| Digestive tract tumor is a major factor threatening people’s life and health and realizing"early diagnosis and early treatment" is an effective way to reduce the threat of digestive tract tumor.However,the existing medical instruments related to digestive endoscopy can only achieve simple endoscopic operation,and it is difficult to complete more complex action,such as suturing and knotting,which restricts the development of endoscopic surgery and the improvement of living standards of patients with digestive tract cancer.Therefore,how to complete complexity surgery in the narrow and tortuous workspace of digestive tract has become a common concern of scholars at home and abroad.In this paper,a surgical robot system is developed to meet the requirements of typical operations under natural cavity.The mechanical structure design,kinematics and dynamics,long-distance transmission loss,contact force perception and other problems are studied.Firstly,the freedom requirements of typical surgical operations under digestive endoscopy were analyzed.Considering the environmental constraints of the stenosis and tortuous conditions of digestive tract,a digestive endoscopic surgical robot system with double manipulators was developed using tendon sheath system for long-distance transmission and the driving unit of typical manipulators was designed and optimized.At the same time,to meet the requirements of multiple surgical instruments in the unified operation,a quick exchange mechanism between the in-body part and the out-of-body part of the surgical robot system was designed to realize the rapid replacement of multiple instruments during the operation.To realize the motion control of the surgical robot,the forward and inverse kinematics of the actuated digestive endoscope and the continuum manipulator were analyzed respectively,and the monte-Carlo method was used to analyze the single-arm workspace and the public workspace of the two manipulators,to verify its ability to meet the requirements of the surgical operation space.Secondly,to analyze the friction loss of the continuum manipulator during the operation of the surgical robot,obtain its dynamic mechanical properties,and lay a foundation for force estimation,the stress-strain balance equation is used to analyze the relationship between the friction and positive pressure between different manipulator joints under the condition of cylindrical contact.The dynamic equation of the robot was established by Lagrange equation.Then,to realize sensorless force estimation of the continuum manipulators of surgical robot,lay the foundation for master-slave force feedback control,improve operation safety and realize master-slave palpation,a method of force estimation under arbitrary bending state was explored based on the aforementioned dynamic model.To improve the accuracy of force estimation,the bending shape of continuum was optimized by using the above dynamic model.To compensate the driving force loss of the surgical robot during long-distance transmission,the friction loss in the transmission path was analyzed.The friction loss between the driving tendon and the winding wheel,and between the driving tendon and the guide wheel is analyzed by using the element method.Considering the influence of velocity,the Stribeck model was used to establish the friction loss model and elastic elongation model between the driving tendon and the sheath,which can accurately estimate the friction force of the silk sheath mechanism at different velocities.Finally,the validation platform of the digestive endoscopy surgical robot was built to verify the multi-degree-of-freedom movement ability,high-precision repetitive movement ability,and so on.At the same time,a variety of simulated typical operations,such as foreign body extraction,needle piercing and ring crossing,were carried. |
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