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AutoDESPATCH: GPS based Mine Production Monitoring System
Kartikeya Verma, V.K. Anand, Amit Kr. “Montu”, Jai Kumar, Jayati Paul, Ashutosh Gopinath, R. P. Singh
Automation Division, Tata Steel, Jamshedpur, India
Kartikeya Verma, V.K. Anand, Amit Kr. “Montu”, Jai Kumar, Jayati Paul, Ashutosh Gopinath, R. P. Singh
Automation Division, Tata Steel, Jamshedpur, India
Introduction [1]:
Opencast coal-mines operate with periodic drilling, blasting and then excavations which in turn is followed by removal of Over Burden (OB) and retrieval of the coal. In the process of coal mining, two main sub processes viz. removal of OB and retrieval of coal are predominant. But most of the effort goes in the removal of OB and this has a dominant influence on the productivity. In the process of OB removal, two of the equipment viz. Rear Dumper and Excavator play a leading role. After the schedule of blasting in an specific zone of the mine has been prepared, the Excavator loads the OB into RD and each RD goes practically through four different machine states i.e. Waiting (near Loading zone), Loading, Full and Empty (at Dumping zone). This sequence of machine states of a RD constitutes one trip. Now it may be understood that to monitor the productivity automatically, one has to monitor the movement of RDs around the corresponding Excavator i.e. Loading zone to Dumping zone and back to Loading zone. For Drilling process to monitor, it is desired to capture actual depth drilled & the location of hole as per the drilling plan to achieve the optimised blasting effort. Fuel consumption is another costly component to run the mine at optimum cost and to monitor it, it is desired to capture actual fuel dispensed in different HEMMs as a result to achieve effective cost control.
AutoDESPATCH system has been designed & developed indigenously by Automation Division, Tata Steel and first implemented at Quarry SE Coal Mine of West Bokaro and also being implemented at Noamundi Iron Ore Mines of Tata Steel. The system is based GPS technology and few other sensor & Communication technologies to offer an online Mine Production Monitoring System for any opencast mines with suitable customisation. The basic system features of AutoDESPATCH are explained in the following sections.
GPS Technology [2]:
GPS is a satellite based tracking system. A total of 24 GPS satellites orbit at 11,000 nautical miles above the Earth. The satellites transmit signals that can be detected by anyone with a GPS receiver. The receiver compares its own time with the time sent by a satellite and uses the difference between the two times to calculate its distance from the satellite. By checking its time against the time of three satellites whose positions are known, a receiver could pinpoint its longitude, latitude, and altitude.
GPS technology has been adopted for use with AutoDESPATCH Field Electronics, to enable the tracking of equipment within Open Cast mines. The GPS position is used to identify the location of dumpers with respect to sources and destinations and thus automate the dumper cycle. Excavators periodically broadcast their positions. These broadcasts are received by electronics on board dumpers, which then update tables that store the excavator co-ordinates. In order to permit accuracy of the order of 5 meters, it is necessary to broadcast differential corrections to the GPS unit. The GPS engine utilised in the AutoDESPATCH field electronics used in Open Cast mines is able to cope with:
Mobile Equipment
The mobile equipment being monitored in this system are of FOUR types viz. Rear Dumper, Excavator, Drill Machine & Fuel Tanker / Stations The operation of the Excavator is very important as it is responsible for taking out the overburden from the mines, which opens the way for digging of the coal. It has very little movement while in operation. The trucks are used to dump the overburden to the dump site. They travel over long distances.
On Board Processing Unit (OBPU)
OBPU is the heart of Field Electronics mounted in the HEMM. The architecture of OBPU is based on Intel’s Embedded Controller and is developed to achieve the objective of Single Board Computer (SBC). The OBPU collects the data from onboard sensors, GPS receiver, GTS, EMS / PMS / DEI (as the case may be with the particular HEMM) and transmits via a Radio Network to AutoDESPATCH Control Room and vice versa.
Graphical Touch Screen (GTS)
The GTS is the logical choice in situations where operator interaction is required. All screens are soft configurable. This allows for user defined menu structures, ability to use icons instead of words and the ability to touch the screen to make a selection, making training of operators quick and the use of the product intuitive. Though integrated into AutoDESPATCH, the GTS can even be used to access information not directly relevant to AutoDESPATCH. Following are some of the areas of usage of the GTS:
Fig.1. AutoDESPATCH Typical Field Electronics on HEMMs
The GTS provides equipment operators with the ability to interact with the system. Via this terminal they login, manually enter reasons for stoppages, assign themselves, request information from the base and are sent information unsolicited from the base.
The OBPU provides all the drivers for communications with on board electronic subsystems, and provide the capability for communications with the base via a radio.
The GPS unit provides the equipment with knowledge of where it is. The position of each equipment is broadcast periodically and this is the mechanism via which the base and other mobile equipment are notified of its location.
