Scientists at the Carnegie Mellon University have created a four-legged bio-inspired robot that climbs like no other. It clings to rough vertical surfaces utilizing a unique mechanism that is highly effective, yet at the same time relatively simple.

While some experimental robots are able to climb smooth surfaces using suction-based gripping mechanisms, this technology is unable to build a seal on rough surfaces like granite, reports Ben Coxworth in NewAtlas.

Utilizing what are referred to as microspine grippers is one substitute. These have a variety of tiny, sharp hooks that catch tiny crevices and nooks in the surface being ascended. When the gripper is taken off to proceed to the next level up, the hooks are removed from that surface.

Certain microspine grippers are passive, meaning they cling to objects by using their body weight. This kind does well on comparatively smooth walls but has trouble on more uneven surfaces, like cliff faces, where a more diverse climbing technique is needed.

In order to overcome this limitation, active microspine grippers use electric actuators that deliberately bury a ring of the hooks into the surface, preserving a motorized hold that functions in either direction. However, these are typically large, energy-consuming, and technically intricate, and they also have a somewhat slow ascending speed.

That's where the LORIS quadruped robot comes in.

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The device, called "Lightweight Observation Robot for Irregular Slopes" after a climbing marsupial, was developed by Paul Nadan, Spencer Backus, Aaron M. Johnson, and associates at Carnegie Mellon University's Robomechanics Lab.

A splayed microspine gripper, with two groups of spines oriented at a right angle to one another, is located at the end of each of the bot's four legs. A passive wrist joint connects the gripper to the leg. In essence, this means that the gripper just flops around in reaction to the leg's movements.

The robot moves its legs strategically such that when the gripper on one leg grabs hold of the climbing surface, the gripper on the other leg, at the opposite end of the body, does the same. This is accomplished by using an onboard depth-sensing camera and CPU.

Those two diagonally opposed legs' grippers remain securely attached to the surface as long as they are able to keep inward tension on them. Meanwhile, the other two opposing legs of the robot are free to advance one step further upward. This climbing technique is called directed inward grabbing (DIG), and it was inspired by insects.