U.S. patent application number 11/553301 was filed with the patent office on 2008-05-01 for blasting system and method.
Invention is credited to Andre Louis Koekemoer, Albertus Abraham Labuschagne, Craig Charles Schlenter.
Application Number | 20080098921 11/553301 |
Document ID | / |
Family ID | 39363427 |
Filed Date | 2008-05-01 |
United States Patent
Application |
20080098921 |
Kind Code |
A1 |
Labuschagne; Albertus Abraham ;
et al. |
May 1, 2008 |
BLASTING SYSTEM AND METHOD
Abstract
The invention provides a blasting system which includes a
plurality of electronic detonators which are configured in a blast
array which has at least one row and a plurality of detonators in
the row, each detonator including a memory in which is stored at
least a respective identity code which is dependent, at least, on
the row on which the detonator is, and on the detonator's position
in the row, a harness which interconnects the detonators, and at
least one control unit, connected to the harness, which generates a
signal to fire the detonators.
Inventors: |
Labuschagne; Albertus Abraham;
(Brakpan, ZA) ; Koekemoer; Andre Louis; (Boksburg,
ZA) ; Schlenter; Craig Charles; (Johannesburg,
ZA) |
Correspondence
Address: |
CANTOR COLBURN, LLP
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Family ID: |
39363427 |
Appl. No.: |
11/553301 |
Filed: |
October 26, 2006 |
Current U.S.
Class: |
102/202.5 ;
102/206; 102/214; 102/312 |
Current CPC
Class: |
F42D 1/055 20130101 |
Class at
Publication: |
102/202.5 ;
102/206; 102/214; 102/312 |
International
Class: |
F42B 3/00 20060101
F42B003/00 |
Claims
1. A method of operating a blasting system which includes an array
of electronic detonators, the method including the step of
assigning an identity code to each detonator which is determined at
least partly by the detonator's location in the array.
2. A method according to claim 1 wherein the array is formed by a
plurality of boreholes arranged in at least one row, each row is
assigned a respective row identifier, each borehole in each row is
assigned a respective borehole identifier, and each borehole
contains at least one detonator, and wherein the identity code for
a detonator is dependent at least on the respective row identifier
and on the respective borehole identifier.
3. A method according to claim 2 wherein at least one borehole
contains at least first and second detonators at different
positions in the borehole and wherein the identity code for the
first detonator is distinguishable from the identity code for the
second detonator.
4. A method according to claim 3 wherein the first and second
detonators are at different positions in the borehole.
5. A method according to claim 2 wherein the identity code for a
detonator is dependent on the position of the detonator within the
respective borehole.
6. A method according to claim 2 wherein the identity code for a
detonator is dependent on the length of a harness which extends
from a collar of the borehole, which contains the detonator, to the
detonator.
7. A method according to claim 2 wherein the identity code for a
detonator is dependent on the position of the detonator within the
respective borehole, in a first direction or in a second direction,
from a reference point, in the respective row.
8. A method according to claim 7 wherein the reference point is
associated with a detonator, in the row, which is to be fired
first.
9. A method according to claim 1 which includes the steps of
storing the identity code of each detonator in a portable
device.
10. A method according to claim 1 which includes the step of
storing the identity code of a detonator in a memory in the
detonator.
11. A method according to claim 2 which includes the steps of
storing the identity code of each detonator in a portable device
and storing the identity code of a detonator in a memory of the
detonator.
12. A method according to claim 9 which includes the steps of
transferring the identity codes of the detonators, stored in the
portable device, to a control unit and, in the control unit,
associating respective firing time information with each identity
code.
13. A method according to claim 10 which includes the steps of
using a control unit to associate respective firing time
information with each identity code.
14. A method according to claim 10 which includes the step of using
a control unit to search for at least one identity code and once
the identity code is located associating firing time information
with the identity code.
15. A method according to claim 12, 13 or 14 wherein the firing
time information for a detonator is dependent on the detonator's
location in the array.