The Radio provides the communication backbone for the site.
The Payload System typically found on board modern trucks provides information of the quantity of material being filled onto a truck.
Engine management systems allow AutoDESPATCH to record parameters of interest to production and maintenance. Thus engine run hours and standby hours may be got from these systems. Vital signs monitoring is also possible using the OBPU. By utilising advanced reporting mechanisms provided by the OBPU (report on delta change, upper limit, etc. instead of the traditional polled methodology) bandwidth requirements may be kept to a minimum.
In many situations no engine management systems exist. Transducers or other methods may then be used to get certain data. For example a digital input off the oil pressure switch can provide the mechanism to get engine hours. The neutral switch may be used to get engine idling hours. Proximity switches may be used to get the body up input of automating the dump cycle (if it does not already exist). Even the GPS provides the system with valuable information of whether the truck is moving or stopped. All of this is made possible because of the wide interfacing capability of the OBPU.
The following section gives additional details on the data gathering and information capability of AutoDESPATCH with respect to various categories of equipment. All the information presented is indicative and can be varied to suit the site’s requirements.
Rear Dumper
Following is a description on the operation of the dumper.
A) The host computer (also known as the base) sends an assignment to the dumper, typically to go to a particular excavator, is loaded, then take the material to a designated dumpsite or storage facility. The operator interface inside the cabin will alert the driver of the new assignment.
Fig.2. Dumper Proceeds to Excavator
B) As the dumper moves towards the assigned excavator, the on-board GPS (Global Positioning System) will notify the base of the dumpers’ location in the mine.
Fig.3. Dumper Sends a GPS Update
C) Once the dumper enters the vicinity of the excavator, slows down and comes to a complete stop, the system will log the dumper as waiting to be loaded by that particular excavator. A “Waiting” message will appear on the operator’s interface.
Fig.4. Dumper Waiting at the Excavator
D) The dumper will remain in waiting until the excavator dumps the first pass onto the tray. This is detected by an increase in the dumper’s weight sensors (pressure struts). The dumper will now be logged as loading and the message “loading” will appear on the operator’s interface.
Fig.5. Dumper Loading at the Excavator
E) Whilst loading the dumper, the excavator operator is shown the lower and upper payload weight tolerances of that particular dumper in both numeric and graphic representation. The Indicators show the ideal weight that the dumper should carry. This target between the tolerances ensures no under or overloading of materials occurs.
If the dumper is either under or overloaded, the supervisor can be alerted accordingly.
F) Once loaded, the dumper hauls the material to its assigned destination. To be registered as hauling full, the dumper must have increased its speed and left the beacon vicinity of the excavator.
The operators interface will now display “Hauling Full”.
Fig.6. Dumper Hauling Material to Destination
G) As the dumper moves along the haul road, it will register its current location with the system via the GPS.
Fig.7. Dumper Sends GPS Update on Haul Road
H) When the dumper arrives at the final destination and the dump switch is activated, the system will acknowledge the dumper has dumped the material at its pre-assigned destination.
Fig.8. Dumper Dumps Load at Destination
When the dumper leaves the dump destination, it will be logged as “Hauling Empty”. This will appear on the operator interface.
The cycle is then repeated or a new assignment is issued from the base.
I) If the dumper suffers a breakdown (e.g. Flat tyre), the operator presses DELAY on the interface and selects a reason for the delay from the selection list provided.
Fig.9. Dumper Goes into Delay
Once selected, the base and supervisors are alerted of the problem and maintenance crews can be dispatched to rectify it immediately. Alternately, delays or other actions can be logged automatically without operator’s input. For example if a fuel level sensor is fitted to the dumper, the onboard electronics can monitor its signals. If the fuel level falls below an assigned value, the system will report the situation automatically, allowing for the immediate dispatch of a fuel/service car.
Excavator
The excavator operator uses the GTS to log in, make assignments and notify of delays and breakdowns. The GTS also displays payload information of the material being filled into a dumper by an excavator along with the target weight range. The GPS on board the excavator periodically transmits position information. Dumpers to use this so that they may automatically identify excavators that they are being loaded by. Engine management systems or transducers may be used to get engine run hours, idle hours etc.
Productivity information of the excavator is computed based on the productivity of the dumpers loading from the excavator. Thus the dumpers payload is attributed to the excavator that filled it. Based on this the following real time KPIs may be monitored. These include:
Key to monitoring of production information of a drill is the Drilled Depth. Transducers connected to OBPU will monitor drill rpm, pull down pressure, and depth. This data is communicated to the OBPU via a device driver. The drill operator uses the GTS to log in, make assignments, enter hole numbers and notify of delays and breakdowns. The GTS also displays hole data such as hole depth, bit speed, bit air pressure (High / Low), rate of penetration, etc, all graphically for the user which is obtained from the Transducer.
