Design Methodology Of The Tendon-driven Configuration For Minimally Invasive Surgical Robotic Instruments

In robotic minimally invasive surgery, the multi-DoF (Degree of Freedom)surgical instrument is the only part that contacts tissues of the patient, and does theoperation. The design of the instrument not only determines the overall performanceof the surgical robot, but also has a great impact on the development of other parts inthe robot. The tendon-driven configuration is an effective driving method forminimally invasive surgical instruments. However, it brings in theoretical problems inmany aspects, such as kinematical analysis, force sensing, and stiffness. This paperstudies the key technologies and design methodologies of tendon-drivenconfigurations for minimally invasive surgical robotic instruments. The main work ofthis paper includes:1. Design methodologies of tendon-driven surgical instruments. Design targets ofinstruments are studied first according to the characteristics of abdominal surgery andmovement of minimally invasive surgical robots. Several configurations oftendon-driven surgical instruments are designed based on analysis of presenttendon-driven configurations. According to design requirements of a series of surgicalinstruments, design methodologies of ‘pull-pull’ endless tendon-driven systems areobtained.2. Expanding kinematic theories of tendon-driven surgical robots andinstruments. The kinematic theories of coupled tendon-driven configurations arecalculated and obtained based on product-of-exponentials. Meanwhile, to elaboratethe analysis methods, calculation rules and processes of the established theories,kinematic analysis of ‘MicroHand A’ minimally invasive surgical robot is presented.The rigidity and feasibility of the kinematic analysis method are verified usingtheoretical calculations and experiments.3. Studying force sensing of instruments for minimally invasive surgical robotsbased on cable tensions. The mathematic modes of the force sensing method areestablished based on the configuration of the tendon-driven surgical instrument. Aprototype of the force sensing system is developed and experimental tested. Thefunction and performance of the developed force sensing system are verified byperformance tests and experiments. 4. Research on stiffness analysis of tendon-driven surgical instrument. Thestiffness model of ‘MicroHand A’ multi-DoF tendon-driven surgical instrument isestablished based on stiffness matrices. Stiffness of the instrument is evaluated in thejoint space. The instrument is optimized by analyzing the impacts of the structuralparameters on the overall stiffness. The function and performance of the instrumentsare verified through animal experiments.