In a breakthrough blending biology, engineering, and environmental exploration, scientists have created a new kind of robot inspired by one of nature’s simplest travelers: the tumbleweed. A recent study published in Nature Communications introduces a hybrid mobile system that merges the effortless wind-driven motion of tumbleweeds with the controlled maneuverability of quadcopters. This new system, called HERMES—short for Hybrid Energy-efficient Rover Mechanism for Exploration Systems—may redefine how robots move across harsh terrain on Earth and other planets.
Why Wind-Driven Robotics Matter
Most robots designed for planetary or terrestrial exploration rely on mechanical parts such as wheels, tracks, or propellers to move. While these systems offer precision and reliability, they consume large amounts of energy. Energy is a precious resource, especially for missions far from Earth, where solar power may be limited and maintenance is impossible.
There have been attempts to use wind-driven designs in the past, including land sails or inflatable rolling spheres. However, these systems often require large structures to catch enough wind, complicated deployment mechanisms, and heavy materials that make them impractical. As a result, researchers have not been able to fully tap into the natural power of the wind—until now.
That changed when Sanjay Manoharan, a Ph.D. researcher at the Laboratory for Advanced Fabrication Technologies at EPFL, found unexpected inspiration in his surroundings.
A Moment of Inspiration on a Windy Afternoon
According to Manoharan, the idea took root during a winter afternoon at Lake Neuchâtel. Watching kite surfers glide with minimal effort across the water, he wondered how that same natural force could be used for robotic mobility. But then he realized that nature had already solved this problem far better than humans had.
His thoughts turned to tumbleweeds—those dry, spherical plants that drift freely across desert landscapes, scattering seeds as they roll. Though they may look chaotic, tumbleweeds have evolved structures that allow them to travel long distances without any energy of their own. This sparked an unexpected scientific question: How do tumbleweeds generate so much motion from so little structure?
This question led to years of research into tumbleweed aerodynamics, ultimately resulting in the hybrid robotic system now known as HERMES.
The Secret Behind Tumbleweed Aerodynamics
Tumbleweeds are far more complex than their tangle of branches suggests. To understand how they interact with wind, the research team used computational fluid dynamics simulations along with wind tunnel testing. What they discovered was a previously unknown feature of their structure: a vertical porosity gradient.
In simple terms, the plant is not equally airy throughout. Instead:
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The top half has about 60% porosity, meaning air flows through it easily.
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The bottom half has about 40% porosity, meaning it is denser and blocks more air.
This uneven porosity dramatically changes how air moves around the plant.
When upright, the porous top lets air pass through while the denser bottom creates more resistance. When flipped, the airflow changes again: the dense portion redirects air like a solid sphere, and the porous bottom creates a twin-lobed wake pattern behind the tumbleweed.
At wind speeds of 12 m/s, the tumbleweed generated 50% more drag than a solid sphere of the same size. That is remarkable because one would expect porous structures to produce less drag, not more.
The team also observed that tumbleweeds experience lift forces depending on their orientation. These forces explain why they sometimes somersault in moderate winds and hop or bounce in stronger gusts. This dynamic behavior helps them travel across uneven and unpredictable ground.
Transforming Nature’s Design Into a Robot
With these aerodynamic insights in hand, the team set out to design a robotic version of the tumbleweed. Using selective laser sintering, they created lightweight spherical shells with engineered porosity gradients similar to those found in natural tumbleweeds.
These artificial spheres offered several advantages:
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They could roll at wind speeds as low as 1 m/s, much gentler than typical desert winds.
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They produced higher drag forces than both natural tumbleweeds and solid spheres.
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They had enough space inside to hold sensors, microelectronics, or even propulsion mechanisms.
Finding the right balance between strength, weight, and porosity was challenging. According to Manoharan, the structure needed to be strong enough to survive impacts, porous enough to generate drag, and spacious enough to carry equipment. Custom computational models helped fine-tune these competing requirements.
Field tests showed the sphere could carry payloads several times its own weight, climb slopes, and spread out across terrain independently. When equipped with GPS and communication systems, multiple spheres could act as a mesh network, relaying geotagged environmental information over large distances.
This capability alone would make the system valuable. But the researchers wanted more.
The Limitations of Purely Passive Motion
Wind-driven motion is incredibly energy-efficient but also unreliable. Without wind, even the best-designed tumbleweed-inspired robot would stop in place. Rough terrain can also trap the sphere in indentations, between rocks, or among plants.
As Manoharan puts it, “When the wind drops or the terrain gets complicated, they get stuck.”
To overcome this challenge, the team added a small quadcopter inside the spherical shell. This addition transformed the system from a passive ball to a hybrid robot capable of choosing between passive rolling and active motion depending on the environment.
