Patent Publication Number: US-2003222758-A1

Title: Vehicle access control and start system

Description:
[0001] This application claims priority to United Kingdom application No. GB0201547.7 filed on Jan. 24, 2002.  
       BACKGROUND OF THE INVENTION  
       [0002] The present invention relates to a vehicle access control and start system. Particularly, but not exclusively, the present invention relates to a vehicle access control system start system that operates using a passive entry authorisation device carried by a vehicle user.  
       [0003] It is known to use keys, active remote keyless entry (RKE) and passive RKE entry type devices for gaining access to a vehicle and/or starting the engine of the vehicle once inside. Passive entry systems comprise a transceiver type scanning device that is associated with the vehicle and which scans for the existence of RKE devices within a given range of the vehicle by using radio frequency waves, for example.  
       [0004] Access control systems have hitherto operated in a relatively simplistic manner and have not been fully integrated into further vehicle systems, meaning that the full potential of such devices to improve vehicle ease of use, security and safety has not been realised.  
       [0005] Access control systems may comprise a plurality of subsystems and devices which operate at various stages of a vehicle entry, start, stop and exit sequence. Prior art devices suffer from a number of problems. These problems are discussed below:  
       [0006] When either key based “central locking” or remote keyless active entry or passive entry systems are used, once the access control system associated with the vehicle has determined that access is to be permitted, it is usual that all closures are unlocked.  
       [0007] However, when a vehicle user approaches a vehicle it is usual for him/her to proceed directly towards the closure at which they wish to enter the passenger compartment or storage area of the vehicle, without first carrying out a visual inspection around the perimeter of the vehicle. This behaviour enables an unauthorised person such as a potential hijacker to hide behind the vehicle in a blind spot and subsequently gain unauthorised access to the vehicle once all of the closures are unlocked. Clearly, such a situation is undesirable.  
       [0008] Furthermore in relation to passive entry systems, it is desirable from the point of view of the vehicle user that the rate of scanning by such devices is relatively high so that the user does not have to wait for a relatively long period of a time before being able to enter the vehicle. However, the higher the scan rate, the greater the rate at which power is consumed by the scanning device.  
       [0009] The power available from either the vehicle battery or a dedicated power source for the scanning device is effectively finite when there is no other source such as a running engine to charge the battery/power source. Thus, if a vehicle having such a scanning device is left for an extended period of time whilst operating at a high scanning frequency, the power source may be exhausted which makes entry into the vehicle difficult and/or prevents the starting of the vehicle.  
       [0010] A number of problems are associated with the use of conventional exterior door handles. Because of the necessary positioning of exterior door handles in an ergonomic position close to the upper edge of the door panel (where they easily fall to hand) and remote from the door hinge in the case of conventional vehicle passenger doors, the styling freedom of the vehicle is restricted. Additionally, positioning is restricted due to the desire for an easy connection to the vehicle latch mechanism which is usually mounted on the rear face of a passenger door.  
       [0011] Another problem with conventional handles is associated with the punching out of a hole in the outer door panel. The hole is needed to accommodate the handle, but may also crease the exterior panel thus compromising its aesthetics. Such holes may also compromise the security of the vehicle and the fact that it is difficult to fit a handle flush with the exterior door panel results in the use of handles that generate wind noise and drag whilst the vehicle is in motion. The use of conventional door handles also adds weight to the vehicle and adds to the number of mechanical parts.  
       [0012] Additionally conventional locking systems require a number of moving parts whose operation may be compromised by dust ingress and wear, for example. Such locks are often relatively noisy in operation and may be relatively slow to change between locked and unlocked states. A further problem with know locking systems is that they do not interface well with electrically operated passive and active entry systems.  
       [0013] If entry permission to a vehicle is granted following a signal being received by an active or passive RKE device, the entry system will signal the unlocking of the vehicle locks. However, as locking mechanisms are essentially mechanical in operation, one or more electrical motors must be fitted to a locking mechanism so as to convert the signals from the entry system to operate the locking mechanism.  
       [0014] Typically, there are three lock states for vehicle door latches: unlocked, in which the door may be unlatched from inside and outside the vehicle; locked, in which the door may be unlatched from the interior but not the exterior of the vehicle (eg using an inside door handle); and double locked (superlocked) in which neither intervention with the interior or exterior handles etc of the door will unlatch the door—unlatching may only be achieved by using a key, RKE device or other authorisation device to first unlock the door.  
       [0015] A further problem with passive entry systems arises when attempting to determine the appropriate locked/unlocked status of the vehicle doors dependent upon the location of an authorised user in relation to the vehicle. In the absence of such a system, the security of the vehicle and/or personal safety of the user may be compromised.  
       [0016] Another problem with passive entry systems arises in relation to starting a vehicle if the system operates with two levels of authorisation in which non-driving vehicle users&#39; authorisation devices have only a first level of authorisation in order to access the vehicle, whereas drivers carry authorisation devices having both the first and second levels of authorisation in order to both enter the vehicle and start the vehicle. In such situations, it is undesirable for a user having the second level of authorisation and sitting in a passenger seat of the vehicle to activate the start system, because this means that a person having only the first level of authorisation, or no authorisation at all, can sit in the driver&#39;s seat and be able to start the vehicle.  
       [0017] A further problem that may be encountered is the possibility that once the start system has been energised, a user could start the vehicle whilst not being properly seated in the driver&#39;s seat.  
