Technical breakthroughs in Soft Robotics promise to bring robots into all aspects our daily lives

Robots have already become an indispensable part of our lives. However currently, most robots are relatively rigid machines which make unnatural movements. Inspired by living organisms, soft material robotics hold great promise for areas where robots need to contact and interact with humans, such as manufacturing and healthcare. Unlike rigid robots, soft robots can replicate natural motion – grasping and manipulation – to provide medical and other types of assistance, perform delicate tasks, or pick up soft objects

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.

The emerging field of soft robotics aims to improve robot/human interactivity promising to bring robots into all aspects our daily lives, including wearable robotics, surgical robots, micromanipulation, search and rescue, and others. Soft robots can become aides for the disabled or the elderly if they can be trusted not to hurt the people they come into contact with. Miniature soft robots could even serve as surgical tools inside the body. Robots with greater flexibility could also help in military operations, where level terrain and unobstructed areas are rare, whether as a fully intact robot or as, say, a strap-on arm with a pneumatically controlled hand that could extend the reach, strength or capability of what a person could do.

Soft Robotics arms can come in handy when carrying these soldiers without causing injury. “We have lost medics throughout the years because they have the courage to go forward and rescue their comrades under fire. With the newer technology, with the robotic vehicles we are using even today to examine and to detonate IEDs [improvised explosive devices], those same vehicles can go forward and retrieve casualties,” Major General Steve Jones, commander of the Army Medical Department Center, said. Evacuating casualties was only one of the roles for robots in battlefield medicine that Jones discussed. Another option is delivering medical supplies to dangerous areas, supporting troops operating behind enemy lines.

“Despite its importance and considerable demands, the field of Soft Robotics faces a number of fundamental scientific challenges: the studies of unconventional materials are still in their exploration phase, and it has not been fully clarified what materials are available and useful for robotic applications; tools and methods for fabrication and assembly are not established; we do not have broadly agreed methods of modeling and simulation of soft continuum bodies; it is not fully understood how to achieve sensing, actuation and control in soft bodied robots; and we are still exploring what are the good ways to test, evaluate, and communicate the soft robotics technologies,” says IEEE Robotics and Automation Society.

Researchers are experimenting with different materials and designs to allow  rigid, jerky machines to bend and flex in ways that mimic and can interact more naturally with living organisms. However, increased flexibility and dexterity has a trade-off of reduced strength, as softer materials are generally not as strong or resilient as inflexible ones, which limits their use.

Scientists are also studying how soft robots could lead to major breakthroughs in the development of self-repairing, growing and self-replicating robots, according to the IEEE Robotics and Automation Society. Borgatti explained how soft robots can react to their environments – a major factor for future government use. For example, soft robots can be designed to navigate difficult terrain like shifting sand and fall without being damaged – picking themselves up and correcting their course.

Soft Robotics

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.

They are crucial in the systems that deal with uncertain and dynamic task-environments, e.g. grasping and manipulation of unknown objects, locomotion in rough terrains such as ocean floor, and physical contacts with living cells and human bodies. These robots must move over rough terrain without getting stuck and need manipulators that can grab whatever strangely shaped Soft and deformable structure objects they encounter.

Number of researchers have been investigating unconventional materials for robotic systems, in which soft materials such as polymer based materials are examined for novel sensory devices and actuators. The newly developed smart materials, sensors and actuators were then integrated into micro-robots of various kinds. Also the flexible body structures of animals were replicated in the reconfigurable robots.

“There is a great need in the health care system for lightweight, lower-cost wearable exoskeleton designs to support stroke patients, individuals diagnosed with multiple sclerosis and senior citizens who require mechanical mobility assistance,” said Larry Jasinski, CEO of ReWalk. Currently in the United States, there are an estimated 3 million stroke patients and 400,000 MS patients who are suffering from limited mobility due to lower limb disabilities.

Many industries are searching for new ways to use robots, including developing machines that can work alongside humans and those that are more versatile than the single-task assembly line bots of years past. Company Soft Robotics has developed fingerlike grippers are made of flexible material, such as silicone, and powered by compressed air especially useful in warehouse and assembly line markets — particularly in the food industry, where robots aren’t typically trusted to handle delicate items like fresh produce.



