Patent Publication Number: US-2006002783-A1

Title: Bolt assembly, method and device for release, and computer system

Description:
TECHNICAL FIELD  
      This invention concerns a new and improved bolt assembly, a method and device for releasing the bolt assembly and a computer system useful in relation to the foregoing, inter alia.  
     BACKGROUND ART  
      A conventional bolt has a metal rod or pin with a head at one end and a screw thread at the other, to take a nut. The bolt is used to join one element to two or more other elements. One or more of the elements is usually mounted on the bolt between the nut and the head.  
      Such a prior art bolt is normally tightened by gripping the head of the bolt and rotating the nut, or vice versa. Conversely, to disengage the bolt, it is necessary to grip the nut or the head and rotate the head or the nut, respectively. The disengagement procedure can be slow, especially where access to the nut and/or the head is difficult. Tools are usually required in order to carry out the holding and rotation functions.  
      In some circumstances, delay in releasing a bolt can have highly undesirable consequences. For example, if bolts are used to anchor a seat belt in a vehicle, and the vehicle is subsequently involved in a collision, fast release of the seat belt anchors may be instrumental in saving the life of a person injured in the accident and hence unable to release the seat belt. Similar considerations may apply if the seat belt release mechanism has been damaged and cannot be released in the normal manner.  
      A quick release bolt could also be useful to enable release of vehicle doors in an accident.  
     DISCLOSURE OF THE INVENTION  
      Accordingly, it is an object of this invention, at least in some embodiments, to provide a bolt which is capable of quick release, especially remotely.  
      While the bolt of the present invention has a wide range of applications and is capable of providing quick release, and optionally remote quick release, for convenience the invention will often be described below in connection with its use as a seat belt anchor.  
      As will be apparent to one skilled in the art, the invention is not limited to this application. In the automotive field alone, the bolt of the invention can be used, for example, to secure not only seat belts and doors but also spare tyres, roof racks and so on.  
      In one aspect, this invention provides a bolt assembly including: 
          a shank having a screw thread and     a head of larger cross section than that of the shank,     wherein the screw thread of the shank is adapted to rotatably engage with a complementary screw thread in a nut, characterised in that the bolt assembly includes means adapted in use to disengage the head or the nut without rotation of the nut or the shank, the disengagement means including a material adapted to change form to facilitate disengagement, when activated.        

      The bolt assembly may be of any suitable material, including plastic, but is preferably principally made of metal, especially steel. The shank is usually cylindrical as per conventional bolts. The head may resemble that of a conventional bolt; for example, the head may be hexagonal in cross section and designed to be engaged during assembly by a suitable tool for holding or rotating. The head may be integral with or separate from the shank. When the head is separate from the shank, the shank may include a socket or may be of a shape appropriate for engagement by a suitable tool, for holding or rotating during assembly.  
      In some embodiments, the head includes the disengagement means. In such embodiments, the head is designed to disengage from the shank. In other embodiments, the disengagement means may be included in the nut. In still other embodiments, the disengagement means may be included in the screw thread of the shank.  
      The disengagement means preferably includes a material responsive to an appropriate energy input in order to achieve the desired release. By way of example, the disengagement means may include shape memory alloy which, when heated to a transformation temperature, withdraws from engagement with a suitable ledge, groove or the like. As another example, the disengagement means may consist of or include a material, such as an adhesive, which can melt at a suitable temperature. In this way, the head of the bolt may disengage from the shank, or the relevant part of the nut may disengage, or the screw thread on the shank may disengage from that of the nut. In each case, disengagement permits an element trapped between the head and the nut to be freed from the shank, because the head has disengaged, or because the nut has disengaged or because the screw thread has withdrawn from engagement with the nut.  
      It should be apparent that any suitable material may be used to facilitate the disengagement. The examples described below in connection with the Drawings show use of shape memory alloy material or heat activatable epoxy resin (as an example of a “smart adhesive”). It is anticipated that other types of suitable materials may include photo polymers, magneto-rheological materials, “smart” gel as well as auxetic materials. Other options may be apparent to those skilled in the art.  
      The energy to activate the disengagement may be supplied by various means. Discussed or mentioned below are hard wiring ( FIGS. 1, 2  and  4 ). Remote activation is possible as an alternative. This can be effected by, for example, using magnetic or ultrasonic energy or by triggering an exothermic or pyrotechnic reaction.  
      Reference is made to International Patent Application No. PCT/AU99/00185, the contents of which are incorporated herein by reference.  
      In connection with the device of the invention, this can incorporate features disclosed in International Patent Application No. PCT/AU01/00812, the contents of which are incorporated by reference. Preferred methods of data communication are ultra high frequency, radio frequency and infra red energy.  
