The Research On Stiffness Controlling Technology Of The Flexible Surgical Robot

The flexible surgery robot with excellent dexterity ability can adapt to the complex minimally invasive surgical environment and ensure the safety of operation.At the same time,the flexible surgery robot should have sufficient stiffness to provide load capacity for the operation needs traction,cutting and so on.Under the condition that the size and driving mode of surgical instruments are limited,there is a contradiction between dexterous robot operation and load capacity.How to improve the robot's load operation ability under the premise of dexterity is the important content of this research field.This paper mainly studies from two aspects: on the one hand,the stiffness of the traditional robot body is eager to enhance by structural innovation;on the other hand,flexible robots with controllable stiffness are eager to design.The details are as follows:The design requirements of robot surgery were investigated and put forward.Investigations of flexible surgical robot configuration at home and abroad are done,In this paper,two innovative structures are put forward :a flexible robot with slotted slots and a flexible robot driven by pieces are studied in order to improve the stiffness characteristics of the robot body.The experimental platforms with a single actuation and six actuations are also built.Stiffness control mechanism based on the variable displacement power is studied,and some research about variable neutral line structure is done,the variable neutral line robot with the single freedom and two DOFs are put forward.Then its stiffness characteristics of the new configuration under external force are described.We establish the equation among joint units,design parameters,joint angle and rigidity in order to provide a theoretical basis to meet the actual needs of the flexible continuum robot.A stiffness controlling robot based on material characteristics are also researched.The paper used phase change alloy whose transformation of two phases(solid and liquid)mainly change by temperature to build a stiffness controlling robot.Based on the verification of a single segment flexible robot,we established a two section flexible stiffness controlling robot and the theoretical response time of phase transition is described by mathematical equations.Based on the experimental platform,the working space and end load tests of the slice driving robot are carried out;the bending posture test,phase change reaction time test and load capacity test of phase change alloy robot are also carried out;The slot flexible continuum robot and the variable neutral line robot are simulated by Abaqus and compared with the theoretical values.The research work of this paper is about the stiffness enhancement technology of the flexible robot,which is of great significance for the stiffness enhancement and precise control of the flexible surgical robot.