The drill monitor can provide the following real time information:
The fuel truck operator uses the GTS to log in, and notify the equipment being filled. Sensors on fuel and oil dispensing lines fed into PLCs can compute the amount of fuel being discharged. The OBPU interrogates the PLC each time a fuelling transaction is completed and transmits the transaction back to the base.
Comprehensive fuel reporting and tracking may be achieved via this mechanism. Some of the real-time KPIs are:
Similarly information from other such systems may be monitored, logged and viewed in real time.
Radio Network
For the data transfer between the mobile equipment and the base server a radio network is installed. Prior to the radio-network design, a thorough radio survey was done to achieve a good understanding of potential bad coverage areas. There were several areas like at the wall of the cut or behind spoil piles and reject dumps. As landscape within a mine is dynamic and therefore it is planned that the radio coverage will be checked regularly. The performance of the system depends heavily on the successful data transmission from both sides i.e. data from the mobile equipment to the base station and from the base station to the mobile equipment. A poor radio coverage can lead to loss of data, which cannot be compromised.
RF data network of AutoDESPATCH system at Quarry SE, West Boakro, is in the UHF band with total 24 nodes operational spread over a span of 2.5 KM. This network is modular in nature and can be further expanded for more nodes. The network comprises of one base station and 23 mobile equipment. Currently we are using 2.4kbps data rate that can be safely increased to 4.8 kbps data rate. Communication protocol designed has three-layer architecture – physical layer, packetization layer and protocol layer. This protocol is built on the CSMA/CD algorithm with added handshaking algorithm for catering hidden terminals. This becomes very important in case of irregular terrain like coal mines. Due to this irregular terrain it may happen that nodes are unable to see each other. As a result multiple nodes keep on trying simultaneously causing large number of collisions. Since radio networks support low data rates, these collisions can reduce the throughput seriously. With our protocol design we have achieved a good throughput keeping collisions at a low level.
Base Station
The Base station consists of basically three units:
Fig.10. Block Diagram of Base Station
OBPU does all the processing between AutoDESPATCH server and the Field equipment. Software coding provides the necessary intelligence, to route the messages properly, depending on the context viz: which message or data has to be sent to the server, which has to be acknowledged, which requires the response from the base, and so on.
AutoDESPATCH Software
Web based Mine Production Monitoring software has several following modules & features which can be customised as per the requirement
Online Server Module
Online server module collects data in real time from field equipment, validates it, generates alerts if it goes out of the limit, and stores it in the database. It also sends data to the field equipment. Online Server Module maintains information on all equipment and locations within the shift. It logs to the database all incoming data that are received during the shift. These data are later used to calculate Key Performance Indicators (KPIs) and generate shift reports. Following are the information it receives from and sends to field equipment:
KPI/KPM module calculates the KPI/KPM defined in the AutoDESPATCH system for each and every equipment and processes involved in mining operations based on the formulae given by the user. This module takes data that was earlier collected by the Online module and calculate KPIs using the formulae or rules provided by the users. A few of the KPIs are: availability, utilisation, productivity, maintenance compliance index, drilling rate, fuel consumption rate etc.
Manual Data Entry (MDE) Module
MDE module is about entering and editing data manually. It is used to add/modify/delete production, delay and KPI data for non-monitored processes and equipment. It also gives facility to modify/delete the production, delay and KPI data for monitored processes and equipment if data cannot be captured in real time due to reasons like communication failure or operator’s inattentiveness.
Online Console module consists of screens, which displays all real time information for the selected shift. Control functionality such as assigning an equipment, sending a message or setting or clearing a delay can also be achieved using this interface.
Online Mapping Module
The mapping functionality shows the current location, status and assignment of monitored equipment in real time. Various color codes are given to identify the status and assignment of equipment. Furthermore the user can select to follow the movement of one particular equipment. The map can have several layers, which allows the user to choose the display of only relevant information. This is to increase the view of the map to a better comprehensible one, which is particular important if the map includes a lot of detailed landmarks such as haul roads, tracks, creeks, stockpiles, dumps, elevation lines, etc. Online Mapping module is used to display the mines map on the screen in digitized form with lots of features e.g. zoom-in, zoom-out, pan etc. It also gives summary of equipment performance in the shift whenever user clicks on icon of the equipment.
Online Mapping Module performs the following:
Fig.11. Online Mapping & Tracking
Reporting Module
Reporting module generates various report as per users requirement. Writing simple database queries can generate the reports. The module is designed so that any user of the system can prepare customize reports using the reports wizard with little effort.
