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Modeling and Control of a Carangiform Fish Robot with Experimental Validation of the Forces Obtained by Large Amplitude Elongated Body Theory of Lighthill

Khaghani, Mehran | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41364 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Vossoughi, Gholamreza
  7. Abstract:
  8. Modeling and Control are fundamental issues for fish robots, which can play basic roles in design, optimization, fabrication, and eventually utilization of them. A review on the literature reveals the shortage of an analytical closed form model with little simplifications and high precision, and also control works based on such models. Studying LAEBT theory, it is shown that this theory is suitable for determining the forces produced due to the tail movements considered in the present work, and then it is used to determine the forces. Experimental investigations by means of the setup made for this purpose showed that the obtained equations for the forces have got acceptable precision. Maximum differences between theoretical and experimental results were 19.6% for the forces along the direction of motion and 23.2% for the forces in the normal direction. Using these forces, dynamic model of fish robot for motion in constant water level is obtained. This model is used to reach two state space models, one regarding the tail angle as input, and the other regarding the torque exerted on the tail as input. Afterwards, the control of fish robot is considered. At first, a simplified model for dynamical analysis of the fish robot is represented using the dynamic model obtained before. This model has a very satisfactory precision and for a specific fish robot, its maximum error was 4.57% in approximation of the radius of path, and 5.81% in approximation of the velocity. Then, control algorithm for reaching any desired point in horizontal plane starting any point is represented. The stability of this controller is proven regarding the simplified model and based on Lyapunov stability theory. After that, this algorithm is used to travel any desired path in the plane, through discretizing the path and reaching the points one after another. Then, reaching the desired velocity in path is considered in two cases, one with knowledge about system dynamic parameters, and the other one without such knowledge and using a method for adaptation of the control algorithm. Finally, a controller is represented that is able to move the fish robot in desired path with desired velocity within its motion capability limitations, only by knowing the minimum radius the fish robot can turn. Validity of this control algorithm is assured by stability proof. Simulation results in all sections exhibited very suitable performance of controller and very satisfying behavior of fish robot
  9. Keywords:
  10. Fish Robot ; Modeling ; Control ; Experimental Investigation ; Lighthill Equation

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