Speedy Soft Robot Inspired by Cheetahs

Innovation: Academia

North Carolina State University

2020

Image: Michael Aleo / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Move in/on Solids

To obtain needed resources or escape predators, some living systems must move on solid substances, some must move within them, and others must do both. Solids vary in their form; they can be soft or porous like leaves, sand, skin, and snow, or hard like rock, ice, or tree bark. Movement can involve a whole living system, such as an ostrich running across the ground or an earthworm burrowing through the soil. It can also involve just part of a living system, such as a mosquito poking its mouthparts into skin. Solids vary in smoothness, stickiness, moisture content, density, etc, each of which presents different challenges. As a result, living systems have adaptations to meet one, and sometimes multiple, challenges. For example, some insects must be able to hold onto both rough and slippery leaf surfaces due to the diversity in their environment.

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Move in/on Liquids

Water is not only the most abundant liquid on earth, but it’s vital to life–so it’s no surprise that the majority of life has evolved to thrive on and under its surface. Moving efficiently in and on this dense and dynamic substance presents unique challenges and opportunities for living systems. As a result, they have evolved countless solutions to optimize drag, utilize surface tension, fine tune buoyancy, and take advantage of various types of currents and fluid dynamics. For example, sharks can slide through water by reducing drag due to their streamlined shape and specially shaped features on their skin.

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Soft Robot from North Carolina State University has a 'bistable' spine that enables it to gallop on land.

Benefits

Increased speed
Increased efficiency

Applications

Search and rescue
Manufacturing

UN Sustainable Development Goals Addressed

Goal 3: Good Health & Wellbeing
Goal 9: Industry Innovation & Infrastructure

The Challenge

For rescue missions, speed is essential. Using robots can help reduce the risk to humans and allows food and medical supplies to arrive much more quickly. Typical soft robots use a crawling mechanism to move on land. This means that the robot must remain in contact with the ground at all times, limiting its maximum speed.

Innovation Details

These new soft, silicone robots are known as “Leveraging Elastic instabilities for Amplified Performance” (LEAP) robots, and are approximately 7 centimeters long and weigh about 45 grams. They were inspired by the spine biomechanics of cheetahs, which are the fastest animals on land. Each robot has a spring-powered, ‘bistable’ spine, allowing it to switch between two stable states by quickly pumping air into channels that line the robot. The switching releases a significant amount of energy, which allows the robot to exert enough force to lift its ‘feet’ up from off the ground. This allows the robot to gallop across a surface much more quickly, up to 2.7 body lengths per second compared to 0.8 body lengths per second of traditional soft robots. The feet of the LEAP robots can also be replaced with fins, allowing them to swim through water at a rate of 0.78 body lengths per second, compared to 0.7 body lengths per second for the previous fastest swimming soft robot.

Biological Model

Cheetahs are the fastest creatures on land, capable of going from 0-60 mph in under 3 seconds. They derive their speed and power from the flexing of their spines, which allows their hind and front legs to overlap with one another underneath the cheetah’s body. The spine then recoils like a spring, propelling the cheetah’s legs back out and allowing it to reach strides of up to 25 feet.

See Related Strategy

a cheetah runs toward a target in a grassland

Biological Strategy

Flexible Spine Increases Speed

Cheetah

The spine of the cheetah increases its running speed because its flexiblity allows longer stride lengths.

References

Journal article

Leveraging elastic instabilities for amplified performance: Spine-inspired high-speed and high-force soft robots

ScienceAdvances

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