新型线驱动式微创手术器械结构设计与运动学分析

Structural design and kinematics analysis of new cable-driven minimally invasive surgical instrument

在微创手术机器人系统中,传统线驱动式手术器械的偏摆关节与夹持器的转动关节之间存在运动耦合,这会对手术器械的运动精度产生不良影响。为此,提出了一种新型的四自由度线驱动式手术器械,其偏摆关节采用行星齿轮式结构,以实现偏摆关节与夹持器之间的运动解耦。首先,对传统线驱动式手术器械的关节运动耦合问题进行了分析。然后,设计了行星齿轮式转动的偏摆关节,并通过几何理论分析证明了其具有极低的关节耦合性,且钢丝绳在运动过程中的受迫形变量极小;同时,通过标准D-H参数法建立了新型手术器械的正运动学模型,并利用解析法求得了其逆运动学的封闭解。最后,分别使用MATLAB软件的Robotics Toolbox和Simulink环境中搭建的仿真模型对手术器械的正、逆运动学模型的准确性进行了验证,并采用蒙特卡罗法分析了其工作空间。仿真结果表明,所提出的手术器械的结构设计可靠,关节之间的运动耦合性较低,其工作空间能够满足微创外科手术的要求。研究结果可为柔性线驱动式手术器械的结构设计与运动学分析提供参考。

In the minimally invasive surgical robot system,there is a kinematic coupling between the yaw joint and the rotating joint of the gripper for the traditional cable-driven surgical instrument,which has an adverse effect on the kinematic accuracy of the surgical instrument.For this reason,a new fourdegree-of-freedom cable-driven surgical instrument was proposed.The yaw joint adopted a planetary gear structure,which could achieve kinematic decoupling between the yaw joint and the gripper.Firstly,the kinematic coupling problem of joints in the traditional cable-driven surgical instrument was analyzed.Then,a jaw joint of planetary gear rotation was designed,and the geometric analysis proved that it had very low joint coupling and the forced deformation of the steel cable was very small during the motion.At the same time,the forward kinematics model of the new surgical instrument was constructed by using the standard D-H parameter method,and the closed-form solution of its inverse kinematics was obtained by the analytical method.Finally,the accuracy of the forward and inverse kinematics models was verified by using the Robotics Toolbox and the simulation model built in the Simulink environment of MATLAB software,and the workspace of the surgical instrument was analyzed by using the Monte Carlo method.The simulation results showed that the structure design of the proposed surgical instrument was reliable,the kinematic coupling between the joints was low,and its workspace could meet the requirements of minimally invasive surgery.The research results can provide reference for the structural design and kinematics analysis of flexible cable-driven surgical instruments.