Columbia University scientists sought inspiration from a hair comb to design and develop a fast, untethered soft robot with elastic instability called the Hair Clip Mechanism (HCM). Each robot features a strip of prestressed plastic connected to an electric servo at the base. Upon applying a small amount of pressure to the plastic, the strip transitions between a convex and concave shape, which amplifies the applied force.
The team performed tests on their mechanism by using it as a tail on a fish robot with an individual servo. They also developed a quadruped robot with a two-servo HCM, allowing it to gallop across flat surfaces. The fish's top speed reached 435 mm (around two body lengths) per second, and the quadruped had a top speed of 313 mm (1.6 body lengths) per second.
These robots performed at significantly faster speeds compared to similarly designed small soft robots. For example, North Carolina State University developed a hairclip-like swimming robot that paddles at nearly 3.75 body lengths per second. Interestingly, the HCM enables the frames to function like a propulsion system on the robot. The team claims that eliminating an individual motor could lead to more affordable and lightweight robots in the future.
Worcester Polytechnic Institute researchers developed a robot called OmniWheg that transforms from a wheeled to a legged configuration based on the environment it navigates. The system relies on upgraded whegs, a mechanism that has gained attention in robotics, to climb stairs or move around small obstacles.
Previous wheel-leg systems proved ineffective because they lacked proper coordination on the right and left sides of the wheel-leg system, which requires perfect alignment as a robot climbs stairs. So, the team used an omnidirectional wheel to solve those issues. It essentially ensures the robot can align without body rotations. This robot moves forward, backward, and sideways and climbs stairs while consuming minimal energy.
OmniWheg also relies on an individual servo motor connected to each wheel and a simple algorithm. Plus, it has a basic and straightforward design that can be replicated by other teams. The team performed experiments on their robotic system, putting it through tasks such as climbing stairs of varying heights, moving around obstacles, and turning omnidirectionally. Their system managed to overcome all obstacles, flexibly and efficiently changing its configuration to take on locomotion obstacles.
OmniWheg could integrate into current and new robots, making them more efficient at navigating indoor environments. Additionally, this could lead to similarly developed wheg systems that utilize omnidirectional wheels.
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