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\title{Surface Mine Truck Safety Training: A VR  Approach to Pre-Operational 
Vehicle Inspection\thanks{This 
work was partially supported by Newmont Gold Co., Echo Bay Minerals, 
the Nevada Division of Industrial Relations, 
and the Mine Safety Health Administration.}}

\author {
Damien Ennis$^{1}$,
%Lu Chun Liao$^{1}$,
%Mohammad Islam$^{1}$,
Benjamin Lucchesi$^{1}$,
Nerissa Oberlander$^{1}$,
Keith Wesolowski$^{1}$, \\
Frederick C. Harris, Jr.$^{1}$,
and Pierre Mousset-Jones$^{2}$ \\
$^{1}$Department of Computer Science, University of Nevada,
Reno, NV~~ 89557 \\{\tt fredh@cs.unr.edu}  \\
$^{2}$Department of Mining Engineering, University of Nevada,
Reno, NV~~ 89557 \\{\tt mousset@mines.unr.edu}
}

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\vspace{1in}

\section*{ABSTRACT}

\vspace{-12pt}

	In the surface mining industry, the cost of workplace accidents
	is high.  One aspect of safety training is the pre-operational
	vehicle inspection.  Training operators to correctly inspect
	vehicles is costly and time consuming in both equipment
	availability and man-hours. This paper outlines the motivation
	for and the development of an alternative training method,
	a virtual reality (VR) based Mine Vehicle Inspection Simulator (MVIS), 
	which can cut costs. Implementation issues are discussed, 
	an attempt is made to draw conclusions on the success of
	this method, and future work is outlined. 



\section{INTRODUCTION}

\vspace{-12pt}

        Workplace accidents in the mining industry reduce production,
        increase costs, and result in temporary and permanent disabilities
        or even death to mine workers.  Accidents are a major concern
        in day-to-day mining operations, where they can be expensive in
        terms of both cost and employee morale.

        One of the most important tools for on-the-job accident prevention
        is worker training.  However, the cost of accident prevention
        training is high, particularly when the method attempts to
        provide a realistic representation of the risks associated with
        mining vehicle operation and the proper  techniques that avoid or
        manage those risks.  Preparing  video demonstrations, conducting
        safety training tours of work sites, and conducting on-site
        safety briefings are all effective training tools, but these
        methods can be disruptive to daily operations and expensive.
        As a general rule, the more realistic a training exercise,
        the more expensive it is.

	Virtual reality (VR) is a technology for developing training
	tools that offers an excellent approach to reducing both job
	accidents and the high cost of training.  The Mine Vehicle
	Inspection Simulator (MVIS) developed at the University of
	Nevada is an example of such a VR training tool.  It provides
	a cost-effective simulation of vehicle inspection without the
	need to take a vehicle out of production.

        This paper provides a brief overview of the challenges facing
        the surface mining industry with particular reference to the
        pre-operational vehicle inspections of off-highway haulage trucks
        that are typically used in this type of mining.  VR technologies
        currently available and their applications are discussed,
        and the approach selected for VR-based vehicle inspection and
        how the implementation was tested are explained.  Finally, the
        results of this testing along with some conclusions and ideas
        for future work are presented.

\section{TRUCK INSPECTION}

\vspace{-12pt}

        General attitudes regarding industrial safety, environmental
        concerns, and industrial design have advanced significantly in
        recent years, and the mining industry has not been an exception.
        The introduction of new safety and environmental legislation
        throughout the world has changed the emphasis of industrial
        law from prescriptive legislation to the adoption of more
        effective management systems. Many mining companies have
        responded to these new ideas by introducing modern management
        philosophies~\cite{staley92:cscatsim}.  A range of new techniques
        has been applied to meet the new legislative and production
        requirements.

        Large mining organizations are now looking for ways to improve
        their performance, including the use of new technologies for
        training employees.  These new technologies include VR, videos,
        simulators, and planning systems.  Their use has resulted in a
        safer working environment for all employees.

	The pre-operational vehicle inspection of a haul truck, such
	as the	   Caterpillar Model 785, is one of the first things
	a new employee at a surface mine learns how to do.  The proper
	operation and maintenance of the haul truck fleet at these mines
	is the lifeblood of their profitability, and employees may be
	rotated to and from these vehicles throughout their employment.
	Therefore, profitability and safety go hand in hand in a company's
	desire to see that the employees perform the pre-operational
	inspection well.