      Where remote activation or communication is not required, data delivery can be via copper wire or fibre optic cable.  
      The shape memory material used in some embodiments of the invention is known. There are several of these. Currently, the best known is a shape memory alloy, predominantly or types made of titanium and nickel, but which may also include other material, such as aluminium, zinc and copper. Such a shape memory alloy is capable of adopting one shape below a predetermined transformation temperature and changing to a different shape once its temperature exceeds the transition temperature. In many cases, when a shape memory alloy cools below the transition temperature, it is capable of adopting the first shape again.  
      While this invention encompasses use of the shape memory alloy referred to above, it is not limited to this material. It is contemplated that other suitable materials may exist now or may come into existence in the future which can be substituted for the shape memory alloy.  
      As indicated above, there is no need to use a conventional tool to rotate the head of the bolt or the nut to cause this disengagement. As a result, it is possible to have rapid disengagement, compared to the prior art situation, where disengagement of the nut from the shank was possible only after either the shank or the nut had been rotated sufficiently to disengage the respective screw threads.  
      In another aspect, the invention provides a method for releasing the bolt assembly of the invention when engaged with the nut, the method including the step of activating the material to change form sufficiently to enable disengagement of the head or the nut without rotation of the nut or the shank.  
      Preferably, the method of the invention is carried out remotely by use of a special tool.  
      Accordingly, in a third aspect, the invention provides a device for release of the bolt assembly of the invention when engaged with the nut, the device including means for conveying a wireless command for activating the material to change form sufficiently to enable disengagement of the head or the nut without rotation of the nut or the shank. The wireless command may be provided by any suitable delivery means but is preferably chosen from the following options: magnetic, electromagnetic, ultrasonic, infra red, microwave or radio frequency energy.  
      While it is preferred to release the bolt assembly remotely, it is to be understood that the bolt assembly may be hard wired. In particular, where the bolt assembly is used in the context of an automobile, and whether or not it is intended that remote release will be used to disengage the bolt assembly in the case of an accident, the bolt assembly may be normally hard wired into the automobile&#39;s system, especially into an on-board computer system (when present). In this way, the vehicle can run a check on the status of the bolt assembly system at each engine start up and can report any failure, in the same way as many vehicles check the viability of brakes, lights and air bags on start up, at present. Hard wiring also enables the bolt assembly of the invention to make use of the general power source for the vehicle, such as the vehicle battery.  
      Regardless of whether the bolt assembly of the invention is hard wired, when it is used in an automotive context it may be preferred that the bolt assembly includes its own power supply. In case of vehicle crash, where the power supply may be damaged or severed, the local power supply for the bolt assembly can ensure that remote disengagement is possible, if that is desired. Local power supply may be provided by a small battery, by chemical means, by a capacitor, by compressed gas, by a clockwork system or in any other suitable way.  
      It is greatly preferred that the bolt assembly of the invention is capable of being manipulated during assembly by regular, conventional tools. In some embodiments, the bolt assembly of the invention is capable of assembly and disassembly repeatedly, including by quick release. In other embodiments, the bolt assembly of the invention can be assembled and disassembled in the conventional way any number of times (i.e., by rotating the nut or the shank), but quickly released only once (i.e., by disengaging the head or the nut without rotation of the nut or the shank).  
      It is desirable that the bolt assembly of the invention, when designed to be remotely activated, can be activated only by authorised personnel via an encrypted message from a hand-held version of the device of the invention. This is especially desirable when the bolt assembly of the invention is used to anchor seat belts in a vehicle. It is preferred that the bolt assembly of the invention is uniquely identifiable and that it is capable of being networked to other bolt assemblies in the vehicle or to other “intelligent” fastening systems. The purpose of this is to ensure that seat belt anchors and the like are not disengaged inadvertently or as a result of mischief.  
      Similarly, it is preferred that the device of the invention can be used only by authorised persons after biometric identification and/or entry of a code or pin number. In this way, the device of the invention may be used only by authorised personnel via an encrypted message from a hand-held device. Biometric identification may identity any convenient part of the user, such as a hand, a digit, a retina, and so on.  
      Specific examples of the bolt assembly of the invention are described below, in connection with the drawings.  
      In a typical example, the bolt assembly of the invention is initially assembled in a conventional way and is adaptable to conventional manufacturing processes. For example, in the case of an anchor for a seat belt, the shank of the bolt assembly is installed through a seat belt mounting plate and into the vehicle chassis. A nut is screwed onto the thread of the shank. The shank is tightened into the nut, either by holding the nut and rotating the head of the bolt assembly, or vice versa, or by using a socket recess in the end of the shank. The first two procedures are those conventionally used in nut and bolt assembly. The third procedure (use of a socket recess) is specific to the bolt assembly of the invention, which may not have a head suitable for holding or rotating by a conventional tool.  
