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Safety and health in mines research advisory board

Annual Review 2004


CONTENTS

SAFETY MANAGEMENT

The Application and Effectiveness of Virtual Reality as a Training Aid

The overall aims of ECSC project PR-134, due for completion in June 2005, are to investigate the effectiveness and benefits that can be derived from using virtual reality (VR) as a training medium within the coal mining industry. UK work on the project is being undertaken by the University of Nottingham, Camborne School of Mines (CSM), Mines Rescue Service Ltd (MRSL) and International Mining Consultants (IMC). Specific objectives of the research include identifying and developing training applications of VR, (a) to improve the hazard awareness and risk perception of mine workers, (b) to simulate emergency scenarios and responses and (c) to be utilised in regard to equipment simulation.

Collaboration between CSM, IMC and MRSL has resulted in the development of:

These VR models are currently being demonstrated to training staff with a view to integrating them with existing course material. The final phase of the project will then focus on assessing their efficacy and the potential value of VR based training aids to the industry.

Extending the Utility of Underground Data Transmission Networks

The general theme of MRSL's study under ECSC project PR-133 is associated with data transmission system resilience, with an emphasis on safety and emergency applications of telemetry in mining. There are 5 sub-areas of research:

  1. Sensing and telemetry within inaccessible locations - Remote powering and data transmission from sealed mine areas and the use of sondes located in the waste to permit spontaneous combustion events to be rapidly detected and located.
  2. Improving the integrity and availability of data transmission systems.
  3. High integrity transmission between mobile plant and personnel. Data transmission techniques are being investigated which increase mutual awareness and provide an effective means of communicating an emergency stop instruction.
  4. Wireless data network communications to provide location information. The use of wireless data communications technologies is being investigated in terms of its ability to provide local data transmission and zonal location information. The focus is on mesh network techniques based on 'Zigbee' technology.
  5. Data exchange standards developments. A component of the work is examining data exchange standards developments and unified application interfaces to permit systems to cooperatively share information and data more cheaply and effectively.

Recent work has encompassed an underground trial programme aimed at testing and verifying the propagation behaviour and resilience of mesh wireless network technologies. Significant progress has been made in this regard. The underground test programme has confirmed that ISM-band low rate personal area network technologies provide favourable local propagation, at least in the test mine environment. Supporting theoretical electromagnetic propagation analyses, taken from key literature on the subject, broadly corroborate the observed behaviour. Various application issues will be examined in the final phase of research within the study, which finishes this year. A programme of tests to be undertaken in a coal mine in conjunction with UK Coal Mining Limited is also planned for the final phase, expected to be completed by mid-2005.

Enhancing the performance of mine communication and warning systems

MRSL is contributing to RFC project 03003, aimed at achieving substantial improvements in the performance of speech communication systems and auditory alarm and warning systems across a wide range of underground and surface mining applications and due for completion at the end of 2006. The broad objectives are:

  1. Improving communication system speech intelligibility. The general principles and developments in speech intelligibility measurement and adaptive filtering are being reviewed. Using acoustic measurement data in mines, the ambient noise and interference in a representative cross-section of coal winning, development heading and coal clearance and transport areas will be assessed. It is intended that these investigations will be used to define suitable anti-noise controller hardware and algorithm/processing requirements.
  2. Improving the effectiveness of mine alarms and alerts. Research considerations include the psychology and perception of audible alarms in the presence of varying masking influences.
  3. Power network communication components and application. German and Spanish partners propose to research and develop core elements of local and mine-wide power network communications systems. MRSL's work will examine how associated local communications requirements can be met, certain aspects of propagation, together with appraising potential applications, including emergency deployment of systems.

Available literature on active noise control has continued to be reviewed in 2004. Practical difficulties exist for many 3-D applications, although two key documents characterising the state-of-the-art have been identified. Investigation into the availability of microprocessor demonstration systems on which simple noise control algorithms can be run has identified two candidate systems, one from a Californian company, Sensory Inc. and one from Australia which is specifically designed for OEM use.

During the year, a computerised model to assess the audibility and likely effectiveness of auditory alarms and alerts within a wide range of mining and other industrial environments has been developed and is currently being further refined. The model addresses a range of issues and is capable of taking into account the effect of any ear defenders that may be in use. Information on the background noise and the characteristics of ear defenders are fed into the model. The output from the model is normally presented in graphical form.