16. A method according to claim 12, 13 or 14 wherein the firing
time information for a detonator is dependent on the detonator's
identity code.
17. A method according to claim 12, 13 or 14 which includes the
step of using the control unit to transfer the respective firing
time information to each respective detonator.
18. A method according to claim 17 which includes the step of using
the control unit to fire the detonators.
19. A method according to claim 1 which includes the step of using
the identity code of each detonator to generate a representation of
the array of detonators.
20. A method according to claim 12, 13 or 14 which includes the
step of using the control unit to generate a representation of the
array of detonators which is based on the identity codes of the
detonators.
21. A method according to claim 20 which includes the step of
displaying the representation in textual or graphical form.
22. A method according to claim 1 which includes the steps of
interrogating the detonators and comparing the amplitude of a
response from the detonators to an expected response amplitude to
detect if at least two detonators have the same identity code.
23. A method of operating a blasting system which includes the
steps of arranging a plurality of electronic detonators which are
spatially distributed from one another in an array, storing in each
detonator a respective identity code which is dependent on the
detonator's location in the array, transferring the identity codes
for the detonators to a control location, storing in each detonator
respective firing time information which is transferred from the
control location, and transmitting a firing signal to the
detonators.
24. A method according to claim 23 wherein the firing time
information is stored in a detonator by overwriting at least part
of the identity code which is stored in the detonator.
25. A method according to claim 24 wherein the array is configured
in at least one row with a plurality of detonators at spaced
positions in the row, and the identity code for each detonator is
dependent on the row in which the detonator is, and on the
detonator's position in the row.
26. A method according to claim 24 wherein a portable device, in
which the identity codes are stored, is used to transfer the
identity codes to the control location.
27. A method according to claim 24 wherein the firing time
information is generated at the control location.
28. A method according to claim 27 wherein the firing time
information for each detonator is dependent on the identity code of
the detonator.
29. A method according to claim 24 wherein the firing signal is
transmitted from the control location simultaneously to all the
detonators.
30. A method according to claim 24 which includes the step of
connecting the detonators in parallel to one another using two
elongate conductors.
31. A blasting system which includes a plurality of electronic
detonators which are configured in a blast array which has at least
one row and a plurality of detonators in the row, each detonator
including a memory in which is stored at least respective firing
time information and a respective identity code which is dependent,
at least, on the row in which the detonator is, and on the
detonator's position in the row, a harness which interconnects the
detonators, and a control unit, connected to the harness, which
generates a signal to fire the detonators.
32. A blasting system according to claim 31 wherein the detonators
are positioned in a plurality of boreholes with at least one
detonator in each borehole.
33. A blasting system according to claim 32 wherein at least one
borehole includes a first detonator and a second detonator and the
identity code for the first detonator is distinguishable from the
identity code of the second detonator.
34. A blasting system according to claim 31 which includes a
portable device with a mechanism for generating the respective
identity code for each detonator, means for transferring the
identity code to the respective detonator and a first memory in
which the identity code is stored,
35. A blasting system according to claim 34 wherein the control
unit includes a control memory and the portable device includes an
interface for transferring the identity codes from the first memory
to the second memory.
36. A blasting system according to claim 31 wherein the control
unit includes a control memory in which is stored firing time
information for each detonator.
37. A blasting system according to claim 36 wherein the control
unit includes an interface for transmitting respective firing time
information to each detonator.
38. A blasting system according to claim 37 wherein the firing time
information is transmitted via the harness.
39. A blasting system according to claim 37 wherein the firing time
information is transmitted via a wireless link.
40. A blasting system according to any one of claims 31 to 39
wherein the harness comprises two elongate conductors which connect
the detonators in parallel to one another.
41. A blasting system which includes a plurality of electronic
detonators which are spatially distributed from one another in an
array, each detonator including a memory in which is stored at
least respective firing time information, a harness which connects
the detonators in parallel to one another, a portable device in
which are stored respective identity codes for the detonators, each
identity code being dependent, at least, on the detonator's
location in the array and a control unit in which are stored the
identity code and firing time information for each detonator and
which transmits a firing signal to the detonators.
