Science Snapshot: The Need for Speed

Most engineered small robots have maximum angular velocities of about 60 radians per second. If the aptly-named trap-jaw ant (Odontomachus brunneus) was capable of scoffing, then surely the insect would scoff at these mechanical weaklings. Trap-jaw ants use a spring-and-latch mechanism to snap their mandibles shut on prey at a blistering speed of 44,000 radians per second. Researchers reported these findings in a study published July 21 in the Journal of Experimental Biology using high-speed videos and mathematical modeling to finally reveal the biomechanics of this tiny animal’s blazing speed.

When the scientists measured the forces acting on the ant’s mandible and on the ligament that functions as a spring, they found a 50-50 distribution. The team initially hypothesized that this even split might optimize the power output of the mandibles, but the mathematical model the researchers developed to capture the rapid-fire event showed otherwise. That model suggested that the split ensures that the stress on the joint between the mandible and the ant’s head is zero. The study authors found that if the energy generated by the jaw closing is unequal, massive force is required in the joint to keep the mandible from flying off the animal. This balanced energy allows the mandible to spin fast and freely, perfectly centered on the joint.

Understanding the design principles of the ants’ jaw could lead to better, faster robots, the researchers say. 

Source: the-scientist.com

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