Cornell University researchers are building soft robots with “robot blood” that is both hydraulic fluid that provides motive force and at the same time a battery that stores and delivers energy required to power the robots. The resulting body configurations are ideal for both slow long-term ocean exploration and inspection of narrow urban spaces like pipes and buried infrastructure.
“There are a lot of robots that are powered hydraulically, and we’re the first to use hydraulic fluid as the battery, which reduces the overall weight of the robot, because the battery serves two purposes, providing the energy for the system and providing the force to get it to move,” says project leader Rob Shepherd, a professor of mechanical and aerospace engineering.
“So then you can have things like a worm, where it’s almost all energy, so it can travel for long distances.”
It’s all very well to build and deploy humanoid robots in warehouses and factories, but there are plenty of spaces human-sized machines can’t go. They wouldn’t be great for oceanic exploration or monitoring, and they won’t fit into small spaces and pipes that we often forget, but are essential to our modern urban lifestyle.
The problem is size and weight: as the researchers explain, the more energy required, the bigger the robot must be to accommodate space for more energy storage. The solution Cornell scientists hit on is to essentially make the battery the body, maximizing energy storage capacity while minimizing extra weight.
It’s similar in concept to Tesla’s structural battery packs that are batteries but are also structural load-bearing components of the car, or modern aircraft that have wings built as fuel tanks rather than wings that contain fuel tanks.
The Cornell researchers chose a “redox flow battery,” which is largely liquid in nature. They then formed this malleable battery into the shapes of a jellyfish for underwater work, and a worm for infrastructure inspection. This key innovation ensures that “the near totality of the body stores electrochemical potential,” researchers say.
In other words, the body is the battery.
The design is inspired by a 2019 project to build a soft robot in the form of a mechanical lionfish, Cornell says, but improved.
“The jellyfish has much more capacity for its weight, so the duration it can travel is even longer than the fish,” sats Shepherd. “The worm is the first version we’ve done above ground. When it’s underwater, you get buoyantly supported, so you don’t need a skeleton. It doesn’t need to be rigid.”
The worm is not fast.
One charge will allow it to cover 105 meters, or about 344 feet, but it will take the worm 35 hours to move that far. That is just 0.00186 miles per hour, requiring over 6 minutes to travel just one foot, or 20 minutes to move a single meter.
However, this is a lab prototype: future versions and shipping products are likely to be much faster.
The jellyfish, on the other hand, is not designed to swim long distances. It would be carried by ocean currents, using its ability to move simply to swim up to the surface to communicate with scientists, then drift back down to continue collecting data.
Future versions, Shepherd says, could be scaled up to robots with actual skeletons and the capability to walk, making something more like a human body.
