Analysis And Design Of A Remote Motion Center Mechanism With One Rotation And One Movement Degree Of Freedom

The concept of minimally invasive surgery is increasingly recognized and valued by doctors and patients,and has become a major trend in the development of surgical procedures.Because it has many advantages compared to traditional open surgery,such as reducing postoperative pain,reducing postoperative recovery time,and reducing infection.However,due to the operating principle of minimally invasive surgery,doctors may encounter some operational problems during the surgical process,such as high difficulty in operating surgical instruments,difficulty in coordinating hands and eyes,and inability to fully see the patient’s internal organs and tissues.To overcome the above difficulties,surgical assistive devices can be used to solve these problems.The surgical auxiliary equipment mainly uses the remote motion center mechanism(RCM)to clamp the surgical instrument,and the degree of freedom characteristics required for operating the surgical tool in the MIS process are consistent with the degree of freedom characteristics of the RCM mechanism,so the RCM mechanism can assume the function of clamping the surgical tool in the MIS process.In this paper,two kinds of planar 1R1T-RCM mechanisms based on parallelogram structure are selected as the research objects,and the kinematics and dynamics analysis,performance analysis and scale optimization of the mechanisms are completed.Firstly,based on the parallelogram structure,some 1R1T-RCM mechanisms with in-plane rotation and movement were designed,and two of them were selected for subsequent analysis.The degrees of freedom of the two configurations were analyzed through the spiral theory,indicating that the two configurations can meet the requirements of degrees of freedom required for minimally invasive surgery.Secondly,the kinematics analysis of the two configurations is carried out,and the forward and inverse position solutions of the two configurations are obtained by position analysis.Perform velocity analysis based on the derivative of the position forward solution analytical formula.Using the Jacobian matrix obtained from velocity analysis,analyze the singularity of the two configurations.By using numerical search methods to obtain two configurations of workspace,it is demonstrated that the workspace can meet the needs of minimally invasive surgery.By establishing a continuous contact model with two configurations,a comprehensive model of motion error is obtained.Once again,kinetic analysis was conducted using the Lagrange equation method,and a two configuration kinetic model was established.The simulation using ADAMS software can demonstrate the correctness of the two configuration dynamic models.Afterwards,performance analysis was conducted on the two configurations,including motion/force transfer performance,dexterity,and motion accuracy,to obtain the distribution of various indicators in the target workspace.Using graph method and particle swarm optimization algorithm,based on global transmission performance indicators,global dexterity indicators,and global motion accuracy indicators,two configuration scale optimizations were completed.Based on the optimization results,a dual parallelogram 1R1T-RCM mechanism was selected to complete the prototype design.Finally,a principle prototype of the dual parallelogram 1R1T-RCM mechanism was designed and constructed.This includes the design of the mechanical and electrical parts of the prototype.Through experiments,it has been proven that the prototype can complete work tasks and its accuracy meets the usage standards.