Scientists develop robot that can feel

Group of roboticists in the Department of Biomedical Engineering at the Georgia Institute of Technology in Atlanta,  has developed a robot arm that moves and finds objects by touch. In a paper published in the International Journal of Robotics Research, the Georgia Tech group described a robot arm that was able to reach into a cluttered environment and use “touch,” along with computer vision, to complete exacting tasks.

Dr. Kemp said the researchers using digital simulations and a simple set of primitive robot behaviors were able to develop algorithms used gave the arm qualities that seemed to mimic human behavior. For example, the robot was able to bend, compress and slide objects. Also, given parameters designed to limit how hard it could press on an object, the arm was able to pivot around objects automatically.

The arm was designed to essentially have “springs” at its joints, making it “compliant,” a term roboticists use to define components that are more flexible and less precise than conventional robotic mechanisms. Compliance has become increasingly important as a new generation of safer robots has emerged.The robot also has an fabric based artificial “skin” equipped with force sensors and thermal sensors that can sense pressure or touch enabling the home care robot to lightly touch different materials and identify it.

According to Georgia Tech, Director of the Healthcare Robotics Lab at Georgia Tech Charles C. Kemp said that, “These environments tend to have clutter. In a home, you can have lots of objects on a shelf, and the robot can’t see beyond that first row of objects.” The combination of the sensors can help the home care robot to know the difference between wood and metal. The experts from IEEE Spectrum indicate that the technique copies the way how the human skin uses thermal conductivity to classify different materials.

New robot has a human touch

A group led by Robert Shepherd, assistant professor of mechanical and aerospace engineering and principal investigator of Organic Robotics Lab, has published a paper describing how stretchable optical waveguides act as curvature, elongation and force sensors in a soft robotic hand.

“Most robots today have sensors on the outside of the body that detect things from the surface,” Doctoral student Huichan Zhao is lead author of “Optoelectronically Innervated Soft Prosthetic Hand via Stretchable Optical Waveguides,”  said. “Our sensors are integrated within the body, so they can actually detect forces being transmitted through the thickness of the robot, a lot like we and all organisms do when we feel pain, for example.”

Optical waveguides have been in use since the early 1970s for numerous sensing functions, including tactile, position and acoustic. Fabrication was originally a complicated process, but the advent over the last 20 years of soft lithography and 3-D printing has led to development of elastomeric sensors that are easily produced and incorporated into a soft robotic application.

Shepherd’s group employed a four-step soft lithography process to produce the core (through which light propagates), and the cladding (outer surface of the waveguide), which also houses the LED (light-emitting diode) and the photodiode.

The more the prosthetic hand deforms, the more light is lost through the core. That variable loss of light, as detected by the photodiode, is what allows the prosthesis to “sense” its surroundings.

“If no light was lost when we bend the prosthesis, we wouldn’t get any information about the state of the sensor,” Shepherd said. “The amount of loss is dependent on how it’s bent.”

The group used its optoelectronic prosthesis to perform a variety of tasks, including grasping and probing for both shape and texture. Most notably, the hand was able to scan three tomatoes and determine, by softness, which was the ripest.

This work was supported by a grant from Air Force Office of Scientific Research, and made use of the Cornell NanoScale Science and Technology Facility and the Cornell Center for Materials Research, both of which are supported by the National Science Foundation.

Robot Octopus Points the Way to Soft Robotics with Eight Wiggly Arms

Cecilia Laschi, professor at the BioRobotics Institute at the Scuola Superiore Sant’Anna, in Pisa, Italy, and her team are investigating soft robots that mimic the form of the octopus. “The octopus has neither an internal nor external skeleton, and its eight arms can bend at any point, elongate and shorten, and stiffen to apply force. It can twist its arms around objects and manipulate them with great dexterity,” she writes. Team has already built robot octopus that could crawl along the seafloor mimicking locomotion of octopus.

The team is creating artificial muscles using materials called shape-memory alloys (SMAs). “When heated, SMAs deform to a predefined shape, which they “remember.” We fashioned SMA wires into springs and ran electric current through them to heat them, causing the springs to scrunch up in a way that imitates muscular contractions.”

“For the Octopus project, my team constructed a prototype arm using SMA springs to stand in for the longitudinal and transverse muscles found in the limbs of a real octopus. By sending current through different sets of springs, we made the underwater arm bend at multiple points, shorten and elongate, even grasp things,” she explains.

