Highly Maneuverable Biorobotic Underwater Vehicles

A Hemispherical Motor Oscillator for Experiments on Swimming and Flying of Small Animals

“…The ball-and-socket structure of the pectoral fin joint in the dolphin is pivoted at a virtual origin. The presence of a real or virtual origin of oscillation and the ball-and-socket construction suggest that the pectoral fins are mechanical resonant oscillators with low damping and with disturbance rejection properties [4,6].…”

“…This contrasts with swimming animals which have oscillatory propulsive surfaces. This is because the motion controller in animals is oscillatory, and the propulsive surface and its wake have similar self-regulating mechanisms [1][2][3][4]. Engineers avoid loading oscillatory surfaces for fear of fatigue failure.…”

“…However, oscillatory surfaces allow quick response at small spatial scales. In our laboratory, it has been possible to determine the force and moment control laws of rigid cylindrical and delta shaped bodies of 1 m in length to which multiple large flapping fins are attached [4][5][6]. Animal-like spatiotemporal responses have been routinely demonstrated both in laboratory and in littoral environments [4].…”

“…In our laboratory, it has been possible to determine the force and moment control laws of rigid cylindrical and delta shaped bodies of 1 m in length to which multiple large flapping fins are attached [4][5][6]. Animal-like spatiotemporal responses have been routinely demonstrated both in laboratory and in littoral environments [4]. However, this progress is limited to flapping fins whose chord (c) Reynolds number (Re c ), which is the ratio of destabilizing inertial forces to stabilizing viscous forces, is greater than 40 Â 10 3 [7].…”

Is there a case for emulating a fish or other sea borne creatures for propulsion of underwater vehicles?

“…From the current progress in the underwater robotics field, it is opined that the smaller the size of the underwater vehicle, easier is the adoption of fish type of locomotion, as has been demonstrated by different researchers. It is reckoned that time frame likely (for adoption of fish locomotion) for different underwater vehicles are as follows; Bandhopadhyay [60] in chapter titled " Highly Manoeuvrable Biorobotic Underwater Vehicles" in the handbook of Ocean Engineering, has contended that the emergent, low-speed platforms complement existing higher speed naval capabilities and are not substitutes for any existing mature system; in this sense, their utility depends on the imaginative nature of future operation concepts -a process that is unpredictable. The greater potential of the biorobotics approach is limited by a serious lack of progress in so-called strong artificial muscle technology, as well as by a lack of understanding of nonlinear temporal control and sensing and how they should be integrated.…”