       [0018] Furthermore, vehicle doors, in particular vehicle passenger doors are provided with a separate inside door engagement means such as a pull handle and inside release means such as an inside release handle. The use of two separate components for these functions increases the part count and door assembly time, and hence the overall assembly cost. It also restricts the design freedom of the inside door trim upon which these components are typically mounted.  
       [0019] It is known to fit power unlatching systems to vehicles. Some systems merely require a switch to be pressed in order to send an unlatching signal to a corresponding door latch. However, there is a risk of accidental actuation if such switches are mounted at an accessible location in the vehicle interior. This is dangerous for the vehicle occupants, particularly if the vehicle is in motion, since they risk falling out of the vehicle. It is also desirable to include a mechanical connection between the release handle and the latch so that users may be able to exit the vehicle even when there is a loss of power to the latch.  
       [0020] The present invention seeks to overcome or at least mitigate the problems of the prior art.  
       [0021] One aspect of the present invention provides a vehicle security sub-system comprising person sensing means arranged to determine whether a person is located in the vehicle, first authorisation device detection means arranged to detect the presence of a cooperating authorisation device having a first level of authorisation in the vehicle, a second authorisation device detection means arranged to detect the presence of a cooperating authorisation device in an area around the driver&#39;s seat and a controller, wherein the controller is arranged to determine the locked state of at least one vehicle closure and the state of a start system of an associated vehicle in response to inputs from the detection means.  
       [0022] A second aspect of the present invention provides a vehicle latch sub-system comprising a lockable latch mechanism having a rheological fluid acting in a first state to unlock the latch and in a second state to unlock the latch, the sub-system further comprising touch sensitive unlocking means arranged such that when touched the unlocking means signals the change of state of the fluid to effect locking or unlocking according to predetermined criteria.  
       [0023] A third aspect of the invention provides a vehicle access control and start system comprising at least two of the following sub-systems:  
       [0024] a) an access control system for a vehicle having at least two closures, the system comprising a receiving means, the receiving means being so constructed and arranged as to determine the angular position of an associated authorisation device relative to the receiving means thereby enabling the system to determine the appropriate vehicle closure(s) to unlock and/or unlatch;  
       [0025] b) an access control system for a vehicle having two or more closures, the system, in use, determining the appropriate closures to unlock and/or unlatch in response to the period of time for which an input signal is received by the access control system from an authorisation device;  
       [0026] c) a transceiver for use in periodically scanning for the existence of at least one corresponding remote authorisation device wherein, in use, the rate at which the transceiver scans for the authorisation device decreases as the time since the detection of a previous authorisation device increases, such that the rate of a power consumption of the transceiver reduces during periods of non-use;  
       [0027] d) a touch sensitive access means fitted to a vehicle and arranged in use, when touched, to unlatch a door of a said vehicle and/or facilitate the deployment of an engagement means to be engaged by a vehicle user to assist in the opening or closing of the vehicle door;  
       [0028] e) a foot operated access means fitted to a vehicle arranged in use, when actuated, to unlatch a vehicle door and/or facilitate the deployment of an engagement means to be engaged by a vehicle user to assist in opening or closing the vehicle door;  
       [0029] f) an exterior mirror access means for a vehicle, the mirror being arranged, in use, such that engagement thereof by a vehicle user unlatches a vehicle door and/or facilitates deployment of an engagement means to be engaged by a vehicle user to assist in opening or closing the door;  
       [0030] g) engagement means for engagement by a vehicle user to assist in the opening or closing of a vehicle door, the engagement means being a handle, the handle being deployed from a retracted position, in use, in response to a signal from vehicle entry or exit means;  
       [0031] h) engagement means for engagement by a vehicle user to assist in the opening or closing of a vehicle door, the means being the waist line portion of a vehicle door, a window pane portion of the vehicle door being retracted in use, in response to a signal from a vehicle entry means so as to permit said engagement;  
       [0032] i) a mechanism, comprising a rheological fluid in operable connection with an output and an input, the fluid acting so as to in a first state prevent actuation of the output upon actuation of the input and in a second state permit such actuation;  
       [0033] j) a vehicle locking system comprising person sensing means, authorisation device detection means and a controller, the sensing means being arranged so as to determine whether a person is located in the vehicle and the authorisation device detection means is arranged to detect the presence of a co-operating authorisation device within the vehicle, wherein, in use, the locked state of the vehicle is controlled by the controller in response to a signal supplied by the sensing means and a signal supplied by the authorisation device detection means;  
       [0034] k) a start system for a vehicle, the system comprising scanning means arranged so as to scan an area around a driver&#39;s seat of the vehicle to detect an authorisation device having a particular level of authorisation so as to ensure that only a person carrying an authorisation device having this level of authorisation and positioned in the area around the driver&#39;s seat may start the vehicle;  
       [0035] l) a start system for a vehicle comprising first and second switches, wherein both switches must be actuated in any order to enable the vehicle to start and wherein the switches are sufficiently mutually spaced to prevent actuation thereof by a single hand of a vehicle user;  
       [0036] m) an inside door release mechanism for a vehicle comprising first and second input means arranged in a mutually spaced relationship on a door inner face and a latch wherein the mechanism is so constructed and arranged to be capable of causing the latch to be unlatched when both input means are actuated simultaneously; and/or  
       [0037] n) a door release and engagement mechanism for a vehicle comprising a combined inside release and door pull handle and a latch operably connected thereto, wherein, in use, the operable connection is disabled when the door is ajar and/or unlatched so as to prevent the latch from being mis-set prior to subsequent re-closure of the door. 
