Design And Analysis Of An MRI-guided Robot Based On Cable-driven

A novel surgical robot with six degrees of freedom for needle insertion isdesigned to meet the need of surgery under MR environment. The mechanism consistsof four layers, namely the2-DOF parallel module, the vertical height coarseadjustment module, the2-DOF rotating head module and the insertion module. Anovel self-guided cable-driven is developed, which makes the robot lighter and morecompact to better fulfill the requirement of limited space and MR-compatibility.The matrix method and vector method are adopted to analyze the forward andinverse displacement, and the workspace. Jacobian matrix is deduced in velocitymapping model, then the configuration singularities are analyzed. A set ofconditioning indexes based on the Jacobian matrix are proposed for kinematicdimensional synthesis. Optimized dimensional parameters are obtained subject todimensional constrain and transmission angle constrain, to achieve a good kinematicand transmission performance throughout the entire task workspace.Error model of the novel cable-driven is established in the case of three differentkinds of layout. The theoretical error rule and influencing factors are deduced.Experimental platform is designed and processed to verify the novel cable-driven, sodoes the control system, in which the PMAC motion control card, the ultrasonicmotor and the optical encoder are adopted. The experimental results qualitativelyshow that the novel cable-driven meets the transmission requirements in the main, butit’s affected by the elasticity of the transmission wire, the less the elasticity, the betterthe transmission performance. At last the indexes such as the delay time, the velocityerror and the velocity fluctuation are proposed to analyze and evaluate thetransmission performance quantitatively.The novel cable-driven developed in the research is self-guided, which is suitablein the MRI-guided robot and other complex mechanism. It has important theoreticalsignificance and practical value for both the surgical robot and the transmission wayin MR environment.