Following types of reports are provided by AutoDESPATCH:
Dynamic scheduling module is used to generate automatic assignment for mining equipment (like dumper and excavator). This module has got built-in intelligence, which ensures that generated assignments result in minimising idle time of excavators and traveling time or waiting time of dumpers. Relevant optimisation techniques are used to achieve the objective of this module.
Production Planning & Monitoring Module
Production planning module facilitates user to plan production of different products (overburden, coal, reject coal etc.) seam-wise on monthly basis.
This module performs the following:
This module calculates performance of operators based on parameters like equipment run hour, number of trips done (in case of dumper), Bench cubic meter (incase of excavator), meterage (in case of drill).
This module performs the following:
The implementation of the AutoDESPATCH spans multiple areas. These include AUTODESPATCH field hardware and operator software. The following tangible and / or intangible benefits are expected to accrued in the following different areas:
1.0 Dynamic Allocation Module (first version) which automatically assigns the dumpers to shovels / excavators depending various inputs like availability of equipment and cycle time etc.
2.0 UNIX based Operating System and system can easily be ported on Windows 2000 OS as and when required.
3.0 Shift Performance / MDE etc can be viewed / done during the current shift without waiting for the shift to end. This is big time saver for the control room incharge for MDE etc.
4.0 Remote Monitoring of AutoDESPATCH System through Internet / Intranet using standard web browser.
5.0 On-line performance monitoring of Drill machine.
6.0 On-line performance monitoring of Fuel Dispensing system. (in implementation phase)
7.0 Production Planning and compliance / adjustment w.r.t. Surveyed Production Figures.
8.0 Implementation of Drill Down Reports for various KPIs.
9.0 Improved method for capturing Engine Run Hour of monitored Equipment and identification of OEM / USER responsibilities for various break downs / delays .
10.0 Operator Performance / Incentive or Bonus evaluation module.
11.0 Vendor / OEM Payment evaluation module.
12.0 Audio Alarms for Equipment Operator
13.0 Online data capturing of Truck Payload Monitoring System (TPMS).
14.0 Improved Hardware i.e. Onboard Processing Unit (OBPU) with additional Digital / Analog I/Os and Serial Ports. Site testing of the hardware was carried out in Dumper #104 for more than 2 weeks and was found reliable.
15.0 Online data capturing of Engine parameters through direct interface OEM’s (Hitachi EX2500) Engine Monitoring System (EMS) (without the need of individual sensors)
16.0 Facility of storing data in the Field OBPUs incase of RF Data Communication failure and to be sent later when RF Link resumes. This ensures improved data integrity.
17.0 Improvement in Production with pay back period less than one year.
18.0 Reduction in Operational and Maintenance Delays.
Conclusion
AutoDESPATCH: GPS Mine Production Monitoring System implemented at Quarry SE, West Bokaro Collieries and being implemented at Noamundi Iron Mines is another good example of GPS Applications and usage of several other sensor & communication technologies to facilitate mining industries to make use of it. Instead it is a continuous process to keep improving the features & facilities as and when it is felt and realised.
Further Scope:
Opencast coal-mines operate with periodic drilling, blasting and then excavations which in turn is followed by removal of Over Burden (OB) and retrieval of the coal. In the process of coal mining, two main sub processes viz. removal of OB and retrieval of coal are predominant. But most of the effort goes in the removal of OB and this has a dominant influence on the productivity. In the process of OB removal, two of the equipment viz. Rear Dumper and Excavator play a leading role. After the schedule of blasting in an specific zone of the mine has been prepared, the Excavator loads the OB into RD and each RD goes practically through four different machine states i.e. Waiting (near Loading zone), Loading, Full and Empty (at Dumping zone). This sequence of machine states of a RD constitutes one trip. Now it may be understood that to monitor the productivity automatically, one has to monitor the movement of RDs around the corresponding Excavator i.e. Loading zone to Dumping zone and back to Loading zone. For Drilling process to monitor, it is desired to capture actual depth drilled & the location of hole as per the drilling plan to achieve the optimised blasting effort. Fuel consumption is another costly component to run the mine at optimum cost and to monitor it, it is desired to capture actual fuel dispensed in different HEMMs as a result to achieve effective cost control.
AutoDESPATCH system has been designed & developed indigenously by Automation Division, Tata Steel and first implemented at Quarry SE Coal Mine of West Bokaro and also being implemented at Noamundi Iron Ore Mines of Tata Steel. The system is based GPS technology and few other sensor & Communication technologies to offer an online Mine Production Monitoring System for any opencast mines with suitable customisation. The basic system features of AutoDESPATCH are explained in the following sections.
GPS Technology [2]:
GPS is a satellite based tracking system. A total of 24 GPS satellites orbit at 11,000 nautical miles above the Earth. The satellites transmit signals that can be detected by anyone with a GPS receiver. The receiver compares its own time with the time sent by a satellite and uses the difference between the two times to calculate its distance from the satellite. By checking its time against the time of three satellites whose positions are known, a receiver could pinpoint its longitude, latitude, and altitude.