	Current methodologies require employees to read about the
	inspection, see pictures of the parts to inspect, and be told
	the proper order in which to inspect parts.  After passing a
	short test, a haul truck is brought out of production and the
	new employee inspects this vehicle under the supervision of a
	safety trainer.  This is an effective training method but can
	be detrimental to company profitability.  In order to perform an
	in-person inspection, an operational truck must be taken out of
	production for most of a shift.  Current ore prices are so close
	to the break-even point that the loss of a truck from production
	will impact a company's profitability.	This method is also
	inconvenient for employees that need to refresh their skills
	either due to the time elapsed since their initial training or
	their rotation to a new position.

\section*{VR TECHNOLOGIES}

\vspace{-12pt}

	The value of virtual reality is that it can offer experiences
	that would otherwise be inaccessible to an individual, because
	such experiences might be too expensive, too dangerous, occur
	at the wrong time, or in the wrong location.  VR can be used as an
	alternative method of training because it can give the individual
	experience beyond training methods currently in use.  One of
	the most successful examples of a VR application is commercial
	aircraft flight simulation.  This extremely expensive
	implementation of VR provides a very realistic setting for pilot
	training that includes all of the sights, sounds, control motions,
	and physical movement associated with flying a modern jet.

	Hardware and software used to implement VR applications have
	improved dramatically over the last few years.	High-end 
	PC-class workstations, with the addition of a 3D accelerated video
	card, have the potential to support VR applications which were
	once restricted to expensive hardware-specific applications.
	In addition, a number of peripheral hardware devices, such as
	VR goggles, gloves, 3D sound, and motion tracking systems are
	designed to heighten the user's sense of reality and increase
	training effectiveness.  Furthermore, software vendors are
	marketing a range of packages for developing VR applications.

	As noted by Foley, van Dam, et al. in \cite{fvdfhp97:itcg},
	``Interactive graphics is a field whose time has come.''  Software
	Application Programming Interfaces (APIs) that draw geometric
	primitives for developing graphically intensive software are
	becoming standardized.	One such API is OpenGL.  The challenge
	of using a low-level graphics API for developing software is
	that the application developer must make a substantial effort to
	create even the simplest 3D object.  To reduce the complexity of
	developing graphically intensive software, toolkits built on top
	of low level graphics APIs are available.  These toolkits focus
	development on user interaction and scene management rather than
	on drawing objects.

	One method of implementing this type of high-level toolkit
	utilizes scene graph technology (SGT).	Scene objects such as
	cameras, lights, and geometry allow the programmer to concentrate
	on scene composition rather than on drawing objects.  Scene graph
	technology shifts the graphics programming paradigm with the
	introduction of scene objects.	 Examples of APIs that implement
	SGT include Open-Inventor, Java3D, and Fahrenheit.  In addition,
	these packages are independent of windowing systems and platforms.

\section*{VR APPLICATIONS}

\vspace{-12pt}

	The growth in the field of virtual reality has been fueled
	by the need for better computer-user interfaces.  For this
	reason, applications of VR have been applied to a broad range
	of industries.	In general, applications of VR can
	be reduced to three main categories: visualization, simulation,
	and control. 

        The idea behind data visualization is that large sets of data
        can be better understood if they are presented in a form that
        allows people to assimilate important features of the data 
        quickly. An obvious example of this concept is a
        simple bar graph. By correlating the numerical representation
        of data to magnitudes of bars in a graph, a person can evaluate
        the importance of the data rapidly. Because people are heavily
        biased toward visual pattern recognition as opposed to analytical
        analysis of numerical data, they respond better to graphical
        representations of data. VR takes this idea one
        step further by fully immersing a person in a representation of
        the data.  Guan et al. \cite{gskhnc:vbtnpitvw} describe an
        application designed to let neurosurgeons study brain pathology,
        blood vessels, skull, and the surrounding tissue using real-time
        volumetric renderings of patient data.  With this information,
        the surgeon can plan the best approach for surgery.

%	( example of data visualization - VR to view stock market data )

	Closely related to data visualization, the field of simulation
	is probably the largest and best known of all VR applications.
	VR allows the simulation of real world (and fictitious)
	situations by giving users experiences that might otherwise
	be infeasible for economic or safety reasons.  Probably the
	best known application of this category is commercial flight
	simulation.  Good examples of this can be seen at
	Reflectone \cite{flightsim}.

