Abstract:
The system contains a central computer unit having a first database controlled by a first logic unit. At least one mobile computer unit is joined with the mobile equipment. Each of the mobile computer units has a second database controlled by a second logic unit. At least one wireless communication device enables communication between said first logic unit and said second logic unit, wherein said mobile computer unit is operable independent of the first logic unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to copending U.S. Provisional Application entitled, “Computerized Mine Production System”, having Ser. No. 60/749,218, filed Dec. 9, 2005, which is entirely incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention is generally related to a method and apparatus for tracking mobile objects within a predefined territory. The invention has particular utility for tracking the location, movement, and related activity of mobile machines at a mine production site and will be described in connection with such utility, although other utilities are contemplated.  
       BACKGROUND OF THE INVENTION  
       [0003]     Several vendors have previously designed and deployed computerized mine production systems. Such vendors include Modular Mining Systems, Caterpillar, Wenco, and Tritronics. Although some of these systems have similar goals to present invention, the architecture of previously deployed systems were significantly different. Initially, these systems were developed using computers and wireless networking technologies available in the early 1980s. At this time, portable microprocessors were limited to approximately 8K to 32K of available RAM memory, 8K to 32K of ROM memory and had processing speeds of approximately 1 MHz. Wireless network technology at this time utilized narrow band UHF or VHF communications which limited the peak data rate to approximately 1200 to 9600 bits/second. Today, inexpensive mobile microprocessors easily provide hundreds of megabytes of RAM, gigabytes of flash storage, and operate at speeds of 1 GHz and higher. Similarly, wireless network technology has evolved to provide 11 to 54 megabits/second peak data transfer speeds. In summary, both microprocessor speeds and network bandwidth provide at least 1000 times more capacity than the technologies used in the design of the earlier mining systems.  
         [0004]     The limited capability of computer technology used in the design of the earlier mining systems dictated a design in which most of the processing was performed by a single central computer. Mobile devices were simple interfaces which mostly transmitted button pushes and displayed text messages or very simple graphical interfaces. Existing prior art systems have a single centralized database, centralized control logic, and typically provide minimal data access capabilities for mobile equipment. Because mobile equipment cannot directly access the database, the mobile software typically communicates with the centralized business logic using short messages called RPCs (remote procedure calls).  
         [0005]     Because existing mine control systems place all data and algorithms on the central computer, these systems must provide network availability close to 100% throughout the entire production area. Although this was possible with narrow-band UHF and VHF technologies, new wireless networking technologies such as 802.11 often have shadow areas in which the network coverage is unavailable. With a centralized system design, mobile users cannot operate in areas where network coverage is unavailable. Coverage and communications issues often plague such installations since the system design cannot operate when the computer network is unavailable. Additionally, modem technologies for equipment monitoring such as video cameras, radars, or high-precision GPS require logic on-board the equipment. Integration of such devices into a system with only centralized control of equipment is impractical because of wireless bandwidth constraints.  
         [0006]     Several vendors have designed and deployed mine production systems which monitor and control trucks in a mining operation. Many of these systems also perform automatic assignment and/or allocation of trucks to loading equipment. Current systems base their allocation strategy on either predetermined assignments stored in a central database, or a mathematical model, which determines optimal flow rates for trucks on each production path. Such allocation strategy models are fairly rigid, expecting all equipment to perform identically, while bearing identical loads and moving lockstep. Although such allocation strategies can perform well in theory, real life operation is less than ideal.  
         [0007]     Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.  
       SUMMARY OF THE INVENTION  
       [0008]     Embodiments of the present invention provide a system and method for tracking mobile equipment at a site. Briefly described, in architecture, one embodiment of the system, among others, can be implemented as follows. The system contains a central computer unit which includes computer usable medium having computer readable program code disposed therein, and having a first database controlled by a first logic unit. At least one mobile computer unit is joined with the mobile equipment. Each of the mobile computer units has a second database controlled by a second logic unit. At least one wireless communication device enables communication between said first logic unit and the second logic unit, wherein the mobile computer unit is operable independent of the first logic unit.  
         [0009]     The present invention can also be viewed as providing methods for tracking mobile equipment at a site. In this regard, one embodiment of such a method, among others, can be broadly summarized by the following steps: tracking information regarding a status of the mobile equipment with a mobile computer unit joined to the mobile equipment; storing information regarding the status of the mobile equipment on the mobile computer unit joined to the mobile equipment; and transmitting information regarding the status of the mobile equipment from the mobile computer unit joined to the mobile equipment to a central computer unit.  