Earlier research, using narrow bandwidth, low frequency inductive communications, confirmed the feasibility of signals operating via extensive power distribution networks. In part, the long distance propagation observed relied heavily on the choice of frequency and parasitic mode coupling between axial tunnel conductor monofilar and bifilar propagation modes. However, the more challenging task is to identify whether long distance high bandwidth communications is a realistic option in underground mines. A particular difficulty is that of exciting signals and abstracting signals from an axial tunnel power conductor.

Single carrier modulation schemes using narrow band techniques have good prospects for wide coverage consistent with a reasonable data error performance, particularly at sub 100 kHz frequencies. However the technology is only capable of low data bandwidth and has low spectral efficiency, and the technology is non-standard (and hence has higher implementation and ownership costs).

Further work within PLC technology studies has confirmed the potential benefits of spread spectrum technologies, particularly DS-SS with CDMA (direct sequence spread spectrum with code division multiple access). The focus of PLC studies has concerned core technologies within current 'HomePlug' standards, including the use of OFDM (orthogonal frequency division multiplexing).

Increasing the Efficiency of Roadway Drivages through the Application of Advanced Information, Automation and Maintenance Technologies

MRSL has started work on its contribution to the new RFC three year project 04001, the aim of which is to improve the efficiency of roadway drivages, through the use of the latest advances in information and automation technologies, applied to:

  1. The automation and assessment of operations that currently are being performed manually.
  2. Providing on-line support and expert diagnostics during maintenance activities, and large assembly-disassembly works, using simultaneous video, audio and data transmissions delivered to the point of use.

Satisfying the programme goals will involve applying advanced Information, Automation and Maintenance Technologies, including:

  1. Accessing the knowledge needed during maintenance operations: drawings, manuals, expert advice on diagnostic approach etc.
  2. Facilitating the adoption of novel support methods and the automation of their placement

The first of these two goals will be addressed through the development and deployment of a Knowledge Based Maintenance System (KBMS). It is intended that this system will concentrate all repair and assembly / disassembly information in a centralised repository connected to a Central Maintenance Control Room (CMCR). Significant reductions to mean time to repair and enhancement of the quality of the repair are anticipated through the application of a range of new technologies:

  1. Free voice communication in underground faces, road headings, rail stations etc. via headset communications (Wireless Voice).

    Online assistance through the local delivery of video, possibly using 'video-glasses' (semi-transparent glasses with simultaneous display and video/camera functions - Wireless Video).
  2. Access to wiring diagrams, part lists and any other documents through the use of pocket PC's (Wireless Data). Underground access of parts books (VAB's Link One System) and operating manuals via on-board PCs.
  3. Access to remote assistance (Remote expert support via the Internet for electronic, mechanical and hydraulic troubleshooting) concerning repair and diagnostic input from the original manufacturer.
  4. Providing online remote diagnosis system for oil sampling (Fe, Si +H2O content ) for preventive exchange of machine components.

The second goal will be addressed through the adoption of new types of support technologies considered promising from a productivity increase perspective; these will include shotcreting and short / long rock bolt placement. This will include consideration of quality assurance (online assessment of the quality of support) and automation system design.

Regarding shotcreting, the following technologies will be developed or adapted:

  1. Methods for accurate concrete flow measurement that will allow the precise dosage of admixtures (accelerator).
  2. Monitoring and/or automatic control of spraying operations, that will allow the deposition of shotcrete layers of known thickness, based on (i) the above flow measurement and (ii) a 3D LADAR (LASER Detection And Ranging) profiling performed before and after shotcreting.
  3. Thickness control of shotcrete layers, based on the above 3D LADAR readings and/or the combination of boom position and attitude info with flow measurements.

Finally, regarding Rock Bolt placement, activities will focus on the technologies that will allow the automation of the process, including sensing methods for detecting coal-rock interface, automatic bolting pattern generation, and on-line assessment of early ground movement.

Activities within the KBMS, Monitoring and Automation fields will share a common base of enabling technologies, including Information Technologies, wired and wireless communications and data transmission, process interfaces, data acquisition equipment, etc.

Updated 2015-08-20