     
    
    
     [0038] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
     [0039]FIG. 1A is a schematic block diagram illustrating a vehicle incorporating a remote keyless passive entry system according to an embodiment of the present invention;  
     [0040]FIG. 1B is a schematic block diagram illustrating a vehicle incorporating a remote keyless active entry system according to another embodiment of the present invention;  
     [0041]FIG. 1C is a schematic block diagram illustrating a vehicle incorporating a key operated active entry system according to another embodiment of the present invention;  
     [0042]FIG. 2 is a plan view of the external directional transceiver of FIG. 1A;  
     [0043]FIG. 3 is a plan view of the vehicle of FIG. 1A illustrating the access control system in use;  
     [0044]FIG. 4 is a plan view of the receiver of FIG. 1B;  
     [0045]FIG. 5 is a plan view of the vehicle of FIG. 1B illustrating the access control system incorporating the receiver of FIG. 1B in use;  
     [0046]FIGS. 6A and 6B are plan views of the vehicle of  1 B having an alternative access control system to the embodiment of FIG. 5;  
     [0047]FIG. 7 is a flow chart illustrating the operation of the access control system of FIGS. 6A and 6B.  
     [0048]FIG. 8 is a graph illustrating a decrease in scan rate over time of the external directional transceiver of FIG. 1A;  
     [0049]FIG. 9 is a schematic diagram of a vehicle locking mechanism according to another embodiment of the present invention;  
     [0050]FIG. 10 illustrates the operation of the mechanism of FIG. 9 when in a locked condition;  
     [0051]FIG. 11 illustrates the operation of mechanism of FIG. 9 in an unlocked condition;  
     [0052]FIG. 12A is a perspective view of a portion of the vehicle including access means according to one embodiment of the present invention;  
     [0053]FIG. 12B is a cross sectional view through a vehicle door having access means according to another embodiment of the present invention;  
     [0054]FIG. 12C is a cut away side elevational view through a door having access means according to yet another embodiment of the present invention;  
     [0055]FIG. 13 is a perspective view of a portion of the vehicle incorporating access means according to another embodiment of the present invention;  
     [0056]FIG. 14 is a perspective view of the portion of a vehicle including access means according to a further embodiment of the present invention;  
     [0057]FIG. 15 is a perspective view of a portion of the vehicle including engagement means according to a still further embodiment of the present invention;  
     [0058]FIG. 16 is a perspective view of a portion of the vehicle including engagement means according to another embodiment of the present invention;  
     [0059]FIG. 17 is a perspective view of an inner face of a door incorporating a inside release mechanism according to another embodiment of the present invention;  
     [0060]FIG. 18 is a flow chart illustrating the functioning of the mechanism of FIG. 17;  
     [0061]FIG. 19 is a perspective view of an inner face of a vehicle door incorporating an inside release mechanism according to a further embodiment of the present invention;  
     [0062]FIGS. 20A and 20B are side and end views respectively of a latch of one embodiment of the present invention in a latched state;  
     [0063]FIGS. 21A and 21B are side and end views respectively of the latch of FIGS. 20A and 20B in an unlatched state;  
     [0064]FIG. 22 is a flow chart illustrating the functioning of the inside release mechanism of this embodiment of the present invention;  
     [0065]FIG. 23 is a flow chart illustrating the overall functioning of a passive entry system according to an embodiment of the present invention as the vehicle is entered and started; and  
     [0066]FIG. 24 is a flow chart illustrating overall functioning of the passive entry system when a vehicle user stops and exits the vehicle. 
    
    
     [0067] Referring to FIG. 1A, a vehicle  12  incorporating an access control system  10  according to an embodiment of the present invention is illustrated schematically. The vehicle  12  comprises a door  14  having a door latch  16 , a passenger compartment  22  and a luggage compartment which in this embodiment is a boot (trunk)  18  having a boot latch  20 .  
     [0068] At the heart of the access control system  10  is a controller  24  which may be a standalone microprocessor, or may be integrated into the overall vehicle ECU (electronic control unit). The controller  24  draws its power from the vehicle battery  48  preferably via a local backup power source  50 . This enables the access control system  10  to operate even when the vehicle has a flat battery.  
     [0069] The controller  24  is in communication with a plurality of input and output devices through electrical connections illustrated by the arrows of FIG. 1A. The arrows may represent wires of a conventional wiring loom, or any other suitable form of connection (eg a radio frequency connection using a system such as BLUETOOTH™) with the direction of the arrows indicating the direction of signal travel. In this embodiment, the controller  24  is in communication with a pop-up handle  28 , lock manual override  30 , outside strain gauge  32 , inside strain gauge  34 , door latch actuator  36 , door lock actuator  38  and door ajar sensor  40  of the passenger door  14 . In this embodiment only one passenger door  14  is illustrated for reasons of clarity. However, it will be appreciated that similar input and output devices maybe provided on further closures including front and rear passenger doors.  
