Mechanism Of Minimally Invasive Surgery Device With Cable Transmission

With the development of science and technology, the minimally invasive surgery(MIS) has been steadily progressing. The MIS equipment can assist surgeons inmicrosurgery and have become a research focus. The mechanical structure and drivenmode of the surgical equipment will directly impact its applicability, flexibility,operability, accurate controllability, and the surgical result. In the dissertation,conceptual and detail design are proposed for novel laparoscopic surgical equipment.The mechanical structure and driven mode of the active manipulator of a novelsurgical robot and the manual instrument are theoretically analyzed using screwtheory. Structures parameter optimization is also performed. The simulated andexperimental verifications of the analysis results and the design scheme are presented.A method combining screw theory and motion decomposition is used todetermine the position of fixed point and Jacobian matrix for the active manipulator ofthe novel MIS robot system ‘MicroHand A’. The method simplifies kinematic analysisand the parameters used are clearer in meaning than those in conventional methods.The Jacobian matrix is more exact than that directly obtained by screw theory.A hybrid-driven system that consists of cables and rigid link is used to design themulti-degree of freedom manual instrument, which is named ‘Easy Grasp’. Thestructure of the instrument is simple. Isomorphic mechanism configurations andparallelogram frame are applied to achieve intuitive control. Characteristics of theparameters of the Euler angles (EA) and the matrix exponential (ME) are studiedusing screw theory and the theory of differentiable manifolds. Cable layout andstructure parameters are optimized using Global Condition Index (GCI).For cable-driven system, the vertical cables are mathematically modelled from ageometric point of view. The cable structure and tension on the calbe are analyzedaccording to the characteristics of screw twist. The structural equations of the cablesin different positions are derived for both non-bent cable and bent cable, respectively.The formulas of tension, cable curvature and torsion are obtained.The tension on the cable is analyzed for the bent part. The slot size of the guidepulley of transmission system is determined for the calbe transmission system in theinstrument of ‘MicroHand A’. Meanwile, formulas that represent the relationship between diameter and the spacing of the mutually perpendicular guide pulleys inlimited space are also derived. The theoretical analysis and the mechanism design areverified by the simulation and experiments.