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Developed by researchers funded by the Swiss National Science Foundation, the Avocado robot – so-called because of the shape of its housing – carries technology that could allow itself to navigate autonomously.
In tropical rainforests, most animals and plants live in the dense canopy. Exploring these habitats is extremely difficult, however – climbing trees only allows research teams to collect data selectively, while drone blades become tangled in foliage and climbing robots struggle with varying thicknesses and textures of branches.
“We came up with the idea of trying to gain access from above,” said Steffen Kirchgeorg, a doctoral student at ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research in Birmensdorf.
Inspired by spiders, the robot is tethered by a cable to one of the top branches of a tree and then lowers itself down. In the current test phase, the researchers are tethering the robot manually by climbing up the tree. In future, a drone could serve as a ‘mothership’, transporting it to inaccessible areas.
Once attached to the tree, Avocado can move up and down on its own thanks to a winch in the upper section of its housing. The robot also has two rotors, which it uses to gain momentum and manoeuvre around branches, foliage and other obstacles.
Kirchgeorg and colleagues carried out simulations to see how the robot could move autonomously through skilful use of its winch and its rotors. It also negotiated a predefined indoor obstacle course and survived a test run in a real tree.
The robot receives information about its environment from an integrated camera. “Lighting conditions in the treetops are very difficult, with light and dark alternating in quick succession. So we’re now trying to get the camera to convey a perception of depth even under these conditions,” said Kirchgeorg.
Once Avocado has fully mastered autonomous movement, Kirchgeorg said it could be used in the rainforest for a longer duration. By remaining tethered, the robot will only use battery power when it has to move. It might also be possible to transmit electricity down the cable from a solar cell mounted above.
As the robot can carry quite a lot of weight, it could be equipped with a variety of instruments, such as humidity and temperature sensors to map the microclimate in different sections of the tree canopy, or gripper arms and air filters for collecting DNA samples. “We might even discover some new animal or plant species,” said Kirchgeorg.
With Avocado and various other research activities, the team – working jointly with other ETH research groups – has made it to the finals of the $10m XPrize Rainforest competition.
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