Design And Control Of A Force-feedback Master Manipulator For Minimally Invasive Surgery

Robot assisted minimally invasive surgery is an important part of advanced medical technology.Traditional surgery has many deficiencies,such as the long operation time,deeply suffering pain by patient,and extreme fatigue of surgeon.The minimally invasive surgical robot can help to solve the problems above.The master manipulator is the human-computer interface,and its reasonability of design directly affects the quality of the operation.At present,most of the products in the market is for universal application,not well satisfying the specific requirements of the minimally invasive surgery.This research designed a force feedback master manipulator,with prototype developed and performance verified by simulation.After analysis of the function requirement of minimally invasive surgery,the overall design scheme was developed.The master manipulator was equipped with eight degrees of freedom,three to adjust the position,four to control the gestures,and the last one to complete the clamp motion.Based on the global conditioning index,the optimization analysis of the configuration was carried out,and the links' length of the master manipulator was obtained.According to the optimized links' length,the detailed structure of the master manipulator was designed,which consist of position adjustment mechanism,attitude adjustment mechanism and clamping mechanism.Among them,the attitude adjustment mechanism had its four joint axes intersecting at one point,enabling the decoupling feature,which increased the flexibility of the attitude adjustment.Based on the CAD model,the kinematics and dynamic analysis of the master manipulator were conducted.Using the D-H method,the forward kinematics and jacobian matrix of the master manipulator were obtained.The dynamic modeling of the position adjustment mechanism and the attitude adjustment mechanism were built by Lagrange equation and Kane equation.Based on the definition of the force feedback principle,the force jacobian matrix was calculated.The maximum torque required by each joint was calculated,and the corresponding motor was selected.After comparison of several force feedback control methods,the one based on dynamic model was selected.With counterweight balance and PD control of the fed back force,its performance was verified by simulation in SIMULINK.Based on the kinematic and dynamics model,the performance of the whole master manipulator is verified by simulation.The virtual prototype of the master manipulator was established in ADAMS,and the reasonable joint drive functions were set.The validity of kinematics and dynamics model is verified by comparing ADAMS simulation and MATLAB calculation results.The simulation also showed that the adding of counterweight balance could lower the requirement of motor and improve the accuracy of force feedback,which helps to improve the performance of master manipulator and lower the cost.