Magnetically driven soft robot achieves high-speed jumping

Image outlining the proposed bistable soft jumper and its fabrication. Credit: Tang et al. (Science Robotics, 2024).

Many animal species, ranging from insects to amphibians and fish, use jumping as a means of moving within their surrounding environment. Jumping can be very advantageous for these animals, for instance, allowing them to reach higher branches of trees, swiftly escape from predators or move faster across long distances.

Many roboticists have been trying to develop robots that can replicate the jumping locomotion styles observed in animals, as these robots could have interesting real-world applications. By jumping, robots could move faster on complex terrains and gain access to surfaces or environments that they might otherwise be unable to reach.

The jumping robots introduced in recent years rely on various actuating methods, ranging from dielectric elastomers to liquid crystal elastomers and soft actuators. While some of these robots achieved promising results, most of them were found to lag behind living organisms that are highly skilled jumpers, both in terms of how high and how fast they can jump.

Researchers at Zhejiang University in China recently developed a new ultrafast, magnetically driven and bistable soft jumper that demonstrated advanced jumping capabilities. This jumper, presented in a paper published in Science Robotics, was found to achieve different jumping locomotion styles, jumping higher and faster than comparable robotic systems introduced in the past. 

Credit: Daofan Tang

Soft jumpers, such as the system developed by these researchers, are based on elastic and deformable materials that often have a greater resistance to impact, preventing damage to the robot while jumping. Yet many existing jumpers based on soft materials were found to be limited in terms of the speed with which they respond to stimuli and takeoff from the ground.

"We report a magnetic-driven, ultrafast bistable soft jumper that exhibits good jumping capability (jumping more than 108 body heights with a takeoff velocity of more than 2 meters per second) and fast response time (less than 15 milliseconds) compared with previous soft jumping robots," wrote Daofan Tang, Chengqian Zhang and their colleagues in their paper. "The snap-through transitions between bistable states form a repeatable loop that harnesses the ultrafast release of stored elastic energy."

The researchers created prototypes of their jumper that varied in size and found that smaller jumpers were more affected by air resistance; thus they could not jump as high as bigger jumpers. Nonetheless, the takeoff velocities of the jumpers remained similar, irrespective of their size

Schematic illustration of bistable soft jumper. Credit: Daofan Tang

Notably, the jumper designed by this research team can perform two different types of locomotion, namely jumping and hopping. The researchers carried out tests in a real-world environment to demonstrate the advantages of these locomotion modes.

"These modes are controlled by adjusting the duration and strength of the magnetic field, which endows the bistable soft jumper with robust locomotion capabilities," wrote Tang, Zhang and their colleagues. "In addition, it is capable of jumping omnidirectionally with tunable heights and distances. To demonstrate its capability in complex environments, a realistic pipeline with amphibious terrain was established."

The researchers tested their jumper in a simple locomotion task that entailed hopping through a narrow tube, jumping through a U-shaped pipeline, and jumping from underwater to above the water level. This task was designed to simulate a scenario in which the robot could be used to clean water inside a pipeline.

In this initial experiment, the mechanically driven jumper was found to perform remarkably well. In the future, its underlying design could inspire the development of other flexible robotic systems for a wide range of real-world applications. 

by Ingrid Fadelli , Tech Xplore

Source: Magnetically driven soft robot achieves high-speed jumping (techxplore.com)