Autonomous Elbow Controller for Differential Drive In-Pipe Robots

Liam Brown,Simon Watson,Joaquin Carrasco

doi:10.3390/robotics10010028

Abstract

The inspection of legacy nuclear facilities to aid in decommissioning is a world wide issue. One of the challenges is the characterisation of pipe networks within them. This paper presents an autonomous control system for the navigation of these unknown pipe networks, specifically focusing on elbows. The controller utilises three low-cost feeler sensors to navigate the FURO II robot around 150 mm short elbows. The controller is shown to allow the robot to safely navigate around an elbow on all 39 attempts comparing that with the brute force method which only completed five of the nine attempts and damaging the robot. This shows the advantages of the proposed controller. A new metric (Impulse) is also proposed to compare the extra force applied to the robot over the time it is slipping in the elbow due to the errors in the drive unit speeds. Using this metric, the controller is shown to decrease the Impulse applied to the robot by 213.97 Ns when compared to the brute force method.

Highlights

Nuclear decommissioning is forecast to cost the UK £121 billion over the 120 years [1]
The robot is able to successfully pass through the elbow and comparing it to the brute force (BF) method on average it has a reduction in the Impulse applied to the robot of 213.97 Ns which is a major decrease
The AEC method allowed the robot to pass through the corner on every attempt (39 in total) whereas the BF method got lodged in the elbow four out of the nine passes it tried

Summary

Introduction

Nuclear decommissioning is forecast to cost the UK £121 billion over the 120 years [1]. One of the major challenges associated with it is the characterisation of the contents of legacy facilities [2]. A common feature within them is an extensive network of pipes which are of unknown geometry but have diameters between 50–150 mm. There is no way of inspecting this pipework without human intervention, which can be dangerous due to the unknown radiological contaminants inside them. An autonomous pipe inspection robot, FURO I, was proposed in [3], which could be used for such inspections, reducing the safety risks to human operators. This paper is an extension of that work, presenting the testing and development of a controller to allow the FURO robot to safely turn through an elbow

Methods

Results

Discussion

Conclusion