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Birds inspire robotic feet design to help drones perch in trees

AFP, December 5, 2021 2:30PM Kids News

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Engineers from Stanford University in the US have designed robotic feet that can be fitted to drones to help them land and perch on tree branches just like birds. Picture: William Roderick/Stanford University/AFP media_cameraEngineers from Stanford University in the US have designed robotic feet that can be fitted to drones to help them land and perch on tree branches just like birds. Picture: William Roderick/Stanford University/AFP


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Inspired by how birds land and perch on branches, a team of engineers has built robotic graspers that can fit on drones, enabling them to catch objects and grip various surfaces.

The advance could allow flying robots to conserve power in situations where they might otherwise be required to hover – for example in search and rescue missions or helping ecologists* collect data more easily in forests.

“We want to be able to land anywhere, that’s what makes it exciting from an engineering and robotics perspective*,” said David Lentink from Stanford University in the US.

The engineering team has dubbed its project “stereotyped nature-inspired aerial grasper,” or SNAG.

closeup of eagle claws on branch media_cameraBirds inspired the ‘stereotyped nature-inspired aerial grasper’ or SNAG. Picture: iStock

Roboticists* often look to animals to resolve difficult engineering problems, but mimicking* the way birds fly and perch after millions of years of evolution* is no easy feat.

Branches differ in size, shape and texture. They can be covered in lichen or moss, or might be slippery from rain.

The team studied previous data they’d gathered on one of the smallest species of parrot, using high-speed cameras to watch how the birds landed on perches of different sizes and materials, including wood, foam, sandpaper and Teflon*.

The perches also contained sensors to capture the level of force associated with landing, roosting* and takeoff.

What they found was the birds approached every landing the same way, using their feet to deal with any variability* they encountered.

Specifically, birds curl their claws around a perch, and they also have soft, wrinkly toe pads that provide reliable friction.

The engineers had to build a grasper large enough to support a small quadcopter drone, and so modelled their design on the legs of a peregrine falcon.

Peregrine Falcon in Tree media_cameraThe engineers modelled their design on the legs of a peregrine falcon like this one. Picture: iStock

The design, which was described in a research paper published in the journal Science Robotics, has a 3D-printed structure that took 20 versions to perfect, with motors and fishing line standing in for muscles and tendons.

Its clutching action takes 20 milliseconds, and once wrapped around the branch, an accelerometer* in the right foot tells the robot it has landed.

This in turn triggers a balancing algorithm*, which tilts the bot forward to avoid falling, again like real birds.

The finished bird bot successfully caught items thrown at it like bean bags and tennis balls, and was able to land in real world conditions in the forests of Oregon.

Beyond possible future use with drones, Dr Lentink said that building such robots could provide new insights into avian* morphology*.

For example, the team tried out the two most common toe arrangements seen in birds – three toes in front and one in the back, versus two in front and two in the back – and found they did not make a difference to the bot’s grasping ability.

This tells biologists* that these evolutionary differences arose for other reasons.

“Part of the underlying motivation of this work was to create tools that we can use to study the natural world,” research paper co-author William Roderick said.


  • ecologists: people who study the relationship between living things and their environment
  • perspective: point of view
  • roboticists: people who are specialists in robots or robotics
  • mimicking: imitating, copying
  • evolution: the gradual development of living things
  • Teflon: a type of smooth, non-stick plastic
  • roosting: resting or sleeping
  • variability: changes, differences
  • accelerometer: a device that measures acceleration
  • algorithm: a set of mathematical instructions that help calculate an answer to a problem
  • avian: to do with birds
  • morphology: the study of the form and structure of things
  • biologists: scientists who study living things


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  1. Which university are the engineers from?
  2. Which birds did they study to understand how they landed on various perches?
  3. Which birds did they model their robotic grasper on?
  4. How many version of the 3D printed structure did they make before perfecting the design?
  5. How long does the robotic clutching action take?


1. Bird Words
Create a three-column table and add the headings nouns, verbs, adjectives.

Find at least eight examples each of nouns, verbs and adjectives in the story and record these in the correct columns on your table.

Time: allow 20 minutes to complete this activity
Curriculum Links: English

2. Extension
Rewrite your words from the above activities onto strips of paper and face them down. Randomly choose three words at a time. You have 20 seconds to put your words into a sentence and say it aloud. Continue until you have used up all of your words.

Time: allow 10 minutes to complete this activity
Curriculum Links: English

Wow Word Recycle
There are plenty of wow words (ambitious pieces of vocabulary) being used in the article. Some are in the glossary, but there might be extra ones from the article that you think are exceptional as well.

Identify all the words in the article that you think are not common words, and particularly good choices for the writer to have chosen.

Select three words you have highlighted to recycle into your own sentences.

If any of the words you identified are not in the glossary, write up your own glossary for them.

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