     [0070] In relation to the boot  18 , the controller  24  is in communication with a boot lock actuator  60 , boot latch actuator  62  and boot outside strain gauge  64 . The vehicle boot may be replaced by a lift gate, tail gate or rear door depending upon the type of vehicle  12  in which the access control system  10  is installed.  
     [0071] In the passenger compartment  22  of the vehicle  12  the controller  24  is in communication with an interior short range transceiver  52  capable of detecting an identification means in the form of an authorisation device  26  (e.g. a transponder card) when the authorisation device (AD) is positioned with passenger compartment  22 , driver&#39;s seat transceiver  53  capable of detecting the AD  26  when positioned in the vicinity of the driver&#39;s seat, infra red sensor  54  capable of detecting the presence of people in the passenger compartment  22 , input means  56  such as an alphanumeric key pad, and a pair of switches  66  and  68  positioned on the vehicle steering wheel (not shown).  
     [0072] The controller  24  is additionally in communication with a vehicle motion sensor  42 , an external directional transceiver capable of detecting the presence of authorisation device  26  when it is outside the vehicle  12 , interrogating the said device and determining the angular position of the device  26  relative to the vehicle  12 . The controller  24  has a further output to a vehicle engine starter system  46  and has associated memory  58  in which the state of various devices may be stored, in addition to any programming instructions. The memory  58  preferably comprises a rewritable portion capable of storing its contents even if no power is supplied thereto.  
     [0073] The operation of these various devices and sub-systems will be described in greater detail below. It will be appreciated that various sub-systems and devices may be employed in various combinations, and that all of the aforesaid do sub-systems need not be present to provide a functional access control system.  
     [0074] Turning to FIGS.  2  to  5 , one aspect of the invention relates to means to enable a vehicle user to unlock one or more vehicle closure latches.  
     [0075] Referring to FIG. 2, there is shown a combined external transmitting and receiving means (hereinafter referred to as transceiver  44 ). The transceiver  44  comprises a transmitter  115  and a receiver  112  mounted at the narrow end of a mouth  114 . The transmitter  115  transmits and the receiver  112  detects signals of a suitable form of electromagnetic radiation or sound waves. In a preferred embodiment, radio frequency (RF) waves such as microwaves are transmitted and detected. The angle over which the signal is transmitted and detected is limited by the angle between the sides of the mouth  114 . It can be seen that in FIG. 2, the angle is approximately 90°, although it may be varied according to particular user requirements.  
     [0076] The transmitter  115 , receiver  112  and mouth  114  are fixedly mounted on a rotatable shaft  118  by a bracket  116 , the shaft  118  being an output shaft of a motor (not shown) such as a suitable electric motor arranged to enable the transmitter, receiver and mouth to rotate in a direction X about an axis substantially perpendicular to the axis in which transmitter is directed. A rotary encoder  120  is provided to determine the relative rotary position of the receiver  112 .  
     [0077] Turning now to FIG. 3, a five door estate (station wagon) type vehicle  12  is illustrated having four side doors  14   a,    14   b,    14   c,    14   d  to access the passenger compartment  22  and rear tailgate  18  to access the storage compartment  129 . However, the present invention may be usefully provided in any vehicle having at least two closures. The transceiver means  44  is mounted on the vehicle  12  in a position where a substantially unobstructed 360° signal transmission and reception may occur. In this embodiment the transceiver  44  is mounted to the underside of the roof of the passenger compartment  22  of the vehicle. In this position, transmission and reception is only hindered by the relatively narrow door pillars  125  of the vehicle.  
     [0078] Referring to FIG. 1A in conjunction with FIG. 3, under normal operating conditions when power is supplied to the system from the vehicle battery  48 , for example, the controller  24  signals the motor to cause the transceiver  44  to rotate continuously through a full 360° arc whilst simultaneously signalling the transmitter  115  to transmit an interrogation signal so as to locate any AD  26  in range. In this embodiment the AD  26  is in the form of a transponder card or the like normally carried by an authorised vehicle user  132 .  
     [0079] If a compatible AD  26  is located within the range of the transmitter  115  the interrogation signal causes AD  26  to power-up and transmit a corresponding coded response signal to the receiver  112 . Because the signal is sent using electromagnetic radiation, the response signal is sent almost instantaneously and there is therefore no danger of the receiver having rotated out of range of the response signal when it is sent. The rate of rotation of the transceiver  44  is advantageously sufficiently high to ensure that approaching authorised users are detected before reaching the vehicle.  
     [0080] When a signal is detected by the receiver  112  it is transmitted to the controller  24  for authentication. If it is determined that the AD  26  is authorised for the particular vehicle  10  in question, the controller  24  queries the position encoder  120  of the transceiver  44  as to the angle θ of the transceiver  44  at the point at which a signal from the AD  26  was received by the receiver  112 . The controller  24  then compares this angle θ to values stored within the memory  58  associated with the controller. For a given range of angles, the memory stores a predetermined instruction as to which of the vehicle latches  16 ,  20  should be unlocked. The controller  24  processes this instruction and signals the door lock actuator  38  of an appropriate one or more of the right front, right rear, left front and left rear door latches  16  for doors  14   a,    14   b,    14   c  and  14   d  to unlock respectively as well as storage compartment closure lock actuator  60  for the tailgate  18 .  
