WO2008078288A1

WO2008078288A1 - Local positioning in a blasting system

Info

Publication number: WO2008078288A1
Application number: PCT/IB2007/055224
Authority: WO
Inventors: Ray Frederick Greyvenstein; Vernon West
Original assignee: Bulk Mining Explosives (Proprietary) Limited
Priority date: 2006-12-22
Filing date: 2007-12-19
Publication date: 2008-07-03

Abstract

A local positioning system (10) for use in an electronic blasting system and a method for locating network nodes in such as system are provided. The local positioning system (10) comprises a plurality of network nodes (14, 14A, 14B, 16, 18) positioned in and/or around a blast area. Each of the plurality of network nodes (14, 14A, 14B, 16, 18) comprises a communications module (30) to communicate with each other over a short range wireless radio link thereby to establish wireless coverage of the blast area. At least some of the network nodes comprise location modules (32) to determine the location of another network node in the blast area.

Description

LOCAL POSITIONING IN A BLASTING SYSTEM

BACKGROUND OF THE INVENTION

THIS invention relates to a local positioning system for use in an electronic blasting system. The invention further relates to a method to locate network nodes, e.g., a mobile handheld unit, detonator, personnel or equipment, in a blast area.

In order to ensure maximum efficiency and safety during large blasting operations in which electronic detonators are used, it is essential that the specific location of each electronic detonator in a blast arrangement is known and that each electronic detonator is allocated a predetermined time or delay at which to detonate. The location and delay time of each electronic detonator are taken into account by the blast operator in designing a suitable blast plan and it is well known that any errors in the blast plan or the implementation of the blast plan may cause significant losses in performance and may even pose safety hazards to personnel or equipment in the vicinity of the blasting operation.

GPS (Global Positioning System) is a known technology used to determine the specific geographic positions of electronic detonators in a blast arrangement. However, the use of GPS technology has been restricted in large open cast mines as the horizon inside a pit is very high when a blasting operation is to occur inside the pit. This reduces the number of satellites "visible" to a GPS unit and hence the accuracy of GPS in determining the geographic positions of the electronic detonators. Also, as GPS signals cannot be received underground, GPS is not a suitable technology for any underground blasting operations. It is an object of the invention to provide an alternative positioning system for use in a blasting system.

SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided a local positioning system for use in an electronic blasting system, the local positioning system comprising a plurality of network nodes positioned in and/or around a blast area, each of the plurality of network nodes comprising a communications module to communicate with each other over a short range wireless radio link thereby to establish wireless coverage of the blast area and wherein at least some of the network nodes comprise location modules to determine the location of another network node in the blast area.

Preferably, the location of the other network node is determined through triangulation.

Typically the other network node may have a location module.

The other network node may form part of a mobile handheld unit used to communicate with detonators in the blast area.

Preferably, the mobile handheld unit may be used to allocate a detonator ID to a particular detonator, to obtain a detonator ID from a detonator having a predefined detonator ID or to program a detonator with a delay time in accordance with a designed blast plan.

In addition the mobile handheld unit may be used to map a particular blast plan with pre-drilled detonator holes. The other network node may be associated with a detonator or a connector of a detonator in order to receive firing commands during a blasting operation.

The other network node may be carried by personnel or equipment operating in the blast area thereby to track or locate personnel or equipment.

The equipment operating in the blast area may be a drilling machine used to enable the design and execution of a suitable blast plan.

Preferably the network node forming part of the drilling machine is monitored by other network nodes thereby to determine a blast pattern.

Preferably the local positioning system forms part of an electronic blasting system.

One of the network nodes may be a coordinating network node in communication with external devices configured to initiate a blast.

The network nodes may be ZigBee modules.

A method of locating network nodes in an electronic blasting system comprising a plurality of network nodes positioned in or around a blast area, the method comprising

establishing communication between a plurality of network nodes over a short range wireless radio link in order to provide wireless coverage of the blast area; and

in response to establishing communication, utilising triangulation methods to determine the relative physical positions of the plurality of network nodes within the network and the blast area. The method may further comprise receiving a communication from a mobile network node positioned in the blast area and establishing the relative position of the mobile network node in the blast area by utilising triangulation between the mobile network node and the other network nodes.

The mobile network node may form part of a mobile handheld unit to communicate with detonators in the blast area.

Preferably, the method further comprises employing the mobile handheld unit to allocate a detonator ID to a particular detonator, to obtain a detonator ID from a detonator having a predefined detonator ID or to program a detonator with a delay time in accordance with a designed blast plan.

