Dariush Eftekhariyazdi - Nano Robotics Laboratory, Mechanical Engineering Department, Sharif University of Technology, Tehran;
Mahshid Mansouri - Nano Robotics Laboratory, Mechanical Engineering Department, Sharif University of Technology, Tehran;
Hossein Nejat Pishkenari - Nano Robotics Laboratory, Mechanical Engineering Department, Sharif University of Technology, Tehran;

The objective of this research was to design and fabricate a small swimming fish-like robot in the water and control its motion by applying an external magnetic field. First, a Helmholtz setup including three pairs of electromagnetic coils was designed and fabricated. Secondly, a robot consisting of a U-shaped head, a trapezoidal tail hinged to the tail, and a cylindrical magnet situated in the hinge was designed and 3Dprinted. Finally, the magnetic field was controlled by changing the current amplitude and frequency in the electromagnetic coils. Consequently, the orientation and motion of the robot were controlled and the robot performance graphs were obtained and analyzed byconducting several experiments for four different robot’s tail length. In these experiments, the magnitude, oscillation angle, and oscillating frequency of the magnetic field were the variables, two of which were kept constant in each experiment and the third parameter was changed and the graph of the robot’s velocity versus the parameter was derived. It was concluded that graph of linear velocity versus frequency had a maximum value whose corresponding frequency decreased with the increase of the robot’s tail length. Additionally, the velocity increased with the increase of the resultant magnetic field’s magnitude and oscillation angle due to the increase in the applied magnetic torque on the tail. Moreover, it was resulted that the open-loop control was not a suitable solution for the control of the robot along closed and more complicated paths due to the water’s intensive disturbances around the robot.

Fish-like robot, Magnetic field, Helmholtz coil, Control.