      In this typical example, when it is desired to quickly disengage the bolt assembly by remote means, the device of the invention is used. This has a reader plate to permit an authorised user to press a thumb print into the plate and to obtain biometric authorisation. As well or alternately the user can enter a pin number to obtain authorisation. Authorisation may be on a plurality of levels, depending on the class of user. Both these procedures are well known. Next, by pressing one or more buttons on the device, the user, once authorised, may cause the device to communicate with a chip embedded in the bolt assembly. The chip is readable as to information including the unique identity of the bolt assembly and its status. Communication between the device of the invention and the bolt assembly may be, for example, by radio frequency, ultrasound or any other suitable wireless technology.  
      After identification of the bolt assembly, the device of the invention is used to trigger the release process, for example by causing heat energy to be supplied to material within the bolt assembly to enable disengagement of the head, or the nut.  
      After disengagement, it is preferred that a spring incorporated in the bolt assembly pushes the nut or the head off the shank so that the seat belt mounting plate (in this case) is released and the seat belt can be removed. Of course, the spring may be omitted, especially when the bolt assembly is installed in a situation where the head of the bolt is attached to the shank and the bolt can easily be withdrawn from the nut.  
      The device of the invention may be designed to activate disengagement of a plurality of bolt assemblies of the invention, if desired, in a chosen sequence.  
      In yet another aspect, this invention provides a computer system and method which may be used with the bolt assembly and device of the invention and which may also be useful in other areas.  
      In this aspect, the invention provides a computer system including the following: 
          means for enquiring as to identification in a target;     means to receive identification data from the target;     a database for comparing the identification data with stored data; and     means for transmitting a command to the target to change status in the target.        

      The identification in the target is intended to be used for the purpose of establishing communications and addressing commands, such as a command to cause activation of the disengagement means.  
      The identification may take any suitable form 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 is also preferred that the identification is unique to the target.  
      By way of non-limiting example, the identification may comprise a serial number, a communications address or a temporary communications address, or any combination of these.  
      When the identification is a serial number, this is preferably a unique number which is programmed into the target and which consequently does not change throughout the life of the target.  
      When the identification is a communications address, this is preferably a communications or network address which may be assigned to the target at the time of installation, or when a network of targets is configured.  
      When the identification is a temporary communications address, this is an address which may be assigned to the target on a transient basis. This may be desired, for example, where the target is configured in a sub-network and use of the full, unique address of the target during a particular session will cause excessive communications traffic and/or require excessive processing overhead during the communications session.  
      The identification may be stored in the target in any suitable manner and in any suitable storage device. Preferably, the storage method is robust and uses known techniques, such as multiple redundancy storage with checksum or CRC protection, reinstatement of backup on detection of errors, etc. Preferably, the storage method includes measures to prevent unauthorised access or tampering with the unique identity.  
      Examples of storage devices are the following: 
          Hardwiring: this includes switches, jumpers, solder blobs and soldered links.     Non-volatile memory: this includes PROM (programmable read only memory), EPROM (erasable programmable read only memory), EEPROM (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.        

      The address or identity of the target 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. Information may appear unencrypted or “in the clear” at communications or 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 points in the communications links.  
      As a third example, both end-to-end encryption as well as transmission 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 target or network of targets, especially where there is a high level of need to prevent any unauthorised party to control targets, change system settings or configurations or cause damage or disruption to the system for any reason.  
      While file encryption is one way to prevent unauthorised entry into a 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 communication techniques can be used to hide radiated signals amongst radio noise. Use of spread spectrum wireless links or 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 bidirectional handshake and identity confirmation process, or by such measures as call-back to an authorised telephone number or a network address, for example.  
      By way of further example, access to and control of targets may require the operator or control system to take part in a dialogue with a master control/database for a specific access code, in order to allow control of the target. As well as such explicit authorisation, there may be tracking of the transaction. For example, the access code and target operation may be recorded in a time stamped log stored by the master control/database, by the target itself or by intermediate system elements. Retrieval of such logs can permit analysis for audit tracking purposes.  
      The status of the target may be represented by, for example, whether the target (if a fastener) is engaged or disengaged, whether it has been damaged (such as by tampering or mechanical stress), and so on.  
      In the context of the bolt assembly of the present invention, the computer system of the invention can read a chip in the bolt assembly containing information as to the unique identity of the bolt assembly and its status. Both data as to the identity and the status are sent back to the enquiring means and, in each case, compared with a database stored in the computer system. If the identity of the bolt is found in the identification database, the computer system can transmit a command to the target (the bolt assembly) to change the status, for example by switching on a heat source which can change the state of shape memory alloy as described in some of the examples in connection with the drawings, below.  