GPS technology has been adopted for use with AutoDESPATCH Field Electronics, to enable the tracking of equipment within Open Cast mines. The GPS position is used to identify the location of dumpers with respect to sources and destinations and thus automate the dumper cycle. Excavators periodically broadcast their positions. These broadcasts are received by electronics on board dumpers, which then update tables that store the excavator co-ordinates. In order to permit accuracy of the order of 5 meters, it is necessary to broadcast differential corrections to the GPS unit. The GPS engine utilised in the AutoDESPATCH field electronics used in Open Cast mines is able to cope with:
- Satellite obstruction problems and signal multi-path where filters are utilised to eliminate reflections of a cliff face.
- High walls and canyons which restrict the view of the sky to a few satellites.
- Jagged faces where satellites are reacquired in less than one second after previously being hidden from view.
Mobile Equipment
The mobile equipment being monitored in this system are of FOUR types viz. Rear Dumper, Excavator, Drill Machine & Fuel Tanker / Stations The operation of the Excavator is very important as it is responsible for taking out the overburden from the mines, which opens the way for digging of the coal. It has very little movement while in operation. The trucks are used to dump the overburden to the dump site. They travel over long distances.
On Board Processing Unit (OBPU)
OBPU is the heart of Field Electronics mounted in the HEMM. The architecture of OBPU is based on Intel’s Embedded Controller and is developed to achieve the objective of Single Board Computer (SBC). The OBPU collects the data from onboard sensors, GPS receiver, GTS, EMS / PMS / DEI (as the case may be with the particular HEMM) and transmits via a Radio Network to AutoDESPATCH Control Room and vice versa.
Graphical Touch Screen (GTS)
The GTS is the logical choice in situations where operator interaction is required. All screens are soft configurable. This allows for user defined menu structures, ability to use icons instead of words and the ability to touch the screen to make a selection, making training of operators quick and the use of the product intuitive. Though integrated into AutoDESPATCH, the GTS can even be used to access information not directly relevant to AutoDESPATCH. Following are some of the areas of usage of the GTS:
- To acquire operator inputs such as pin number, assignment and breakdowns.
- To display information sent from the base to the operator
- To allow the operator to request information on performance and production from the base.
- Generally, Engine Management status and breakdown information is displayed in codes. The GTS integrated with the OBPU is able to allow these codes to be displayed in words and even sent to the base.
- As an integrated console for display of any relevant information onboard the equipment via the OBPU.
Fig.1. AutoDESPATCH Typical Field Electronics on HEMMs
The GTS provides equipment operators with the ability to interact with the system. Via this terminal they login, manually enter reasons for stoppages, assign themselves, request information from the base and are sent information unsolicited from the base.
The OBPU provides all the drivers for communications with on board electronic subsystems, and provide the capability for communications with the base via a radio.
The GPS unit provides the equipment with knowledge of where it is. The position of each equipment is broadcast periodically and this is the mechanism via which the base and other mobile equipment are notified of its location.
The Radio provides the communication backbone for the site.
The Payload System typically found on board modern trucks provides information of the quantity of material being filled onto a truck.
Engine management systems allow AutoDESPATCH to record parameters of interest to production and maintenance. Thus engine run hours and standby hours may be got from these systems. Vital signs monitoring is also possible using the OBPU. By utilising advanced reporting mechanisms provided by the OBPU (report on delta change, upper limit, etc. instead of the traditional polled methodology) bandwidth requirements may be kept to a minimum.
In many situations no engine management systems exist. Transducers or other methods may then be used to get certain data. For example a digital input off the oil pressure switch can provide the mechanism to get engine hours. The neutral switch may be used to get engine idling hours. Proximity switches may be used to get the body up input of automating the dump cycle (if it does not already exist). Even the GPS provides the system with valuable information of whether the truck is moving or stopped. All of this is made possible because of the wide interfacing capability of the OBPU.
The following section gives additional details on the data gathering and information capability of AutoDESPATCH with respect to various categories of equipment. All the information presented is indicative and can be varied to suit the site’s requirements.
Rear Dumper
Following is a description on the operation of the dumper.
A) The host computer (also known as the base) sends an assignment to the dumper, typically to go to a particular excavator, is loaded, then take the material to a designated dumpsite or storage facility. The operator interface inside the cabin will alert the driver of the new assignment.
Fig.2. Dumper Proceeds to Excavator
B) As the dumper moves towards the assigned excavator, the on-board GPS (Global Positioning System) will notify the base of the dumpers’ location in the mine.
Fig.3. Dumper Sends a GPS Update
C) Once the dumper enters the vicinity of the excavator, slows down and comes to a complete stop, the system will log the dumper as waiting to be loaded by that particular excavator. A “Waiting” message will appear on the operator’s interface.