In addition the method may further include employing the mobile handheld unit to map a particular blast plan with pre-drilled detonator holes.

The method may further comprise associating the mobile network node with a detonator or a connector of a detonator in order for the detonator to receive firing commands during a blasting operation.

The mobile network node may be carried by personnel or equipment operating in the blast area thereby to track or locate personnel or equipment.

The equipment operating in the blast area may be a drilling machine, thereby to assist in the design and execution of a suitable blast plan.

Preferably the method may further comprise monitoring the network node forming part of the drilling machine thereby to determine a blast pattern. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram illustrating a local positioning system or network comprising a plurality of network nodes located in a blast area, in accordance with the invention;

Figure 2 is a schematic block diagram of one of the network nodes of Figure 1 ; and

Figure 3 is a simplified flow diagram of a method of locating network nodes in an electronic blasting system, in accordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention aims to provide a local positioning system for use in a blasting system. In one example embodiment the local positioning system forms part of an electronic blasting system. The local positioning system is to provide location information of particular network nodes forming a communication network in a blast area and, depending on the particular application, the communication network may be used in the allocation of detonator identification information or delay times or may be used to apply certain blasting rules. The invention aims to increase the efficiency and safety of blasting operations.

In the embodiment described below, a plurality of network nodes is adapted to communicate with each other over short range wireless radio links using the IEEE 802.15.4 standard for wireless personal area networks (WPAN), e.g., using the ZigBee protocol. However, it will be appreciated that any suitable short range wireless radio communication technology having location-determining modules may be used to implement the invention. Turning to Figure 1 , a local positioning system or network 10 is shown as used in an open cast mine. Reference numeral 12 generally indicates the pit or blast area of the open cast mine. A plurality of network nodes 14 and 16 are positioned around the edges of the pit 12, while a number of network nodes 14A, 14B and 16 are located inside the pit 12. A mobile network node 18 may be associated with a particular person or piece of equipment, and may move around inside the blast area.

In an example embodiment, all of the network nodes 14, 14A, 14B, 16 and 18 communicate with each other using the ZigBee communications protocol. The network nodes 14, 14A, 14B and 16 may be different types of ZigBee devices depending on their particular application and use in the network. For example, the network nodes 14, 14A and 14B may be ZigBee Routers (ZR) used to relay data received from other network nodes in their vicinity.

The network node 16 may be a coordinating network node forming the root of a network tree (e.g., network 10 formed by all the network nodes 14, 14A, 14B, 16 and 18). A ZigBee Coordinator (ZC) may be used as the coordinating network node 16 and may be configured to communicate with outside devices such as a remote blast device 20 or a monitoring computer at central offices 22 of the mine. The coordinating network node 16 may either be connected to the remote blast device 20 at the blast point and the computers at the central offices 22 by a wired connection or may communicate over a separate wireless network, which may be an additional short range or medium range radio network.

The communication between the different network nodes 14, 14A and 14B enables the establishment of wireless coverage of the blast area. The network nodes 14 and 16 located around the edge of the pit 10 are static during blasting operations and may be permanent or semi-permanent, e.g., the network nodes may form part of fixed structures. Alternatively, the network nodes 14 and 16 may be incorporated in portable base stations, which can be moved around the blast area but would typically remain stationary during a blasting operation. The network nodes 14A and 14B are examples of network nodes incorporated in portable base stations, and in the example of Figure 1 , are used to provide sufficient wireless coverage inside the pit 12. Depending on where in the pit 12 a blasting operation is planned, the base stations of the network nodes 14A and 14B may be relocated.

During blasting operations, detonators 24 in a blast zone 26 may be connected to an appropriate, e.g., the closest, network node through a physical harness wire.

At least some of the static network nodes 14, 14A, 14B and 16 comprise location modules (e.g., a location engine of a ZigBee device) to determine the location of other network nodes with location modules (i.e. location enabled network modules) in the blast area. As a first step, the location modules of the static network nodes are used to determine the relative physical positions of the static network nodes in the network 10, e.g., through triangulation.

The location of other network nodes with location modules may also be determined, e.g. mobile network nodes, such as mobile network node 18. This mobile network node 18 moves around the blast area in which wireless coverage has been established by the static network nodes 14, 14A, 14B and 16. It will be appreciated that not all the network nodes 14, 14A, 14B and 16 need to include location modules, but that the ability of the network to locate other network nodes would be dependent on the number of network nodes having location modules. Some of the network nodes 14, 14A, 14B and 16 may only relay information to network nodes in their vicinity.

