Soft robotics

Soft robotics is the development of robots composed of soft components. In nature, soft body parts are adaptable; the same reasoning applies to robotics. Whereas traditional robotic components are rigid links in a mechanical chain and move in mathematically predictable ways, soft robotics may be soft materials that contain some rigid components or may even be made entirely of soft components. They can conform themselves to their environment and adapt to different situations. Soft robotics also describes the variable resistance of the control systems of the robots.

Development of soft robotics began around 2006. Applications potentially include the biomedical field, the service industry, manufacturing of delicate materials, and surgical procedures.

Background

Although clockwork automatons have been around since at least the Middle Ages, robotics developed primarily to serve industry. George Devol designed the first programmable robot in 1954. He and Joseph Engelberger produced the prototype, the Unimate #001, in 1959. They focused on creating a robotic arm that would perform tasks that put human workers at risk. The prototype was installed in a General Motors die-casting plant in Trenton, New Jersey. Unimate took heated die-castings from machines and performed welds. Industrial robots became common in the auto industry and other manufacturing industries within a short time and grew increasingly complex with the advancement of computer chips. The US space program developed robotic rovers, robotic arms, and experimental robotic astronauts. Other applications include search-and-rescue robots and consumer products such as vacuum cleaners, personal assistant devices, and toys such as robotic animals and building kits.

Traditional robots, with hard components, are not suitable for all applications, however. While industrial robots can pick up hard objects, they are less capable of handling delicate items or items that are not uniform shapes and sizes. They must have multiple controllable joints and force-sensing components to handle such items. Robots meant to interact with humans and other living things may have difficulty with some tasks. Their ability to adapt is limited by their rigid components.

Twenty-first-century soft robotics developers responded with a variety of approaches. Researchers at Harvard University developed a series of soft robots using pneumatic actuation, meaning they use pistons inside hollow cylinders. Pressure moves the piston along its axis, creating linear force, and a spring-back force on the opposite side returns the piston to its original position. Harvard's silicone-based soft robots use a pneumatic network, which inflates and deflates various parts of the soft body to create movement. These and other soft robots were often inspired by living creatures, including caterpillars, starfish, and octopuses. The Octobot developed at Harvard University has no batteries, circuit boards, or other rigid components at all—it is entirely soft.

Topic Today

Soft robotics is developing in two primary areas. One approach involves robots built with rigid links, like traditional robots, with control systems for the interaction with the robot's environment, such as gripping abilities. In simple terms, these robots have rigid skeletal structures and soft exteriors. The other approach involves robots primarily or entirely made of soft materials, which experience vast shape changes in operation. Many of these soft-bodied robots are made of materials that can adjust to various degrees of stiffness.

One development in gripping technology uses soft components to handle the objects, while much of the robot is composed of solid components. A soft sack made of elastic or another material, for example, can be filled with sand. Sand is granular, and when close together, the grains jam together. The sack of sand is connected to a pneumatic component, which allows a gas, such as air, into the sand. The robot lowers the sack onto the object to be gripped and vacuums the gas out of the sand. The granular jamming envelops the object; to release it, the robot puts the gas back into the sack of sand, which unjams the grains, and the sack no longer conforms to the object. In addition to gripping objects of inconsistent size and shape, such granular jamming components can also pick up multiple items at once and place them, in the same configuration, in another location.

Flexible, soft components can be constructed to move in many ways. They can expand, contract, bend, and twist with adjustments to pressurized fluid or gas. For example, a tube can be constructed with a smooth side and a reinforced ribbed side. When unpressurized, the tube is straight; under pressure, the ribbed side expands, forcing the smooth side into a curve. The degree of curvature is determined by the amount of pressure.

Soft robotics development has been aided by polymer science and in particular 3-D printing. Some 3-D printers can create items out of soft, polymer-based materials. This enables roboticists to design and create any shape using soft materials, including silicone, that were previously impossible to build. The Harvard Octobot is one example of this use. The team individually printed each 3-D component needed inside the soft robot body, including fuel storage and power components. Hydrogen peroxide was used as liquid fuel. A reaction using platinum inside the Octobot created gas, which inflated the eight arms. A microfluidic logic circuit controlled the movement.

Soft robotics offers a wide range of possibilities in many fields. Researches have developed soft robotic gloves to help stroke patients grip objects and soft robots that can squeeze through small, irregular gaps during rescue operations. Some researchers are working on rubbery robots that can be used to perform surgery. These devices would operate more gently around soft tissues and organs, reducing risk of injuries such as punctured arteries and organs that have occurred using traditional rigid robotic systems. Researchers are also exploring the possibility of developing a device that would surround a damaged or malfunctioning heart and rhythmically contract to mechanically aid the organ in pumping blood. By 2024, they were also experimenting with using soft robotics to replace damaged muscles and organs and assist with the construction industry.

Bibliography

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