     [0081] For example, if an authenticated signal is received from the AD  26 , as shown in FIG. 3, the angular position θ of this is determined by the position encoder  120  as being approximately 45°. The controller  24  then determines from its associated memory  58  that the authorised user  132  is at the right hand side of the vehicle and will thus signal door lock actuators  38  to unlock the right front and right rear door latches  16 . If, however, the AD  26  is detected at an angle θ of approximately 180°, the controller  24  will signal the actuator  60  to unlock the storage compartment latch  20  and if an angle θ of 270° is detected, the controller will signal the unlocking of the left front and left rear door lock actuators  38  to unlock latches  16 .  
     [0082] Where two or more persons carrying ADs  26  approach different sides of the vehicle  12 , the access control system  10  signals the unlocking of vehicle doors on both sides of the vehicle.  
     [0083] In one embodiment, two levels of authorisation may exist, one for an authorised vehicle driver, and a second for authorised vehicle passengers. In this embodiment, the controller  24  distinguishes between the authorisation levels and only unlocks the driver&#39;s door latch  16  if a person carrying an AD  26  having a driver&#39;s level of authorisation approaches this side of the vehicle. If a person  132  carrying an AD  26  enters the vehicle, and wishes to permit entry to other users not carrying ADs, a manual override  30  is provided in an accessible location to cause additional, although not necessarily all of the vehicle closures  14   a,    14   b,    14   c,    14   d,    18  to be unlocked. The manual override  30  may also enable the doors to be locked when the vehicle  12  is occupied.  
     [0084] To lock the vehicle once an authorised user  132  has exited the passenger compartment  22 , a delay timer (not shown) coupled to a latch position sensor (not shown) may be built into the access control system  10  to cause the controller  24  to signal locking once a certain time has elapsed after the vehicle  12  has been exited. Alternatively, locking occurs once the AD  26  has left the range of the transceiver  44 .  
     [0085] If the vehicle is left unattended for an extended period of time (eg airport parking) rotation of the transceiver  44  may be suspended or the rate of rotation reduced to reduce the power consumption thereof and thereby minimise the risk of a flat battery upon the user&#39;s return to the vehicle. The transmitter power may also be reduced to minimise power consumption. If rotation is suspended, it is preferable for the transceiver  44  to be directed towards the driver&#39;s door  14   a  during suspension as it is most likely that the authorised user  132  will approach this door first. Once a user is detected, the rotation recommences. Optionally, the motion sensor  42  be integrated into the system so that the transceiver  44  may be powered down whilst the vehicle is moving.  
     [0086] In one class of embodiments the system  10  is programmable by the authorised user or by workshop personnel to change the range of angles over which certain closures are unlocked, as well as the particular closures to be unlocked over each angle so that the system may be tailored to user requirements. For this to be achieved, the system of this embodiment employs input means  56 .  
     [0087] One advantage of this embodiment is that a transceiver  44  having a relatively narrow angle of signal transmission may require a reduced power consumption, or have a longer range for the same power consumption in comparison with known passive entry transmitting devices.  
     [0088] Turning now to FIGS. 1B, 4 and  5 , a second embodiment of the present invention is disclosed in which like numerals have, where possible, been used for like parts with the addition of the prefix “2” as compared with FIGS. 2 and 3.  
     [0089] This embodiment differs from the first embodiment in that no transmitter  115  is provided as part of the access control system  10 , and in that the receiver  244  is stationary and comprises in this embodiment four separate receivers designated  212   a,    212   b,    212   c  and  212   d.  The horizontal angle over which each receiver is capable of detecting a signal is restricted by vertical dividers  214   a,    214   b,    214   c  and  214   d.  Thus, by providing multiple receivers it is unnecessary for the receiver to rotate as in the first embodiment, since the angular position of the AD  226  can be detected dependent upon which receiver  212   a,    212   b,    212   c,    212   d  a signal therefrom is incident.  
     [0090] Referring to FIG. 5, the receiver  244  is shown located in a similar position to the transceiver  44  of the first embodiment and as such effectively divides the area surrounding the vehicle into four sectors  260 ,  262 ,  264  and  266  which substantially correspond to the right side, rear, left side and front of the vehicle respectively. In one class of embodiments, receiver  212   d  is omitted since no closure suitable for unlocking using the system is provided at the front of the vehicle  212 .  
     [0091] The second embodiment is intended for use with an “active” remote keyless entry (RKE) ADs (commonly known as a “plip”) or passive entry systems in which the AD transmits periodic signal without being interrogated by a transceiver. RKE ADs  226  generally comprise an infra-red, radiofrequency or ultrasonic transmitter and have their own power source such as a battery. Because the user themselves actively sends an unlocking signal to the receiver  244  or the AD  226  sends a periodic signal, it is unnecessary to provide a corresponding transmitter on the vehicle  12  to actively search for and interrogate the AD as in the previous embodiment. Once a signal is received from the AD  226 , the controller  24  of the access control system  10  determines the appropriate closure(s) to unlock and sends unlock signals to the corresponding lock actuator(s)  38  in a similar manner to the controller  24  of the first embodiment. Again, the manual override  30  may be used to lock/unlock the remaining closures. When a user wishes to lock the vehicle, he/she actuates the identification means a second time to trigger the locking of all of the latches  16 ,  18  if an “active” AD is used. If a periodic signalling AD  226  is used, locking is triggered once the transceiver fails to receive a signal from the AD for a predetermined period of time.  
