Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FASTENER NETWORKS
Technical Field
This invention relates to fasteners. In particular, this invention relates to
a particular
type of network of fasteners.
s Background Art
Monitoring of equipment status is becoming increasingly. important. As one
example,
an aircraft monitoring system has been introduced recently under the name
"Airplane
Health Management". The intention of such a monitoring system is to assist in
streamlining aircraft maintenance and to minimise disruption to flight
schedules.
A monitoring systeTa. such as the"Airplane Health Management" system desirably
can
carry out the functions of collecting data about the aircraft ~or other
equipment being
monitored and transmit the data to a central or remote processing system. For
the .
aircraft example, the remote processing system may be on board the aircraft or
it may be
on the ground, so that problems, or potential problems, have already been
identified
is before the aircraft lands. Maintenance can then be ready with the necessary
labour
schedule and/or parts to service the aircraft.
It is understood that aircraft maintenance is a significant cost, which at
present is
continuing to increase. It is also understood that a 10% reduction in
maintenance costs
may increase net profit by up to 40%.
as It is an obj ect of this invention to facilitate monitoring systems,
especially monitoring
systems in aircraft, but not limited to that application. It is a further
object of this
invention to enable not only monitoring but also a system which enables an
action to be
taken in.response to the situation monitored.
Reference is made to International Patent Application No. PCTlAU20031000759,
(the
2s contents of which are incorporated herein by reference) which was published
as
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W02QQ4/OOI235 ("the International Patent Application"). The International
Patent
Application discloses in its second aspect a network or system of fasteners,
in which
each fastener includes an address means to distinguish that fastener from the
other
fasteners in the network. The fastener can be any fastener, including the
fastener
disclosed in the first aspect of the invention in the International Patent
Application.
The fastener in that first aspect may be intelligent and may have a second
function
which makes use of the intelligence or switching capacity of the fastener. An
example
is given of a vehicle which has several of the fasteners in intelligent form.
The fasteners
have a first function which enables the fixing and releasing of light bulbs in
the vehicle.
1o The fasteners have a second function, which is to sense the amount of
ambient light and
to turn the Light bulbs on or off depending on the amount of light sensed.
Data as to the
amount of arnbient~ light is sent to a. central processor which activates the
fastener
according to desired criteria as to automatic switching on or off of the
lights.
The International Patent Application also . discloses that the fastener may
include a
is sensor able to convey information as to the condition of the fastening
element included
in the fastener in one embodiment and the actuating means (in the same
embodiment).
The sensor may sense the current state of the fastening element (engaged or
disengaged). The sensor may sense to allow optimised control of the
application of
energy to the actuation means. The sensor may sense in order to report
performance,
2o degradation or impending. failure of the fastening element or actuation
means.
Disclosure of the Invention
The invention provides a fastener for use in a network of fasteners, the
fastener
including an address means to distinguish the fastener from the other
fasteners in the
network and being adapted for distribution throughput the assembly, either:
2s (i) in an ordered pattern; or
(ii) to form a three-dimensional network;
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or both. The invention also provides a network of such fasteners, also
referred to below
as a "system".
The present invention represents a further aspect of the network of fasteners
disclosed in
the International Patent Application: In this further aspect, the network of
fasteners has
one or more of the following characterisfiics.
(a) the fasteners are distributed throughout an assembly in an ordered
pattern;
(b) the fasteners are distributed throughout an assembly to form a three
dimensional network. ~ .
As already indicated in the International Patent Application, the fasteners
may be any
Io suitable fasteners, including those disclosed in the International Patent
Application.
The fastener may be any other suitable fastener. One example is the bolt
assembly
farming subject of International Patent Application No. PCT/AU03l001539.
Another
example is the fastener forming subject of International Patent Application
No.
PCT/AU2004/000371. The contents of both specifications are imported herein by
~s reference.
Tlie address means is intended to enable a network system to identify the
fastener, for
the purpose of establishing communications and addressing commands, such as a
command to cause activation of actuating means.
The fastener may have actuating means which is any suitable actuating means
and
2o which will depend to a large extent on the nature of the fastener. Examples
of actuating
means are as follows: magnetic (linear solenoid), magnetic (rotary solenoid),
magnetic
(linear actuator), magnetic (motor), piezo-elecfiric, electrostatic, thermal
(shape memory
alloy), thermal (bimetallic), thermal (state change), pneumatic, hydraulic,
chemical,
pyrotechnic or explosive, acoustic or ultrasonic, ionising radiation, ionising
particles,
2s luminescent and gravitational.