         [0010]     Other systems, methods, features, and advantages of the present invention will be or become apparent upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Many aspects of the invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.  
         [0012]      FIG. 1  is a first schematic representation of a mine production system, in accordance with a first exemplary embodiment of the present invention.  
         [0013]      FIG. 2  is a second schematic representation of the mine production system, in accordance with the first exemplary embodiment of the present invention.  
         [0014]      FIG. 3  is a block diagram of the mine production system, in accordance with the first exemplary embodiment of the present invention.  
         [0015]      FIG. 4  is a block diagram of an exemplary general purpose computer for the mine production system, in accordance with the first exemplary embodiment of the present invention.  
         [0016]      FIG. 5  is a first graphical user interface view for the mine production system, in accordance with the first exemplary embodiment of the present invention.  
         [0017]      FIG. 6  is a second graphical user interface view for the mine production system, in accordance with the first exemplary embodiment of the present invention.  
         [0018]      FIG. 7  is a third graphical user interface view for the mine production system, in accordance with the first exemplary embodiment of the present invention.  
         [0019]      FIG. 8  is a fourth graphical user interface view for the mine production system, in accordance with the first exemplary embodiment of the present invention.  
         [0020]      FIG. 9  is a fifth graphical user interface view for the mine production system, in accordance with the first exemplary embodiment of the present invention.  
         [0021]      FIG. 10  is a sixth graphical user interface view for the mine production system, in accordance with the first exemplary embodiment of the present invention.  
         [0022]      FIG. 11  is a front view of a mobile electronic device used with the mine production system, in accordance with the first exemplary embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0023]     Referring to  FIGS. 1-3 , the mine production system  100  in accordance with a first exemplary embodiment of the present invention may be used to create a comprehensive data acquisition, communications, control, and optimization system for the mining industry. The mine production system  100  includes an SQL database  124  on a central computer unit  105 . The SQL database  124  is in communication with a plurality of mobile computer units  105  located on mobile equipment  104 . That communication with a plurality of computers located on mobile equipment is achieved with a plurality of wireless communication devices  106 , which may be located with or within the central computer unit  105 , with or within the mobile equipment  104 , and/or at other points local to a site. The central computer unit  105  is also in communication with at least one user access point  108 , which may allow a user or electronic agent to manage the activity of the mobile equipment  104 .  
         [0024]     The plurality of mobile computer units  105  located on the mobile equipment  104  may include control and graphic display computers using modern wireless systems such as 802.11b, 802.11g or other IP based wireless network technology. At least one of the mobile computer units  105  located on the mobile equipment  104  may utilize GPS positioning technology to periodically track a position, speed, and heading of the mobile equipment  104 . The mobile computer units  105  located on the mobile equipment  104  may interface with one or more existing on-board monitoring systems that provide information such as payload, engine status, tire pressure, or other relevant data.  
         [0025]     The mine production system  100  may be utilized to increase efficiency of the mining haulage cycle by continuously monitoring the location and status of all trucks, shovels and support equipment in the mine, and making optimal work assignments. Mines that employ computer optimization systems typically achieve significant gains in equipment operating time, productivity, and cost savings.  
         [0026]     The at least one access point  108  to access information regarding the mine production system  100  or any of the mobile devices connected to the mine production system  100  may operate through an Intranet or the Internet  110 . The access point  108  may be accessed through computers on the mobile equipment  104 , PCs, laptops, PDAs, or other electronic devices capable of interacting with the central computer unit  105  using wired and/or wireless communication positioned locally or remotely.  
         [0027]     Referring in particular to  FIG. 3 , the central computer unit  105  communicates with the plurality of mobile computer units  105  located on the mobile equipment  104  through the wireless communication devices  106 . The wireless communication devices  106  may be located with or within the central computer unit  105 , with or within the mobile equipment  104 , and/or at other points local to a site. The central computer unit  105  comprises one or more general-purpose computers as described herein in relation to  FIG. 4 . The central computer unit  105  may include a mine control unit  118 , a central SQL database server  120 , a central SQL database  124 , and/or a messaging and database replication server  122 . The mine control unit  118  may control the operation of the mine production system  100 , in whole or in part. That is, the mine control unit  118  may operate and store at least some of the logic and software routines useful to controlling operation of the mine.  