42. A blasting system according to claim 41 wherein the firing
signal is transmitted on the harness to the detonators.
43. A blasting system according to claim 41 or 42 wherein the
harness comprises two elongate conductors and a plurality of
connectors, at least one connector for each detonator, connected at
intervals to the conductors.
44. A portable device for use in a blasting system which includes a
housing, a data input mechanism for inputting data relating to a
detonator's location in an array of detonators, a processor which,
in response to the input data, is operable under the control of an
algorithm to generate an identity code for the detonator which is
dependent at least on the detonator's location in the array, a
first memory in which the identity code is stored, and a
two-connection interface for transferring the identity code to the
respective detonator.
45. A control unit for use in a blasting system which includes a
housing, a control memory in which are stored firing time
information for each of a plurality of detonators in an array of
detonators and a respective identity code for each of the plurality
of detonators, each identity code being dependent at least on the
location of the respective detonator in the array, and a
two-connection interface for transferring the firing time
information to the respective detonators.
46. A control unit according to claim 45 which includes a generator
for generating a firing signal which is transmitted via the
two-wire interface to the detonators.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a blasting method which makes use
of electronic detonator.
[0002] In one respect electronic blasting systems can be divided
into systems which are implemented using two wires which
interconnect the detonators, and systems which make use of more
than two wires.
[0003] In a system of the former kind blast times for the various
detonators are usually assigned while a blaster is working at a
blasting bench.
[0004] In a multi-wire system (of the latter kind) the additional
wires allow the connection order of the detonators to be
established and the wiring order can be used to determine blast
timing factors. This type of system can be easier to use as the
blaster can readily configure the blast pattern in terms of
inter-detonator and inter-row timing increments.
[0005] Some blasting systems make use of a location system such as
a global positioning system (GPS) to collate the identity of a
particular detonator with a geographical location in the blasting
system. A blast time is then assigned to the detonator using the
geographical coordinates of the detonator in the blast system. A
GPS based system, in order to be sufficiently accurate, does
however require the use of a GPS reference station. A further
factor is that GPS location data may not be sufficiently accurate
or readily available, due for example to a rock wall or rock body
which blocks reception of a GPS signal.
[0006] Although, as noted, a multi-wire blast system is generally
easy to use a two-wire blast system has an economic benefit in that
the cost of the wire and of the components used to make connections
within the system is lower than the cost of a multi-wire
system.
[0007] The invention is concerned with a blasting system which is
readily implemented in a two-wire mode and which, if required,
allows the visualisation of a blast pattern.
SUMMARY OF INVENTION
[0008] The invention provides a method of operating a blasting
system which includes an array of electronic detonators, the method
including the step of assigning an identity code to each detonator
which is determined at least partly by the detonator's location in
the array.
[0009] The array may be formed by a plurality of boreholes arranged
in at least one row. Each row is assigned a respective row
identifier and each borehole in each row is assigned a respective
borehole identifier. Each borehole may contain at least one
detonator and the identity code for the detonator is dependent at
least on the respective row identifier and on the respective
borehole identifier.
[0010] The meaning of the term "row" in one respect may be
notional. The term is intended to include at least a succession of
boreholes which may be positioned along a straight, curved or
irregular path. For example, in an underground situation at a
workface e.g. a tunnel end, the boreholes may be grouped in
circular or other arrays.
[0011] A row identifier, or a borehole identifier, may then be
determined by an actual row or borehole count, or by means of a
sequential notation system e.g. an ordering arrangement based on a
sequence in which the detonators, individually or in groups (rows),
are to be fired.
[0012] If a borehole contains at least first and second detonators
either at the same position or at different positions in the hole,
i.e. if use is made of multiprime or decking techniques, then the
identity code for the first detonator may be distinguishable from
the identity code for the second detonator.