The ZigBee devices forming the network nodes 14, 14A, 14B and 16 may use a RSSl-based (Received Signal Strength Indication) algorithm to determine the location of any location enabled network node through triangulation. In one example embodiment, the mobile location enabled network node 18 forms part of a mobile handheld unit. This mobile handheld unit is used to communicate with detonators 24 in a blast zone 26 within the blast area, e.g., to allocate a detonator identifier (ID) to a particular detonator, to obtain a detonator ID from a detonator having a predefined detonator ID and/or to program a detonator with a delay time or period in accordance with a designed blast plan.

The mobile handheld unit may be physically connected to each of the detonators 24 in the blast zone 26 during the communication process with a particular detonator. Once the handheld unit has been used to either allocate the detonator IDs or delay time, each detonator 24 may be connected to an appropriate network node through a physical harness wire, in order to receive firing commands during the blasting operation.

In an example embodiment, the mobile handheld unit comprising a mobile location enabled network node 18 is also used by a blast operator to map a particular blast plan with pre-drilled detonator holes, thereby to ensure that a detonator is correctly identified (by either allocating or obtaining the detonator ID) and that the correct delay time is programmed in the detonator.

In another example embodiment, the delay times need not be programmed into the detonator. For example, a unique code in a detonator may be associated with the detonator's particular delay time. This unique code may be stored in the handheld device or even on the communication network itself. In the scenario where the information is stored on the network, it may enable the remote adjustment or altering of delay times and blast plans from the convenience of the central offices 22.

The mobile location enabled network node 18 or another mobile location enabled network node (not shown) may form part of a drilling machine to enable the design of a suitable blast plan. By including a mobile location enabled network node 18 in a drilling machine a blast pattern can be mapped without user input, as the location where drilling takes place will be determined through the monitoring of the mobile network node 18 by the various network nodes 14, 14A, 14B and 16. This information may then be transferred via the coordinator network node 16 to the computer at the central offices 22 and may then be used to design a suitable blast plan (e.g., by allocating appropriate delay times to the blast pattern). Mapping the blast plan to the detonator hole locations would include the step of loading the blast information, e.g., detonation delay times for each detonator, onto the mobile handheld unit mentioned above. With the handheld unit having a mobile location enabled network node 18, a blast operator would be able to allocate the delay information to the correct detonator, based on the location of the hole, as described above.

It will be appreciated that more than one mobile handheld unit may be used to program the various detonators, thereby to facilitate their deployment.

The blast information or detonation delay times may also be stored on the network 10 formed by the static network nodes 14, 14A, 14B and 16, e.g., the information may be transmitted from the computer at the central offices 22 to the coordinator network node 16 where it will be stored. The coordinator network node 16 may then make the information accessible across the network through the other network nodes 14, 14A and 14B. By storing the blast information on a network node and making it accessible across the network 10, the dependence on the mobile handheld unit during detonator programming may be reduced. The malfunction or failure of one mobile handheld unit would have minimal impact as the handheld unit could be replaced without the reloading of the blast information onto the replacement handheld unit at the central office 22. Instead, the mobile location enabled network node 18 forming part of the handheld unit will access the information from the network 10, and map it to the correct location, whereafter the detonators will be programmed. Similarly, by storing the blast information on multiple network nodes 14, 14A, 14B and 16 in the network 10, significant redundancy is established as failure of one node will not impede operations.

In another example embodiment, the blast information or detonation delay times may be stored on any network node 14, 14A, 14B, 16 and 18. In these circumstances it may be necessary for the relevant network nodes to be configured or adapted to store the information e.g., by having additional processors or memory.

The mobile location enabled network node 18 may also be carried by personnel or other equipment operating in the blast area. By carrying a mobile location enabled network node 18, the local positioning network 10 has the ability to track and/or locate equipment or personnel in the blast area, which may increase the safety measures available during blasting operations. For example, if any personnel or equipment is located in the blast area before or during any blasting operations, this information may be transmitted via the various network nodes 14, 14A and 14B and the coordinator network node 16 to the computer at the central offices 22. An operator monitoring the computer may then either take the necessary action to warn the personnel of the pending blast or may instruct personnel to move the equipment still in the blast area. The information on the equipment or personnel located within the blast area may also be transmitted to the remote blasting device 20 which may be configured to refuse blasting operations if any mobile location enabled network nodes associated with equipment or personnel are in a dangerous area (i.e. the blast area).

