Amphibious Robot Inspired by Lizards and Cockroaches

Innovation: Academia

Ben Gurion University of the Negev

2020

Image: Kyaw Tun / 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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Robot from Ben-Gurion University of the Negev has propellers on its underside that enable it to both crawl on the ground and run across water.

Benefits

Versatile on both land and water
Increased speed
Agile

Applications

Search and rescue
Surveillance

UN Sustainable Development Goals Addressed

Goal 9: Industry Innovation & Infrastructure

The Challenge

Robots often use extra limbs or wheels to move around. These appendages can be restrictive in certain environments or rough terrain, limiting the area the robot is capable of working in.

Innovation Details

The robot, known as AmphiSTAR, was inspired by cockroaches and it is designed to run on water at high speeds like the basilisk lizard. It is fitted underneath with four propellors, which act like wheels on the ground and like fins in the water. The axes of the propellors can be tilted and adjusted as needed and it also has two arms that hold the motor housing and propellers. The arms are able to move symmetrically away from the body to induce the sprawling mechanism that enables the robot to navigate rough terrain. When the propellers are at a certain angle and rotating at a high speed, the hovering mechanism is induced, enabling the robot to ‘run’ on water. Because the robot can move on land and on water, it is amphibious. The robot is able to crawl on land at speeds up to 8 mph (3.5 m/s) and on water up to 3.3 mph (1.5 m/s).

Watch the AmphiSTAR robot in action.

Biological Model

Basilisk lizards are able to run on water at high speeds because of the configuration of their toes. Their toes have have wrinkles of skin that spread out on the water to increase the surface area. As they run, they pump their legs rapidly and slap their feet on the water.

Cockroaches move over surfaces by moving their legs systematically. The long back legs, also called metathoracic legs, control the speed of the cockroach.

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