[0013] The identity code for a detonator may be dependent on the
position of the detonator, for example on the length of wire which
extends from a mouth or collar of the borehole to the
detonator.
[0014] The identity code may additionally depend on the position of
the borehole, in a first direction or in a second direction, from a
reference point, in the respective row. The choice of the reference
point may vary but, conveniently, a detonator in the row which
fires first i.e. has the shortest time delay period, is used to fix
the reference point.
[0015] The identity code of a detonator may be stored in a memory
in the detonator and in the memory of a portable device. The
portable device may be used for generating the identity code.
[0016] The portable device may be used for transferring the
identity codes of the detonators to a suitable destination e.g. a
control unit, a storage device, a memory stick, a computer, etc.
This transfer may be done using a physical connection e.g. wire or
fibre optic, or wirelessly e.g. by using a radio frequency,
infrared or other technique. The control unit may be used for
associating respective firing time information with each identity
code. The firing time information for a detonator may be dependent
on the detonator's location in the array e.g. on the detonator's
identity code.
[0017] The control unit may transfer the firing time information to
each respective detonator and may be used for firing the
detonators. One or more intermediate control units (slave units)
can be used between the control unit and the detonators to achieve
a larger blast pattern than what is possible using the control unit
alone, or to exercise localised or specific control techniques over
some of the detonators in the array.
[0018] The method may be implemented in conjunction with safety and
security protocols of any appropriate kind to ensure that adequate
safeguards are in place to control the authorisation of the
blast.
[0019] The identity code of each detonator may be used to generate
a visual or textual representation of the detonator array.
[0020] In a variation of the invention the method includes the
steps of arranging a plurality of electronic detonators which are
spatially distributed from one another in an array, storing in each
detonator a respective identity code which is dependent on the
detonator's location in the array, transferring the identity codes
for the detonators to a control location, storing in each detonator
respective firing time information which is transferred from the
control location, and transmitting a firing signal to the
detonators.
[0021] The firing time information may be generated or allocated
using any suitable technique or algorithm based for example on a
regular inter-row and inter-hole time difference. Irregular holes
or unusual situations can be accommodated by allowing an operator
to allocate specifically determined firing time information to the
corresponding detonators.
[0022] The invention also provides a blasting system which, in one
form, includes a plurality of electronic detonators which are
configured in a blast array which has at least one row and a
plurality of detonators in the row, each detonator including a
memory in which is stored at least a respective identity code which
is dependent, at least, on the row on which the detonator is, and
on the detonator's position in the row, a harness which
interconnects the detonators, and at least one control unit,
connected to the harness, which generates a signal to fire the
detonators.
[0023] Firing time information may be stored in the memory. This
may be in addition to the identity code, or the firing time
information may, at the appropriate time, overwrite at least part
of the identity code.
[0024] The detonators may be positioned in a plurality of boreholes
with at least one detonator in each borehole.
[0025] If use is made of multiple control units then these can be
configured in a master-slave relationship with each slave firing a
respective group of detonators.
[0026] In a different form of the invention the blasting system
includes a plurality of electronic detonators which are spatially
distributed from one another in an array, each detonator including
a memory in which is stored, at least, a respective identity code
which is dependent, at least, on the detonator's location in the
array, a harness which interconnects the detonators in parallel to
one another, a portable device in which are stored the identity
codes for the detonators, and a control apparatus in which are
stored the identity codes and firing time information for each
detonator and which transmits a firing signal on the harness to the
detonators.
[0027] The control apparatus may comprise a single control unit or
a number of control units configured to act in parallel in a
synchronised way, or in a master-slave relationship.
[0028] The harness may comprise two elongate conductors and a
plurality of connectors, at least one connector for each detonator,
connected at intervals to the conductors.
