Research On Continuum Robot For Minimally Invasive Surgery

Traditional interventional operation sends long endoscopes and ducts to the lesion and carry out the necessary diagnosis and treatment,under the guidance of the medical imaging equipment and natural orifice.During the operation,the doctor needs to wear heavy lead clothes.It is extremely inconvenient for doctor and the health may be injured.Robot-assisted intervention operation can greatly reduce the intensity of doctor's work,simplify the surgical procedure,improve the accuracy and avoid the harm of X-ray to the doctor.However,the traditional interventional catheter can only be flexed passively along the direction of the guide wire,which is easy to cause damage to the blood vessels of the human.In view of these shortcomings of the interventional catheter,a minimally invasive surgical robot capable of active bending and twisting is developed,which adopts the multi-segment continuum configuration,cablepulley system.At the same time,in consideration of the nonlinearity friction,the cable-pulley system transmission characteristics is studied to establish the relationship between friction and wrap angle,and relationship between friction and contact characteristics of the material is also analyzed.During the transmission process,the input and output forces on the cable are measured by tension sensors.The friction of system is tested by changing the wrap angle,and the accuracy of the transmission model is analyzed.The trajectory of the robot in the vessel is studied according to the mission of the preoperative planning for cardiovascular interventional surgery.The 3-D voxel model is introduced and skeleton is extracted by parallel topological thinning algorithm.Then,an extraction algorithm based on the inner vessel wall is proposed and the discrete skeleton curve is found.The skeleton is extracted for the enlargement glass model and fitted to generate the trajectory of robot for semi-autonomous intervention experiments.According to simulation and analysis of the continuum robot structure,the mapping relationships are discussed between the driving space,the operating space and the joint space.After the dynamic of robot derived,and the sliding mode controller is designed by using the computational torque method.Then,the simulation is carried out to analyze its trajectory tracking effect.The master-slave control strategy is proposed.Then,two control models which include joint control and position control are designed.The system for minimally invasive surgery robot prototype is designed by distributed control system,the hardware part is introduced,and semi-autonomous motion software with 3D navigation is programmed.The robot with 4-DOF is tested to verify the kinematics.At the same time,the master hand is used to achieve invasive interventional operation,and simulate the catheterization.Finally,two kinds of control methods are compared to verify the accuracy of extracted vascular skeleton.