Soft robotics differ from traditional counterparts in some important ways: Soft robots have little or no hard internal structures. Instead they use a combination of muscularity and deformation to grasp things and move about. Rather than using motors, cables or gears, soft robots are often animated by pressurized air or liquids. In many cases soft robotics designs mimic natural, evolved biological forms hence also called bio-inspired robots. This, combined with their soft exteriors, can make soft robots more suitable for interaction with living things or even for use as human exoskeletons.
In 2015, NASA began studying the use of a soft, tentacled robots that could some day explore watery moons like Jupiter’s Europa. The US Military is seeking to harness the flexibility of invertebrate creatures to produce robots that benefit from less structural rigidity than what robotics currently allows for. The results suggest a 3D printed robotic squid may be among the next generation of military robots. These robots would be better equipped for working in cramped spaces, using range of movement rather than sheer propelling force.
Soft robots have received an increasing attention due to their advantages of high flexibility and safety for human operators but the fabrication is a challenge. Recently, 3D printing has been used as a key technology to fabricate soft robots because of high quality and printing multiple materials at the same time. Functional soft materials are particularly well suited for soft robotics due to a wide range of stimulants and sensitive demonstration of large deformations, high motion complexities and varied multi-functionalities.
With the advent of three-dimensional (3D) printing technologies, a wider variety of geometries and materials became accessible for the fabrication of soft actuators. Because of their ease in processing, biocompatibility, and high stretchability, silicones have been the material of choice in this newer generation of actuators. 3D printing platform is also being used for the seamless digital fabrication of pneumatic silicone actuators exhibiting programmable bioinspired architectures and motions.
In 2016, team of researchers at Case Western Reserve University created a robot made from the muscle of a sea slug in a flexible 3D-printed polymer body. Robots such as these could be used in surveillance and search missions in the ocean.
The development of soft actuators is fundamental to the advancement of soft robots and bio-inspired machines. Researchers have recently created a prototype of soft 3D-printed dielectric elastomer actuator — an electroactive polymer that changes shape when hit with an electrical charge. This 3D-printed actuator can make extreme bending motions, which means it could be used to fit through spaces humans can’t maneuver.
The researchers also want to design these flexible robots to be self-aware, self-sensing and capable of adjusting their own shapes to adapt to different external and internal conditions, according to Ed Habtour, an ARL researcher who specializes in nonlinear structural dynamics.
US military studies invertebrates for 3d printing active materials in robots
US Military scientists and researchers at the University of Minnesota (UMN) have developed an advanced 3D printer capable of creating “soft” robots. Named the Solider, this printer is essentially an autonomous FFF/FDM platform designed around our current understanding of invertebrate mobility.
According to Dr. Ed Habtour, a researcher at the Army Research Laboratory, “Successful stealthy maneuvering requires high structural flexibility and distributive control to sneak into confined or restricted spaces, operate for extended periods, and emulate biological morphologies and adaptability.”In addition, the Solider “can print functional materials and devices – to generate soft actuators and potentially tether-less soft robots on demand, on the fly, and at the point of need.”
Prof Michael McAlpine of UMN also described the team’s approach to developing this technology, “In the initial phase of the project, our team began by investigating new methods for emulating the location of invertebrates, which provided fundamental insights into the machineries of their soft distributed actuation circuitries that allow for high bending motions without skeletal support.”
Magnetic Soft Robots Could Perform Military Tasks
Investigators at the Army’s Institute for Soldier Nanotechnologies (ISN), located at MIT, have developed a 3-D printing platform that can enable both the modeling and design of complex magnetically actuated devices. ISN’s mission is to help the Army dramatically improve the protection and survivability of the Soldier by working at and extending the frontiers of nanotechnology.
The technology utilizes a 3-D printing platform fitted with an electromagnet nozzle and a new type of 3-D printable ink infused with magnetic particles.The findings could lead to new biomedical applications, magnetic ink optimized to strengthen soft robotic functionality, and new on-demand flexible material systems for integration into Soldier systems.
