robotic construction references: Soft robots

Soft Robotics is the specific sub-field of robotics dealing with constructing robots from highly compliant materials, similar to those found in living organisms. Similarly, soft robotics also draws heavily from the way in which these living organisms move and adapt to their surroundings. In contrast to robots built from rigid materials, soft robots allow for increased flexibility and adaptability for accomplishing tasks, as well as improved safety when working around humans. (via: https://en.wikipedia.org/wiki/Soft_robotics)

Biology has long been a source of inspiration for engineers making ever-more capable machines. Softness and body compliance are salient features often exploited by biological systems, which tend to seek simplicity and show reduced complexity in their interactions with their environment. Several of the lessons learned from studying biological systems are now culminating in the definition of a new class of machine that we, and others, refer to as soft robots. Conventional, rigid-bodied robots are used extensively in manufacturing and can be specifically programmed to perform a single task efficiently, but often with limited adaptability. Because they are built of rigid links and joints, they are unsafe for interaction with humans. A common practice is to separate human and robotic work spaces in factories to mitigate safety concerns. The lack of compliance in conventional actuation mechanisms is part of this problem. Soft robots provide an opportunity to bridge the gap between machines and people. In contrast to hard-bodied robots, soft robots have bodies made out of intrinsically soft and/or extensible materials (for example, silicone rubbers) that can deform and absorb much of the energy arising from a collision.
We define soft robots as systems that are capable of autonomous behavior, and that are primarily composed of materials with moduli in the range of that of soft biological materials. (more on)

Characterizing and predicting the behavior of soft multi-material actuators is challenging due to the nonlinear nature of both the hyper-elastic material and the large bending motions they produce. (research on: https://biodesign.seas.harvard.edu/soft-robotics)

Harvard soft robot: Pneumatic octopus is first soft, solo robot

At its heart is a "fluidic logic circuit" where valves act as logic gates, allowing gas to flow and inflate compartments inside the eight separate limbs.

The gas is pumped into that circuit by a little fuel cell filled with hydrogen peroxide, which reacts with particles of platinum left in the system by the printing process.

All Mr Truby and his colleagues had to do - after several years perfecting the design - was to fill the robot with fuel and watch it go.

"We had all the components in place for quite a while, and it took many months trying to bring it all together," he said.

"It was back, I guess last October, there was this one day when it just started working. Michael [Wehner, co-first author] and I looked at each other and thought: OK, we finally did it.

"Several iterations later, we kept fine tuning, and at one point we could just take these things out of the oven, fill them up with fuel and they'd start moving. (via: http://www.bbc.com/news/science-environment-37169109)

Soft robots — which don't just have soft exteriors but are also powered by fluid flowing through flexible channels — have become a sufficiently popular research topic that they now have their own journal, Soft Robotics. In the first issue of that journal, out this month, MIT researchers report the first self-contained autonomous soft robot, a "fish" that can execute an escape maneuver, convulsing its body to change direction, in just 100 milliseconds, or as quickly as a real fish can.
"We're excited about soft robots for a variety of reasons," says Daniela Rus, a professor of computer science and engineering, director of MIT's Computer Science and Artificial Intelligence Laboratory, and one of the researchers who designed and built the fish. "As robots penetrate the physical world and start interacting with people more and more, it's much easier to make robots safe if their bodies are so wonderfully soft that there's no danger if they whack you."
The robotic fish was built by Andrew Marchese, a graduate student in MIT's Department of Electrical Engineering and Computer Science and lead author on the new paper, where he's joined by Rus and postdoc Cagdas D. Onal. Each side of the fish's tail is bored through with a long, tightly undulating channel. Carbon dioxide released from a canister in the fish's abdomen causes the channel to inflate, bending the tail in the opposite direction. (more on: http://news.mit.edu/2014/soft-robotic-fish-moves-like-the-real-thing-0313)

The Project PoseiDRONE aims at providing a disruptive perspective into underwater operations by introducing an entirely new concept of underwater robot. (marine research and also surgery survailance on: http://sssa.marinerobotics.it/research/activegrants/01_PoseiDRONE.php)