%	( example of simulation - example of flight sim )

	Virtual reality applications in the category of control offer
	some of the best possibilities for industrial applications. By
	simulating the environment where a remotely controlled device is
	located, users can control that device as if they were actually
	there. Applications of this technology allow users to control
	devices in economically prohibitive, hazardous, or inaccessible
	locations.
	%
	%( examples such as defusing bombs, Mars pathfinder, 
	%deep sea probes, etc. )
	One of the most famous examples of this was the microrover 
	(named Sojourner) that NASA sent to Mars in 1996.  
	Sojourner was man's first attempt to operate a remotely
	controlled device on another planet \cite{sojourner}.


\section*{APPROACH TO VR AND VEHICLE INSPECTION}

\vspace{-12pt}

	The goal of this virtual reality application is to provide
	an efficient and cost effective platform for users to learn
	the skills necessary for a vehicle inspection.	These skills
	include identifying problems with the vehicle and determining
	the steps needed to correct these problems. Using this objective
	as a baseline for the content of the simulation, a system was
	implemented that presents the user with a model of a vehicle
	allowing the user to maneuver around the scene with an interface
	for selecting individual parts of the vehicle.

	It was first necessary to resolve two fundamental concerns
	of implementation common to all VR systems: presentation and
	interaction. The first involves how information is presented
	to the user both in terms of display technology and visual
	representation of data. The second deals with how the user
	interacts with the data presented.

	The key reason for using VR is to enhance computer user
	interaction by utilizing the user's ``natural talents for
	analysis and pattern recognition''\cite{pt95:vrttlg}.  By making
	information easier for the user to assimilate, the user becomes
	more involved in what is seen and determines  what action to take
	rather than simply evaluating the information.  For example,
	the vanishing point of a simple drawing gives the viewer a sense
	of position, direction, and depth. The user can be mentally
	positioned relative to objects in the drawing because they relate
	to natural perceptions.  For this reason, in this implementation
	of VR, data is displayed in a perspectively correct 3D scene.
	The data presented in the vehicle inspection is sky, ground,
	horizon, and a vehicle for inspection. As the user moves, the
	display interactively updates to reflect the user's position and
	perspective relative to the objects in the scene. As a result,
	users have a sense of position, size, and orientation while in
	the VR scene.

	A flat-screen display is used to display a 3D scene.
	A flat display was chosen over more expensive technologies
	like head-mounted displays due to cost and availability
	considerations. However, the flexibility of the hardware and
	software technologies used to implement the system allows the
	addition of other hardware including stereo-scopic glasses to
	add additional realism. Stereo-scopic glasses, which are worn
	like regular glasses, consist of two lenses that can change
	their opacity at a high frequency. By alternating the left and
	right eye's opacity from transparent to opaque while at the same
	time alternating the scene being displayed on the flat screen
	from a left eye's perspective to a right eye's perspective,
	the optical illusion of three dimensionality and perspective is
	further enhanced.

	To facilitate natural movement within a 3D environment, the
	software utilizes a six degree-of-freedom (6DOF) input device,
	such as a Space Orb$^{\tt TM}$. Using this hand-held device,
	the user can translate and rotate their location within the
	3D scene. Other input devices for moving in VR worlds, such as
	keyboard, mice, and most joysticks force the user to move in a
	single plane with no rotation. However, a 6DOF device allows
	a user to translate both position and viewing orientation
	simultaneously. This results in natural movement in 3D space
	using a single intuitive device (See Figure~\ref{fig:person}).


	%The next step in implementing the VR system is to incorporate
	%user interaction with the scene. 
	In order to select parts of a vehicle for inspecting, a
	standard mouse is used. By positioning the mouse pointer over
	the part of interest and clicking the mouse button, parts can be
	selected. Once selected, a dialog box containing information about
	the part is displayed. This information includes the name of the
	part and a description of the part.  An edit box is made 
	available for the user to
	enter the problem description and the appropriate action to take.
	As an additional feature, the user can re-inspect any part up to a
	maximum number of inspection attempts. This number can be set by
	the designer of the inspection scenario.    During an inspection
	of a vehicle, all interaction the user has with the scene
	objects are recorded and timed. At the end of the inspection,
	a full account of the inspector's performance can be produced
	with information such as the amount of time taken to inspect the
	vehicle, a list of parts inspected, a list of parts not inspected,
	and the action taken by the inspector on inspected parts.
\newpage
	The following steps summarize a user's interaction with a VR
	world while performing a vehicle safety inspection.
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	\item First, the user locates a part on the vehicle. To do
	this the user moves around the 3D scene using the 6DOF input device.
	\item Second, the user selects a part to inspect with the mouse.
	\item Third, the user types a course of action 
	to correct the problem.
                \end{list}