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The address means may be any suitable means but.preferably is capable of
storage in a
non-volatile manner, in order to resist corruption and intentional or
unintentional over-
writing or reprogramming. It i's also preferred that the address means does
not enable
more than one fastener to have the same identity, unless there is requirement
for a
replacement fastener to'assume the same identity as the original fastener
being replaced.
By way of non-limiting example, the address. means may comprise a serial
number, a
communications address or a temporary conununications.address, or any
combination of
these.
When the address means is a serial number, this ispreferably a unique
nurnber.which is
1o programmed into the fastener as part of the manufacturing process and which
consequently does not change throughout the life of the fastener.
When the address means is a communications address, this is preferably a
communications or network address which may be assigned to the fastener at the
time of
installation, or when the network is configured.
is Then the address means is a temporary communications address, this is an
address
which may be assigned to the fastener on a transient basis. This may be
desired, for
example, where the fastener is configured in a sub-network and use of the
full, unique
address of the fastener during a particular session will cause excessive
communications
traffic andlor require excessive processing overhead during the communication
session.
2o The address means may enable the unique identity of the fastener to be
stored in any
suitable way, and in any suitable storage device. Preferably, the storage
method is
robust and uses known techniques, such as multiple redundant storage with
checksum or
. CFZC protection, reinstatement of backups on detection of errors, etc.
Preferably, the
storage~method includes measures to prevent unauthorised access or tampering
with the ,
2s unique identity. .
Examples of storage devices are following:
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Hardwiring: this includes switches, jumpers, solder blobs and soldered links.
Non-volatile memory: this includes PROM (programmable read only memory),
EPROM (erasable programmable xead only memory), EBPROM (electrically
erasable programmable read only memory), Flash memory, battery backed
random access memory (RAM); ferromagnetic RAM and optical storage.
Storage of the unique identity may be combined with the operating program code
of a microcontroller. '
Semiconductor: storage in this form can incorporate the unique serial number
programmed during manufacture and capable of being read by a microcontroller.
i0 The address yr identity of the fastener may be encrypted. There are many
forms of
available encryption techniques which may be suitable to the present
invention. By way
of example, the following are mentioned.
The first example is link encryption, where each communications link in which
the
information may be intercepted is protected by encryption of information on
that link.
is I,nformatiommay appear unencrypted or "in the clear" at communications ør
control
nodes, and may need to be protected by other means, such as physical access
control -
discussed further below - at those points.
The second example is end-to-end encryption, in which information is encrypted
at its
source and decrypted at its destination and does not appear "in the clear" at
intermediate
2o points in the communications links.
As a third example, both end-.to-end encryption as well as transrriission over
individually
encrypted links may be used to result in a hybrid system.
In relation to physical access control, it may be desirable to incorporate
further security
'measures to prevent unauthorised access to a system or network of fasteners
of the
2s invention, especially where there is a high level of need to prevent any
unauthorised
party to control fasteners, change system settings ar configurations or cause
damage or
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disruption to the system for any reason. By way of example, fasteners may
attach
valuable items to a vehicle or attach a door to its surround so as to lock the
door.
Obviously in such circumstances unauthorised operation of the fasteners could-
allow
theft of the valuable items or infirusion through the door to occur.
While file encryption is one way to prevent unauthorised entry into a fastener
system,
there are other ways of controlling access. Some non-limiting examples are set
out
below.
Physical access to a system and its elements may be prevented by physically
isolating
the system or making it difficult to locate. For example, wiring for the
system can be
disguised within the loom of a vehicle. As another example, spread spectrum
wireless
comrnunicatiori techniques can be used to hide radiated signals amongst radio
noise.
Use of spread spectrum wireless links ar other communications methods, such as
optical
fibres, can make ~it difficult to intercept, modify, disrupt or jam commands
or
communications to the system.
By way of further example, secure methods of identification may be used. For
example,
biometric information techniques may be used to identify authorised personnel
and/or
systems. Electronic security certificates may be required to authorise access
by
computer based systems. Valid access may require confirmation by personnel or
systems
by a bi-directional handshake and identity confirmation process, or by such
measures as
2o call-back to an authorised telephone number or a network address, for
example.
