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Localization and Control of a Continuum Robot

Yousefi, Masoud | 2023

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 56607 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Nejat Pishkenari, Hossein; Alasty, Aria
  7. Abstract:
  8. Magnetic steering of continuum robots is a promising technology that uses a magnetic field to control the robot without contact and can improve the accessibility, safety, and accuracy of the robot. On the other hand, magnetic localization can also be used as a positioning method without direct line of sight in various applications. Common magnetic localization methods face the challenge of dependence on initial guess, divergence, and high computational cost. In this research, by eliminating the unknowns related to the orientation and rewriting the equations, a new method for magnetic localization has been presented. The advantage of the new method in convergence and increasing the speed of computations up to two times has been shown through the conducted experiments. In these tests, the positioning error of a cube-shaped permanent magnet with a side of 5 mm is less than 2 mm and the orientation error is less than 2 degrees. In order to control the motion of the continuum robot with visual feedback, an approach based on optimal control is introduced and practically implemented, in which the root mean square error of the position is calculated as 0.6 mm for a robot with a diameter of 7 mm. Afterward, simultaneous magnetic localization and control is investigated, which provides the possibility of using continuum robots in closed environments, unlike visual feedback. One of the most important challenges of simultaneous magnetic localization and control is the saturation of magnetic sensors. In this research, the controller has been designed to minimize the magnetic field at the location of the sensors while controlling the position of the robot. The results of the practical implementation show the success of the proposed idea. In the practical tests of this section, the average magnetic positioning error is less than 4 mm. In addition to motion control, magnetic localization has also been used to estimate the shape and contact forces applied to the continuum robot. Based on the experiments, the proposed process has been able to estimate the forces acting on the robot in addition to estimating the shape using the robot model
  9. Keywords:
  10. Magnetic Actuation ; Optimal Control ; Continuum Robot ; Magnetic Localization ; Continuum Robot Shape and Force Estimation ; Robot Arm

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