Cornell engineers provide vision for robots with ‘embodied energy’

Humans and other animals store energy using body fat, but that tissue also plays an important role in regulating temperature, producing hormones and protecting vital organs. Robots, too, can benefit from energy sources being integrated throughout their structures. It’s an emerging concept called “embodied energy,” and it could change the field of autonomous robotics, according to Cornell engineers writing in the journal Nature.

The perspective article “Towards enduring autonomous robots via embodied energy,” published Feb. 16 and was co-authored by Robert Shepherd, associate professor in the Sibley School of Mechanical and Aerospace Engineering, graduate student Cameron Aubin, and researchers from eight other universities and labs.

The article examines how system integration and multifunctionality in nature has inspired a new paradigm for powering autonomous robots.

“Whereas most untethered robots use batteries to store energy and power their operation, recent advancements in energy-storage techniques enable chemical or electrical energy sources to be embodied directly within the structures and materials used to create robots, rather than requiring separate battery packs,” write the authors.

“By housing the energy supply directly within the robot’s architecture and materials, it is readily available for use, can be efficiently converted into useful work and, ideally, can be replenished through onboard energy-harvesting mechanisms,” the authors write. “For example, batteries can be configured to serve load-bearing or architectural functions. Compliant materials and actuators can provide structure while storing and reusing elastic energy.”

The article details potential embodied energy systems using specific energy-storage and transduction methods, highlights embodied energy design principles, and outlines challenges and future advancements for the field.

It also provides examples of how some research groups have been achieving this design philosophy. One example is an aquatic soft robot engineered in Shepherd’s Organic Robotics Lab. The robot, detailed in its own 2019 Nature paper, includes a synthetic vascular system capable of pumping an energy-dense hydraulic liquid that stores energy, transmits force, operates appendages and provides structure, all in an integrated design.

“We’re hoping that this perspective piece motivates other robotics researchers to focus more on multifunctionality when developing new energy storage systems. This design philosophy brings us a lot closer to a reality where robots can operate independently in the field for extremely long durations,” Cameron said.

He added: “What excites me most about embodied energy is the prospect of robots that can seamlessly exist within their own environments, whether that be an office building or a tropical rainforest. The idea of a highly efficient robot that can harvest energy directly from its surroundings, store it, and use it to power control systems and muscle-like actuators – that’s a really compelling image. We’re a long way away from that reality, but designing with embodied energy in mind can help us approach that goal.”

The authors were funded by the Office of Naval Research, Air Force Office of Scientific Research, and the National Science Foundation.