         [0028]     The central SQL database server  120  may control access to and distribute information from the central SQL database  124 . The central SQL database  124  may store at least some of the information useful to control operations of the mine production system  100 . Tables contained in the central SQL database  124  may contain real-time and/or historical operating data including, but not limited to, the location and/or health of the mobile equipment  104 , performance information, etc. The central SQL database  124  may also contain data regarding the mining site, including, but not limited to known paths along the site, grades and conditions of the paths, and similar information. Some data regarding the mining site may be collected based on the travels of the mobile equipment and communication with the mobile computer unit.  
         [0029]     The mine production system  100  is known to be operable using a PostgreSQL database for the central SQL database  124  described herein, although other commercially available or privately designed databases may be used for the central SQL database  124  without departing from the scope of the present invention. The central SQL database  124  may also be able to interface to other database servers such as, but not limited to, MySQL, Oracle, or SQL Server through the central SQL database server  120 .  
         [0030]     The central SQL server  124  may be in communication with the messaging and database replication server  122 . This communication may be used to receive, process and/or update information for the central SQL database  124 . That communication may further be used to replicate updated information to one or more of the plurality of mobile computer units  105  located on the mobile equipment  104 . The central SQL server  124  may also be able to interface with other mining systems.  
         [0031]     The plurality of mobile computer units  105  located on the mobile equipment  104  may include a messaging and database replication client  126 . The messaging and database replication client  126  may communicate through the wireless communication devices  106  with the messaging and database replication server  122 . The messaging and database replication client  126  may upload local changes to and/or receive replication updates from the messaging and database replication server  122 . The messaging and database replication client  126  may further handle central SQL database  124  queries and database notifications with on-board clients. The messaging and database replication client  126  may be used to copy some or all of the data stored on the central SQL database  124 .  
         [0032]     The plurality of mobile computer units  105  located on the mobile equipment  104  may include a mobile SQL database  128 . The mobile SQL database  128  may be a duplicate of the central SQL database  124 . It may be periodically, regularly, and/or continually updated and synchronized with the central SQL database  124 . Updating and synchronization of the mobile SQL database  128  may be achieved through the messaging and database replication client  126 . If one of the mobile computer units  105  located on the mobile equipment  104  loses contact with central computer unit  105 , the mobile SQL database  128  may store any local changes. The mobile computer units  105  located on the mobile equipment  104  may be designed to primarily or solely use the mobile SQL database  128  when the central SQL database  124  is unavailable. Once the network connection for the mobile computer units  105  located on the mobile equipment  104  is restored, the central SQL database  124  and the mobile SQL database  128  may be synchronized. The mobile SQL database  128 , for example, may utilize the open-source sqlite (www.sqlite.org) database, which provides a lightweight embedded SQL database, although other commercially available or otherwise created databases may similarly be utilized without departing from the scope of the present invention.  
         [0033]     One possible table in the mobile SQL server  128  is a distributed system configuration table. The configuration of at least some of the devices is stored in the distributed system configuration table. At boot time, at least some of the devices may query the mobile SQL database  128  to initiate software modules unique to that device. This architecture may allow centralized configuration of the mine production system  100  software on the mobile equipment  104 .  
         [0034]     The plurality of mobile computer units  105  located on the mobile equipment  104  may include a mobile device control module  130 , a device monitoring system  138 , and an on-board GPS system  140 . The mobile device control module  130  may run the mine production system  100  software on the mobile equipment  104 . The device monitoring system  138  may be able to accurately determine speed and position of the mobile equipment at regular intervals, if not continuously. The speed and position may be tracked and stored as information on the mobile computer unit  105 . The speed and position information may be stored with a time stamp at regular intervals, if not continuously.  
         [0035]     The mobile device control module  130  may include a mobile equipment control and data acquisition logic mechanism  132 . The mobile equipment control and data acquisition logic mechanism  132  may interface with the on-board GPS system  140  and the device monitoring system  138 . The mobile equipment control and data acquisition logic mechanism  132  may also track the current activity and status of the mobile equipment  104  and compute and/or store production information from the mobile SQL database  128 . The mobile equipment control and data acquisition logic mechanism  132  may periodically or continuously calculate an arrival time to a known destination, based on speed and position data. The calculated arrival time may be periodically or continuously related to the central computer unit  102 . The mobile control module  130  may also include an object/relational mapping software  134 . The object/relational mapping software  134  may map one or more SQL relational database tables to an object model used by the mobile equipment control and data acquisition logic mechanism  132  and maintain referential integrity in the mobile SQL database  128 .  
