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Study on the Design of Soft Surgical Robots for Endoscopic NOTES Application

Gifari, Muhammad Wildan (2018) Study on the Design of Soft Surgical Robots for Endoscopic NOTES Application.

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Abstract:With the advance of surgical operation from open surgery toward Minimally Invasive Surgery (MIS) and recently Natural Orifice Transluminal Endoscopic Surgery (NOTES) the surgeons are barely keeping up with the instrumentation. Endoscope that was originally a tool to examine the inside of patient body is now developed to perform surgical task. Advances have been made in the conventional endoscopic instruments, however several problems still arise. The conventional endoscopic instruments can be categorized into two categories: rigid and flexible instrument. When the target organ is near incision point, such as in MIS, surgeons will place trocar and insert rigid endoscopes (can be several endoscopes at once) to perform the surgery. While this tool provide stability, it does not have flexibility. This rigid instrument is only effective when the target organ is directly in front of the incision point. When the target organ is deep inside patient body, or obscured by other organ, such as in gastrointestinal (GI) surgery, then flexible endoscope is the choice. Clearly this endoscope allows flexible navigation inside patient lumen. However, when a surgical intervention is performed, this flexible endoscope is not stable enough to perform the required operation. Other problem of flexible endoscope is the trackability of the instrument inside the patient lumen. In case of rigid endoscope, trackability is not an issue because the instrument is not deeply inserted. In case of flexible endoscope, the view of endoscopic camera is usually narrow and currently the endoscope is not trackable inside the lumen. The endoscope may end up in wrong branch or arriving at incorrect operation target. Another limitation of flexible endoscope is the control method. Currently, the surgeons push the instrument manually inside patient body, and control is possible only at the tip of endoscope. This may cause the endoscope to form a loop inside patient body. In this case, further pushing of the endoscope is painful and the endoscopy is incomplete. Our study aimed to design new surgical endoscope that can fulfill four important capabilities to tackle the problems mentioned: bendability, trackability, stiffness adjustability, and controllability. To attain the research aim, the idea is to design octopus-like soft robots actuated by pneumatic chambers. We improved previous pneumatic soft surgical robots (STIFF-FLOP) by increasing the number of chambers to four and merging stiffening and bending capability in each chamber. Benefits of having four chambers includes more intuitive control, antagonistic activation, and increase in resultant moment arm when activating two adjacent chambers. The embedding of stiffening sac into the chambers enable multi-level stiffness adjustment. Mechanical experimentation is conducted to verify the intended mechanical capabilities. Our design (MOLLUSC) manipulator can bend up to 90°. With the inclusion of jamming material, four level stiffness is attained, however the bending performance is reduced. The four chamber designs improved two chambers bending angle compared to STIFF-FLOP. By freeing the robot from electromechanical components, it is possible to operate the robot under MR-scanner. The robot position can now be tracked using MRI. For the control, 2D control algorithm termed Passive Chamber Compensation (PCC) has been implemented with error less than 5°. For 3D control, the implemented algorithm is effective to achieve rotation angle multiple of 45°. Dynamic control is also verified. However, the robot traced rhombus shape instead of intended circular trajectory.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:52 mechanical engineering, 53 electrotechnology
Programme:Biomedical Engineering MSc (66226)
Link to this item:http://purl.utwente.nl/essays/76537
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