This research provided new insight on ways to cause fast changes in 3-dimensional shapes of parts such as robot’s limbs, said research manager, Dr. Aura Gimm. “The MIT group demonstrated this success using auxetic metamaterials — synthetic composite materials that have an unusual internal structure and the unusual property that when exposed to external magnetic actuation, they shrank in both longitudinal and transverse directions.”
“Such complex shape-morphing structures could have great potential for the Army, because they may help create soft robots – robots with pliable limbs similar to natural organisms. Compared to the current generation of rigid robots, soft robots could move much more dexterously on a complex battlefield terrain,” said Army Research Laboratory Dr. Alex Hsieh.
Functions demonstrated from these complex shape changes include reconfigurable soft electronics, mechanical metamaterial that can jump, and a soft robot that can crawl, roll, catch fast moving objects or deliver pharmaceuticals.Although other groups have fabricated magnetically activated materials to accomplish simple movements, this new approach enables both the modeling and the design of magnetically controlled device sections to perform complex Army-relevant soft robotic tasks.
Harvard Engineers Create a 3D Printed Autonomous Robot
SEAS researchers have built one of the first 3-D printed, soft robot that moves autonomously. The design offers a new solution to an engineering challenge that has plagued soft robotics for years: the integration of rigid and soft materials.
The robot is constructed of two main parts: a soft plunger like body with three pneumatic legs and the rigid core module, containing power and control components and protected by a semisoft shield created with a 3-D printer. This integration of the rigid components with the body of the soft robot through a gradient of material properties eliminates an abrupt, hard-to-soft transition that is often a failure point.
This design combines the autonomy and speed of a rigid robot with the adaptability and resiliency of a soft robot and, because of 3-D printing, is relatively cheap and fastThe robot is combustion-powered, to initiate movement, the robot inflates its pneumatic legs to tilt its body in the direction it wants to go. Then butane and oxygen are mixed and ignited, catapulting the robot into the air. It’s a powerful jumper, reaching up to six times its body height in vertical leaps and half its body width in lateral jumps. In the field, the hopping motion could be an effective way to move quickly and easily around obstacles.
“The wonderful thing about soft robots is that they lend themselves nicely to abuse,” said Nicholas Bartlett, first author of the paper and a graduate student at SEAS. “The robot’s stiffness gradient allows it to withstand the impact of dozens of landings and to survive the combustion event required for jumping. Consequently, the robot not only shows improved overall robustness but can locomote much more quickly than traditional soft robots.”The robot’s jumping ability and soft body would come in handy in harsh and unpredictable environments or disaster situations, allowing it to survive large falls and other unexpected developments.
3D-Printed ‘Bionic Skin’ Could Give Robots the Sense of Touch
Engineering researchers at the University of Minnesota have developed a revolutionary process for 3D printing stretchable electronic sensory devices that could give robots the ability to feel their environment. The discovery is also a major step forward in printing electronics on real human skin.
This ultimate wearable technology could eventually be used for health monitoring or by soldiers in the field to detect dangerous chemicals or explosives.“While we haven’t printed on human skin yet, we were able to print on the curved surface of a model hand using our technique,” McAlpine said. “We also interfaced a printed device with the skin and were surprised that the device was so sensitive that it could detect your pulse in real time.”
McAlpine and his team made the unique sensing fabric with a one-of-a kind 3D printer they built in the lab. The multifunctional printer has four nozzles to print the various specialized “inks” that make up the layers of the device—a base layer of silicone, top and bottom electrodes made of a conducting ink, a coil-shaped pressure sensor, and a sacrificial layer is later washed away in the manufacturing process. “This is a completely new way to approach 3D printing of electronics,” McAlpine said. “We have a multifunctional printer that can print several layers to make these flexible sensory devices. This could take us to so many directions from health monitoring to energy harvesting to chemical sensing.