Stanford University researchers have developed a device called a nature-inspired aerial grasper，or SNAG，which can be attached to a quadcopter drone （四軸無人機） to give it feet and legs like those of an eagle.When equipped with the device，the drone is able to fly around catching and carrying objects and perching（棲息）on various surfaces，according to a Stanford news release dated Dec.1，2021，describing the work.
But copying the flexibility of birds wasn't easy to do.The researchers shot videos of small parrots flying back and forth between special perches that contained sensors to measure the physical forces of landing，perching and takeoff.
"What surprised us was that they did the same aerial military exercise，no matter what surfaces they were landing on，" one of the researchers，William Roderick，explained in the news release. "They let the feet handle the variability and complexity of the surface texture itself，" he said.
Giving a drone similar abilities required technological feat.SNAG has a -3 D-printed structure that imitates an eagle's lightweight bones，and each of its legs is equipped with a motor for moving back and forth and a second one for grasping.
Mechanisms in the robot's legs are designed to absorb impact energy and passively change it into grasping force，the way that a bird's muscles would.As a result，a drone equipped with the device can grasp something strongly in just 20 milliseconds.Once the robot's feet are wrapped around a perch，its ankles lock and an accelerometer—a device that measures vibration-detects the landing and activates a balancing algorithm（算法）to stabilize it on the perch.
Elsewhere，researchers at other institutions also have been working for years on giving drones the ability to land and hang onto something.As this 2019 Smithsonian article explains，being able to land in various places helps drones to conserve energy that would expend by having to remain in the air.That's important，because the flight time of robotic aircrafts is limited by their battery power.
（1）What inspired the SNAG's development？ AA
A．The way parrots perch.
B．The military exercise.
C．The 3 D-printed technology.
D．The eagle's lightweight bones.
（2）What makes the drones' grabbing something strongly so quickly possible？ DD
A．The powerful battery.
B．Their ability to imitate parrots' taking off.
C．The application of advanced flying techniques.
D．The mechanical devices modeling a bird's muscles.
（3）What can we infer from the last paragraph？ CC
A．Flight time is not vital to the drones.
B．After 2019，researchers quit efforts to improve flight time.
C．Flight time has been a problem before this study.
D．Researching the ability to land and hang onto something is meaningless.
（4）What is the most suitable title for the text？ BB
A．Drones，an application to the military
B．Robotic drones，really like birds
C．Robotic drones，a comparison of birds
D．Quadcopter drones，advanced technology
【考點】自然科學(xué)研究成果．
【答案】A；D；C；B
【解答】
【點評】
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發(fā)布：2024/5/27 14:0:0組卷：3引用：6難度：0.6
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D．The Close Cooperation between OverDrive and Amazon發(fā)布：2025/1/1 16:0:1組卷：1引用：3難度：0.5 -
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