Research On Slave Robot For Laparoscopic Minimally Invasive Surgery Robot System With Force Sensing

Nowadays, the development of the minimally invasive surgical robot(MISR) system had been the pioneer technology in robot research. Minimally invasive robotic surgery(MIRS) can reduce patient trauma, alleviate the suffering of the patient, reduce scars, and help to shorten the rehabilitation time. Because of the merit above, the MISR had been developed by many research institutes. However, the major defect of the MIRS is a lack of force sensing. The operation lacking of force sensing can not only damage the tissue, but also miss the information which only can be obtained by the force sensing. The difficulty of the operation during surgery was increased by the lack of force sensing, so the precision of the operation was reduced. The lack of force sen sing has been considered as the major restraining factor of the development of MISR.In order to solve the problem of lacking force sensing in the development of MISR, this paper introduced a 6-dimensional force/torque sensor met the requirement for the tiny size of laparoscopic robotic surgery, and the sensor developed can be integrated into the slave robot of master-slave laparoscopic robot developed. The content of the research includes as follows, construction of the slave robot and kinematic analysis, the solution of designing elastomer met the requirement for tiny size of MIRS, the development of the 6-dimensional force/torque sensor and the experiments of the force sensing. According to the character of the minimally invasive surgery, the salve robot of laparoscopic surgical robot owning force sensing had been developed.Aimed at competent in all the operation during laparoscopic surgery, the slave robot of laparoscopic surgical robot integrated with the sensor developed was designed and manufactured. The slave robot consisted of the support structure and the end instrument, and owned seven degree of freedoms(DOFs). The enough DOFs can assure that the slave robot can be operated flexibly in the coelom. The parallelogrammic structure can make sure that the slave robot was prevented from damaging the wound. The dismounting structure can meet the requirement for changing the surgical instruments during the surgical operation, thus, the operation can be completed successfully. Considering the narrow space of the end instruments, the cable-pulley structure was designed. With the cable-pulley structure, the transmission of the movement was achieved during the narrow space. Based on the method of D-H, the forward kinematics and inverse kinematic had been analyzed, and the forward kinematic matrix and inverse kinematic matrix had also been introduced. The workspace of the slave robot had been calculated based on the forward kinematic matrix.The solution of the structure of the elastomer with non-coupling had been introduced. The structure of the elastomer can meet the requirement for the tiny size of the slave robot developed. Because of the narrow space, the structure of the elastomer was designed as the crossing structure, thus, the cables can move through the elastomer without damaging. It’s important for obtaining the dimensional force information to achieve non-coupling, because of the narrow space, it’s difficult to design the elastomer to achieve non-coupling. The elastomer was divided as two elastomer crossing structure sensitive to 6-dimensional force information, thus, the decoupling directly was achieved, and the calculation of decoupling was rather simple.Based on the double-hole parallel crossing beam slide structure, the sensor which can be used in minimally invasive robotic surgery was developed. The size of sensor is 9.8mm(diameter)×6mm(height).The decoupling and finite element analysis(FEA)of the sensor was also carried out.The analysis of machining error proved that the the sensor can be manufactured by numerical control machining with the desired accuracy from the design.With the calibration experiment,the direct decoupling based on the character of the sensor developed was proved. The tissue experiment proved that the slave robot integrated with the sensor developed can obtain the force information.In general, a novel slave robot was designed and manufactured. The slave robot can meet the specific requirements of MIRS. A novle six dimensional sensor which can be decoupled directly in structure was designed. The slave robot integrated with the sensor developed can obtain the force information during MIRS. The tissue models were constructed based on medical graphic data, and can be applied in the virtual surgery training system and surgical planning.