{"id":25839,"date":"2025-04-11T16:53:20","date_gmt":"2025-04-11T11:08:20","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=25839"},"modified":"2025-04-12T12:00:12","modified_gmt":"2025-04-12T06:15:12","slug":"hopping-gives-this-tiny-robot-a-leg-up","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/hopping-gives-this-tiny-robot-a-leg-up\/","title":{"rendered":"Hopping gives this tiny robot a leg up"},"content":{"rendered":"\n

MIT engineers developed an insect-sized jumping robot that can traverse challenging terrains and carry heavy payloads.<\/strong><\/em><\/p>\n\n\n\n

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IMAGE: Melanie Gonick, MIT<\/em><\/figcaption><\/figure>\n\n\n

Adam Zewe<\/p><\/div><\/div>\n\n\n

CAMBRIDGE, MA \u2013 Insect-scale robots can squeeze into places their larger counterparts can\u2019t, like deep into a collapsed building to search for survivors after an earthquake.<\/p>\n\n\n\n

However, as they move through the rubble, tiny crawling robots might encounter tall obstacles they can\u2019t climb over or slanted surfaces they will slide down. While aerial robots could avoid these hazards, the amount of energy required for flight would severely limit how far the robot can travel into the wreckage before it needs to return to base and recharge.<\/p>\n\n\n\n

To get the best of both locomotion methods, MIT researchers developed a hopping robot that can leap over tall obstacles and jump across slanted or uneven surfaces, while using far less energy than an aerial robot.<\/p>\n\n\n\n

The hopping robot, which is smaller than a human thumb and weighs less than a paperclip, has a springy leg that propels it off the ground, and four flapping-wing modules that give it lift and control its orientation.<\/p>\n\n\n\n

The robot can jump about 20 centimeters into the air, or four times its height, at a lateral speed of about 30 centimeters per second, and has no trouble hopping across ice, wet surfaces, and uneven soil, or even onto a hovering drone. All the while, the hopping robot consumes about 60 percent less energy than its flying cousin.<\/p>\n\n\n\n

Due to its light weight and durability, and the energy efficiency of the hopping process, the robot could carry about 10 times more payload than a similar-sized aerial robot, opening the door to many new applications.<\/p>\n\n\n\n

\u201cBeing able to put batteries, circuits, and sensors on board has become much more feasible with a hopping robot than a flying one. Our hope is that one day this robot could go out of the lab and be useful in real-world scenarios,\u201d says Yi-Hsuan (Nemo) Hsiao, an MIT graduate student and co-lead author of a paper on the hopping robot.<\/p>\n\n\n\n

Hsiao is joined on the paper by co-lead authors Songnan Bai, a research assistant professor at the City University of Hong Kong; and Zhongtao Guan, an incoming MIT graduate student who completed this work as a visiting undergraduate; as well as Suhan Kim and Zhijian Ren of MIT; and senior authors Pakpong Chirarattananon, an associate professor of the City University of Hong Kong; and Kevin Chen, an associate professor in the MIT Department of Electrical Engineering and Computer Science and head of the Soft and Micro Robotics Laboratory within the Research Laboratory of Electronics. The research appears today in Science Advances<\/em><\/a>.<\/em><\/p>\n\n\n\n

Maximizing efficiency<\/strong><\/p>\n\n\n\n

Jumping is common among insects, from fleas that leap onto new hosts to grasshoppers that bound around a meadow. While jumping is less common among insect-scale robots, which usually fly or crawl, hopping affords many advantages for energy efficiency.<\/p>\n\n\n\n

When a robot hops, it transforms potential energy, which comes from its height off the ground, into kinetic energy as it falls. This kinetic energy transforms back to potential energy when it hits the ground, then back to kinetic as it rises, and so on.<\/p>\n\n\n\n

To maximize the efficiency of this process, the MIT robot is fitted with an elastic leg made from a compression spring, which is akin to the spring on a click-top pen. This spring converts the robot\u2019s downward velocity to upward velocity when it strikes the ground.<\/p>\n\n\n\n

\u201cIf you have an ideal spring, your robot can just hop along without losing any energy. But since our spring is not quite ideal, we use the flapping modules to compensate for the small amount of energy it loses when it makes contact with the ground,\u201d Hsiao explains.<\/p>\n\n\n\n

As the robot bounces back up into the air, the flapping wings provide lift, while ensuring the robot remains upright and has the correct orientation for its next jump. Its four flapping-wing mechanisms are powered by soft actuators, or artificial muscles, that are durable enough to endure repeated impacts with the ground without being damaged.<\/p>\n\n\n\n

\u201cWe have been using the same robot for this entire series of experiments, and we never needed to stop and fix it,\u201d Hsiao adds.<\/p>\n\n\n\n

Key to the robot\u2019s performance is a fast control mechanism that determines how the robot should be oriented for its next jump. Sensing is performed using an external motion-tracking system, and an observer algorithm computes the necessary control information using sensor measurements.<\/p>\n\n\n\n

As the robot hops, it follows a ballistic trajectory, arcing through the air. At the peak of that trajectory, it estimates its landing position. Then, based on its target landing point, the controller calculates the desired takeoff velocity for the next jump. While airborne, the robot flaps its wings to adjust its orientation so it strikes the ground with the correct angle and axis to move in the proper direction and at the right speed.<\/p>\n\n\n\n

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