      Optionally, the computer system of the invention also includes means for enquiry as to the identification of a user, means to receive identification data from the user, a database for comparing the identification data with stored data and means to inactivate further use of the computer system if the identification data is not found in the database.  
      As another option, the computer system may include means for enquiring as to history of the target, means to receive history data and means to store the history data.  
      The history of the target (if a fastener) can include whether the fastener has been engaged or disengaged previously and, if so, the number of times this has occurred. The history data may be used to determine whether the target needs to be serviced and, if so, the type of service required.  
      As a further option, the computer system of the invention may recognise user identification on several levels and may restrict operation of the computer system accordingly. In the context of the bolt assembly invention, for example, a particular user may be authorised to change the status of the bolt assembly to quickly release it, but not to enable reassembly.  
      Where not already described, the choice of the elements in the computer system of the invention will be apparent to the person skilled in the art.  
      In some embodiments, the computer system may transfer data received and/or processed to a third party, such as another computer. This may occur in parallel (real time) or at a different time. The third party may have means to override authorisation to change status or in any other respect.  
      The computer system may be wholly or partly contained in a hand-held computer. It may be convenient if the device of the invention incorporates all or part of the computer system of the invention. For simplicity, the device of the invention may enquire as to the identification of the target, receive the identification data and send this data to a remote centre for comparison with stored data in a database. The remote centre may then authorise the device of the invention to authorise the change in status of the target, for example, by activating the disengagement means in the case of the bolt assembly of the invention.  
      It may be recalled that in a second aspect the invention provides a method for releasing the bolt assembly of the invention. This may be regarded as only one species of a different concept of method, which is also provided by this invention. The method includes the steps of: 
          enquiring as to identification in a target;     receiving identification data from the target;     comparing the identification data with stored data in a database;     enquiring as to status in the target;     receiving status data from the target;     comparing the status data with stored date in a database; and     authorising a change in the status.        

      Optionally, the last mentioned method may also include the steps of enquiring as to the identification of a user, receiving identification data from the user, comparing the identification data with stored data in a database and authorising the steps set out immediately above (enquiring as to identification in a target, etc).  
      As another option, the method may include the steps of enquiring as to the history of the target, receiving history data from the target and perhaps storing the history data in a database. As further options,, the method may include the step of transferring data to a third party.  
      The tool of the present invention may incorporate means to enable the computer system and method of the invention to operate.  
      The computer system and the process of the invention may be used in a situation where a service is being provided to a third party. For example, the service may involve the disassembly of apparatus and replacement or repair of a part which can only be located after disassembly. In such a service situation, the present invention allows automatic billing of the third party for whom the service is being carried out.  
      This can be achieved by including in the computer system means for obtaining payment for the service provided from a third party fund. The method associated with the computer system of the invention can include the step of requesting transfer of funds from the third party fund and authorising acceptance of the finds to a nominated fund.  
      It will be appreciated that using this procedure it is possible to bill automatically and to have the funds paid immediately for the carrying out of service to an apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will now be described in connection with certain specific examples thereof. It is to be understood that these examples are not intended to be limiting on the scope of the invention in any of its aspects.  
      Reference is made to the accompanying drawings, in which:  
       FIG. 1  is side elevation, partly in cross section, of a first embodiment of the bolt assembly of the invention, in which the head of the bolt is designed to disengage;  
       FIG. 2  is a side elevation, partly in cross section, of a second embodiment of the bolt assembly of the invention, being a modification of that in  FIG. 1 ;  
       FIG. 3  is a side elevation, partly in cross section, of a third embodiment of the bolt assembly of the invention, in which the nut is designed to disengage;  
       FIG. 4  is a side elevation of a fourth embodiment of the bolt assembly of the invention, in which the thread on the shank is designed to disengage;  
       FIG. 5  is a side elevation, partly in cross section, of a fifth embodiment of the bolt assembly of the invention, in which the head is designed to disengage;  
       FIG. 6  is a side elevation, partly in cross section, of a sixth embodiment, similar to that in  FIG. 5 , in which the head is designed to disengage;  
       FIG. 7  is a perspective view, partially cut away, of an embodiment of a tool which may be used as the device of the invention;  
       FIG. 8  shows a side elevation of the tool of  FIG. 7  as part of a flow chart, also illustrating an embodiment of the computer system of the invention;  
       FIG. 9  is a block diagram illustrating an embodiment of the computer system of the invention where the target is in an “intelligent fastener”;  
       FIG. 10  is a block diagram showing a network of the fasteners of  FIG. 9 ;  
       FIGS. 11 and 12  show different forms of encryption in relation to the intelligent fastener of  FIG. 9 ;  
       FIG. 13  is a block diagram illustrating identification in the form of an address and a unique serial number; and  
       FIG. 14  shows how embodiments of various aspects of the invention can work in relation to fasteners in a motor vehicle. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      Referring first to  FIG. 1 , bolt assembly  10  has shank  12  with an external screw thread (not shown) adapted to engage a complementarily-threaded nut (not shown). Bolt  10  also includes head  14 . In this embodiment, head  14  is not integral with shank  12  but forms a type of collar. Concentric grooves  16  are formed in shank  12 . Head  14  includes shape memory alloy rings  18  which, in the state illustrated, fit into grooves  16  and retain head  14  on shank  12 .  
