Magnecko: Design and Control of a Quadrupedal Magnetic Climbing Robot

TL;DR

This work presents Magnecko, a quadrupedal magnetic climbing robot designed as a research platform for legged climbing locomotion. It combines an insect-inspired leg topology with three active DOF per leg, a passive ankle, and electro-permanent magnets for adhesion, enabling crawling on ground, vertical walls, and ceilings, including 90-degree concave corners. Control relies on a model predictive controller with a simplified single rigid body dynamics model and quaternion-based orientation, optimized over a horizon $T$ to determine ground reaction forces and joint torques, while handling contact constraints and magnet switching delays. Experimental results show MPC-driven speeds up to $0.15$ m/s on the ground and successful transitions between orientations, with payloads up to $7.5$ kg, highlighting the platform’s potential for inspection and maintenance tasks on ferrous structures. Limitations include surface imperfections affecting adhesion, magnet-switching speed, and the need for enhanced perception to operate in more complex environments; future work aims to integrate foothold planning and more robust foot designs.

Abstract

Climbing robots hold significant promise for applications such as industrial inspection and maintenance, particularly in hazardous or hard-to-reach environments. This paper describes the quadrupedal climbing robot Magnecko, developed with the major goal of providing a research platform for legged climbing locomotion. With its 12 actuated degrees of freedom arranged in an insect-style joint configuration, Magnecko's high manipulability and high range of motion allow it to handle challenging environments like overcoming concave 90 degree corners. A model predictive controller enables Magnecko to crawl on the ground on horizontal overhangs and on vertical walls. Thanks to the custom actuators and the electro-permanent magnets that are used for adhesion on ferrous surfaces, the system is powerful enough to carry additional payloads of at least 65 percent of its own weight in all orientations. The Magnecko platform serves as a foundation for climbing locomotion in complex three-dimensional environments.

Figures (11)

• Figure 1: The magnetic climbing robot Magnecko on two I-beams.
• Figure 2: Insect style joint configuration of Magnecko with the RoM and dimensions.
• Figure 3: Actuator cross-section, visualizing motor, gearbox, and encoder.
• Figure 4: Section view of the magnetic foot showing the structure, ankle joint, and spring mechanism.
• Figure 5: The fully assembled foot with springs for centering the ankle joint position.