Design And Visual Servo Control Of Abdomen Minimally Invasive Surgery Robot's Remote Center Of Motion Mechanism

In recent years,with the rapid development of robotics,robotics has begun to be applied in the field of minimally invasive surgery.Robot-assisted minimally invasive surgery can not only improve the accuracy of surgical operations and make it possible to implement previously inoperable surgery,but also reduce the risk of surgical failure due to human factors,reduce the physical labor of doctors,and accelerate the recovery of patients.At present,there are many researches and achievements in robot-assisted abdominal minimally invasive surgery.In the minimally invasive surgical robot system,the robot needs to have functions such as clamping an endoscope,a surgical forceps,and other operators,and positioning their swing fulcrum at the surgical incision.While,the remote center of motion mechanism can perform this function very well.This article is a study of the remote center of motion mechanism under the demand above.This paper first designed the structure of the remote center of motion mechanism,which was based on the actual requirements of minimally invasive surgery in the abdominal cavity.In order to enlarge the motion space of the remote center of motion mechanism without making the space occupied by the mechanism itself too large,after consulting the configuration of the currently common remote center of motion mechanism,an arc structure was selected for improvement and a trip multiplication is realized.The effect is that this structure is more innovative than the current structure.Afterwards,using 3D modeling software to perform 3D modeling of the overall mechanism.After completing the design of the remote center of motion mechanism structure,this paper conducted kinematics and mechanics analysis.In kinematics analysis,the D-H method was used in this paper to establish the reference coordinate system for each joint of the mechanism.The D-H parameters of the joint were derived to derive the forward kinematics transformation matrix and the scope of the work space of the mechanism was simulated.Besides,calculated the inverse kinematics and used the principle of virtual work to analyze the statics of the mechanism.With respect of the remote center of motion mechanism's control method,this article used an uncalibrated visual servo method.Firstly,an overall kinematics-based visual servoing control scheme was established.Then,based on the uncertainty of uncalibrated camera parameters,an adaptive algorithm for estimating camera parameters was designed,and the stability was verified using the Lyapunov function.After the calculation of the projection transformation matrix,the calculation of the image Jacobian matrix and the design of the visual servo controller were performed.The stability of the closed-loop system was also verified using the Lyapunov function.Finally,the functional test and visual servo control of the physical prototype of the remote center of motion mechanism were carried out through experimental research,which verified the stability and practicality of the control algorithm.