Robot Technology: Physicists Reveal Secrets of Automatic Stopping!

Robot Technology: Physicists Reveal Secrets of Automatic Stopping!

Physicists at the Heinrich Heine University Düsseldorf (HHU) and the University of La Sapienza in Rome have discovered how active robots can be stopped by impacts by losing their kinetic energy through static friction. This technology could have wide-ranging applications, particularly in robotics, where efficiency and energy consumption are key issues. The results of this study were published in the prestigious journal Nature Communications and show that static friction, when it occurs between robots, is very effective in bringing them to a standstill.

The key to this research lies in the phenomenon of static friction, which ensures that two solids remain at rest until a critical angle of inclination is exceeded. The experiments used 3D printed mini-robots powered by a vibrating plate. These robots exhibited fascinating stop-and-go behavior, forming clusters where they were “cold” when occupancy density was high and driving force was low.

Friction as a motor and brake

As the research shows, the scientists expect that the complexity of friction behavior can create dynamic clusters that contain both cold and hot areas. This is a balance not normally achieved and it explains the competition between activity and coulomb friction. First author of the study Dr. Alexander Antonov made a significant contribution to recreating this physical mechanism through model simulations. Prof. Caprini emphasizes that the system works extremely autonomously, cooling itself through shocks without the need for external intervention.

These insights into friction also offer promising perspectives for future applications. Prof. Löwen sees opportunities to automatically control the collective behavior of robots and bulk materials. Using static friction to save energy could be important for various technologies in the future, including vehicle tires.

Insights into applications and mechanisms

The influence of friction on technical systems is often underestimated. Dynamics in mechanical engineering shows that nonlinearities in structure and contact are crucial, especially in applications such as vehicle drives where friction plays a role. Various research projects in this area, such as studies of stability and bifurcation under the influence of friction, have contributed to sharpening the understanding of friction behavior. These findings are relevant not only for mechanical systems, but also for cell biological questions.

Another consideration is the use of lubricants, which are often used to reduce wear and improve heat transfer. However, these add additional complexity to the existing friction mechanisms. Research into fluid reduction aims to promote environmentally sustainable solutions, which could represent a significant step in the right direction.

Considering the diverse implications and mathematical analogy that exists between friction and other dynamic problems in engineering, it is clear that a deeper understanding of friction and its effects is of great importance for the future. Innovative approaches to research will help to further develop technologies and find new solutions.

The original publication is entitled “Self-sustained frictional cooling in active matter” by Antonov et al. (2025) can be found in Nature Communications: here.

For detailed information on the mathematical models and their applications in research, as well as current publications in the field of friction, we refer to the work of Kassel University and further findings of the Technical University of Braunschweig.