         [0036]     An operator of the mobile equipment  104  may interface with one or more mobile computer units  105  on the mobile equipment  104  through a graphical user interface (GUI)  136 . The GUI  136  may allow the user to interact with the mobile device control module  130 , perform queries against the mobile SQL database  128 , and/or receive database update notifications. The GUI  136  may present a rich graphical interface to the operator, displaying a map with all the roads, current location of all equipment, and other on-board status information.  
         [0037]      FIG. 5  is a first graphical user interface  136 A view for the mine production system  100 , in accordance with the first exemplary embodiment of the present invention. The first GUI  136 A view is of a vehicle health display GUI. The mining production system  100  may allow the user real-time access to data for the vehicle health monitoring systems, including, for example, oil temperature  142 , oil pressure  144 , water temperature  146 , and water pressure  148 , as well as charting the values for that data over time and showing an alarm state if values for that data reach a predetermined alarm value. The mining production system  100  may also allow the user to perform trend analysis of at least a portion of current data and/or historical data, which may be accessible within one or more mobile computer units  105  on the mobile equipment  104  or through the wireless communication devices  106 .  
         [0038]      FIG. 6  is a second graphical user interface  136 B view for the mine production system  100 , in accordance with the first exemplary embodiment of the present invention. One of the possible features of the mine production system  100  includes an ability to calculate a preferred travel path for mobile equipment  104  in the mine. The second GUI  136 B view shown in  FIG. 6  is related to this feature. The second GUI  136 B view may display detailed path information for each loaded truck and automatic audio-visual alarms for misrouted loads. Additionally, GPS velocity information and real-time comparison with planned values can be displayed.  
         [0039]      FIG. 7  is a third graphical user interface view  136 C for the mine production system  100 , in accordance with the first exemplary embodiment of the present invention. As shown in  FIG. 7 , the mine production system  100  may provide a detailed GPS  136 C view of one or more excavator locations and update excavator movement to all field units.  
         [0040]      FIG. 8  is a fourth graphical user interface  136 D view for the mine production system  100 , in accordance with the first exemplary embodiment of the present invention, and  FIG. 9  is a fifth graphical user interface  136 E view for the mine production system  100 , in accordance with the first exemplary embodiment of the present invention. The fourth GUI  136 D view is a mobile unit bench display, which may include an ability to display different layers of information. The fifth GUI  136 E view is a sample loading unit display. The mine production system  100  may load bench information from a mine-planning package and allow the user to query the mine production system  100  for complete polygon information from one or more active benches.  
         [0041]      FIG. 10  is a sixth graphical user interface  136 F view for the mine production system  100 , in accordance with the first exemplary embodiment of the present invention. The sixth GUI  136 F view contains active dump information. The user may use the GUI  136  to track dump information, perform trend analysis for dumping rates, and coordinate with sub-3 meter accuracy on dumping locations.  
         [0042]      FIG. 11  is a front view of a mobile electronic device  150  used with the mine production system  100 , in accordance with the first exemplary embodiment of the present invention. The mobile electronic device  150  may, for instance, include platform-independant software application(s) that can be deployed in any commercially available ruggedized computer. The mobile electronic device  150 , for example, may be equipped with external 2.4 antennas, GPS receivers and serial interface capabilities that can communicate locally with the health monitoring systems of the mobile equipment  104 , and with the central computer unit  105  via a standard 802.11x or infrastructure for any other wireless communication devices  106 . Those having ordinary skill in the art will recognize that similar equipment having varying specifications may be used in conjunction with the mobile electronic device  150  without departing from the scope of the present invention.  
         [0043]     The mine production system  100  can be implemented in hardware, software, firmware, or a combination thereof. The mine production system may be implemented in software or firmware that is stored in a memory and that is executed by a suitable instruction execution system. If implemented in hardware, the mine production system  100  can be implemented, for example, with any or a combination of the following technologies, which are all well known in the art: a discrete logic circuit(s) having logic gates for implementing logic functions upon data signals, an application specific integrated circuit (ASIC) having appropriate combinational logic gates, a programmable gate array(s) (PGA), a field programmable gate array (FPGA), etc.  
         [0044]     The mine production system  100  can be implemented in software (e.g., firmware), hardware, or a combination thereof. The mine production system  100  may be implemented in software, as an executable program, and is executed by a special or general-purpose digital computer, such as a personal computer (PC; IBM-compatible, Apple-compatible, or otherwise), workstation, minicomputer, or mainframe computer.  