The Hybrid HERMES System: Four Modes, One Efficient Strategy
HERMES is built around a simple but powerful philosophy: use energy only when necessary.
The robot can operate in four distinct modes:
1. Tumbling Mode
The sphere rolls naturally with the wind, requiring zero energy. This is the preferred mode and is used whenever possible.
2. Spinning Mode
Brief bursts from the quadcopter reposition the robot to change direction or maximize wind capture. These adjustments often require only 0.25 to 0.5 seconds of motor activity.
3. Gliding Mode
The quadcopter provides slight lift to reduce friction with the ground, allowing smoother movement over flat terrain.
4. Aerial Mode
The sphere can take flight when absolutely necessary—usually to jump over obstacles, escape traps, or reposition itself. Full hover time is limited (around two minutes), but flight is treated as a last resort.
This approach significantly reduces energy use compared with a robot that flies or drives continuously.
Proving the Concept: Laboratory Performance
To demonstrate the effectiveness of their design, the researchers tested HERMES in controlled maze experiments. The results were impressive:
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48% less energy consumption than full active control
(26 mWh vs. 50 mWh) -
37% faster course completion
(105 seconds vs. 166 seconds) -
Up to 95% energy savings using short directional pulses instead of continuous flight
These results highlight how a simple system inspired by nature can outperform sophisticated robots that rely entirely on powered motion.
Potential Applications on Earth and Beyond
The researchers see enormous potential for HERMES across a wide range of environments.
1. Planetary Exploration
On planets like Mars, where wind is abundant and terrain is unpredictable, a swarm of HERMES robots could travel great distances with very little energy.
Rather than following pre-planned routes, they could:
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drift naturally across the landscape,
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spread out to cover more ground,
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search for biomarkers or signs of life,
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and adapt to environmental conditions on the fly.
Given the high risk and cost of planetary missions, a passive-driven swarm could revolutionize exploration strategies.
2. Disaster Response
In disaster zones where humans cannot safely enter—such as areas with radiation leaks, toxic chemical plumes, or collapsed structures—HERMES could provide critical data. Wind-driven robots could drift through hazardous areas while relaying information through GPS and wireless mesh networks.
3. Landmine Detection
Regions in Ukraine, Afghanistan, Yemen, and other conflict zones require safe ways to detect mines without risking lives. HERMES robots could roll across dangerous fields, using lightweight sensors to identify buried hazards.
4. Environmental Monitoring
Large areas of farmland, forests, or coastlines could be monitored passively, reducing the need for drones or vehicles that consume more energy.
However, the team did encounter some limits. Tall grass can trap the sphere, and flight endurance remains limited. But ongoing research aims to address these issues.
What Comes Next: Smarter, More Independent Robots
Future versions of HERMES may include:
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On-board autonomy driven by IMU-based decision-making
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Swarm coordination that allows robots to collaborate without human input
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Solar harvesting systems to extend mission life
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Adaptive shells that change porosity depending on wind speed
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Improved flight systems for longer airborne operation
Early lab experiments have already shown that short, well-timed bursts from the quadcopter can reorient the robot in ways that maximize wind capture. The system is learning to “sail” more effectively, just as Manoharan envisioned.
A Return to the Original Insight
Reflecting on the project, Manoharan emphasizes the elegance of letting nature take the lead. Rather than fighting against the environment, HERMES embraces it.
The entire project began with a simple question:
What if robots stopped fighting the wind—and started using it instead?
This shift in thinking led to a system that is lighter, more robust, and far more energy-efficient than traditional designs. By learning from tumbleweeds, researchers have created a technology that could explore worlds both familiar and alien in ways we never imagined.
Conclusion
The development of HERMES marks a major milestone in robotics. By combining biological inspiration with cutting-edge engineering, the research team has created a hybrid robot capable of traversing harsh landscapes using almost no energy. Its tumbleweed-like structure allows it to roll freely with the wind, while its internal quadcopter provides the agility needed to escape obstacles or navigate complex terrain.
The implications of this work extend far beyond robotics. It challenges the assumption that machines must always rely on active power to move. Sometimes, the most efficient solution is to let the world move you.
From Mars exploration to minefield mapping, the future of autonomous mobility may very well roll forward on the same principles that have guided desert plants for millions of years.
HERMES offers us a glimpse of that future: a future where innovation and nature move together, carried by the wind.
Reference: Manoharan, S., Lemecho, B., Fadlelmula, M.M. et al. Tumbleweed-inspired robots with hybrid mobility for terrestrial exploration. Nat Commun (2025). https://doi.org/10.1038/s41467-025-66513-1
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