Fig.4. Dumper Waiting at the Excavator
D) The dumper will remain in waiting until the excavator dumps the first pass onto the tray. This is detected by an increase in the dumper’s weight sensors (pressure struts). The dumper will now be logged as loading and the message “loading” will appear on the operator’s interface.
Fig.5. Dumper Loading at the Excavator
E) Whilst loading the dumper, the excavator operator is shown the lower and upper payload weight tolerances of that particular dumper in both numeric and graphic representation. The Indicators show the ideal weight that the dumper should carry. This target between the tolerances ensures no under or overloading of materials occurs.
If the dumper is either under or overloaded, the supervisor can be alerted accordingly.
F) Once loaded, the dumper hauls the material to its assigned destination. To be registered as hauling full, the dumper must have increased its speed and left the beacon vicinity of the excavator.
The operators interface will now display “Hauling Full”.
Fig.6. Dumper Hauling Material to Destination
G) As the dumper moves along the haul road, it will register its current location with the system via the GPS.
Fig.7. Dumper Sends GPS Update on Haul Road
H) When the dumper arrives at the final destination and the dump switch is activated, the system will acknowledge the dumper has dumped the material at its pre-assigned destination.
Fig.8. Dumper Dumps Load at Destination
When the dumper leaves the dump destination, it will be logged as “Hauling Empty”. This will appear on the operator interface.
The cycle is then repeated or a new assignment is issued from the base.
I) If the dumper suffers a breakdown (e.g. Flat tyre), the operator presses DELAY on the interface and selects a reason for the delay from the selection list provided.
Fig.9. Dumper Goes into Delay
Once selected, the base and supervisors are alerted of the problem and maintenance crews can be dispatched to rectify it immediately. Alternately, delays or other actions can be logged automatically without operator’s input. For example if a fuel level sensor is fitted to the dumper, the onboard electronics can monitor its signals. If the fuel level falls below an assigned value, the system will report the situation automatically, allowing for the immediate dispatch of a fuel/service car.
Excavator
The excavator operator uses the GTS to log in, make assignments and notify of delays and breakdowns. The GTS also displays payload information of the material being filled into a dumper by an excavator along with the target weight range. The GPS on board the excavator periodically transmits position information. Dumpers to use this so that they may automatically identify excavators that they are being loaded by. Engine management systems or transducers may be used to get engine run hours, idle hours etc.
Productivity information of the excavator is computed based on the productivity of the dumpers loading from the excavator. Thus the dumpers payload is attributed to the excavator that filled it. Based on this the following real time KPIs may be monitored. These include:
- Operator, assignment, location, status, etc
- Loads, tons, bcm
- Tons/hour, bcm/hour
- Pass number, pass weight, pass duration, payload weight, target weight, etc
- Tons and BCM moved by the excavators daily, weekly, etc.
- Tons/hour, bcm/hour, average pass weights, pass times, load times etc. can be monitored and compared between equipment, operators, shifts, etc.
- Availability, utilisation, MTBF, and the complete range of KPIs derived from the analysis of stoppages
Key to monitoring of production information of a drill is the Drilled Depth. Transducers connected to OBPU will monitor drill rpm, pull down pressure, and depth. This data is communicated to the OBPU via a device driver. The drill operator uses the GTS to log in, make assignments, enter hole numbers and notify of delays and breakdowns. The GTS also displays hole data such as hole depth, bit speed, bit air pressure (High / Low), rate of penetration, etc, all graphically for the user which is obtained from the Transducer.
The drill monitor can provide the following real time information:
- Operator, assignment, status, etc
- No. of holes drilled, meters drilled etc
- Hole depth, RPM, bit air pressure, pulldown pressure, rate of penetration, etc
- Productivity on a shift, daily, weekly, operator basis
- Hole statistics
- Bit statistics
- Availability, utilisation, MTBF, and the complete range of KPIs derived from the analysis of stoppages of the drill
The fuel truck operator uses the GTS to log in, and notify the equipment being filled. Sensors on fuel and oil dispensing lines fed into PLCs can compute the amount of fuel being discharged. The OBPU interrogates the PLC each time a fuelling transaction is completed and transmits the transaction back to the base.
Comprehensive fuel reporting and tracking may be achieved via this mechanism. Some of the real-time KPIs are:
- Operator, status, etc
- Number of equipment filled
- Quantities of fuel and other materials dispensed
- Average fuel consumption for all equipment (liters/operating hour, liters/km)
- Total fuel consumption of the mine daily, weekly, monthly, etc
- Tons/liter for production equipment
- Availability, utilisation, MTBF, and the complete range of KPIs derived from the analysis of stoppages
Similarly information from other such systems may be monitored, logged and viewed in real time.
