Meet MARVEL, the quadrupedal robot that can climb walls and ceilings

Investigating industrial sites is no easy task. It involves work at high altitudes and confined spaces, like steel bridges or shipyard welding platforms, all of which could be dangerous to human workers.

Now, a team of researchers at the Korea Advanced Institute of Science and Technology have developed a quadrupedal climbing robot with magnetized feet in an effort to solve the problem. Their research work was recently published in the journal Science Robotics. 

Named MARVEL, short for Magnetically Adhesive Robot for Versatile and Expeditious Locomotion, the 17.6 pounds (eight kilograms) device can rapidly move on diverse surfaces such as metal floors, walls, and ceilings.  

MARVEL is intended to be utilized in situations that involve a certain amount of risk for humans. According to the study, "Legged robots could potentially perform various maneuvers in such confined and complex three-dimensional (3D) environments."

How capable is MARVEL? 

The foremost challenge in front of the team was to sort out the adhesion mechanism, which enables the robot to hold on to metal surfaces and facilitate its movement against the natural force of gravity.

The solution was found with the use of electromagnets and magnetic elastomers, allowing the robot to alter the magnetic properties of each of its feet. 

MARVEL also has the ability to scan surfaces for gaps and holes. Researchers have programmed the robot to move around or over such obstacles by simulating how a cat makes use of its front paws to analyze objects before moving forward. 

MARVEL navigated various testing scenarios like "stepping over a 10-centimeter-wide gap, overcoming a 5-centimeter-high obstacle, and performing transitions from floor to wall and from wall to ceiling," according to the study's abstract.

The team has successfully tested the robot to speeds of up to 0.7 meters per second (m/s) and with a maximum payload of 6.6 pounds (three kilograms).  

The team tested MARVEL's abilities on an industrial steel storage tank. "Although the storage tank surface was curved and covered with dust and paint, MARVEL was able to climb on the surface at a speed up to 0.35 m/s while avoiding collision with protrusions and overcoming obstacles."

Various use cases for MARVEL

The idea is that the quadrupedal robot could replace physical inspection by humans at risky altitudes or tight spaces. The study highlighted Marvel has the potential to "investigate industrial sites, such as steel-structured buildings, bridges, ships, or storage tanks."

The team has managed to achieve these results based on various well-designed learning scenarios for Marvel to explore. Still, the team mentioned that "using a vision sensor, motion planner, and trajectory optimization, MARVEL will be able to climb and perform various tasks autonomously."

Abstract:

A climbing robot that can rapidly move on diverse surfaces such as floors, walls, and ceilings will have an enlarged operational workspace compared with other terrestrial robots. However, the climbing skill of robots in such environments has been limited to low speeds or simple locomotion tasks. Here, we present an untethered quadrupedal climbing robot called MARVEL (magnetically adhesive robot for versatile and expeditious locomotion), capable of agile and versatile climbing locomotion in ferromagnetic environments. MARVEL excels over prior climbing robots in terms of climbing speed and ability to execute various motions. It demonstrates the fastest vertical and inverted walking speed, whereas its versatile locomotion ability enables the highest number of gaits and locomotion tasks. The key innovations are an integrated foot design using electropermanent magnets and magnetorheological elastomers that provide large adhesion and traction forces, torque control actuators, and a model predictive control framework adapted for stable climbing. In experiments, the robot achieved locomotion on ceilings and vertical walls up to 0.5 meter (1.51 body lengths) per second and 0.7 meter (2.12 body lengths) per second, respectively. Furthermore, the robot exhibited complex behaviors such as stepping over 10-centimeter-wide gaps; overcoming 5-centimeter-high obstacles; and making transitions between floors, walls, and ceilings. We also show that MARVEL could climb on a curved surface of a storage tank covered with up to 0.3-millimeter-thick paint with rust and dust.