     [0092] Whilst the second embodiment has been described with reference to a powered AD  226 , it should be appreciated that if a suitable transmitter (not shown) were to be provided, the access control system of the this embodiment could be used with a non powered AD  26  similar to that disclosed in the previous embodiment. Preferably, the transmitter may be provided in the middle of receivers  212   a,    212   b,    212   c  and  212   d.    
     [0093] It should be understood that numerous changes may be made within the scope of this aspect of the present invention. For example, the transmitter and receiver may be physically separated from one another. The receivers of the second embodiment may also be mutually separated so as to have, for example, receivers proximate the front, rear and side windows. Rather than determining the location of a person relative to the vehicle, the system of the first embodiment could be used to track the vector of a person walking towards a vehicle and from this determine the appropriate door to be unlocked. The system may also unlatch the closures by being connected to the corresponding power latch mechanisms. This would be particularly advantageous in the case of a rear boot/trunk lid as they are often not provided with an external latch release means. The system may enable closures to be unlocked sequentially. For example, a user may first walk to the boot causing the boot lid to be unlocked, and the subsequentially walk to the driver&#39;s door causing this to then be unlocked. The controller may also output to actuators and the like for adjusting the seating, steering wheel and mirror positions, for example, in order to personalise the vehicle settings for a particular user carrying a response device. The system may be retrofittable to vehicles or may be fitted at the time of vehicle manufacture.  
     [0094]FIGS. 1C, 6A and  6 B illustrate another aspect of the present invention which relates to an alternative arrangement for enabling access to a vehicle for use exclusively with identification means in the form of “active” RKE devices or conventional keys operable in key barrels fitted to vehicle door(s).  
     [0095] Referring to FIG. 6A, an authorised vehicle user  332  can be seen approaching a vehicle  12 . The user&#39;s angle of approach results in him having a blind spot illustrated by the hatched area  318  in which an unauthorised vehicle entrant  316  may hide.  
     [0096] In a clockwise direction, the vehicle has closures comprising right front (RF) door  14   a,  right rear (RR) door  14   b,  a storage area  18 , left rear (LR) door  14   c  and left front (LF) door  14   d.  As illustrated in FIG. 6A, if an authorised user  32  were to unlock all of the closures on the vehicle using a conventional “central locking” access control system, in order to enter the vehicle through right front door  14   a,  unauthorised users  316  would simultaneously be able to enter the vehicle through any one of closures  18 , or doors  14   c  or  14   d  without user  332  being aware of this until the vehicle is entered.  
     [0097] Turning to FIG. 6B, it can be seen that even if two authorised users  332  approach the vehicle, an unauthorised user  316  may still hide in a blind spot  318  towards the rear of the vehicle.  
     [0098] Returning to FIG. 1C, the first embodiment of this aspect of the present invention is illustrated schematically. In this embodiment, the controller  24  takes input signals from the key barrel  330  of the right front  14   a,  left front  14   d  doors. A signal is supplied when identification means in the form of a matching key (not shown) is inserted and turned in the barrel  330  by the authorised vehicle user  332 . Additional inputs to the controller  24  are provided by a lock manual override  30  to the operation of the system and from the input means  56  to change the settings on the system. Also in communication with the controller  24  is a rewritable memory  58  (eg EPROM memory) preferably capable of storing the settings of the system without requiring a permanent power supply. The controller may optionally output to a display means (not shown) within the vehicle to assist in the setting of the system, as well as optionally providing diagnostic data.  
     [0099] The controller  24  may send output signals to right front, right rear, left rear and left front door lock actuators  38  as well as lock actuator  62  on the boot  18  of the vehicle  12 .  
     [0100] Turning now to FIG. 7, operation of the access control system  10  is illustrated as a flow chart. In use, a vehicle user inserts and turns his/her key in the barrel  330  of door  14   a  and if the key matches the barrel  330 , a signal is transmitted by the barrel  330  to controller  24 . In turn, the controller  24  sets a look-up value for the lock x 0 and starts a timer that is associated with the controller  24 . The look-up values stored by memory  58  are summarised by Table 1 below.  
                           TABLE 1                                   Lock x   Time y                          Lock 0 = RF door lock 34   Time 0 = 1 s           Lock 1 = LF door lock 42   Time 1 = 1 s           Lock 2 = RR + LR door 36 + 40   Time 2 = 1 s           Lock 3 = Storage area door lock 38                      
 
     [0101] Once the timer has started, the controller  24  signals the door lock actuator  38  to unlock the right front latch  16  immediately thereafter, having queried the memory  58  to determine that lock x is initially set as lock 0. The controller  24  then waits a time y which for lock 0 equates to 1 second. If, after this time y, the key is no longer turned, the controller  24  ends the unlocking procedure. If, however, the key is still turned, the controller  24  then checks whether the look-up value for lock x is at its maximum value (ie all of the locks have been unlocked). If this is the case the controller ends the unlocking procedure. However, if the maximum has not been reached, the controller then refers to the next lock x in the table, which in this case is the left front door lock  42  and signals the left front door lock actuator  38  to unlock this, and then waits a time y which for lock 1 again equates to 1 second. This procedure is then repeated until either the user has decided that sufficient doors have been unlocked and he/she can thus cease turning the key in the key barrel  330 , or all of the locks have been unlocked and the procedure also therefore ends.  