Other network nodes may also be associated with particular detonators or connectors of detonators, or may form part of such detonators or connectors of detonators. In this configuration, automatic discovery of the location of each detonator is possible without any user input, minimising the possibility of operator error. The network nodes associated with detonators or their connectors may be ZigBee End Devices (ZED), which may be location enabled. These network nodes may have limited functionality and may, in certain example embodiments, not be able to relay data from other devices, although a ZED can communicate with a parent device (e.g. a ZigBee Router).

In one example embodiment, any one of the network nodes may be configured to fire a blast. For example, each network node may be configured to include an internal power supply, which may include a solar power backup module. The network node may also be configured to have sufficient processing capacity to enable it to function as a blast initiator, simply by adding terminals for connection to the detonator wires. An advantage of this configuration is the ability to segment large blasts into smaller more manageable sections, each section being controlled by a separate network node.

A further aspect relating to the invention is the ability to provide additional safety measures when firing blasting operations remotely. In order to limit the risk of receiving counterfeit communications or messages instructing network nodes to fire detonators, a number of rules may be preprogrammed into the remote blast device. For example, the remote blast device 20 may be configured to only receive FIRE messages directly from a specified network node, which may typically be the coordinator network node 16. It will be appreciated that the configuration of the remote blast device 20 may be changed to accept messages from another network node, depending on the requirements or geographical location of the blast zone 26. For example, the network node closest or furthest from the blast zone 26 may in each case be designated. The network node which is to communicate with the remote blast device 20 may be identified through the local positioning system described above.

The network node which is to communicate with the remote blast device 20 may also be "locked" into a predefined communication path to ensure no counterfeit messages are produced within the system. For example, by "locking" certain network nodes in the blast area, a specific path of communication can be established in the network, with only designated network nodes being able to communicate with the remote blast device 20. Commands received from other network nodes would be ignored if the network nodes are not configured as part of the designated physical path of communication. By this means an additional level of redundancy and/or safety is introduced.

The present invention may further provide yet another level of redundancy by transmitting disarm or lock-out instructions not only to the remote blast device 20, but also directly to the network 10 formed by the network nodes 14, 14A, 14B and 16. This addresses the problem where a blast fails to initiate after it was legitimately instructed to do so or where the remote blast device 20 enters an unknown state, e.g., where the remote blast device 20 is instructed to disarm and confirmation of such disarming is not received.

By not storing firing commands in the detonators or their connectors, but rather by initiating a blast over the network 10, the possibility of unexpected firing due to an unknown state of the remote blast device 20 would also be minimised. Commands may simply be placed on the harness as is, for example, by transmitting the firing command from the network, to a particular network node and then, in an example embodiment, through a physical connection to the detonator.

Although the embodiments described above relates to blasting operations in an opencast mine, it will be appreciated that the same system could be implemented in any other mining environment, e.g., any type of surface operations or underground mining operations.

Turning to Figure 2, an example embodiment of the coordinator network node 16 is shown. The node 16 comprises a communications module 30, which may be a transceiver, to communicate with other network nodes over short range wireless radio link, e.g., ZigBee, thereby to establish, with the other network nodes, wireless coverage of the blast area. The network node 16 may further comprise a location module 32 which may use RSSI (or other appropriate technology) to determine the location of another location enabled network node in the blast area through triangulation. It will be appreciated that the location of other location enabled network nodes would only be possible in a network formed by at least three location enabled network nodes.

The network node 16 may be powered by a power source 34 comprising an internal battery which may have an associated solar panel. By using ZigBee technology, and with the limited communication required for blasting operations, the power requirements for network nodes would be minimal.

The network node 16 may also include a memory 36 to store certain information received from the computer at the central offices 22 or from the remote blast device 24. This information may relate to detonator identification, delay times or specific blasting plans to be used across the network.

The configuration of other network nodes may be similar to that of the coordinator network node 16 described in accordance with Figure 2, although not all network nodes may necessarily include a memory 36.

Turning to Figure 3, a simplified flow diagram of a method 40 of locating network nodes in an electronic blasting system is shown. In one example embodiment, this method may be implemented by the system of Figure 1.

