the trajectory planning by the quintic polynomial interpolation method can meet the requirements of stationarity and safety in the operation.