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Design, Development and Experimental Evaluation of a Local Actuated Gripper for Robotic Laparoscopic Surgery

Saedi, Soheil | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 40740 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Farahmand, Farzam; Kazemzadeh Hannani, Siamak
  7. Abstract:
  8. The actuation mechanism of the tip of the laparoscopic instrument is the main problem in designing the process of miniature scale motorized instruments especially when high level of functionality and multi degrees of freedom (DOF) are concerned. Previous studies suggest local actuation as the best design for this kind of end effectors. In the present study, different actuation methods of needle holders were reviewed, related capabilities and drawbacks were evaluated and a hybrid local actuated design was appointed. The hybrid design included a micro DC motor and a PZT actuator. The main idea behind it was to combine the advantages of DC motors and piezoelectric (PZT) actuators in providing long courses of movement and high gripping force, respectively. The DC motor provided the opening-closing action of the gripper while the PZT guaranteed the high gripping force required for holding the needle. The DC motor and the PZT were designed in a compact serial configuration so the size of the actuation system did not exceed the required dimensions of such instruments. The overall size of the designed actuator for the needle holder was 12 mm in diameter and 40 mm in length. The capability of the design, especially piezoelectric actuator, in terms of providing performance goals was examined by FEM analyses using ABAQUS/CAE (SIMULIA) soft ware. To verify the feasibility of the idea a mockup that was about 4 times of the designed one was examined and the results were compared to the analyzed results. For this purpose, 38mm piezoelectric ring ceramics and 15mm DC motor were used. Testing experiments verified the simulation results. In spite of the needs for improvement, the tested actuation system presents acceptable specifications in terms of granting the required gripping force during the suturing, response time, etc
  9. Keywords:
  10. Smart Materials ; Laparoscopic Surgery ; Piezoelectric ; Local Actuation ; Hybrid Actuation

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