By way of further example, access to and control of fasteners may require the
operator
or control system to take part in a dialogue with a master control/database
fox a specific
access code; in order to allow control of the fastener. As well as such
explicit
authorisation, there may be tracking of the transaction. For example, the
access code and
fastener operation may be recorded in a time stamped log stored by the master
control/database, by the fastener itself or by intermediate system elements.
Retrieval of
such logs can permif analysis for 'audit tracking purposes.
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In the system of the invention, each activating means may actuate one or more
fastening
elements. The system preferably includes a control means for controlling
actuation of
the actuating means, typically by energy from an energy source. Each control
means
may control one or more of the actuation means.
s It is further preferred that the system of the invention includes an
intelligent controller
device for controlling the control means, and, through it, the actuating
means, typically
in response to an external stimulus. Each intelligent controller device may
control one
or moze control means.
Also, in this system of the invention, it is preferred that there is an energy
source for
1o providing energy to the actuating means. The energy source may include
local storage
of energy, such as in a battery, or externally applied energy, or a
combination of both.
The system may include a sensor, which is discussed below. The system may
further
include an external sensing means far. determining and reporting. the
condition of
external elements, for example, relating to an element which is engaged by the
fastener
~ 5 and the engagement condition.
The network may be constructed in any suitable manner. Preferably, the network
forms
a star.or a daisy chain. When the network forms a star, a power switch or
processor is
located in the center of the star, with each of the fasteners being separately
connected to
the central power switchlproeessor. In the case of a daisy chain, the
connectors are
2o arranged in a series, with a power source in the chain. Optionally, a data
feed may also
form part of the chain, using the power cable or separate data cables.
Especially in the case of the neturork of fasteners, the fastener may include
a sensor able
to convey information as to the condition of the fastening element and the
actuating
means, including sensing the current state of the fastening element (engaged
or
25 disengaged), sensing to allow optimised control of the application of
energy to the
actuation means and sensing in order to report performance, degradation or
impending
failure of the fastening element or actuation means.
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A sensor may operate in a number of ways, such as by use of one or more limit
switches
which may employ electrical contact, magnetic, optical, capacitive or any
other suitable
sensing mechanism, to sense the current fastener condition (i.e., open,
closed,
intermediate or any one of a number of stable positions). Another example is
one or
more strain gauges or equivalent strain sensing devices which are installed on
or in
association with the fastener to sense position and condition and, having high
levels of
resolution, which can allow fine position determination and control. As
another
example, force sensors or force sensing devices may be installed on or
associated with
the fastener, in order to sense the force exerted on or by the fastener, and
the condition
of the fastener, with high levels of resolution and once again allowing fme
position
determination and contral. Proximity sensors or equivalent positioning sensing
devices
may be used to sense the position of the fastener. Temperature sensors or
equivalent
temperature sensing devices can be used to sense the temperature of the
fastener and, .
depending on the fastener type, these may be used to optimise control of the
fastener
t s and to sense condition of the fastener. Qther examples of sensors wilt be
apparent to
one. skilled in the art.
As well as enabling reports as to fastener~position and canditian to other
areas of a
network system, sensors may be used to optimise fastener control operations.
Non-
limiting examples are as follows.
2o In a first example, sensors in the form of limit switches are used to sense
movement of
the beam to the disengagement position. Power is supplied at a high level to
the
actuating means until the disengagement position is reached, whereupon the
limit
switches report this position. At that stage, power can be reduced to a lower
level,
being still sufficient to sustain the fastener in the disengagement position.
Qperating
zs fiime, energy consumption and heating is minimised.
In a second example, a strain gauge is attached to the beam. Power can be
applied at a
high level to the actuating means until the beam is deflected to the
disengagement
position. Detection of this position by the strain gauge enables the power to
be reduced
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to a lower level, once again being sufficient to sustain the fastener in the
disengaged
position, but at the same time minimising operating time, energy consumption
and
heating. In addition, analysis of the.degree ofbending of the beam as a
function of
applied power and time will allow degradation of the beam to be detected arid
signal the
s need' for replacement prior to complete failure.
As a variation on the second example, there may be two strain gauges on the
beam, one
an either side. Differential measurement allows the beam position to be
determined
throughout its travel, with high resolution. Common mode measurement can allow
linear extension or compression of the beam to be measured and hence axial
loading on
1o the beam to be determined.
