| Cancer has become a major killer threatening human health,currently 50% of the world’s digestive tract cancer occurs in China.Early diagnosis and treatment of digestive tract cancers are particularly critical.The five-year survival rate of the cancers after early diagnosis and treatment can reach above 80%,while this figure for late treatment is only about 10%.However,the rate of early diagnosis for digestive tract cancer in China is low,and more than 85% of patients with the cancer are diagnosed as middle and advanced stage.In recent years,natural orifice transluminal endoscopic surgery(NOTES)has been increasingly introduced to diagnose and treat the early gastrointestinal cancers,and provides advantages in terms of less trauma,fewer complications and shorter hospital stay.The early diagnosis and treatment of cancers also put forward new requirements for the NOTES robots in terms of operability,universality and patients’ comfort.The master manipulator plays an important role for quality and efficiency improvement in these robot-assisted surgical systems.And the design for the master manipulator with good operation performance,wide adaptability and good ergonomics is of great significance for NOTES robot in the diagnosis and treatment of early digestive tract cancers.According to the requirement analysis of NOTES robot systems,this paper proposes a new type of NOTES robots master manipulator based on robotics and ergonomics theory.It uses an isomorphic type and has three degrees of freedom(Do Fs)with one driving unit for each Do F,including translation and two rotation forms.To reduce the system damping,a simplified and improved parallel mechanism with a planar six-linkage configuration is proposed for translational motion.In kinematics analysis and parametric design,the singularity and workspace of the mechanism is analyzed,and the design has been improved to avoid reaching singular positions.The static analysis of the master manipulator mechanism was carried out by ANSYS software based on finite element method.The mechanical structure design of each part of the master manipulator is completed.The control strategy of the master manipulator has been proposed based on the requirement of NOTES robot system,and a joint-to-joint control strategy has been investigated for motion mapping between the master-slave sides to realize an intuitive control.And both the master manipulator hardware system and mechanical prototype has been implemented.The operation comfort for the design of the master manipulator has been analyzed ergonomically.And this paper proposes an evaluation model of upper limb operating comfort based on joint torque through the Lagrange equation and NASA joint torque model.The reliability of the proposed evaluation model has been verified by the rapid upper limb assessment(RULA)by software DELMIA.Finally,this work proposed performance experiments for the master manipulator,such as zero calibration experiment,damping performance test of the linear mechanism,position accuracy experiment to validate its effectiveness and advantages for NOTES robot system.Also,the muscle fatigue experiments by both robotic and traditional manual modes has been implemented with EMG signal collection.Combining the muscle fatigue experiments and RULA simulation results,the reliability of the comfort evaluation model was verified and the respective characteristics for operation comfort of robot-assisted surgery and manual endoscope operation were analyzed. |
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