         [0045]      FIG. 4  is a block diagram of an exemplary general-purpose computer  200  for the mine production system  100 , in accordance with the first exemplary embodiment of the present invention. Generally, in terms of hardware architecture, the general-purpose computer  200  includes a processor  212 , a memory  214 , and one or more input and/or output (I/O) device(s)  216  (or peripherals) that are communicatively coupled via a local interface  218 . The local interface  218  can be, for example but not limited to, one or more buses or other wired or wireless connections, as is known to those having ordinary skill art. The local interface  218  may have additional elements, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers, to enable communications. Further, the local interface may include address, control, and/or data connections to enable appropriate communications among the aforementioned components.  
         [0046]     The processor  212  is a hardware device for executing software, particularly that stored in memory  214 . The processor  212  can be any custom made or commercially available processor, a central processing unit (CPU), an auxiliary processor among several processors associated with the general-purpose computer  200 , a semiconductor based microprocessor (in the form of a microchip or chip set), a macroprocessor, or generally any device for executing software instructions. Examples of suitable commercially available microprocessors include PA-RISC series microprocessors from Hewlett-Packard Company, 80×86 or Pentium series microprocessors from Intel Corporation, PowerPC microprocessors from IBM, Sparc microprocessors from Sun Microsystems, Inc, and 68xxx series microprocessors from Motorola Corporation.  
         [0047]     The memory  214  can include any one or combination of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, etc.)) and nonvolatile memory elements (e.g., ROM, hard drive, tape, CD-ROM, etc.). Moreover, the memory  214  may incorporate electronic, magnetic, optical, and/or other types of storage media. Note that the memory  214  can have a distributed architecture, where various components are situated remote from one another, but can be accessed by the processor  212 .  
         [0048]     The software  210  in memory  214  may include one or more separate programs, each of which comprises an ordered listing of executable instructions for implementing logical functions. In the example of  FIG. 4 , the software  210  in the memory  214  may include the mine production system  100  as described herein.  
         [0049]     The memory  214  may further include a suitable operating system (O/S)  222 . A nonexhaustive list of examples of suitable commercially available operating systems  222  include: Windows operating systems available from Microsoft Corporation; Netware operating systems available from Novell, Inc.; Macintosh operating systems available from Apple Computer, Inc.; UNIX operating systems which are available from many vendors including Hewlett-Packard Company, Sun Microsystems, Inc., and AT&amp;T Corporation; LINUX operating systems, which are freeware that are readily available on the Internet; and appliance-based operating systems, such as that implemented in handheld computers or personal data assistants (PDAs) (e.g., PalmOS available from Palm Computing, Inc., and Windows CE available from Microsoft Corporation). The operating system  222  essentially controls the execution of other computer programs, such as the mine production system  100 , and provides scheduling, input-output control, file and data management, memory management, and communication control and related services.  
         [0050]     The software  210  may include a source program, an executable program (object code), a script, or any other entity comprising a set of instructions to be performed. When a source program, then the program needs to be translated via a compiler, assembler, interpreter, or the like, which may or may not be included within the memory  214 , so as to operate properly in connection with the O/S  222 . Furthermore, the software  210  can be written as (a) an object oriented programming language, which has classes of data and methods, or (b) a procedure programming language, which has routines, subroutines, and/or functions, for example but not limited to, C, C++, Pascal, Basic, Fortran, Cobol, Perl, Java, and Ada. The core messaging system used for the mine production system  100  may be written in objective-C and pure Java to assure portability to any operating system.  
         [0051]     The I/O devices  216  may include input devices, for example but not limited to, a keyboard, mouse, scanner, microphone, touchscreen, etc. The I/O devices  216  may also include output devices, for example but not limited to, a printer, display, etc. The I/O devices  216  may further include devices that communicate both inputs and outputs, for instance but not limited to, a modulator/demodulator (modem; for accessing another device, system, or network), a radio frequency (RF) or other transceiver, a telephonic interface, a bridge, a router, wireless router, etc.  
         [0052]     If the general-purpose computer  200  is a PC, workstation, or the like, the software  210  in the memory  214  may further include a basic input output system (BIOS) (omitted for simplicity). The BIOS is a set of essential software routines that initialize and test hardware at startup, start the O/S  222 , and support the transfer of data among the hardware devices. The BIOS is stored in ROM so that the BIOS can be executed when the general-purpose computer  200  is activated.  
