Biomimetic design employs the principles of nature to solve engineering problems. Such designs which are hoped to be quick, efficient, robust, and versatile, have taken advantage of optimization via natural selection....Biomimetic design employs the principles of nature to solve engineering problems. Such designs which are hoped to be quick, efficient, robust, and versatile, have taken advantage of optimization via natural selection. In the present research, an environment-friendly propulsion system mimicking undulating fins of stingray was built. A non-conventional method was considered to model the flexibility of the fins of stingray. A two-degree-of-freedom mechanism comprised of several linkages was designed and constructed to mimic the actual flexible fin, The driving linkages were used to form a mechanical fin consisting of several fin segments, which are able tO produce undulations, similar to those produced by the actual fins. Owing to the modularity of the design of the mechanical fin, various undulating patterns can be realized. Some qualitative observations, obtained by experiments, predicted that the thrusts produced by the mechanical fin are different among various undulating patterns. To fully understand this experimental phenomenon is very important for better performance and energy saving for our biorobotic underwater propulsion system. Here, four basic undulating patterns of the mechanical fin were performed using two-dimensional unsteady computational fluid dynamics （CFD） method. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive re-meshing was used to compute the unsteady flow around the fin through twenty complete cycles. The pressure distribution on fin surface was computed and integrated to provide fin forces which were decomposed into rift and thrust. The pressure force and friction force were also computed throughout the swimming cycle. Finally, vortex contour maps of these four basic fin undulating patterns were displayed and compared.展开更多
A bioinspired autopilot is presented, in which body saccadic and intersaceadic systems are combined. This autopilot en- ables a simulated hovercraft to travel along corridors comprising L-junctions, U-shaped and S-sha...A bioinspired autopilot is presented, in which body saccadic and intersaceadic systems are combined. This autopilot en- ables a simulated hovercraft to travel along corridors comprising L-junctions, U-shaped and S-shaped turns, relying on mini- realistic motion vision cues alone without measuring its speed or distance from walls, in much the same way as flies and bees manage their flight in similar situations. The saccadic system responsible for avoiding frontal collisions triggers yawing body saccades with appropriately quantified angles based simply on a few local optic flow measurements, giving the angle of inci- dence with respect to a frontal wall. The simulated robot negotiates stiff bends by triggering body saccades to realign its tra- jectory, thus traveling parallel with the wall along a corridor comprising sharp turns. Direct comparison shows that the per- formance of this new body saccade-based autopilot closely resembles the behavior of a fly using similar body saccade strategy when flying along a corridor with an S-shaped turn, despite the huge differences in terms of the inertia.展开更多
文摘Biomimetic design employs the principles of nature to solve engineering problems. Such designs which are hoped to be quick, efficient, robust, and versatile, have taken advantage of optimization via natural selection. In the present research, an environment-friendly propulsion system mimicking undulating fins of stingray was built. A non-conventional method was considered to model the flexibility of the fins of stingray. A two-degree-of-freedom mechanism comprised of several linkages was designed and constructed to mimic the actual flexible fin, The driving linkages were used to form a mechanical fin consisting of several fin segments, which are able tO produce undulations, similar to those produced by the actual fins. Owing to the modularity of the design of the mechanical fin, various undulating patterns can be realized. Some qualitative observations, obtained by experiments, predicted that the thrusts produced by the mechanical fin are different among various undulating patterns. To fully understand this experimental phenomenon is very important for better performance and energy saving for our biorobotic underwater propulsion system. Here, four basic undulating patterns of the mechanical fin were performed using two-dimensional unsteady computational fluid dynamics （CFD） method. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive re-meshing was used to compute the unsteady flow around the fin through twenty complete cycles. The pressure distribution on fin surface was computed and integrated to provide fin forces which were decomposed into rift and thrust. The pressure force and friction force were also computed throughout the swimming cycle. Finally, vortex contour maps of these four basic fin undulating patterns were displayed and compared.
文摘A bioinspired autopilot is presented, in which body saccadic and intersaceadic systems are combined. This autopilot en- ables a simulated hovercraft to travel along corridors comprising L-junctions, U-shaped and S-shaped turns, relying on mini- realistic motion vision cues alone without measuring its speed or distance from walls, in much the same way as flies and bees manage their flight in similar situations. The saccadic system responsible for avoiding frontal collisions triggers yawing body saccades with appropriately quantified angles based simply on a few local optic flow measurements, giving the angle of inci- dence with respect to a frontal wall. The simulated robot negotiates stiff bends by triggering body saccades to realign its tra- jectory, thus traveling parallel with the wall along a corridor comprising sharp turns. Direct comparison shows that the per- formance of this new body saccade-based autopilot closely resembles the behavior of a fly using similar body saccade strategy when flying along a corridor with an S-shaped turn, despite the huge differences in terms of the inertia.