      Bolt assembly  10  also includes controller head  20 , which has a battery or capacitor  22  and a printed circuit board  24 . Power and information travel via cable  34  which communicates with a power connector  26  on head  14 . Spring  28  biases head  14  and controller head  20  away from shank  12 .  
      Bolt assembly  10  also includes hexagonal drive socket  30  and heater elements  32 . Electric power cable  34  connects bolt assembly  10  to the computer and power system of the vehicle (not shown).  
      Bolt assembly  10  may be used as a quick release bolt when activation is required within the vehicle from, for example, a dash board or console control. Bolt assembly  10  can be used in this environment to release a spare tyre or roof racks, for example. In that environment, power cable  34  would be used not only to monitor the status of bolt assembly  10  but also to deliver power and instruction to bolt assembly  10  to disengage. In that environment, battery or capacitor  22  may be omitted.  
      Power supply via cable  34  can be used to activate heater elements  32  and supply sufficient heat to shape memory alloy rings  18  to cause them to change shape and withdraw from grooves  16  in shank  12 . At this stage, head  14  can be withdrawn linearly from shank  12 , thus releasing any element trapped between head  14  and the nut (not shown) screwed onto the far end of shank  12  via a screw thread (not shown).  
      Conventional assembly of bolt assembly  10  is achieved by using an Allen key or similar conventional tool to tighten shank  12  within the nut (not shown), by inserting the Allen key into drive socket  30  and rotating. Controller head  20  is then pushed onto the end of head  14 , snap fitting into recess  36 .  
      Bolt assembly  10  is shown with four shape memory rings. The number of grooves  16  and hence the number of shape memory alloy rings  18  is dependent on the strength of the material used for the shank and for the rings, the dimensions of the grooves and the desired load capacity of the bolt. In the example illustrated, the depth of the grooves is designed to allow disengagement of the shape memory alloy rings (nickel titanium) at their maximum useable strain of 6%.  
      Head  14  fits in a tight sliding fit over shank  12 , allowing shank  12  to rotate without appreciable play. When an Allen key or similar tool is used to rotate shank  12  to tighten the thread (not shown) on shank  12  into the nut (not shown), head  14  may be compressed against the part to be secured (such as a seat belt mounting plate), as is the case with a normal bolt head. If shank  12  is rotated in the opposite direction, head  14  is “backed off” from the seat belt mounting plate. As controller head  20  must be removed during the tightening or loosening process, the shape memory alloy rings  18  are encapsulated in head  14  in such a way as to transfer load from the rings  18  to head  14 .  
      In this embodiment, head  14  is circular in cross-section, because no torque is applied to head  14  in the tightening or loosening process, this taking place via drive socket  30 .  
      Shape memory alloy rings  18  are designed to be thin enough to ensure rapid heating but thick enough to give adequate shear strength. They are separated in grooves  16  in shank  12  to prevent over stressing of the shank material.  
      When heater elements  32  are activated to heat rings  18 , once the transformation temperature has been reached, the crystal structure of the alloy in rings  18  transforms from martensite to austenite. For this application, it is envisaged that the material of rings  18  is nickel titanium material, class H, giving a transformation temperature (Active finish temperature Af) in the range of 95° to 115° C.  
      In this embodiment, heater elements  32  cause the transmission of compressive load from shape memory alloy rings  18  to the body of head  14 . Heater elements  32  must therefore be made of a suitable material with regard to heating and mechanical properties. As necessary, heater elements  32  may need to be electrically insulated from metal components. In this case, the design may require adjustment from that shown in  FIG. 1 , or else heating may be carried out in a manner other than by electrical resistance heating. For example, an exothermic chemical reaction could be used, although this would limit the bolt assembly to a once-only release according to the method of the invention.  
