The inchworm may not be the first thing that springs to mind when you think of planetary explorers, but a recent ESA Discovery activity led by the University of Gothenburg looked to one of nature's most elegant crawlers for a new approach to soft robot locomotion. This project, funded by ESA's Discovery element, aimed to create a robot that could explore other planets with minimal power and maintenance, while withstanding extreme temperatures and radiation. The key innovation was the use of a dielectric elastomer actuator (DEA) - a type of artificial muscle that mimics biological muscle in its ability to deform significantly, respond quickly, and store and release energy efficiently. The team built their robot around this DEA, using a rolled version (RDEA) to drive the inchworm-like motion by contracting and extending axially.
One of the critical challenges for planetary exploration robots is operating reliably in harsh radiation environments. The compliant electrodes in the DEA, made from single-walled carbon nanotubes (SWCNTs), offer fault-tolerant properties that can withstand mechanical damage and provide partial shielding against Martian radiation, specifically alpha and proton particles. This feature significantly extends the operational lifespan of the robot, which is crucial when it's millions of kilometres away from a repair technician. The design also operates at relatively low voltages, reducing power consumption and minimizing the risk of failure.
Dr. Hari Prakash Thanabalan, the project's lead researcher, explains that the core challenge was achieving multidirectionality in soft robots without complex electronics or multiple actuators. The inchworm's simple yet effective design, controlled mainly by contraction and extension of its body, inspired the robot's locomotion. Biomimicry, the practice of imitating nature, is increasingly central to advanced space concepts, and this project is a testament to that.
An unexpected discovery was made during testing. The robot's legs were hooking onto 3D-printed substrates with groove patterns, causing it to align itself with the groove direction. By varying the groove angle, the team demonstrated that passive surface interaction alone could steer the robot precisely. This finding opens up a new line of research, suggesting that complex onboard control systems could be substituted with simpler, lighter, and more resilient surface interaction mechanisms.
The next steps for the research include improving the robot's robustness to thermal cycling and radiation exposure, integrating sensors for more intelligent environmental response, and combining the groove-guided principle with onboard sensors and feedback systems for natural terrain navigation. The long-term goal is to test the robot on terrain that mimics other planets' surfaces, such as the Mars Yard at ESA's ESTEC facility, as a step towards validating its performance under realistic exploration conditions.
In conclusion, this project showcases the potential of biomimicry in robotics and space exploration. By drawing inspiration from nature's elegant designs, such as the inchworm, we can create robots that are more adaptable, efficient, and resilient. As the design matures, the incorporation of multiple actuators could enable not only locomotion but also controlled steering, independent of the terrain's texture, bringing us one step closer to truly autonomous planetary explorers.