[0029] The portable device may include a housing, a data input
mechanism for inputting data relating to a detonator's location in
the detonator array, a processor which, in response to the input
data, is operable under the control of an algorithm to generate an
identity code for the detonator which is dependent at least on the
detonator's location in the array, a first memory in which the
identity code is stored, and a two-connection interface for
transferring the identity code to the respective detonator.
[0030] The portable device may include communication means for
receiving data or signals from, or transferring data or signals to,
an external device such as control apparatus or a control unit of
the kind referred to, a computer, a storage device or the like.
[0031] The data and signal transfer may be done via physical links
(wire or cable) or wirelessly (at infrared or radio
frequencies).
[0032] The control unit may include communication means for
receiving data or signals from, and for transferring data or
signals to, by wireless links (radio frequencies, infrared etc.) or
via physical links (wire, fibre optic cable etc.), the portable
device referred to or one or more of the detonators.
[0033] The control unit may include a housing, a control memory in
which are stored firing time information for each of a plurality of
detonators in the array and a respective identity code for each of
the detonators, each identity code being dependent at least on the
location of the respective detonator in the array, and a
two-connection interface for transferring the firing time
information to the respective detonators.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The invention is further described by way of example with
reference to the accompanying drawings in which:
[0035] FIG. 1 illustrates an array of electronic detonators in a
blasting system;
[0036] FIG. 2 shows, in block diagram form, a portable device used
in the blasting system of the invention, connected to a
detonator;
[0037] FIG. 3 is a block diagram illustration of a control unit;
and
[0038] FIG. 4 is a flow chart of steps in the method of the
invention.
DESCRIPTION OF PREFERRED EMBODIMENT
[0039] FIG. 1 of the accompanying drawings illustrates a number of
boreholes 10A, 10B . . . 10N respectively formed at predetermined
positions in the ground using conventional techniques. The depth of
a borehole and its size may vary according to requirements known in
the art.
[0040] Each borehole contains explosive material 12 and at least
one respective detonator 14A, 14B . . . 14N.
[0041] A two-wire harness 16 is used to connect the detonators to
one another in an array 18 which is defined by rows of detonators
20A, 20B, 20N and, within each row 20, the boreholes 10A, 10B . . .
which are in the row. The array can be further particularised by
the number of detonators in a borehole. As is shown in FIG. 1 most
of the boreholes contain one detonator but a limited number contain
two detonators and one borehole contains three detonators. A number
can be assigned to each detonator when they are decked or stacked
in this way and this feature also characterises the blast array.
Apart from the deck number the depth of a detonator inside a
borehole can be used to characterise the blast array yet further.
This can be assessed in any appropriate way, for example by the
length 22 of a portion of the wire or harness which extends from
the mouth or collar of the borehole in question to the
detonator.
[0042] Another factor which can characterise the blast array is an
indication of whether a particular detonator is to the left or the
right of a chosen point in a row of detonators. This point can be
chosen according to various criteria but conveniently can be
determined by the position of a detonator in the row which will be
fired first i.e. has the shortest time delay period.
[0043] The aforegoing parameters together with other information
such as the spacing between rows of detonators and the spacing
between adjacent detonators in a row, can be used, preferably with
a suitable computer program, to generate a textual or graphical
representation of a blast pattern.
[0044] The concept of "row" as used herein could be physical e.g. a
group of boreholes could be configured or associated with each
other in a definite pattern (such as a straight or curved line, a
circle or the like) which is discernable as a "row", or notional in
the sense that a sequence or string of detonators at chosen yet
irregularly situated positions, are referred to as a "row".
[0045] FIG. 2 illustrates in block diagram form a portable device
24 connected to a detonator 14. The detonator is generally of
conventional construction and includes a tube 26 which contains
primary explosive 28. A bridge 30 is exposed to the primary
explosive. The bridge is connected to a processor 32 or a dedicated
or custom-designed device (ASIC), which has resident memory 34.
Power for the operation of the circuit inside the detonator is
provided from a capacitor 36. Two leads 38 and 40 extend from the
detonator and terminate in a connector block 42.