      As an alternative, rings  18  can be used directly as resistance heaters, by supplying a current to the rings. In this case, rings  18  would need to be coated with an electrically insulating surface finish, such as polytetrafluroethylene (PTFE), in order to prevent short circuiting.  
      Once rings  18  have been heated in a suitable manner, and have expanded, head  14  is ejected, fully or partially, from shank  12  by spring  28 . After rings  18  cool down, they are forced to return to the martensitic (room temperature) crystal structure or small diameter state by annular return spring  38 , located around rings  18 . In this embodiment, rings  18  will not return to the “small state” without the bias provided by return spring  38 . Head  14  may be put onto shank  12  when rings  18  are in the austenitic crystalline structure (hot) or large diameter state. In the large diameter state, rings  18  do not engage in grooves  16 .  
      In order to work in the desired way, it is necessary to “train” the shape memory alloy material used for rings  18 . A one-way memory may be employed to achieve the desired strain of 8%, with return spring  38  being used to restore the low temperature state on cooling. The “training” of rings  18  may be conducted by constraining the rings to the desired small diameter shape, heating rings  18  to between 400° and 500° C. and then rapidly cooling them by water quenching or air cooling.  
      Referring now to the embodiment in  FIG. 2 , this is similar to the embodiment in  FIG. 1 . However, in the  FIG. 2  embodiment, shank  12  terminates in a hexagonal (or other suitable shape) spigot  42 . This engages in socket  44  in head  14 .  
      Whereas in bolt assembly  10  in  FIG. 1  drive socket  30  was used to tighten or loosen shank  12 , in the case of bolt assembly  40  in  FIG. 2  the external surface of head  14  is hexagonal to resemble the shape of a normal bolt head and can be used to tighten or loosen the bolt. Controller head  20  (for delivery of power and data) is placed over head  14  after the desired amount of tightening or loosening has taken place, as was the case with bolt assembly  10  in  FIG. 1 .  
      Bolt assembly  40  can be used for the same applications as those described for bolt assembly  10 .  
      Referring now to  FIG. 3 , this shows bolt assembly  50  in which the disengaging means forms part of the nut rather than the head of the bolt. This form of the invention can be particularly useful where a flush design is preferred, the bolt to be inserted in the nut when required, for example when installing child seat restraints.  
      In this embodiment, shank  52  has two different cross sectional sizes. The first part  46 , is of larger size and is on that part of shank  52  which is attached to or integral with traditional bolt head  54 . The second part  48  is of a smaller size, for the purpose explained below.  
      Nut  56  has two main parts, sleeve  58  and collar  60 . Sleeve  58  has approximately the same cross sectional size as first part  46  of shank  52 . Consequently, when sleeve  58  is mounted on second part  48  of shank  52 , bolt assembly  50  (minus collar  60 ) can pass through a standard sized bolt hole. Alternately, shank  52  may be of uniform size (as for first part  46 ) and sleeve  58  would have a larger cross sectional size than part  46 . The bolt hole would need to be larger.  
      Sleeve  58  includes a number of grooves  66  in which are inserted shape memory alloy rings  68 . Return spring  38  is as described in connection with  FIG. 1 . Rings  68  prevent axial movement of collar  60  on sleeve  58 .  
      The second part  48  of shank  52  also has a hexagonal or other suitably shaped up-stand  70  to engage with collar  60 . Internally, sleeve  58  is threaded to mate with a complementary thread on second part  48  of shank  52  (the thread not being shown in this Figure).  
      Controller head  62  is attached to nut  56  and includes a printed circuit board  64  and a radio frequency coil  72 . Heater elements  74  carry out a similar function to heater elements  32  in  FIGS. 1 and 2 . No ejector spring is shown in the embodiment in  FIG. 3 . This can be included if desired but may not be necessary, because once rings  68  are heated in order to change shape and disengage from grooves  66 , conventional bolt head  54  may be gripped to withdraw the bolt from nut  56 .  
      To activate shape memory alloy rings  68  (by heating them sufficiently to change shape), a device of the invention (not shown) transmits a radio frequency signal to coil  72  and printed circuit board  64  processes the signal to heater elements  74 .  
      Turning now to the embodiment in  FIG. 4 , in this embodiment the thread on the shank is made from shape memory alloy.  
      In this embodiment, bolt assembly  80  has head  84  and shank  82 . Shank  82  is in two parts. The first part  76  is integral with part of head  84 . The second part  78  includes thread  86  made of shape memory alloy material. Insulating material  88  is inserted between thread  86  and second part  78  of shank  82 . A return spring  90  is incorporated between thread  86  and insulating material  88 .  
