For years the animal kingdom has been a source of inspiration for scientists, and now researchers are looking to snakes to inspire new approaches for search-and-rescue robots.

Capable of fitting through small gaps, moving over rough terrain, and climbing sheer inclines, snakes are physically suited to navigate the wreckage of a collapsed building much like they are suited to traverse the dense undergrowth of a forest.

To date, researchers have created a number of prototype snake robots; however, these robots are hampered by a lack of flexibility that limits their utility in cluttered, maze-like environments. These rigid snakes articulate at discrete points and can only imitate the smooth body motions of biological snakes with many small links operated in coordination. The result is higher energy consumption, reduced range of motion, and complex controls—factors that make accessing unpredictable and constrained environments difficult.

To address this issue, researchers from Worcester Polytechnic Institute in Massachusetts, designed OriSnake, a snake-like robot made of flexible and lightweight origami-like cylinders.

“The study aims to overcome the limitations of rigid-link snake robots in unstructured environments, especially for search-and-rescue applications,” said Professor Cagdas D. Onal. “OriSnake moves like a biological snake by deforming each modular body and is a lightweight, low-cost alternative to the heavier, less agile robots performing this function.”

Figure 1 : The 3D origami snake robot

Taking inspiration from the Japanese art of origami, OriSnake consists of four origami-like modules (Figure 1) mounted in series; these modules follow a diamond pattern called the Yoshimura crease pattern (Figure 2) and can bend, contract and extend while inherently resisting torsional deformation. The hollow nature of the origami-like body allows cables that transfer power and information to be fed through a series of holes in the crease pattern, protecting them from external contact. Along with motors, these cables provide each module with three degrees of freedom, while also keeping them in position and maximizing the bending moment that articulates the snake-like gait and movement.

Figure 2 : The individual modules used to construct the OriSnake

The snake robot has two locomotion modes: serpentine (or lateral undulation) and side-winding. In order for lateral undulation to function properly, passive wheels were added to the bottom of each module to mimic the properties of snake skin, which provides a large amount of lateral friction and a lesser amount of longitudinal friction. As the body of the snake is so light, weights were added to the top of the wheels to encourage contact with the ground, increasing the rate of movement and demonstrating the robot’s ability to carry a workload.

To laterally undulate, OriSnake oscillates left and right in the horizontal plane, propelled by the wheel friction. For sidewinding locomotion, the snake physically lifts its body off the ground as though it’s making a stepping motion (Figure 3). With this unique gait, the snake body forms a helical shape and moves to turn the helix from head to tail, causing a diagonal motion.

Figure 3 : The OriSnake performing sidewinding locomotion


“The modules exhibit very large torsional stiffness. This is a useful property for a long and slender continuum robot, but in the case of snake-like locomotion, it also means that the body will not twist and maintain contact with the ground. We added a suspension mechanism for this,” said Professor Onal.

To improve OriSnake, the researchers plan to optimize the mechanical design of the robot and increase the velocity with different motors. Currently, the robot snake is best suited to soil, sand, and flat surfaces; more research is required to allow it to go over and around rocks that are larger than its height.

OriSnake provides a unique approach to mobility on unstructured terrain and is a viable alternative to the relatively large, wheeled and tracked mobile robots that are sent into uncertain environments. In many instances, this light, soft and low-cost solution may be better suited to navigate complex and narrow environments. As the researchers further develop OriSnake’s agility, it may soon be used in exploratory and search-and-rescue situations.

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