     [0102] Once seated in the vehicle, the vehicle users may override the current locked state of any of the closures by actuating the manual override  30 . This may be in the form of a conventional sill button in relation to the vehicle side doors  14   a,    14   b,    14   c,    14   d  or may be one or more electrical switches actuable by the vehicle user. To lock the vehicle after exit, the user turns the key in the key barrel  330  in the opposite direction and in response the controller  24  signals the door lock actuators  38  to lock the latches  16  for all of the closures.  
     [0103] Referring now to FIG. 1B, the system of this embodiment may alternatively be used with an AD  226  in the form of a remote keyless entry (RKE) device. Therefore, in this embodiment, key barrels  330  for the right front, left front doors and the storage area closure are replaced by a receiver  244  is capable of detecting signals from whatever type of RKE it is intended to be used therewith.  
     [0104] In one class of embodiment, a short press of the AD  226  results in the driver&#39;s door (either the right front or left front door latches  16 ) being unlocked by default. However, in another class of embodiment, receiver  244  is capable of determining the angular position of the AD  226  relative to the vehicle (as in the embodiment of FIGS. 1B, 2,  3 ,  4  and  5 ) and then signalling the unlocking of the closure lock nearest to the AD  226 . Therefore, if the AD  226  is detected as being at the rear of the vehicle a single press of the actuator on the AD results in the boot latch  20  being unlocked, but if the AD is detected near the left front door  14   d,  the controller signals door lock actuator  38  to unlock the left front door latch  16  first. However, independent of the angular location at which the AD  226  is actuated, extended actuation will result in the controller  24  signalling the unlocking of all closures.  
     [0105] As in the first embodiment of this aspect of the invention, a manual override  30  is provided to lock any closures as desired when one or more users are seated within the vehicle. Once the vehicle user has exited the vehicle, a short actuation of the AD  226  will cause all of the latches  16  to be locked.  
     [0106] In many cases, conventional key barrels  330  are provided on a vehicle fitted with a remote keyless entry system in order to provide a back-up should the AD  226  be lost or malfunctioning. As such, it is anticipated that the embodiments of FIGS. 1B and 1C may be combined to provide for both the convenience of remote keyless entry and the back-up of having a conventional key, whilst maintaining the unlocking function described above using either the AD  226  or keys.  
     [0107] It should be understood that numerous changes may be made within the scope of this aspect of the present invention. For example, the system may be adapted for vehicles having fewer or more closures than shown in the Figures. Access to the vehicle may be provided by a user supplying biometric data to the vehicle such a fingerprint or a voice input, in which case the term “identification means” should be construed to include such data. The system may also be arranged so as to signal power latches and thereby unlatch the closures. The controller may also output to actuators and the like for adjusting the seating, steering wheel and mirror positions, for example, in order to personalise the vehicle settings for a particular user carrying a AD.  
     [0108] Turning to FIGS. 1A and 8 a further aspect of the present invention is disclosed which relates to means for conserving the power consumed by a vehicle access control system. As explained above, in use, authorised users of the vehicle carry an authorisation device  26  which preferably takes the form of a transponder having an identifier code stored therein. The transceiver  44  periodically scans for the existence of such ADs  26  within its range of operation under the control of controller  24 . When such an AD  26  is detected, the transceiver interrogates the response device to obtain the identifier code which is then passed to the controller  24  so that it may be authenticated against codes held within the memory  58  associated with the controller  24 . If there is a match, the controller  24  then sends a signal instructing the door lock actuator  38  to unlock one or more door latches  16 , and the authorising the starting of the engine starter  46 . Once the user is seated in the vehicle, switches  66  and  68  may be closed to start the vehicle engine.  
     [0109] In normal use, the transceiver  44  preferably draws its power from an external power source such as vehicle battery  48  or a dedicated local power source  50  for the system  10 . The controller  24  ensures that the dedicated transceiver power source is fully charged from the battery  48 . However, during long term parking, when the vehicle is not being used, the battery  48  may become exhausted. In such circumstances, the controller  24  senses when the battery  48  falls below a predetermined certain level of charge and instead draws power from the dedicated backup power source, in order to prolong the period during which the vehicle may be accessed beyond the point at which the battery  48  becomes exhausted.  
     [0110] Because vehicle users wish to gain access to the vehicle  12  rapidly, the scanning rate (frequency) is normally set relatively high at, say, two second intervals (0.5 Hz). However, at this scanning rate, the battery and in particular the local power source  50 , become rapidly exhausted during a long period of non-use.  
     [0111] Therefore, the transceiver  44  of the present invention reduces the scan rate dependent upon the time elapsed since a AD  26  device was previously detected. In some classes of embodiment, the scan rate reduction may be in direct proportion to the time elapsed or may reduce exponentially, logarithmically or in accordance with another suitable mathematical relationship. However, in preferred embodiments, the scan rate reduces in a ‘stepped’ manner. The reduction may be a single step or multiple steps.  
     [0112] Referring now to FIG. 8, a graph illustrating an example of such variable scan rate is shown. The scan rate, elapsed times and number of steps may, of course, be altered according to particular user requirements. It can be seen from FIG. 8 that for an initial period of one day since the AD  26  was detected, the scan rate is once every two seconds (in order to allow for a rapid response to the approach of a potential vehicle user when the vehicle is merely left overnight, for example). Beyond one day, the rate then drops to once every ten seconds (0.1 Hz) to allow for a slightly less rapid response when the vehicle is left for a longer period, such as during airport parking, for example. This rate reduction results in a reduction in power consumption that potentially extends the life of the power source by five times in comparison with the two second scan rate.  