      Head  84  includes a printed circuit board  92  and a capacitor  94 . Power connector  96  provides power and data from an external source via cable  34  through the centre of first part  76  of shank  82  to thread  86 .  
      When power is supplied to thread  86  via power connector  96 , thread  86  contracts at its transformation temperature, causing a change in diameter sufficient to fully disengage thread  86  from a nut (not shown) mounted on it. Because current material technology allows only an 8% reduction in diameter, a special low profile thread is required. This may change as technology develops. A low profile thread may have a significantly lower load rating than a standard thread. Increases in permissible strain can increase the load rating of the fastener.  
      Bolt assembly  80  may be suitable for a once-only quick-release use (according to the method of the invention). Alternately, the shape memory alloy may be trained to assume the threaded configuration when it cools and bolt assembly  80  may be reusable in accordance with the method of the invention as required.  
      Preferably, at the transformation temperature, thread  86  changes from a threaded cylinder to a smooth cylinder, to aid linear withdrawal from the nut.  
      The embodiment in  FIG. 5  is particularly useful for once-only applications, for example in the case of remotely releaseable door hinge mounts, etc. These could be used to release doors in the case of vehicle accident where occupants are trapped inside the vehicle, for example.  
      In  FIG. 5 , bolt assembly  100  has head  104  and shank  102 , bearing threads (not shown) to engage a nut (not shown). Head  104  is not integral with shank  102  but is engaged by inserting hexagonal or other suitably shaped spigot  98  in complementary cavity  106  in shank  102 . Head  104  is secured in engagement in cavity  106  by heat activatable epoxy adhesive  108 , against the bias provided by ejector spring  110 .  
      Head  104  also includes printed circuit board  112 , battery or capacitor  114  and switch  116 .  
      When switch  116  is activated, adhesive  108  is heated and becomes viscous. The bond between spigot  98  and cavity  106  is broken and spring  110  ejects head  104  from shank  102 . Heating can take place via a battery powered heating coil  118  or else an exothermic reaction can be used.  
      With reference now to the embodiment in  FIG. 6 , bolt assembly  120  is similar to bolt assembly  100  in  FIG. 5 , except that head  124  engages the outside of shank  122 , ejector spring  130  is external to shank  122  and insulator  126  is included.  
      Head  124  includes printed circuit board  112 , capacitor or battery  114  and switch  116 .  
      Adhesive  108  provides sufficient bond between head  124  and shank  122 , in the unheated state, to permit torque to be transmitted from head  124  to shank  122 , as well as providing sufficient shear load to cope with the rated axial load of the bolt.  
      It will be appreciated from the description of the above specific embodiments that the disengaging means can be incorporated in the head of the bolt, as in  FIGS. 1 and 2 , in the nut as in  FIG. 3 , in the thread as in  FIG. 4  or between the head and the shank as in  FIGS. 5 and 6 .  
      With reference to  FIG. 7 , tool  160  has an actuator  162  and a detector  164  as well as a read-out screen  166  and user interface/menu selection buttons  168 . Tool  160  also includes a modular head  170  (so that the module containing actuator  162  and detector  164  can be exchanged for a different module which may link to a different process of activation and/or detection).  
      Tool  160  also includes an aerial  172  for reception and transmission, communication module  174 , processing module  176 , memory module  178  and switching module  179 . Tool  160  has power supply  180  and insertable external memory card  182 . In the embodiment shown, tool  160  also has biometric authorisation means  184 , so that use of tool  160  can be authorised by detection of an acceptable thumb print, for example.  
      By use of buttons  168 , tool  160  may be placed into any one of several different modes. In one mode, detector  164  can detect the identity of a bolt assembly (not shown). In the same or a different mode, detector  164  can diagnose the status of a bolt assembly—for example, whether the bolt assembly is in the fixed or released state or whether it has been damaged. Tool  160  may then interpret the action required in relation to a particular bolt assembly and display this on screen  166 . In yet another mode, tool  160  can send a command to the bolt assembly, for example, to cause it to disengage. Tool  160  can also record relevant information, by transferring it to the bolt assembly or by recording it in tool  160  itself or by transmitting it to a remote data centre.  
      To further detail the type of functions of tool  160 , it may determine security issues, such as whether the person using tool  160  or tool  160  itself is authorised to activate the bolt assembly. Tool  160  can record the service history of the bolt assembly. Lastly, tool  160  can send a command to activate the bolt assembly.  
      Turning now to  FIG. 8 , tool  160  is shown in the flow chart in its relationship with remote centre  186  and bolt assemblies  188  and  190  in wall assembly  192 . As indicated, tool  160  can interrogate bolt assembly  188  and receive information from it. Tool  160  can activate bolt assembly  188  by applying a force or sending a message. Tool  160  can report to bolt assembly  188  and receive a report from bolt assembly  188 .  
