Robotic tuna makes use of variable-stiffness tail for extra environment friendly swimming



Given that they are such naturally proficient swimmers, the bodily construction of fish is more and more being copied within the design of underwater robots. Scientists have now found that by adjusting the stiffness of their tails, these bots can swim far more effectively.In actual fish, the tail muscle mass will be stiffened up for optimum high-speed sprinting, or loosened off for higher low-speed cruising and maneuverability. Fish-inspired robots, nevertheless, need to compromise – their tails are set to at least one stiffness which is not ultimate in all conditions.”Having one tail stiffness is like having one gear ratio on a motorcycle,” says the College of Virginia’s Prof. Dan Quinn. “You’d solely be environment friendly at one velocity. It might be like biking by way of San Francisco with a fixed-gear bike; you’d be exhausted after just some blocks.”Sadly, it is very troublesome to find out when and if fish do really change their tail stiffness. Working with postdoctoral researcher Qiang Zhong, Quinn turned to fluid dynamics and biomechanics to derive a theoretical mannequin. In a nutshell, the mannequin acknowledged that tail stiffness ought to improve with swimming velocity squared.

Qiang Zhong (left) and Dan Quinn with their AutoTuna robotDaniel Benjamin Quinn / The College of Virginia

In an effort to put their idea to a real-world check, the scientists constructed a robotic tuna often known as AutoTuna. Based mostly on the tail-stiffness mannequin, the system makes use of a programmable tendon to robotically range the stiffness of its tail because it swims in a lab-based water channel. Remarkably, it could swim over a wider vary of speeds than an otherwise-identical fixed-tail-stiffness robotic, whereas utilizing virtually half as a lot vitality.The researchers are actually investigating how the know-how might be utilized to robots based mostly on different forms of swimming animals.”Stiffness-tuning mechanisms like ours will be miniaturized fairly simply, so they may assist robots of varied shapes and sizes,” Quinn tells us. “The tougher half is to determine how stiff the robotic must be at varied swimming frequencies and speeds. We used a bodily mannequin and water channel checks to develop a management legislation for our robotic to make use of because it tuned its tail stiffness robotically. That mannequin would should be recalibrated in case you made the robotic a lot greater (e.g. a dolphin-like robotic) or switched to a special swimming sort (e.g. a stingray-like robotic), however that’s completely doable.”A paper on the analysis was lately revealed within the journal Science Robotics.Supply: College of Virginia by way of EurekAlert