“Our work is primarily meant to demonstrate the potential of soft robotics, and much work remains before a robot octopus will be ready to crawl out of the lab.”

Harvard researchers have created the first soft octopus robot that is completely self-contained. It is basically a pneumatic tube has no hard electronic components—no batteries or computer chips—and moves without being tethered to a computer.

The octobot is powered by hydrogen peroxide is pumped into two reservoirs inside the middle of the octobot’s body. Pressure pushes the liquid through tubes inside the body, where it eventually hits a line of platinum, catalyzing a reaction that produces a gas. From there, the gas expands and moves through a tiny chip known as a microfluidic controller.

It alternately directs the gas down one half of the octobot’s tentacles at a time which enables octopus to wiggle its tentacles. The octobot can move for about eight minutes on one milliliter of fuel.

“You have to make all the parts yourself,” says Ryan Truby, a graduate student in Jennifer Lewis’s lab at Harvard, where the materials half of this research is taking place. The mold for the octopus shape and the microfluidic chip were among the things developed nearby in Robert Woods’s lab.

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 fast

The 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.


Soft Robotic Fingers Recognize Objects by Feel

Rus and her team at Distributed Robotics Lab at CSAIL have created bendable and stretchable robotic fingers made out of silicone rubber that can lift and handle objects as thin as a piece of paper and as delicate as an egg.

Rus incorporated “bend sensors” into the silicone fingers so that they can send back information on the location and curvature of the object being grasped. Then, the robot can pick up an unfamiliar object and use the data to compare to already existing clusters of data points from past objects.

“By embedding flexible bend sensors into each finger, we got an idea of how much the finger bends, and we can close the loop from how much pressure we apply,” says Katzschmann. “In our case, we were using a piston based closed pneumatic system.”

Currently, the robot can acquire three data points from a single grasp, meaning the robot’s algorithms can distinguish between objects which are very similar in size. The researchers hope that further advances in sensors will someday enable the system to distinguish between dozens of diverse objects.

 Research Challenges

Due to the soft materials used, these robots can not only squeeze into tight spaces, but also recover more easily from collisions and pick up and handle irregularly-shaped objects. However, because of soft robots’ flexibility, they often struggle with correctly measuring where an object is, or whether they actually picked the object up.

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. Key challenges in the design and manufacture of soft robots include the complex fabrication processes and the interfacing of soft and rigid components.

Fully soft sensors that can be incorporated into the actuator design during the manufacturing process are needed to control soft actuators; they provide means of monitoring their kinematics, interaction forces with objects in the environment and internal pressure.

The university research is focused on developing new materials like dielectric elastomers, carbon nanotube yarn and self-healing materials and on designing the controllers and actuators that animate them. New actuator technologies and fabrication approaches will bring about better force-speed operating points, variable impedance, more convenient form factors, and actuators without transmission mechanisms.

Polymer Embedded With Metallic Nanoparticles Enables Soft Robotics

Researchers at North Carolina State University (NCSU), in Raleigh, have developed a technique through movement can be induced into polymer through application of magnetic field by embedding nanoparticles of magnetite—an iron oxide—into a polymer.

“Using this technique, we can create large nanocomposites, in many different shapes, which can be manipulated remotely,” said Sumeet Mishra, lead author of the paper, in a press release. “The nanoparticle chains give us an enhanced response, and by controlling the strength and direction of the magnetic field, you can control the extent and direction of the movements of soft robots.”

In research described in a paper published in the journal Nanoscale, the NCSU researchers describe a process that starts with dispersing the nanoparticles in a solvent. Next, a polymer is dissolved into the mixture and the resulting fluid is poured into a mold. Then a magnetic field is applied that arranges the magnetite nanoparticles into parallel chains. Once the solution dries in the mold, the chains of nanoparticles are locked into place.

“The key here is that the nanoparticles in the chains and their magnetic dipoles are arranged head-to-tail, with the positive end of one magnetic nanoparticle lined up with the negative end of the next, all the way down the line,” said Joe Tracy, an associate professor at NCSU and corresponding author of the paper, in the press release. “When a magnetic field is applied in any direction, the chain re-orients itself to become as parallel as possible to the magnetic field, limited only by the constraints of gravity and the elasticity of the polymer.”


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