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 muscular tissues will be stiffened up for optimum high-speed sprinting, or loosened off for higher low-speed cruising and maneuverability. Fish-inspired robots, nonetheless, should compromise – their tails are set to at least one stiffness which is not ideally suited 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 pace. It might be like biking via San Francisco with a fixed-gear bike; you’d be exhausted after only a few blocks.”
Sadly, it’s totally tough to find out when and if fish do truly 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 said that tail stiffness ought to improve with swimming pace squared.
In an effort to put their idea to a real-world take a look at, the scientists constructed a robotic tuna referred to as AutoTuna. Based mostly on the tail-stiffness mannequin, the system makes use of a programmable tendon to routinely fluctuate the stiffness of its tail because it swims in a lab-based water channel. Remarkably, it could possibly swim over a wider vary of speeds than an otherwise-identical fixed-tail-stiffness robotic, whereas utilizing nearly half as a lot vitality.
The researchers at the moment are investigating how the know-how may very well be utilized to robots primarily based on different forms of swimming animals.
“Stiffness-tuning mechanisms like ours will be miniaturized fairly simply, so they may help robots of assorted configurations and dimensions,” Quinn tells us. “The more durable half is to determine how stiff the robotic ought to be at numerous swimming frequencies and speeds. We used a bodily mannequin and water channel assessments to develop a management legislation for our robotic to make use of because it tuned its tail stiffness routinely. That mannequin would must be recalibrated for those who made the robotic a lot larger (e.g. a dolphin-like robotic) or switched to a distinct swimming kind (e.g. a stingray-like robotic), however that’s completely doable.”
A paper on the analysis was not too long ago revealed within the journal Science Robotics.