As a third example, sensors may sense the contents (or lack of contents) of
fastened
elements and provide an appropriate response. For example, if the elements
joined by
the fastener are pipes, a sensor may sense presence of fluid in the pipe and
refuse to
disengage the pipes, even if given a command to do so. Similarly, the sensor
may sense
t5 electrical current in a cable joined by the fasteners and refuse to
disengage if to do so
would cause a dangerous situation.
In a further example, the sensor may be a local temperature probe, which can
sense
ambient temperature and report to an embedded processor. The processor could
then
calculate and distribute the appropriate amount of power required to activate
the
zo actuating means. Shape memary alloy is usually activated by a pulse
ofpower, for
example, a 150°C pulse of power. This Works well if the ambient
temperature is in the
range of -50°C to 75°C. However, if the ambient temperature is
high, such as over
75°C, the 15D°C pulse of power may cause the shape memory wire
to overheat.
Consequently, the sensor, having sensed the ambient temperature, can enable
the
2s processor to work out and distribute the appropriate amount of power to the
fastener,
increase the operating temperature window of the system at lower ambient
temperatures,
or save power if the ambient temperature is already relatively high.
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The system may include status indication means (such as ari LED or an audible
signal),
to indicate the current condition of the fastener or the external sensing
means and/or any
other aspect of the system.
Further, the system may include communication means far enabling an external
device
s or system to communicate with the fasteners of the invention in the system,
both for
control and fvr status reporting functions.
In one preferred embodiment, the system of the invention includes one or more
fasteners
together with one or more control means, one or more sensors, an energy
source, an
intelligent control device, a status indicator and an external sensing means.
1o In an expanded form of the system, a plurality of fastener systems as per
the last
mentioned preferred embodiment is networked with one or more optional
communications concentrators, one or more intelligent control units and one or
more
master controlldatabase units. Examples of these are given below in connection
with
the drawings.
is It will be appreciated that the invention in its various aspects set out
above has
particular application areas for product assembly, product disassembly,
product
recycling, product servicing and maintenance.
In relation to product assembly, disassembly and product recycling,
application of the
invention in its various aspects is useful in relation to automobiles, for
example in
2o connection with exterior trims and accessories, interior trims, air
conditioning units,
sound systems and auto-electrical subassemblies.
In relation to product servicing and maintenance, the fasteners of the
invention can
provide faster and more secure (because authorised) access to parts and
subassemblies
gf products or equipment for the purposes of repair, replacement or
maintenance. The
zs fasteners can provide a significant saving in labour, since they can reduce
the average
time for repair. They can also provide a cost effective and secure method of
access to
internal components.
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The fasteners can reduce the need for skill, because the process of assembly
and
disassembly can be directed by a computer.
The fasteners may be networked in any way as disclosed above or in any other
suitable
way. For example, the fasteners may be networked by hard r~~iring or by, for
example,
s "blue tooth" communication or by other wireless means.
The fasteners may coritmunicate with each other and/or with a central monitor,
such as a
computer, in any one or more of the following ways: by cable, by wireless
link, by
custom radio link, "Blue Tooth", "Zigbee", "Wifi" (802.11),. inductive
coupling, infra-
red, microwave, visible .light or using ultra-sound or other acoustic energy.
Wireless
to link may be via an external system, which then communicates with the
fasteners in the
network, for example by global positioning system (GPS), by SMS or MMS, by
GPRS
or by Wifi to an intemet access point.
The foregoing examples are not limiting with respect to the invention.
Preferably, the network of fasteners is distributed throughout the assembly so
as to
is provide, essentially, a three dimensional model of the assembly:
The assembly can be chosen from a wide range of objects. For example, the
assembly
may be a building, a motor vehicle, an aircraft or any ofa myriad of
otherobjects.
Whether the fasteners are distributed throughout the assembly in an ordered
pattern or to
form a three dimensional network, it is not essential that every fastener in
the network is
2o mufti-functional. However, it is preferred thatevery fastener is mufti-
functional.
The invention may be, particularly useful in providing to a central monitoring
point an
environmental picture of alI or most of the assembly at the location of each
fastener.
For example, a fastener or a group of fasteners may sense ambient temperature
and
compare this to the temperature sensed by anotheir fastener ~or group of
fasteners. The
2s comparison may activate some of the fasteners. For instance, if the
assembly is a
building and a temperature differential is detected by comparison of the
temperature
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reports from various fasteners or groups of fasteners, air conditioning may be
activated,
or one or more windows in the building may be opened or closed, or both air
conditioning and windows may be activated. This can provide automatic
temperature
control. The fasteners may take part in the activation, for example, by
releasing a
s window biased to the open position. Alternately, the fasteners may report to
an
activating mechanism which then carries out the required task.