As shown by block 42, the method comprises establishing communication between a plurality of network nodes over short range wireless radio link in order to provide wireless coverage of a blast area. In response to establishing communication, triangulation is used to determine the relative positions of the plurality of network nodes within the network and the blast area (see block 44). A communication may be received from a mobile network node positioned in the blast area (shown by block 46) and by triangulation between the mobile network node and the network nodes that provide wireless coverage, a relative position of the mobile network node in the blast area may be determined (block 48).

As mentioned, the mobile network node may form part of a mobile handheld unit to communicate with detonators in the blast area. Alternatively, the mobile network node may be carried by personnel or equipment operating in the blast area or may be associated with a detonator or a connector of a detonator.

Claims

CLAIMS:

1. A local positioning system for use in an electronic blasting system, the local positioning system comprising a plurality of network nodes positioned in and/or around a blast area, each of the plurality of network nodes comprising a communications module to communicate with each other over a short range wireless radio link thereby to establish wireless coverage of the blast area and wherein at least some of the network nodes comprise location modules to determine the location of another network node in the blast area.

2. A local positioning system as claimed in claim 1 , wherein the location of the other network node is determined through triangulation.

3. A local positioning system as claimed in claim 1 or claim 2, wherein the other network node has a location module.

4. A local positioning system as claimed in any one of claims 1 to 3, wherein the other network node forms part of a mobile handheld unit used to communicate with detonators in the blast area.

5. A local positioning system as claimed in claim 4, wherein the mobile handheld unit is used to allocate a detonator ID to a particular detonator, to obtain a detonator ID from a detonator having a predefined detonator ID or to program a detonator with a delay time in accordance with a designed blast plan.

6. A local positioning system as claimed in claim 4, wherein the mobile handheld unit is used to map a particular blast plan with pre-drilled detonator holes.

7. A local positioning system as claimed in any one of claims 1 to 3, wherein the other network node is associated with a detonator or a connector of a detonator in order for the detonator to receive firing commands during a blasting operation.

8. A local positioning system as claimed in any one of claims 1 to 3, wherein the other network node is carried by personnel or equipment operating in the blast area thereby to track or locate the personnel or equipment.

9. A local positioning system as claimed in claim 8, wherein the equipment operating in the blast area is a drilling machine used to enable the design and execution of a suitable blast plan.

10. A local positioning system as claimed in claim 9, wherein the network node forming part of the drilling machine is monitored by other network nodes thereby to determine a blast pattern.

11. A local positioning system as claimed in any one of claims 1 to 10, wherein one of the network nodes is a coordinating network node in communication with external devices configured to initiate a blast.

12. A local positioning system as claimed in any one of claims 1 to 11 , wherein the network nodes are ZigBee modules.

13. An electronic blasting system comprising the local positioning system as claimed in any one of claims 1 to 12.

14. A method of locating network nodes in an electronic blasting system comprising a plurality of network nodes positioned in or around a blast area, the method comprising

establishing communication between a plurality of network nodes over a short range wireless radio link in order to provide wireless coverage of the blast area; and in response to establishing communication, utilising triangulation methods to determine the relative physical positions of the plurality of network nodes within the network and the blast area.

15. A method of locating network nodes as claimed in claim 14, wherein the method further comprises receiving a communication from a mobile network node positioned in the blast area and establishing the relative position of the mobile network node in the blast area by utilising triangulation between the mobile network node and the other network nodes.

16. A method of locating network nodes as claimed in claim 14 or claim 15, wherein the mobile network node forms part of a mobile handheld unit to communicate with detonators in the blast area.

17. A method of locating network nodes as claimed in claim 16, wherein the method further comprises employing the mobile handheld unit to allocate a detonator ID to a particular detonator, to obtain a detonator ID from a detonator having a predefined detonator ID or to program a detonator with a delay time in accordance with a designed blast plan.

18. A method of locating network nodes as claimed in claim 16, wherein the method further includes employing the mobile handheld unit to map a particular blast plan with pre-drilled detonator holes.

19. A method of locating network nodes as claimed in claim 15, wherein the method further comprises associating the mobile network node with a detonator or a connector of a detonator in order for the detonator to receive firing commands during a blasting operation.

20. A method of locating network nodes as claimed in claim 15, wherein the mobile network node is carried by personnel or equipment operating in the blast area thereby to track or locate personnel or equipment.

21. A method of locating network nodes as claimed in claim 20, wherein the equipment operating in the blast area is a drilling machine, thereby to assist in the design and execution of a suitable blast plan.

22. A method of locating network nodes. as. claimed in claim 21 , wherein the method further comprises monitoring the network node forming part of the drilling machine thereby to determine a blast pattern.