[0046] The portable device 24 includes a housing 44 and, within the
housing, a battery 46, a processor 48, a memory 50 and software 52
resident in further memory. A display 54 and a keypad 56 are
mounted externally to the housing. An output interface module 58 is
connected to two leads 60 and 62 which terminate in a connector
block 64. The connector block is releasably engageable with the
block 42, as required. The device 24 includes another communication
interface 66 which enables communication to take place with an
external apparatus such as a control unit (see FIG. 3), a computer,
a memory stick or the like via wires or wirelessly as required.
[0047] FIG. 3 illustrates in block diagram form a control unit 70
which is used in the blasting system of the invention. The control
unit can be configured as an integrally constructed item or from a
number of discrete modules. The control unit includes a housing 72
and, inside the housing, a power supply 74, a processor 76, a
memory 78, a data interface 80 and a software algorithm 82 stored
in additional memory. A display 84 and a keypad 86 are externally
fixed to the housing. The control unit can have another
communication interface 88 to allow communication with an external
device such as the portable device 24, a computer, a memory stick
or the like, by wires or wireless, as required.
[0048] The control unit can be a single device or it can be one of
a plurality of similar devices which make up apparatus which
controls the blast. In the latter case the control units can be
configured in a master-slave relationship, with the slave control
units reacting to a single master control unit, or in parallel,
with suitable synchronising controls to ensure that the control
units, each of which can be used to fire a distinct respective
group of detonators, are operated in step with one another.
[0049] The method of the invention is based on the principle of
identifying a detonator by means of identifiers or data associated
with the location in which the detonator is installed in the array
18. Under factory conditions each detonator 14 is manufactured
according to known criteria. The memory 44 is not necessarily
pre-programmed, as is often the case, with a unique identifier. The
detonator includes a single capacitor 36 which is used for powering
the detonator when required as is explained hereinafter. The
battery 46 in the portable device 24 has a voltage which is
inadequate to charge the capacitor 36 to a voltage which is
sufficiently high to fire the bridge 30. Also, the voltage from the
battery is not able, in any other way, to fire the bridge due to
the presence of safety protocols and components which protect the
bridge using techniques known in the art.
[0050] Once the boreholes 10 have been drilled in the ground the
explosive material 12 and the detonators 14 are placed in the
boreholes according to requirement. An operator, also referred to
as a blaster, makes use of the portable device 24 and goes from
borehole to borehole. At each borehole the connector 64 is
connected to the connector 42 of the relevant detonator. The keypad
56 is manipulated by the blaster to input data pertaining to the
position of the detonator in the blast array e.g. row one left,
hole 3, deck 1, depth (22).times.meters. These identifiers are
processed by the processor 48, using an algorithm in the software
52 to generate a unique code which is used to distinguish the
detonator in question. The identifiers may for example be used in
the generation of a word (the identity code) as follows: the first
byte of the word may represent the row number, the following byte
may represent the hole number and a subsequent byte may represent
the deck number.
[0051] Provision can however be made for the generation of specific
identifiers which are used to identify specific conditions. For
example it can be useful, to a blaster, to have knowledge or to be
notified of a detonator at an end (physical or notional) of a row.
Similarly a blaster might require notification or marking of a
detonator at a branch or of some other irregularity, or chosen
location, in the array.
[0052] This can be done by adding to or modifying the identity code
for the particular detonator e.g. by adding one or more specific
bits to the identity code. The "modified" identity code is, as
before stored in the portable device and in the memory of the
detonator.
[0053] Depending on options chosen in the software one of the
identifiers (row or hole) can automatically increment as the
blaster moves to a following hole. For example the hole number may
increment automatically thus allowing the blaster to move to the
next hole and detonator, and generate the identity code. The
keyboard 56 can be used as required to change the direction of the
parameter the blaster is entering e.g. next row, next deck, etc.
