A team led by researchers at the University of Gothenburg has developed an inchworm-inspired soft robot that could help future planetary missions navigate harsh and unpredictable terrain with fewer electronics and lower power demands.

The project, backed by the European Space Agency (ESA), uses artificial muscles instead of traditional motors and rigid joints. Researchers say the design could eventually help robots move through rocky, uneven environments on Mars or the Moon while surviving radiation exposure and mechanical damage.

Unlike conventional planetary rovers, the soft robot is built around a rolled dielectric elastomer actuator (RDEA), a flexible artificial muscle that contracts and expands when voltage is applied. The movement allows the robot to crawl forward in a motion similar to an inchworm.

Researchers say the approach reduces mechanical complexity while improving adaptability on irregular surfaces where rigid robots may struggle.

Radiation-ready soft crawler

The actuator uses compliant electrodes made from single-walled carbon nanotubes (SWCNTs), which researchers say can tolerate damage while also offering partial shielding against Martian radiation.

Experiments and simulations showed the material could withstand alpha and proton particle exposure at 10 MeV energy levels. The robot also operates at relatively low voltages, reducing power requirements and lowering the risk of system failure during long-duration missions.

“The core challenge we were trying to solve was achieving multidirectionality in soft robots without the need for complex electronics or multiple actuators,” explained Dr. Hari Prakash Thanabalan, lead researcher at the University of Gothenburg.

“The inchworm became a model due to its simple yet effective design – its locomotion is controlled mainly by contraction and extension of its body, which makes it a well-suited source of inspiration for a robot that needs to adapt to the surface on which it moves.”

ESA officials say the technology could support future space exploration systems that must continue operating even after sustaining damage.

“The key enabling technology is the rolled dielectric elastomer actuator – a cylindrical artificial muscle that continues to function even when partially cut or punctured,” said Ugo Lafont, ESA’s Space Materials and Technology Specialist.

Grooves guide movement

During testing, researchers discovered the robot could steer itself simply by interacting with grooves patterned into the test surface. The finding was accidental but opened a new research direction for passive robotic navigation.

The team observed the robot’s legs hooking into grooves on 3D-printed substrates, causing it to align with the groove direction as it moved. Researchers then tested different groove angles ranging from 0 degrees to 30 degrees.

As the groove angle increased, the robot adjusted its direction more strongly, allowing it to perform left and right turns without extra actuators or onboard steering electronics.

“Initially we tested the robot on groove angles that were perpendicular to the direction of motion,” Thanabalan said. “We realised that the robot was ‘hooking’ its front legs onto the grooves on the surface.”

Researchers say the current setup still works in controlled laboratory conditions and is not yet ready for real planetary terrain. The next phase includes testing the robot under thermal cycling and radiation exposure while integrating lightweight sensing systems.

The team also plans to test the robot at ESA’s Mars Yard facility in the Netherlands, which simulates extraterrestrial terrain. The project, titled “Soft Annelid-Inspired Robot with Peristaltic Gait using Low Voltage Fault-Tolerant Artificial Muscles for Planetary Exploration,” was funded through ESA’s Discovery program.