Radio Network
For the data transfer between the mobile equipment and the base server a radio network is installed. Prior to the radio-network design, a thorough radio survey was done to achieve a good understanding of potential bad coverage areas. There were several areas like at the wall of the cut or behind spoil piles and reject dumps. As landscape within a mine is dynamic and therefore it is planned that the radio coverage will be checked regularly. The performance of the system depends heavily on the successful data transmission from both sides i.e. data from the mobile equipment to the base station and from the base station to the mobile equipment. A poor radio coverage can lead to loss of data, which cannot be compromised.
RF data network of AutoDESPATCH system at Quarry SE, West Boakro, is in the UHF band with total 24 nodes operational spread over a span of 2.5 KM. This network is modular in nature and can be further expanded for more nodes. The network comprises of one base station and 23 mobile equipment. Currently we are using 2.4kbps data rate that can be safely increased to 4.8 kbps data rate. Communication protocol designed has three-layer architecture – physical layer, packetization layer and protocol layer. This protocol is built on the CSMA/CD algorithm with added handshaking algorithm for catering hidden terminals. This becomes very important in case of irregular terrain like coal mines. Due to this irregular terrain it may happen that nodes are unable to see each other. As a result multiple nodes keep on trying simultaneously causing large number of collisions. Since radio networks support low data rates, these collisions can reduce the throughput seriously. With our protocol design we have achieved a good throughput keeping collisions at a low level.
Base Station
The Base station consists of basically three units:
- On Board Processing Unit (OBPU)
- AutoDESPATCH Server
- UHF/VHF Antenna
Fig.10. Block Diagram of Base Station
OBPU does all the processing between AutoDESPATCH server and the Field equipment. Software coding provides the necessary intelligence, to route the messages properly, depending on the context viz: which message or data has to be sent to the server, which has to be acknowledged, which requires the response from the base, and so on.
AutoDESPATCH Software
Web based Mine Production Monitoring software has several following modules & features which can be customised as per the requirement
Online Server Module
Online server module collects data in real time from field equipment, validates it, generates alerts if it goes out of the limit, and stores it in the database. It also sends data to the field equipment. Online Server Module maintains information on all equipment and locations within the shift. It logs to the database all incoming data that are received during the shift. These data are later used to calculate Key Performance Indicators (KPIs) and generate shift reports. Following are the information it receives from and sends to field equipment:
- Login and Logout by equipment operator.
- Replies to Login and Logout from control room.
- Assignment selection from equipments by equipment operator.
- Assignment selection from control room.
- During status change of equipment (e.g. wait, load, full, empty status of dumpers).
- Locations of equipment from Global Positioning System (GPS).
- Engine Run Hour reading of Equipment.
- After loading is completed (in case of excavator).
- After drilling is completed (in case of drilling machine).
- After fueling is completed (in case of fuel station or fuel tanker).
- When the trip is updated (in case of dumper or excavator) from control room.
- Any other message sent from control room to equipment.
KPI/KPM module calculates the KPI/KPM defined in the AutoDESPATCH system for each and every equipment and processes involved in mining operations based on the formulae given by the user. This module takes data that was earlier collected by the Online module and calculate KPIs using the formulae or rules provided by the users. A few of the KPIs are: availability, utilisation, productivity, maintenance compliance index, drilling rate, fuel consumption rate etc.
Manual Data Entry (MDE) Module
MDE module is about entering and editing data manually. It is used to add/modify/delete production, delay and KPI data for non-monitored processes and equipment. It also gives facility to modify/delete the production, delay and KPI data for monitored processes and equipment if data cannot be captured in real time due to reasons like communication failure or operator’s inattentiveness.
- MDE Module performs the following:
- Opens the shift data as specified by the user from database.
- Displays the data requested by the user
- Provides facilities to Edit the data
- Save the data to database.
Online Console module consists of screens, which displays all real time information for the selected shift. Control functionality such as assigning an equipment, sending a message or setting or clearing a delay can also be achieved using this interface.
Online Mapping Module
The mapping functionality shows the current location, status and assignment of monitored equipment in real time. Various color codes are given to identify the status and assignment of equipment. Furthermore the user can select to follow the movement of one particular equipment. The map can have several layers, which allows the user to choose the display of only relevant information. This is to increase the view of the map to a better comprehensible one, which is particular important if the map includes a lot of detailed landmarks such as haul roads, tracks, creeks, stockpiles, dumps, elevation lines, etc. Online Mapping module is used to display the mines map on the screen in digitized form with lots of features e.g. zoom-in, zoom-out, pan etc. It also gives summary of equipment performance in the shift whenever user clicks on icon of the equipment.
Online Mapping Module performs the following:
- Displays the mines map in the digitised format with different features.
- Tracks the equipment & its path on the map.