      While tool  160  can repeat these functions in relation to bolt assembly  190 , it is also possible to have communication between bolt assemblies  188  and  190  themselves.  
      In summary, the link between tool  160  and bolt assembly  188  allows detection and reporting of identity, status, sequence, history and authorisation requirements. This can be done using infra red, radio frequency, electromagnetic, microwave or ultrasound energy, amongst others. Tool  160  can also command the disengagement means in bolt assembly  188  to activate, using any of the above forms of energy and also by using digital instruction, alone or in combination with energy transmission and also variations such as electromagnetic pulse and induction.  
      The link between tool  160  and remote centre  186  can permit the downloading of manuals, instructions, procedures and customer files, the giving of authorisation, billing, encryption control of bolt assemblies, the uploading of service information, diagnostics, information as to parts replaced, the facilitation of inventory, and the location and history of bolt assemblies.  
      Also shown is a link between remote centre  186  and bolt assemblies  188 . This link can provide reports on status, relay history, provide diagnosis and control encryption links.  
      While examples have been given above of the way in which functions carried out by tool  160  may be effected, it is to be understood that these functions may be carried out in any suitable way and, as will be appreciated by one skilled in the art, there already exists relevant technology which can be adapted for this purpose.  
      Referring to  FIG. 9 , the target in accordance with the computer system and method of the invention is in an intelligent fastener in this embodiment. The block diagram is essentially self-explanatory.  
      In  FIG. 10 , there is a system of intelligent fasteners, each as shown in  FIG. 9 .  
      The communications concentrator, which is an optional element, provides a mechanism for partitioning system complexity, e.g., by providing an interface between a relatively costly-to-implement radio frequency network and an inexpensive RS-485 network which interconnects a number of the fasteners via a subnetwork. The subnetwork may use any communications which may also be useful for the intelligent fastener, such as unidirectional, bidirectional, full duplex, half duplex, simplex, point-to-point, network, asynchronous and synchronous, via such 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 circuit, an application specific integrated circuit, a printed wiring assembly or an embedded PC.  
      The optional sensing mechanism may be binary, multi-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 acoustic/ultrasonic or mechanical.  
      The status indication may be optical, acoustic or mechanical.  
      The control mechanism may also be binary, multi-state or linear. It may operate by techniques such as electrical (switch, relay/contactor, semiconductor, transistor, FET, thyristor, mechanical (lever, valve, piston) or biological (human or animal).  
      The energy source and optional storage may be local, external or a combination, using a technique such as primary or secondary cell or battery, mains derived power, capacitor or supercapacitor, electromagnetic radiation (RF or light), inductive coupling, acoustic, chemical, fuel cell, gravity, mechanical, kinetic or biological.  
      Turning now to  FIG. 11 , this illustrates a form of link encryption, in which each communications link where the information (address data) may be intercepted is protected by encryption of information on that link.  
       FIG. 12  shows a form of end-to-end encryption, where information is encrypted at its source and decrypted at its destination.  
       FIG. 13  shows storage of a unique identity for a fastener, using a microcontroller-based intelligent controller which incorporates internal program code memory programmed 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.  
      The block diagram in  FIG. 14  embodies many of the concepts of the invention. The system shown consists of a fastening system for a car radio which is housed behind a fascia which must be removed before the radio can be removed or installed.  
      The fascia and radio are each retained by multiple fasteners similar to those shown in the early embodiments, above. The fascia is retained by intelligent fastener A which controls three “slave” fasteners wired in series/parallel combination. The radio is retained by intelligent fastener B which controls one slave fastener wired in series with the fastener. The intelligent fasteners have external sensing switches to determine whether or not the item attached by the fastener is in place. Power for fastener electronics and actuators is derived from the vehicle electrical system.  
      The handheld PC in the intelligent control unit runs custom software and the unit can report the installation or otherwise of the radio and fascia and can guide the operator through a step-by-step installation procedure.  
      The database in the master control unit may contain records relating to vehicles being serviced by the system.  
     INDUSTRIAL APPLICABILITY  
      The bolt assembly of the invention has wide industrial applicability, especially where rapid release is required. For example, if used as a seat belt anchor, individuals in a severe automobile crash can be released from their seat belts where the individuals are disabled or where the seat belt release mechanism has been damaged.  
      It would be readily appreciated by one skilled in the art that the computer system and method (in the last aspect) of the invention are capable of extremely broad application, not limited to the environment of the bolt assembly invention disclosed in this document. For example, the system and method may be applied to the invention disclosed in International Patent Application No. PCT/AU99/00185, and may have other applications.