The network of fasteners may pass on other sensed data, for example to a
computer
which analyses and displays the real time situation against the ideal state.
For example,
the assembly may be a building and the network of fasteners may be used to
adjust the
lighting levels in response to natural light availability. As another example,
the
fasteners in the building may detect fire at an early stage, by sensing an
unacceptable
rise im temperatuxe (and activate an alarm or water sprinklers, for example).
The
fasteners may report overstressing or damage to a fastener in the system.and
control the
5iiuation by increasing the level of fastening of adjacent fasteners or by
activating 'a
1s redundant fastener: The network of fasteners may function to release a
particular part of
the assembly in an emergency. For example, in case of fire or explosion, the
network
may instruct certain fasteners to release part of the assembly such as a beam
or a door if
this is calculated to reduce the seriousness of the outcome of the fire or
explosion.
The fasteners may have a single function in addition to the fastening
function, ar some
zo ..or all of the fasteners may have more than one additional function. For
example, a
fastener may be both heat sensitive and light sensitive as well as having its
primary
fastening function.
It will be apparent to one skilled in the art that the invention has an
extremely wide
range of application. Some further examples are referred to below. . It is to
be
2s understood that these are not limiting on the scope of the invention.
The assembly may be the hull of an oil tanker. The network of fasteners may be
adapted to detect breach to the hull and generate an alarm.
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The network of fasteners may be built into the &arne of an aircraft and
sensitive to
changes in temperature; thus being able to detect, at an extremely early
stage, that a fire
has started, for example in an electrical system. The .generation of an alarm
at this early
stage can enable swift action to prevent major damage.
s The network of fasteners may be built into the body of a military vehicle
and be adapted
to detect the presence of chemicals or.adverse biological conditions, and
cause action to
be taken to ensure the safety of the occupants or generate an alarm.
Especially in the case of the .fasteners disclosed in the first aspect of the
International
Fatent Application, the sensors may be incorporated in the fasteners in a very
to economical manner. There can be virtually no extra costs in including a
suitable sensor
in the electronic chip controlling the fastener.
As indicated above, the response of the fastener to the sensor may be to
release or
fasten, or.may be to generate some other type of response, such as an alarm or
activate
another mechanism.
is Brief Description of the Drawings
The invention will now be described in connection with certain non-limiting
examples
described in the attached drawings. In the drawings:
Figures 1 and 2 show in side and rear elevation respectively a first
embodiment of a
fastener which can be used in connection with the invention;
2o Figures 3 and 4 show in side elevation and rear elevation respectively a
second
embodiment of such a fastener;
Figure 5 is a block diagram of an embodiment of fastener which can be used in
the
networkor system of the invention;
Figure 6 is a block diagram showing an embodiment of a network of fasteners;
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Figure ? is a block diagram showing a form of encryption.
Figure 8 is another block diagram showing a different form of encryption;
Figure 9 is a block diagram dealing with address means;
Figure 10 is a perspective view of aw aircraft showing an embodiment of
network of
s fasteners according to the invention; and.
Figure 11 shows the network of fasteners of Figure 10 excluding the aircraft.
Detailed Description of the Drawings
In Figures 1 to 4, the size of the base to the fastener has been exaggerated
for clarity of
detail. These Figures show packaging and integration of intelligent forms of a
fastener
which may be used in the network of the invention. Other fasteners may be
substituted.
Referring first to Figures 1 and 2, this embodiment of fastener is made of
moulded
plastic and the actuating means is a smart 'memory alloy wire. The fastener 10
has
flexible beam I2 with at one end engagement means 14 and at the other mounting
block
.16.
is Engagement means 14 is wedge shaped at 15 to engage a ledge {not shown),
the
engagement means on a second fastener or any other suitable surface.
When shape memory alloy wire 1 ~ is heated sufficiently, it contracts, drawing
wedge 15
out of engagement.
As can be seen from Figure I, shape memory alloy wire I8 is attached to
circuit board
20 112 and to a conductive base 113 for earth return connection . A singje
wire 114 carries
power and superimposed communications and makes connection via an insulation
displacement connector 116.
In, the embodiment in Figures 3 and 4, fastener 10 clips into base 118. Wire
18 connects
to printed circuit board I 12, in this case integrated into fastener 10. Base
1 I8
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accommodates a four-way ribbon cable 120 which runs through base 118 and which
is
crimped into place. Cable 120 carried power and communication, with connection
to
fastener 10 by electrical contacts 122.
