Vishwam Sankaran
Wed, 28 June 2023
Image of Morphobot (Eric Sihite et al., Nature Communications)
Scientists have designed a new robot nicknamed “morphobot” that can travel on different terrains, including land and air by shapeshifting its parts into wheels, propellers, or legs as required.
Researchers, including Alireza Ramezani from Northeastern University in the US, say the morphobot can transform its shape to navigate the environment by flying, rolling, crawling, crouching, balancing, and tumbling.
Several animals have adapted the use of their limbs to allow them to tackle different terrains.
Sea lions, for instance, walk on land using their flippers that they also use to swim, and meerkats use their hindlimbs to scout their surroundings.
Chukar birds have also shown adaptations to use their wings to walk on all fours up steep inclines.
Similarly, the morphobot, described this week in the journal Nature Communications, performs different modes of movement inspired by animals like birds, meerkats, and seals by mimicking the animals’ limb repurposing abilities.
The robot, which weighs 6kg (13lb), has four legs each comprising two joints, along with ducted fans fixed at the leg ends.
It spans 70cm in length and has a width and height of 35cm.
The new study shows that the morphobot’s fans can shapeshift to function either as legs, propellor thrusters, or wheels as required.
The robot has demonstrated the ability to alter its movements to walk on rough terrain, traverse steep slopes, tumble over large obstacles, fly to higher levels, and crawl under low-ceiling pathways.
Based on the study, researchers say future mobile robots can be designed with multi-functional limbs to navigate complex terrains by adapting their movement strategies.
The new innovation could help further improve the design of robots to traverse harsh environments, such as those used in search and rescue responses after natural disasters, space exploration, and automated package delivery.
The findings, according to scientists, demonstrate the advantages of designing robots with multipurpose appendages that can be used to travel over varied and challenging terrains.
Emulating how krill swim to build a robotic platform for ocean navigation
Developed by a team of Brown-led researchers, Pleobot is a krill-inspired robot offering potential solutions for underwater locomotion and ocean exploration, both on Earth and moons throughout the solar system.
Peer-Reviewed PublicationIMAGE: PLEOBOT IS A SMALL ROBOTIC PLATFORM THAT EMULATES KRILL-LIKE SWIMMING. view more
CREDIT: PHOTO PROVIDED BY THE WILHELMUS LAB.
PROVIDENCE, R.I. [Brown University] — Picture a network of interconnected, autonomous robots working together in a coordinated dance to navigate the pitch-black surroundings of the ocean while carrying out scientific surveys or search-and-rescue missions.
In a new study published in Scientific Reports, a team led by Brown University researchers has presented important first steps in building these types of underwater navigation robots. In the study, the researchers outline the design of a small robotic platform called Pleobot that can serve as both a tool to help researchers understand the krill-like swimming method and as a foundation for building small, highly maneuverable underwater robots.
Pleobot is currently made of three articulated sections that replicate krill-like swimming called metachronal swimming. To design Pleobot, the researchers took inspiration from krill, which are remarkable aquatic athletes and display mastery in swimming, accelerating, braking and turning. They demonstrate in the study the capabilities of Pleobot to emulate the legs of swimming krill and provide new insights on the fluid-structure interactions needed to sustain steady forward swimming in krill.
According to the study, Pleobot has the potential to allow the scientific community to understand how to take advantage of 100 million years of evolution to engineer better robots for ocean navigation.
“Experiments with organisms are challenging and unpredictable,” said Sara Oliveira Santos, a Ph.D. candidate at Brown’s School of Engineering and lead author of the new study. “Pleobot allows us unparalleled resolution and control to investigate all the aspects of krill-like swimming that help it excel at maneuvering underwater. Our goal was to design a comprehensive tool to understand krill-like swimming, which meant including all the details that make krill such athletic swimmers.”
The effort is a collaboration between Brown researchers in the lab of Assistant Professor of Engineering Monica Martinez Wilhelmus and scientists in the lab of Francisco Cuenca-Jimenez at the Universidad Nacional Autónoma de México.
A major aim of the project is to understand how metachronal swimmers, like krill, manage to function in complex marine environments and perform massive vertical migrations of over 1,000 meters — equivalent to stacking three Empire State Buildings — twice daily.
“We have snapshots of the mechanisms they use to swim efficiently, but we do not have comprehensive data,” said Nils Tack, a postdoctoral associate in the Wilhelmus lab. “We built and programmed a robot that precisely emulates the essential movements of the legs to produce specific motions and change the shape of the appendages. This allows us to study different configurations to take measurements and make comparisons that are otherwise unobtainable with live animals.”
The metachronal swimming technique can lead to remarkable maneuverability that krill frequently display through the sequential deployment of their swimming legs in a back to front wave-like motion. The researchers believe that in the future, deployable swarm systems can be used to map Earth’s oceans, participate in search-and-recovery missions by covering large areas, or be sent to moons in the solar system, such as Europa, to explore their oceans.
“Krill aggregations are an excellent example of swarms in nature: they are composed of organisms with a streamlined body, traveling up to one kilometer each way, with excellent underwater maneuverability,” Wilhelmus said. “This study is the starting point of our long-term research aim of developing the next generation of autonomous underwater sensing vehicles. Being able to understand fluid-structure interactions at the appendage level will allow us to make informed decisions about future designs.”
The researchers can actively control the two leg segments and have passive control of Pleobot’s biramous fins. This is believed to be the first platform that replicates the opening and closing motion of these fins. The construction of the robotic platform was a multi-year project, involving a multi-disciplinary team in fluid mechanics, biology and mechatronics.
The researchers built their model at 10 times the scale of krill, which are usually about the size of a paperclip. The platform is primarily made of 3D printable parts and the design is open-access, allowing other teams to use Pleobot to continue answering questions on metachronal swimming not just for krill but for other organisms like lobsters.
In the published study, the group reveals the answer to one of the many unknown mechanisms of krill swimming: how they generate lift in order not to sink while swimming forward. If krill are not swimming constantly, they will start sinking because they are a little heavier than water. To avoid this, they still have to create some lift even while swimming forward to be able to remain at that same height in the water, said Oliveira Santos.
“We were able to uncover that mechanism by using the robot,” said Yunxing Su, a postdoctoral associate in the lab. “We identified an important effect of a low-pressure region at the back side of the swimming legs that contributes to the lift force enhancement during the power stroke of the moving legs.”
In the coming years, the researchers hope to build on this initial success and further build and test the designs presented in the article. The team is currently working to integrate morphological characteristics of shrimp into the robotic platform, such as flexibility and bristles around the appendages.
The work was partially funded by a NASA Rhode Island EPSCoR Seed Grant.
JOURNAL
Scientific Reports
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Pleobot: a modular robotic solution for metachronal swimming
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