- Gives the status of the moving equipment whenever the user clicks on the icon of the moving equipment. For dumpers, the status gives the equipment number, state of dumper if full or empty, number of trips done till that point of time during the shift. For excavator, the status shows the equipment number, equipment location and total load given till that point of time during the shift.
- If any equipment is under maintenance a red cross appears on it indicating that it is not available for use. A yellow cross will appear over a equipment if the equipment is idle, for example during tea break or any other operational delay.
Fig.11. Online Mapping & Tracking
Reporting Module
Reporting module generates various report as per users requirement. Writing simple database queries can generate the reports. The module is designed so that any user of the system can prepare customize reports using the reports wizard with little effort.
Following types of reports are provided by AutoDESPATCH:
- Shift based report including truck, loader production.
- Fuelling based report.
- Delay based report.
- Time based reports for availability, utilisation, etc.
Dynamic scheduling module is used to generate automatic assignment for mining equipment (like dumper and excavator). This module has got built-in intelligence, which ensures that generated assignments result in minimising idle time of excavators and traveling time or waiting time of dumpers. Relevant optimisation techniques are used to achieve the objective of this module.
Production Planning & Monitoring Module
Production planning module facilitates user to plan production of different products (overburden, coal, reject coal etc.) seam-wise on monthly basis.
This module performs the following:
- Gives facility to user to enter the plan figure seam-wise in the beginning of the month.
- Tracks the actual production figure on daily basis.
- Calculates the balance for the remaining period of the month based on the surveyed figure.
This module calculates performance of operators based on parameters like equipment run hour, number of trips done (in case of dumper), Bench cubic meter (incase of excavator), meterage (in case of drill).
This module performs the following:
- Measures performance of operators on shift basis.
- Helps to track the performance of the operators on daily, weekly and monthly basis.
- Finds out the best operators of a particular class of equipment on daily, weekly and monthly basis
- Calculates the performance bonus of each operator after making the adjustment for the weekly surveyed figures.
The implementation of the AutoDESPATCH spans multiple areas. These include AUTODESPATCH field hardware and operator software. The following tangible and / or intangible benefits are expected to accrued in the following different areas:
1.0 Dynamic Allocation Module (first version) which automatically assigns the dumpers to shovels / excavators depending various inputs like availability of equipment and cycle time etc.
2.0 UNIX based Operating System and system can easily be ported on Windows 2000 OS as and when required.
3.0 Shift Performance / MDE etc can be viewed / done during the current shift without waiting for the shift to end. This is big time saver for the control room incharge for MDE etc.
4.0 Remote Monitoring of AutoDESPATCH System through Internet / Intranet using standard web browser.
5.0 On-line performance monitoring of Drill machine.
6.0 On-line performance monitoring of Fuel Dispensing system. (in implementation phase)
7.0 Production Planning and compliance / adjustment w.r.t. Surveyed Production Figures.
8.0 Implementation of Drill Down Reports for various KPIs.
9.0 Improved method for capturing Engine Run Hour of monitored Equipment and identification of OEM / USER responsibilities for various break downs / delays .
10.0 Operator Performance / Incentive or Bonus evaluation module.
11.0 Vendor / OEM Payment evaluation module.
12.0 Audio Alarms for Equipment Operator
13.0 Online data capturing of Truck Payload Monitoring System (TPMS).
14.0 Improved Hardware i.e. Onboard Processing Unit (OBPU) with additional Digital / Analog I/Os and Serial Ports. Site testing of the hardware was carried out in Dumper #104 for more than 2 weeks and was found reliable.
15.0 Online data capturing of Engine parameters through direct interface OEM’s (Hitachi EX2500) Engine Monitoring System (EMS) (without the need of individual sensors)
16.0 Facility of storing data in the Field OBPUs incase of RF Data Communication failure and to be sent later when RF Link resumes. This ensures improved data integrity.
17.0 Improvement in Production with pay back period less than one year.
18.0 Reduction in Operational and Maintenance Delays.
Conclusion
AutoDESPATCH: GPS Mine Production Monitoring System implemented at Quarry SE, West Bokaro Collieries and being implemented at Noamundi Iron Mines is another good example of GPS Applications and usage of several other sensor & communication technologies to facilitate mining industries to make use of it. Instead it is a continuous process to keep improving the features & facilities as and when it is felt and realised.
Further Scope:
- Implementation of Engine Monitoring System (EMS) for Rear Dumper.
- Online Integration with Mine .Planning System
- Online Integration with Attendance Recording System
- GPS based Truck Dispatch System at West Bokaro Collieries, paper published in The Proceedings, The Asian GPS Conference 2001.
- A Comprehensive Guide to Land Navigation with GPS by J. Hotchkiss, 3rd edition.
- Functional Specification Document, Quarry SE, West Bokaro , 2003.