Research On Force Feedback Master-slave System And Control Strategy For Lung Puncture Robot

CT guided percutaneous pulmonary puncture interventional diagnosis and treatment technology has the advantages of small trauma,high safety and good local effect.It plays an important role in the treatment of lung cancer,such as biopsy,ablation,radioactive particle implantation and so on.However,this technology has radiation hazards in the clinical process.Doctors can not perform operation according to the real-time intraoperative images in CT environment.The operation still depends on doctors' subjective experience or virtual image navigation equipment.The accuracy of puncture is low,and the movement of lesion,bleeding and pneumothorax in the process of puncture can not be found in time.It restricts the development of this technique and the quality of lung puncture operation.Therefore,it is urgent to establish a new real real-time image guided puncture robot system to achieve a comprehensive improvement of lung puncture operation under CT intervention.The aim of this study is to solve the problems of poor real-time,low puncture accuracy and difficult in lung puncture operation.A master-slave lung puncture robot system is developed,which enables doctors to perform the puncture operation through teleoperation,and then realize non radiation real-time puncture.The theme of this paper is force feedback master-slave system and control strategy of lung puncture robot.It focuses on the motion performance,bilateral control algorithm and force interaction technology of robot,and carries out relevant experiments to verify and research.The specific contents are as follows:First,by analyzing the clinical requirements of percutaneous lung puncture under the guidance of CT,combining the techniques of image,teleoperation and robot,a set of masterslave lung puncture robot system based on force feedback is developed,and the corresponding operation methods and procedures are put forward.Second,for the master-slave isomeric operating robot system,the kinematics modeling of the master manipulator is carried out,and all explicit analytic expressions of the positive and inverse kinematics solutions are obtained in order to realize the real time motion control.For the slave robot,the kinematics model of robot is constructed based on D-H parameter method and the forward and inverse kinematics of robot is analyzed.Based on Monte Carlo method,the motion space of robot is analyzed.The trajectory planning of robot joint space is analyzed by the linear interpolation method of parabola transition,and the related simulation experiment is carried out.Third,the control strategy of lung puncture robot system is studied.The different bilateral control strategies are modeled and the force-position hybrid control strategy is selected.The work space mapping of system is studied,and an incremental position control strategy is used to obtain the mapping relationship between the master and slave workspace.Master-slave workspace can be flexibly adjusted by variable proportions control strategy.The master-slave tracking error is introduced to position feedback to improve the position control accuracy and following performance of system.In addition,the task of robot is analyzed,the motion control strategy based on position and posture separation is studied,and a task oriented motion control algorithm is proposed.Fourth,the force feedback algorithm of master-slave lung puncture robot system is studied.The digital filter is designed to filter the original force value information collected by six axis force sensor.Through gravity and zero drift compensation and coordinate transformation algorithm,the real interaction between the surgical instrument and environment is obtained and fed back to master end.In addition,the position error and force feedback information in the master-slave operation process are fused and feedback to operator together,and the accuracy and security of master-slave control process are further improved.Finally,based on the analysis of master-slave control system,the experimental platform is built to verify the effectiveness of robot system and control strategy.The experimental results show that the positioning accuracy of lung puncture robot system can meet the needs of puncture surgery.The master-slave control system based on the force feedback enables doctors to operate in a far away radiation environment,protects the health of doctors and nurses,and provides better operational flexibility and sense of presence.