\begin {figure}[h]
   \centerline{\psfig{figure=mvc-003f.ps,height=4in}}
   \caption{A Person Conducting an Inspection with a SpaceOrb by SpaceTec [6]}
   \label{fig:person}
\end{figure}

	Traditionally limited to workstations, VR can be prohibitively
	expensive to implement.  In addition to realism, another objective
	was to make the system cost effective. As a result, the cost of
	the target platform was made an important consideration. Due to
	high availability of inexpensive components, PC-class workstations
	running Microsoft Windows NT with high-end video hardware was
	the obvious answer. This platform choice allows implementation
	on existing desktop PCs with minor modifications while at the
	same time remaining compatible with the next generation of
	PCs. Furthermore, the decision to use a high-level graphics API
	built on top of OpenGL and a standardized programming language
	makes it possible to rapidly port to platforms other than the PC.


\begin {figure}[h]
   \centerline{\psfig{figure=new_fig2-bw.ps,width=6.5in}}
   \caption{Screen Shots of MVIS.}
   \label{fig:inspection}
\end{figure}


\section*{TESTING AND RESULTS}

\vspace{-12pt}


	The testing sequence, using approximately 15 individuals,
	was organized into two stages.	The first stage was designed
	to determine how long it would take for the users to become
	familiarized  with the interface and acclimated to using
	the SpaceOrb$^{{\tt TM}}$ for navigating in the VR world.
	The second stage was designed to test the accuracy of the graphics
	representation by analyzing the ability of the user to correctly
	interpret the size of the vehicle.

	In the first stage, the testers were  presented with 3
	simple objects (cube, sphere, cone) positioned in a VR world.
	The testers were told that two objects could be inspected and one
	could not.  The task of the testers was to find the inspectable
	objects while exploring the scene.  This simple exercise allowed
	the user to practice using the SpaceOrb$^{{\tt TM}}$ and 
	the interface for
	inspecting objects.  Testers became proficient with the 
	SpaceOrb$^{{\tt TM}}$
	and navigation in approximately 10 minutes on average.


	In the second stage, the testers were presented with a full
	scale model of a CAT 785 haul truck placed in a VR world (See
	Figure~\ref{fig:inspection}).  The truck was the only object
	in the scene.  In this stage, the task of the testers was to
	navigate the scene and to explore the truck presented to them.
	Although testers were encouraged to find as many inspectable parts
	on the truck as possible, the intention was for the user to see
	as much of the scene from as many different angles as possible.

	At the end of the simulation the testers were asked several
	questions one of which was the approximate height of the truck.
	Those who tested the system were initially told that their height
	was five  feet six inches.  Sixty-seven percent answered within
	two feet and eighty-nine percent answered within four feet of
	the actual truck height (18 feet).  Other than their height,
	the testers were given no visual clues.


\section*{CONCLUSIONS AND FUTURE WORK}

\vspace{-12pt}


%	\begin{itemize}
%	\item Overall results \\
%		itemize benefits of VR training. \\
%		brief summary of results
%	\item Future work \\
%		stereo-scopic glasses.\\
%		scenario setup \\
%		vehicle tear-apart.
%	\end{itemize}



	This paper describes a VR-based Mine Vehicle Inspection Simulator
	(MVIS).  MVIS provides a method of training that is superior
	in several ways to traditional training methods including book
	work, live vehicle inspections, and training videos. First, this
	method allows the user to learn through interaction rather than
	viewing static material. Second, it is cost effective because a
	vehicle does not need to be taken out of production for practicing
	inspections as with live vehicle inspections. Third, our system
	automatically records the user's progress as he or she interacts
	with the program providing a metric for performance. Finally,
	the vehicle used in the program is fully configurable so that
	different scenarios can be created and tested. In summary,
	our implementation of VR for training is more flexible and cost
	effective than other available training methods.

	The current product is being enhanced with the ability to
	separate an equipment model into parts that can be modified
	for the inspection application.  This will make it possible
	to do inspection training for any vehicle for which there is a
	3D model.  VR has considerable potential for other applications
	in the areas of mining and mine safety.  A vehicle operation
	training program is currently in development.  This VR application
	involves creating a driving simulation for a haul truck along with
	the associated scenario set-up applications.  This will allow
	trainers to place static and dynamic hazards into a particular
	open-pit mine model and have the trainees drive a vehicle in the
	mine while spotting and dealing with the hazards that have been
	arranged in different locations of the mine.  Other applications
	being investigated are modeling of environmental reclamation of
	mines and underground mine evacuation training.

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