Visual and audible confirmation can provide feedback to the blaster
if desired or even announce the current detonator number, hole
number and so on.
[0054] Each of the detonators in the blast array is thus assigned a
unique identity code which is stored in the memory 34 of the
detonator. Also, during this process the identity codes for the
detonators are accumulated in the memory 50 of the portable device.
The codes can automatically be accumulated, or accumulation can
take place only when the respective code has been loaded into a
respective detonator which then transmits the code to the portable
device, for storage in the portable device.
[0055] Once all the detonators have been identified the blaster
connects the harness 16 to the detonators. The harness is a
two-wire device and the detonators are thus linked to one another
in parallel.
[0056] The portable device 24 is then placed in communication with
the control unit 70. This can be done by directly coupling the
device to the unit via the interfaces 58 and 80 or use can be made
of another technique such as a short range radio frequency or
infrared link. The control unit 70 then reads the identity codes
from the memory 50. The connections of the harness to the
detonators can be validated. The connected detonators can be
counted to ensure that all detonators in the system are connected
to the harness. Also, at an appropriate time each detonator can be
calibrated, particularly to take account of thermal or other
factors which can affect the accuracy of operation of timer
circuits in the detonator.
[0057] The control unit 70 can also engage in an auto-search
routine by issuing queries on the harness, possibly via a slave
unit, to search for detonators. There is not necessarily a
requirement, in this respect, for the control unit to interact with
the portable device to identify which detonators are present in the
installation. Appropriate heuristics can for example be applied to
ensure that if a hole exists, a preceeding hole must logically
exist, or for example to ensure that the last detonator in each row
is identified appropriately, as the last detonator, so that useful
messages can be presented to a blaster if there are errors.
[0058] The blaster may choose to use the portable device or the
control unit to search for faults. One possible problem that may
occur for example is if a blaster incorrectly assigns the same
identity code to each of two detonators. One way of addressing this
is for the portable device to warn if the blaster attempts to
assign an identity code that has already been used. Another
technique when testing the harness installation is to send an
interrogating signal to the detonators and to examine the amplitude
of a current modulated reply from the detonators. If a given
detonator reply amplitude is larger than expected it could imply
that two or more distinct detonators have the same identity code
and are replying at the same time to a request from the portable
device or control unit. The blaster is thereby alerted to this
problem and can use techniques known in the art, such as a binary
search, to find the detonators with the duplicate identity.
[0059] Once the relevant identity codes have been loaded into the
control unit the blaster is presented with a representation of the
number of detonators, holes, rows and the location of each
detonator. This information is used to provide a textual or
graphical depiction of the blast system or, if required, the
information presents an image which can easily be inspected or
assessed by a blaster to establish the correctness of the blast
system. This, in turn, helps to identify an incorrect connection
sequence, a "missing" detonator, or a similar fault.
[0060] At this stage in the process the detonators have not been
programmed with firing time information. This can be done in a
number of ways. In one approach an algorithm in the software 82 is
used to generate firing times for the respective detonators using
fixed inter-row, inter-detonator (for deck blasts) and inter-hole
timings as is known in the art. Alternatively the detonators are
programmed by the blaster using other criteria. In another approach
the timing information is externally generated, for example in a
separate computer which is coupled to the control unit and,
thereafter, the timing information is loaded into the memory 78. If
desired a subset of the detonators or, in extreme cases all the
detonators, can be assigned firing times individually. This feature
allows detonators which are not part of a regular blasting pattern
to be easily accommodated. The use of auto-search and
auto-programming features simplifies the task of assigning firing
times to the detonators, compared to the use of a technique in
which the times are manually assigned to the detonators.
[0061] In the control unit 70 a table is thus established in which
the various detonators, which are designated by their respective
identity codes, have respective firing times uniquely associated
with the detonators. These firing times may vary from one another
or, depending on the blasting requirements, the firing times for
certain detonators may be the same.
