Research On Human-robot Collaborative Interaction Method For Joint Replacement Surgery Robot

According to statistics,the volume and difficulty of joint replacement surgery are increasing in various countries around the world.In order to improve the surgical effect of joint replacement surgery,joint replacement surgery robots have been introduced into the surgery to assist doctors in operation,and have become the hot spot of the current research in robotics and medical fields.However,the safety of the surgical robot and the flexibility of human-robot interaction also added a lot of mental stress to the doctor.At the same time,it is impossible to avoid the influence of the doctor's misoperation on the surgical effect.Based on this,this paper uses a human-robot interaction method in the process of joint replacement surgery robot-assisted doctor operation,and combines fuzzy control theory and virtual fixture technology to improve the safety and flexibility of the surgery at different surgical stages,and simultaneously performs a human-robot interaction robot bone grinding experiments to verify the effectiveness of the method.The main research contents of this paper include:First,based on the second type of Lagrangian dynamics modeling method,the inverse dynamics model of the six-degree-of-freedom manipulator used in the experimental platform of this paper is established.The parameters in the dynamic model are determined and the dynamic model of the robot is provided for the human-robot collaborative interaction control.On this basis,the impedance control method based on position is proposed to realize human-robot collaborative interaction.Considering the need of doctors dragging robots from outside the surgical area to inside the surgical area before joint replacement surgery,a human-robot collaborative interaction method for surgical robots based on fuzzy model reference learning control was proposed.This method takes characteristics of human arm natural movement as a reference model for fuzzy learning control,and trains the fuzzy admittance controller's variable damping coefficient adjustment parameter rules by an offline learning mechanism to realize variable admittance control,and with the doctor's dragging force on the robot and the speed of the robot as input,the desired speed of the robot is used as the output to construct a variable admittance control method based on variable damping parameter adjustment.The offline training experimental results show that after 10 offline trainings,under the drag speed of 250mm/s,the maximum error of the man-machine cooperation trajectory is less than 17mm/s,and the maximum error of the human-machine cooperation velocity curve is less than 15mm.It is verified by experiments that the method can better match the operation process of doctor operation,and its flexibility meet the requirements for rapid movement of medical surgical robots.Thirdly,aiming at the process of the doctor dragging the joint replacement surgical robot into the critical area of the operation,considering the safety of the dragging process,a virtual fixture control method based on the kinematic model of the human arm is proposed.This method constructs a human arm kinematics model through experiments,and uses this as a guide line to construct a guided virtual fixture.Experiment results show that the constructed guided virtual fixtures with the trajectory of the human arm model as the central axis,with radius 30mm,and restrict area 5mm can effectively limit the robot motion to a certain range.Simultaneously,the output speed of the robot in tangent direction of the central axis can well follow the change of the force applied by the doctor,and the output speed in the normal direction of the central axis can converge to zero stably at the pipeline boundary.Consequently,the purpose of improving the safety and flexibility of the surgical robot before surgical operation is realized.Finally,Based on the technology of virtual fixtures,a bone-grinding experiment of a human-robot collaborative robot is carried out in this paper for the process of drag operation in the critical area of the surgery assisted by the robot.A three-dimensional model of the human knee is created from the CT image data of the right lower limb of the human body,and the cut surface of the knee is constructed using the reconstructed three-dimensional model of the knee prosthesis and the biomechanical axis theory of the human lower limb for the accuracy.The robot-assisted doctor's bone grinding experiments show that the virtual fixture can well limit the robot's movement so that it cannot exceed the grinding area for ensuring the safety of the bone grinding process.