| dc.description.abstract | This thesis offers an overview of tensegrity systems and the historical and novel research and development of swimming robotics. A robotic dolphin (with two tail designs) was designed and manufactured using a tensegrity theory approach and experimentally analyzed for its biomimetic capabilities. The simple tail structure (i.e. one with less vertebrae) was found to be more efficient at producing thrust with the given low thrust servomotor (35kg-cm). The observed swimming performance was characteristic of Strouhal numbers in the range of 0.57 < St < 0.84. The relationship between forward speed and tail beat frequency was found to be linear in frequencies from 0.83 < f < 2.38 Hz, in which tail beat amplitude decreased significantly with increasing frequency.
The flexing tail structure was modeled as a morphing airfoil through the control of string pretension and length change, as a first step towards implementation of information architecture in future studies. In addition, CFD was used to simulate turbulence, boundary layer characteristics, and coefficients of drag. Two turbulence models, SST k-omega and k-epsilon, were compared and it was found that the k-epsilon method may underpredict frictional drag by roughly 7% at Re = 3.1e6. Laminar-turbulent flow transitions were calculated near Re = 6e5 – 7e5 for the gliding dolphin at straight body position. With increasing Reynolds number, delaying of flow separation along the body surface, as well as a narrowing of the wake was found. Preliminary data suggests narrowing of the wake through modifying the dolphin body with a bulbous melon. | |
