MIRRAX: A Reconfigurable Robot for Limited Access Environments

TL;DR

MIRRAX is a reconfigurable robot designed for inspection in extreme, cluttered, and restricted environments, capable of self-adjusting to navigate narrow gaps and complex terrains, demonstrated through experimental validation and deployment at a nuclear site.

Contribution

This paper introduces MIRRAX, a novel reconfigurable robot with controllability analysis and practical deployment in a nuclear facility for remote inspection.

Findings

Minimum footprint width for stable configuration is 0.19 m.

Reconfigurable to access ports as small as 150 mm diameter.

Successfully deployed for remote inspection at a nuclear site.

Abstract

The development of mobile robot platforms for inspection has gained traction in recent years with the rapid advancement in hardware and software. However, conventional mobile robots are unable to address the challenge of operating in extreme environments where the robot is required to traverse narrow gaps in highly cluttered areas with restricted access. This paper presents MIRRAX, a robot that has been designed to meet these challenges with the capability of re-configuring itself to both access restricted environments through narrow ports and navigate through tightly spaced obstacles. Controllers for the robot are detailed, along with an analysis on the controllability of the robot given the use of Mecanum wheels in a variable configuration. Characterisation on the robot's performance identified suitable configurations for operating in narrow environments. The minimum lateral footprint width achievable for stable configuration ($<2^\text{o}$~roll) was 0.19~m. Experimental validation of the robot's controllability shows good agreement with the theoretical analysis. A further series of experiments shows the feasibility of the robot in addressing the challenges above: the capability to reconfigure itself for restricted entry through ports as small as 150mm diameter, and navigating through cluttered environments. The paper also presents results from a deployment in a Magnox facility at the Sellafield nuclear site in the UK - the first robot to ever do so, for remote inspection and mapping.