[0062] The control unit 70 is then connected to the harness 16 and
is used to transfer the timing information to the respective
detonators. This connection can be physical, via two wires, fibre
optic cables etc, or can be done wirelessly by means of a radio
frequency or infra red link. Also, the control unit may form part
of control apparatus which embodies a number of control units
connected and regulated to act in parallel and in synchronisation,
or connected in a master-slave configuration wherein a master
control unit regulates the operation of a number of slave control
units, with each slave control unit controlling the initiation of a
separate group of detonators. The timing information is correctly
targeted to each detonator through the use of the corresponding
identity code which allows the processor 32 to recognise the
identity code and then to accept the timing information which is
stored in the memory 34 in addition to the identity code or,
alternatively, by overwriting the identity code in the respective
detonator.
[0063] The detonators can be configured to respond, universally, to
a broadcast address or signal. Thus with a single detonator
connected to the harness communication can be established with the
detonator irrespective of its identity code.
[0064] FIG. 4 is a flow chart summary of the preceding description.
Each detonator 14A, 14B . . . 14N (FIG. 3) is placed (80) in a
respective borehole and positional information (82), dependent on
the location of the detonator in the blast array, is input (84)
into the portable device. This device generates the identity code
(86) which is stored in the device (88) and transferred to the
detonator (90). This process is repeated until all the detonators
have been identified in this way.
[0065] Thereafter the identity codes are transferred to the control
unit (92). Either the portable device is transported to the control
unit and data transfer then takes place directly by direct or
wireless links, or the codes are transferred by an intermediate
medium. Another possibility is that the control apparatus, or a
control unit therein, once connected to the harness, searches for
particular identity codes to establish which detonators are
connected to the harness, and where the detonators are. The timing
information is then generated (94) or acquired from any external
source. The control unit is thereafter connected to the harness
(96) and the timing information is transferred to the detonators
(98). A blast pattern can be generated and displayed at the control
unit (100).
[0066] As noted the individual detonators are calibrated, at any
appropriate time, using any suitable technique to ensure that the
timing information is accurately employed at each respective
detonator.
[0067] A validation procedure can be effected (102) and thereafter
a firing sequence is initiated (104).
[0068] When blasting is to occur the power supply 74 (FIG. 3) is
used, under the control of protocols which are known in the art, to
charge the various capacitors 36 in the detonators. Each capacitor
then acts an energy source to power the further operation of the
detonator. A firing signal which is generated by the software 82 is
then broadcast on the harness 16 (FIG. 1) and triggers the start of
the programmed time interval at each respective detonator. At the
end of the respective time interval the corresponding bridge 30
(FIG. 2) is fired.
[0069] As has been pointed out the portable device 24 (FIG. 2) is
incapable of firing any detonator and is used merely to assign
identity codes to the detonators and to collect this information
for transfer to the control unit. The control unit directs firing
time information to the various detonators in a unique manner,
charges the capacitors and generates the blast signal.
[0070] In the preceeding description the portable device and
control unit are represented as being physical separate. This is
not necessarily the case for the distinction could be notional, or
functional, only, and the portable device could be integrally
constructed in a physical sense with the control unit.
[0071] The invention is based on the allocation of unique identity
codes to the detonators using the criteria referred to. However,
due to human error or other factors, a detonator in the array may
not be assigned an identity code. This type of oversight can be
detected in different ways.
[0072] Firstly each detonator, under factory conditions, can be
assigned the same identity code (e.g. all zero) and, when the
detonator is installed, the location--dependent identity code is
then used to overwrite the factory code. The blaster, when testing
an installation, can use the portable device or control unit to
search for detonators which still carry the factory assigned code
i.e. these detonators which have not been given location--dependent
codes.
[0073] Secondly, the processor 32 in each detonator can be
programmed to indicate, in response to a suitable interrogating
signal, whether or not a location--dependent identity code has been
assigned to the detonator. This is easily done for example by
setting a check bit in a memory of a detonator once an identity
code has been allocated to the detonator.
* * * * *