Research Of Minimally Invasive Surgery Device Based On Wire Driven Parallel Mechanism

Minimally invasive surgery is the forefront development direction of the clinical, it has the characteristics of small trauma, less pain and quick recovery, it has got revolutionary success in more and more areas of traditional surgery, becoming the main theme of global surgery development gradually. The reasonable design of mechanical structure, transmission manner and other aspects of minimally invasive surgical instruments will affect its flexibility, maneuverability, control accuracy and other properties directly, as well as the effect of surgery; Due to the small working space of minimally invasive surgery and poor flexibility of traditional minimally invasive surgical instruments. For improving the flexibility and Operability of minimally invasive surgical instruments while remedying, the loss of DOF owing to the incisions. This paper, according to the structural characteristics of abdominal surgery and minimally invasive surgery instruments, designs a hand-held multi-degree of freedom invasive surgical instrument based on the wire driven parallel mechanisms. The study includes the following aspects:(1) Determine the expected demand for new multi-DOF surgical instruments based on the deep and detailed analysis of the minimally invasive surgical procedures and traditional minimally invasive surgical instruments; Specify the design requirements based on the objective tasks of the surgical instruments then obtained the minimum DOF of surgical instruments for four; Propose the pitch and yaw schemes of the wrist joints based on the unit combination of parallel mechanism; Design the 4-DOF hand-held minimally invasive surgical instrument by adopting the wire driven manner combined with flexible rod and soft shafts constraints.(2) Derive the mechanism structure of wrist joints based on the unit combination of parallel mechanism by using the position and orientation characteristic set theory, determining the 4SPS-1U as the unit configuration; Analyze the range of rotation angle and the rotation radius of parallel mechanism based on the work space that the wrist joints required and then determine a reasonable scale parameter of the parallel mechanism unit.(3) Based on the dimension compatibility conditions to build kinematic equations of 4SPS-1U parallel mechanism by using D-H matrix and then solve the positive position utilizing the Newton iterative method; Obtain the Jacobi matrix of speed and acceleration through the derivation of kinematic equations then build the kinematic equations of speed and acceleration; Making use of the ADAMS to carry out the kinematics and dynamics simulation analysis of this parallel mechanism, Solving the dynamics of parallel mechanism unit; Construct the experimental model of wrist joint and conduct the experimental analysis to verify the rationality and the correction of the designed mechanism.(4) Establish the force balance equation of wire to perform its stress analysis during the transmission process and the stress analysis in stretching and bending state. Obtained the danger point distribution of rope during transmission; Conduct the element simulation analysis by using of Solid Works Simulation to obtain the maximum stress of wire in transmission process and compare the element simulation results and mathematical model results to verify the correctness of the wire force model; Conduct the analysis of friction and fatigue life of rope during the transmission process to draw the conclusion that the chosen wire has minimal impact on the life of surgical instruments.The 4-DOF hand-held minimally invasive surgical instruments that this article designed provides a theoretical basis for the further development of high-performance minimally invasive surgical instruments.