NYU Robot WorMa Shifts Water for Seamless Land and Water Travel
NYU Tandon Assistant Professor Nana Obayashi and Ph.D. student Daniil Filimonov have developed WorMa, an amphibious robot designed to traverse varied environments. This machine adjusts its internal weight by shifting water, allowing it to move across land, ascend steps, and navigate open water. The robot maintains a consistent undulatory gait regardless of the terrain encountered.
Existing amphibious robotic designs often handle diverse landscapes by altering gaits, incorporating specialised attachments, or reconfiguring mechanically. Such methods can introduce additional complexity and potential points of failure, particularly at the junctures between different terrains. WorMa, named for "worm" and "mass," approaches this problem differently, focusing on adaptive mass redistribution rather than mechanical alterations, according to a paper published in *Advanced Robotics Research*.
WorMa is a five link, four joint robot measuring 50 centimetres in length and weighing just over 1 kilogram. It contains latex balloon water tanks positioned in its head and tail. A central pump shifts approximately 300 grams of water between these two tanks. So, this internal fluid transfer accounts for 28 per cent of the robot's total mass, allowing for dynamic weight adjustment.
The distribution of this internal water dictates the robot's functional capabilities. When confronting an incline, shifting water towards the head increases the downward force exerted by the robot's front contact points against the surface. This provides enhanced traction. The head biased placement proved to be the sole configuration capable of successfully moving WorMa up the steepest tested incline of 19.5 degrees. Every other tested setup failed, sliding backwards. It also reduced the robot's transport cost by a minimum of 33 per cent compared to alternative configurations.
Movement in water presented an inverted advantage. With its weight concentrated towards the tail, WorMa achieved speeds up to 26 per cent faster and operated with 52 per cent greater efficiency than when its mass was biased towards the head. These findings indicate distinct optimal weight placements for aquatic and inclined terrestrial movement.
Navigating steps required a specific operational sequence. Researchers observed that neither a consistently head heavy nor a continuously tail heavy robot could independently clear a step. Instead, WorMa approached a step with water in its head for initial traction, subsequently shifting the water to its tail while raising its head and neck. And this allowed the tail to provide a pushing force, drawing the robot closer. Once its head secured an anchor on the step's edge, the water then shifted back to the head, enabling the robot to continue its forward progression. This method allowed WorMa to surmount steps reaching 15 centimetres in height.
Exiting water onto a sloped surface was achievable only when the robot's weight was consolidated at its head. The other mass distribution configurations failed to generate sufficient force at the robot's front end to pull itself onto the incline. This demonstrates a critical specific requirement for successful water exit.
These combined strategies permitted WorMa to complete a single course incorporating flat ground, an elevated step, a slope, and open water. The robot altered its internal water distribution at each stage of the progression. The researchers state this marks the first instance of an undulatory robot executing amphibious terrain transitions, encompassing both entry into and exit from water bodies.
The practical justification for this design lies in its inherent adaptability. Instead of requiring specialised components for every potential environment, the robot adjusts to changing terrain by redistributing its existing mass. But further enhancements are planned for WorMa, including faster pumps and sensor driven controls, which could eventually enable the robot to independently detect terrain changes and dynamically modify its weight.
This work follows Professor Obayashi's previous development of ScaFi, a fish inspired robot. ScaFi was engineered to be constructed in various sizes from a singular blueprint for deployment in environments ranging from shallow streams to expansive open water. Both projects, WorMa and ScaFi, address a similar engineering challenge from different perspectives: creating robots that can adapt to their surroundings without necessitating a distinct machine for each specific condition.
WorMa is an amphibious robot capable of navigating land, steps, and water.
Its adaptability stems from internally shifting 300 grams of water to redistribute its mass.
The robot maintains a singular undulatory gait across all terrains.
Specific weight distribution patterns are critical for ascending inclines, swimming efficiently, and clearing steps.
This approach reduces the need for specialised components, offering a unified design for diverse environments.
Source: TechXplore