Figure 5 is a block diagram of an intelligent fastener configuration,
applicable to the
5 network of the invention when there are multiple fastening mechanisms. It is
self
explanatory.
The block diagram in Figure 6 represents a system of fasteners. Each
intelligent fastener
is as shown in Figure S. The communications concentrator, which is an optional
element, provides a mechanism for partitioning system complexity, eg, by
providing an
1o interface between a relatively costly-to-implement radio frequency network
and an
inexpensive RS-485 network which interconnects a number ofthe fasteners via a.
subnetwork. The subnetwork may use any communications which may also be useful
for the.intelligent fastener, such~as uni-directional, bi-directional, full
duplex, half
duplex, simplex, point-to-point, network, asynchronous and synchronous, via
such
15 techniques as electromagnetic radiation, radio (AM or FM}~ magnetic
coupling, low
frequency RF, microwave radio, spread spectrum radio, light (visible,
infrared}, optical
fibre, electrical {wire, cable} or sonic {ultrasonic, audible or infra-sound}.
The intelligent control unit may be a discrete device, an integrated circuit,
a
microcontroller,.a microcomputer, a programmable logic device, a hybrid
integrated
zo circuit, an application specific integrated circuit, a printed wiring
assembly or an
embedded PC.
The optional sensing mechanism may be binary, rnulti-state or linear and
operate by any
of the following techniques: electrical (switch, contact, strain gauge, piezo-
electric,
piezo-resistive,, magneto-resistive, resistive), magnetic/Hall effect,
capacitive, optical
zs acoustic/ultrasonic or mechanical.
The status indication may be optical, acoustic or mechanical.
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The control mechanism may also be binary, mufti-state or linear. It may
operate by
techniques such as electrical (swirch, relaylcontactor,~semiconductor,
transistor, FET,
thyristor, mechanical (lever, valve, piston} or biological (human or animal).
The energy source and optional starage may be local, external or a
combination, using a
s technique such as primary or secondary cell or battery, mains derived power,
capacitor
orsupercapacitor, electromagnetic radiation (RF or light), inductive coupling,
acoustic,
chemical, fuel cell, gravity, mechanical, kinetic or biological.
Turning now to Figure 7, this illustrates a form of link encryption, in which
each
communications link where the information (address data) may be intercepted is
~ o protected by encryption of information on that link.
Figure 7 shows a form of end-to-end encryption, where information is encrypted
at its
source and decrypted at its destination.
Figure 9 shows storage of a unique identity for a fastener, using a
microcontroller-based
intelligent controller which incorporates internal program code memory
programmed
1s with a unique serial number during manufacture. Also included is an EEPROM
which
stores a network address programmed as part of installation and commissioning.
Each of
these is stored redundantly with checksum protection.
Figure 10 shows an assembly which is an aircraft 210 having a network of
fasteners 220
(refer Figure 1 I ) distributed throughout the aircraft. Each fastener .212
(some only are
20 labelled) has a primary function of holding the, aircraft assembly 210 ,
together. The
fasteners 212 are within some cases within the aircraft 2I0, in other cases
just beneath
the internal or external skin 214 of the aircraft 210 and in other cases
penetrating the
skin 214 (similarly to a rivet} on a conventional aircraft assembly.
It is an option that other fasteners (not shown} are included in aircraft 210
but are not
2s part of the network of fasteners 220. Some of these fasteners which are not
part of
network of fasteners 220 may be present in case of need (redundancy) or may
not be
part of the network of the fasteners 220 for some other reason.
CA 02560091 2006-09-15
WO 2005/090798 PCT/AU2005/000358
17
Fasteners 212 in network 220 may, for example, report on whether those
fasteners 212
which hold engine 21 fi to mounting , 21 ~ are stressed in any way. If any
stress is
detected, other fasteners 212 in the vicinity of the stressed fasteners may
increase the
degree of fastening in order to make up for any shortcoming in fastening by
the stressed
fastener or fasteners.
Similarly, fasteners 212 located between skin 214 and the aircraft lining (not
shown
may report on any significant rise in temperature, which may indicated
commencement
of a fire, for example in electrical cabling.
Industrial Applicability
io As the above description amply demonstrates, the invention in its various
aspects
represents a. major advance in the art and is readily applicable industrially.
