Small, autonomous robots that can access tight environments could help in future search and rescue operations and inspecting infrastructure details that are difficult for humans or larger bots to access. However, traditional, rigid motors that many robots rely on are difficult to miniaturize to these scales because they break easily when they get smaller or can no longer overcome frictional forces.
Now researchers have developed a muscle-based elasto-electromagnetic system that can create insect-sized models. “soft” robots from flexible materials. “It became clear that existing soft robotic systems of this scale still lack efficient and autonomous actuators,” says Hanqing JiangProfessor of Mechanical Engineering at Westlake University in Hangzhou, China. Instead, they “often require sharp incentives, such as high voltagestrong external fields or intense light that interfere with their use in the real world.”
Muscles function similarly drivesin which parts of the body move due to the contraction and relaxation of muscle fibers. When connected to the rest of the body, the brain and other electrical systems of the body allow animals perform a range of movements, including movement patterns that generate disproportionately large forces compared to their body weight.
Muscle-inspired drive technology
The new drive is made from a flexible silicone polymer called polydimethylsiloxane. neodymium magnetand an electric coil intertwined with soft magnetic iron. spheres. The researchers made the actuators using a 2D casting process that allows them to be produced at millimeter, centimeter and decimeter scales. It can also be scaled to larger and more powerful software devices. “We shifted the focus from material response to structural design of soft materials and combined it with static magnetic forces to create a new actuator,” says Jiang. The researchers published their work in Natural communications.
The new actuator is able to contract like a muscle, using a balance between elastic and magnetic forces. When the drive is compressed, it generates an electric current to create a Lorentz force between the electric coil and neodymium magnet. The actuator then deforms as the iron spheres react to the increased force, which can be used to power the robot itself. The flexible polymer ensures that the system can both deform and return to its original state when current is no longer applied.
The system tested by the researchers achieved a force output of 210 newtons per kilogram, a low operating voltage of below 4 volts and is powered by onboard batteries. It can also undergo large deformations, with compression rates of up to 60 percent. The researchers made it more energy efficient by not requiring a continuous supply of power to maintain a stable state when the actuator is not moving—a method similar to how clams stay in place by using their catch muscles, which can maintain high tension for long periods of time by binding thick and thin muscle fibers together to conserve energy.
Autonomous size of insect Soft robots
Researchers used actuators to develop a series of insect-sized soft robots that could exhibit autonomous adaptive movements of crawling, swimming and jumping in a variety of environments.
One such series of beetle-sized bots was a group of compact soft crawler caterpillars measuring just 16 by 10 by 10 millimeters and weighing just 1.8 grams. The robots were equipped with a translational joint, a voltage of 3.7 V (30 milliamp-hours). lithium ion batteryand an integrated control circuit. This setup allowed the robots to crawl using successive contractions and relaxations—much like a caterpillar. Despite its small size, the crawler robot demonstrated a force output of 0.41 N, which is 8 to 45 times greater than existing insect-sized soft crawler robots.
This force output allowed the robot to negotiate difficult terrain, including soil, rough stone, PVC, glass, wood, and slopes ranging from 5 to 15 degrees, while maintaining a constant speed. Beetle bots have also been found to be highly resistant to impacts and falls. They were not injured and continued to work even after falling from a 30-meter height from the building wall.
The researchers also developed crawler robots measuring 14 x 20 x 19 mm, weighing 1.9 g and having an output force of 0.48 N that crawled like inchworms. They used rotary elasto-electromagnetic joints to move their legs forward and backward and weighed only 1.9 g. The researchers also built The floating robot measures 19x19x11 mm, weighs 2.2 g and has an output force of 0.43 N.
In addition to testing how the bots move on different surfaces, the researchers built a series of obstacle courses for them to navigate while performing touch operations. The caterpillar bot was placed on an obstacle course with narrow and complex paths and used a humidity sensor to detect sources of moisture. The swim bots were tested both in the laboratory and in the river. A track was built in the laboratory where the swimmer had to perform chemical probing operations in a narrow chamber using a built-in miniature device. ethanol gas detector.
Jiang says researchers are now looking at developing sensor-rich swarms of robots capable of distributed sensing, decision-making and collective behavior. “By coordinating the work of many small robots, we aim to create systems that can cover larger areas, adapt to dynamic environments and respond more intelligently to complex tasks.”
Jiang says they are also exploring the possibility of flight and other swimming movements enabled by the elasto-electromagnetic system. including jellyfish-like soft robot for deep sea exploration and marine exploration.
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