This Bio-Inspired 3D-Printable Robot Waves Its Body to Speed Across Land and Water Alike

Engineers at the Ben Gurion University of the Negev have taken inspiration from nature for a new 3D-printable amphibious robot design, which moves like a wave to crawl across land and swim over the seas — with, they claim, better speed and efficiency than rival designs.

"The single motor and bioinspired design contribute significantly to the robot's efficiency," engineer David Zarrouk, PhD, explains of the robot, which was developed with student Omer Guetta, "and the relative simplicity of its design means it is scalable to any size."

The robot in question, AmphiSAW, was inspired by the movement of sea snakes and salamanders for movement in water and by how centipedes travel across land. Regardless of whether it's on land or water, the robot uses a single brushless motor to move its body in a vertical wave-like movement — and can, the team says, be fitted with legs or wheels plus additional motors at its front in order to boost its land speed. A servo, meanwhile, drives a rudder for steering on water.

Even without legs or wheels, the robot's performance impresses. In testing, a prototype proved able to crawl across land at 1.5 body lengths per second and of swimming at 0.74 body lengths per second. Despite this speed, the robot is also efficient: the team claims it has "the lowest cost of transport among all amphibious robots reported in literature," where the cost of transport is the energy expended divided by the product of the robot's weight times the distance traveled.

"We invested considerable effort in simplifying the design of the robot so that it can be easily prototyped using widely available printers and off the shelf electronics," the team explains. "We used an fused deposition modeling (FDM) Ultimaker 5 printer whose accuracy is roughly 0.2mm to print the motor housing and links. The helix, measuring 37 cm in length was too long to be fitted in the Ultimaker and was printed in a [Creality] CR-10 S5 printer."

"The robot is controlled with a 3DR [Holybro] Mini Pixhawk controller which has a relatively simple interface that allows for simple control and easy data acquisition," the researchers continue. "A human operator can use this controller to drive the robot like a radio-controlled car or boat, without any previous training. The controller can also be programmed for autonomous swimming missions using its GPS although we did not implement this feature in our experiments."

The team's paper has been published under open-access terms in the journal Bioinpiration & Biomimetics.