Tiny robot hops to improve search and rescue missions

In disaster areas, for example, there may be unstable surfaces, debris, or confined spaces that can bring real risks to both the rescue teams and to the trapped individuals. By using robotic systems, the chances of reaching and assessing these zones safely can be increased. There are lots of types of robots designed to do these jobs, however, crawling robots, for example, might struggle to scale steep or slippery obstacles, while aerial drones, although more agile, can be limited in its flight time and payload due to high energy demands.

Meet the hopper

The MIT-developed hopper can jump to a height of approximately 20cm – roughly four times its own height – at a lateral speed of around 30cm per second. Trials across a variety of surfaces, including wet glass, ice, grass, and loose soil, showed that the robot could maintain its motion even under challenging conditions. It can even land on moving targets such as a hovering drone. Despite its agility, it consumes about 60% less energy than a drone of similar scale.

Its hopping motion is driven by a mechanical spring, similar in design to that found in a click-top pen. As the robot lands, its spring stores kinetic energy and releases it to propel the next jump. To mitigate energy loss caused by imperfect materials, the robot uses four flapping-wing mechanisms powered by soft actuators – components designed to withstand repeated impact without damage. These wings not only maintain the robot’s stability mid-flight but also assist in take-off and directional control.

A motion-tracking system, combined with a control algorithm, determines the robot’s landing and adjusts its orientation and energy input accordingly. This allows it to react in real time to changes in terrain or slope. Tests demonstrated the robot’s ability to perform flips and to transition smoothly between surfaces with different levels of traction or incline.

One advantage of this hopping mechanism is its efficiency in carrying additional components. Unlike flying robots, which typically sacrifice payload for agility, this hopper can carry around 10 times its weight. The team believes this opens the door to equipping it with onboard batteries, sensors, or microprocessors – enabling autonomous operation in the field.

The research, published in Science Advances, involves collaboration between MIT and institutions including the University of Hong Kong and the City University of Hong Kong.

While numerous miniature robots have been developed with search and rescue in mind, this design offers occupies a middle ground in terms of adaptability, retaining energy efficiency, and having a compact footprint, while also achieving rapid, repeated motion over rough surfaces and carrying comparatively larger onboard systems – making it especially suited for tasks requiring agility, endurance, and payload capacity in challenging environments.