         [0053]     When the general-purpose computer  200  is in operation, the processor  212  may be configured to execute software  210  stored within the memory  214 , to communicate data to and from the memory  214 , and to generally control operations of the general-purpose computer  200  pursuant to the software  210 . The O/S  222 , may be read by the processor  212 , perhaps buffered within the processor  212 , and then executed.  
         [0054]     When the mine production system  100  is at least partially implemented in software  210 , as is shown in  FIG. 4 , it should be noted that portions of the mine production system  100  can be stored on any computer readable medium for use by or in connection with any computer related system or method. In the context of this document, a computer readable medium is an electronic, magnetic, optical, or other physical device or means that can contain or store a computer program for use by or in connection with a computer related system or method. The mine production system  100  can be embodied, in part, in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “computer-readable medium” can be any means that can store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer readable medium can be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a nonexhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic) having one or more wires, a portable computer diskette (magnetic), a random access memory (RAM) (electronic), a read-only memory (ROM) (electronic), an erasable programmable read-only memory (EPROM, EEPROM, or Flash memory) (electronic), an optical fiber (optical), and a portable compact disc read-only memory (CD-ROM) (optical). Note that the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.  
         [0055]     Using accurate position information derived as described herein, a truck allocation algorithm, stored in logic units of the central computer unit  102  and/or the mobile computer units  105 , may compute a set of optimal truck assignments which minimize excess travel time, truck waiting time, and shovel idle time. By way of example, the algorithm may compute and/or manipulate one or more of the following variables:  
         [0056]     N(t) The total number of trucks being allocated.  
         [0057]     N(l) The total number of loading units being allocated.  
         [0058]     T(i) The travel time for the i&#39;th LP selected path F(i) The target feed rate for the i&#39;th LP selected path.  
         [0059]     R(i) The current moving average feed rate allocated to the i&#39;th LP selected path.  
         [0060]     S(i) The j&#39;th assignment set of truck allocations to paths feeding loading units.  
         [0061]     T(j) The excess travel time incurred by all trucks in the j&#39;th assignment set  
         [0062]     X(T) Relative cost weighting factor for excess travel time  
         [0063]     W(j) The total truck waiting time incurred by all trucks in the j&#39;th assignment set  
         [0064]     X(W) Relative cost weighting factor for truck waiting time  
         [0065]     l(j) The total loading unit idle time incurred by all shovels in the j&#39;th assignment set.  
         [0066]     X(l) Relative cost weighting factor for loading unit idle time  
         [0067]     C(j) Cost function of S(j), evaluated as X(T)*T(j)+X(W)*W(j)+X(l)*I(j)  
         [0068]     Each discrete mobile equipment  104  assignment affects a truck waiting time W(j) and loading unit idle time I(j) for all other assignments. The assignments of the individual mobile equipment  104  can be coordinated to improve efficiency. The total T(j), W(j), and I(j) for each assignment set S(j) may be evaluated and compared.  
         [0069]     Because the total number of possible assignment sets is N(l)**N(t), performing an exhaustive search of all possible assignment sets may be undesirable. For example, a typical mining operation could have 10 or more loading units and 50 or more trucks, making the total number of possible assignments 10 50 . It may also be undesirable to investigate all possible assignment sets because a goal of the discrete assignment algorithm is to minimizes waiting, idle, and travel times for a given assignment set and vetting 10 50  possible assignments could generate additional delays. This algorithm may be constructed to avoid all the blending, digging rate, dumping capacity, and other constraints already optimized in the LP optimization algorithm. Thus, the assignment algorithm may be constrained to only investigate those assignment sets which closely match an optimal LP selected feed rates F(i), which greatly decreases the dimensionality of the search.  
         [0070]     The truck assignment algorithm consists of the following steps: creating an assignment set S which includes an ordered queue of all mobile equipment  104  currently assigned to each loading unit; finding the neediest path P(j) which minimizes T(i)*(R(i)-F (i)); evaluating C(j) for allocating each unallocated truck, A(j) to path, P(j); and for the smallest N values of C(j), allocating truck A(j) to the assignment set S(j) and repeat the algorithm at step  2 .  
         [0071]     The algorithm may continue until the assignment set with minimum cost C(j) is found. Note that the dimensionality of this algorithm increases proportional to N 2 , where N is the number of potential assignments evaluated for each truck. In practice, small values of N (eg. N=2 to N=4) yield optimal results, since higher values of cost C(j) are increasingly unlikely to yield optimal values for the assignment set S(j).  
         [0072]     It should be emphasized that the above-described embodiments of the present invention are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.