Development and Validation of an Integrated LiDAR-Camera System for Real-Time Monitoring of Underground Longwall Operations

TL;DR

This paper develops and validates a flameproof LiDAR-camera system for real-time underground longwall operation monitoring, addressing safety, visibility, and communication challenges with integrated sensing and processing.

Contribution

It introduces a novel integrated LiDAR-camera system with flameproof enclosure, enabling real-time 3D monitoring and data fusion in hazardous underground environments.

Findings

Thermal management reduced enclosure surface temperature from 106°C to 70°C.

Over 97% of LiDAR points were within the camera's field of view.

Colorised point clouds were transmitted at 10 Hz with bandwidth below 25 Mb/s.

Abstract

Real-time spatial monitoring in underground longwall operations is challenging due to methane-related safety risks, poor visibility, elevated thermal loads, spatial confinement, and bandwidth-limited communications. Currently available camera-based monitoring provides visual context but lacks direct depth information, while standalone underground LiDAR scanners are limited to monochromatic or periodic 3D mapping. This paper presents the design, integration, and experimental validation of a LiDAR-camera monitoring system built around a certified flameproof enclosure that prevents flame propagation into the surrounding atmosphere. The system combines a solid-state LiDAR, an industrial RGB camera, and an onboard processor within a compact hardware assembly, supporting LiDAR-camera fusion, low-light image enhancement, and real-time processing. Laboratory experiments evaluated LiDAR and camera performance through the protective polycarbonate dome and quantified optical and geometric distortions introduced by the enclosure. Thermal testing showed that iterative component placement, heat sinking, and passive conduction reduced peak surface temperature from 106 {\deg}C to 70 {\deg}C, with internal temperature stabilising at 57 {\deg}C. Furthermore, a representative longwall simulation was created to evaluate the complete sensing, fusion, and transmission workflow under controlled geometric and low-light conditions. In the final configuration, more than 97% of LiDAR points fell within the camera field of view, supporting reliable colourisation. Enclosure-aware calibration and correction maintained geometric accuracy, while processed colourised point clouds were transmitted at up to 10 Hz with sustained bandwidth below 25 Mb/s.