     [0113] After seven days of non-use, which could in practical terms represent the vehicle being left for sale with a dealer, or during a winter layup, the scan rate reduces to once every thirty second (0.033 Hz), thereby potentially increasing the battery life fifteen fold with respect to the two second interval scan rate.  
     [0114] Clearly, such a response delay would be unacceptable in day to day use, but would not present a problem when the vehicle is to be operated for the first time after a long period of non-use.  
     [0115] In order to determine the time elapsed since the last detection of a AD  26 , a time logging device such as an in-built quartz timer and counter (not shown) are advantageously incorporated into the controller  24 .  
     [0116] It should be understood that numerous changes may be made within the scope of this aspect of the present invention. For example, alternative types of scanner using other forms of electromagnetic radiation such as microwave, or infra-red, may be employed, as may sonar or ultrasonic scanners. It is envisaged that the scanning device may be used in other fields such as building access control, for example.  
     [0117] A further aspect of the present invention is disclosed in FIGS. 9, 10 and  11 . Referring to FIG. 9, there is shown generally at  410  a locking mechanism comprising a door lock actuator  38  in the form of a motion control device and a linkage arrangement  414  mounted in the latch  16  of vehicle door  14  so as to lock the door when in a closed position relative to the vehicle  12 .  
     [0118] The motion control device  38  comprises a cylinder  418  containing a magneto-rheological (hereinafter referred to as MR) fluid  416 . A perforated piston  420  is securely mounted on a ram  426 , the piston being axially slidable within cylinder  416 .  
     [0119] In this embodiment, the piston  420  is shaped to enable movement from right to left in the Figures to require less force than movement left to right. This may act to damp the return of a door handle to which the mechanism is attached. In other embodiments, the piston design may be altered to reverse this, or to make the required force equal in both directions in accordance with the particular requirement of the mechanism or components with which the mechanism interacts.  
     [0120] The cylinder  18  is at least partially surrounded by an electromagnet  422  connected by a circuit  424  to an electrical power source such as the vehicle battery  48 . A switch  426  is provided to enable the circuit to be energised, such that when the switch is closed, a magnetic field is induced in the MR fluid by the electromagnet  422 . Closure of the switch is preferably controlled by controller  24  (e.g. by using a solenoid type device—not shown). Magnetic shielding (not shown) is preferably provided to ensure that the MR fluid  416  is not influenced by external magnetic fields.  
     [0121] Magneto-rheological fluids are suspensions of small magnetisable particles in a liquid such as oil. MR fluids are normally free flowing and have a viscosity similar to that of motor oil. However, once a magnetic field is applied across the fluid, the fluid consistency becomes almost instantly more viscous. The increase in viscosity is proportional to the magnitude of the magnetic field applied. Electro-rheological fluids (hereinafter ER fluids) function in a similar manner upon application of a potential difference across the fluid.  
     [0122] In this embodiment, the linkage  414  comprises an input arm  430  which in this embodiment is connected to an internal and/or external door handle (not shown) of the associated vehicle door  14  and/or power door latch actuator  36 , and an output member  432  connected to an input of a latching mechanism (not shown) of the latch  16 . Ram  427  and input arm  430  are pivotally interconnected by a connecting arm  428  at the distal ends of ram  427 , arm  430  and connecting arm  428 . Output arm  432  is pivotally connected to the connecting arm  428  at a position intermediate the ends of connecting arm  428 .  
     [0123] When the locking mechanism  410  is in a first locked state, the potential difference is not applied to electromagnet  422 . Therefore, the MR fluid is in a first state with a low viscosity such that the fluid may pass through the perforations in the piston  420  and the piston may move along cylinder  418  in a relatively unhindered manner.  
     [0124] Thus, when arm  430  is caused to moved in a direction X shown in FIG. 10 by operation of the handle connected thereto, the force required to displace the piston  420  is lower than the force required to cause arm  432  to unlatch the latching mechanism. Movement of arm  430  in a direction X merely causes a corresponding movement of piston  420  and ram  427  in the direction Y, with substantially no movement of arm  32 , resulting in the latch  16  remaining latched.  
     [0125] Referring now to FIG. 11, it can be seen that switch  426  is now closed under the control of controller  24 , thus energising the electromagnet  422 . This causes the viscosity of MR fluid  416  to increase so that movement of arm  430  by the door handle in the direction X in turn causes arm  432  to move in a direction Z because in this second unlocked state, the force required to unlatch the latch  16  is lower than the force required to displace the piston  420 .  
     [0126] It is therefore apparent that the locking mechanism of this embodiment of the present invention requires fewer moving parts than prior art devices, and is particularly suited to use with or integration into the passive/keyless entry systems described above, that are by their very nature electrically controlled. A particular advantage of this mechanism is that the locking mechanism consumes no power when in the locked state.  
     [0127] It should be understood that numerous changes may be made within the scope of the this aspect of the present invention. In particular, it should be understood that the linkage described is for illustrative purposes only, and that the mechanism may be altered as required. In alternative embodiments, an ER fluid may be used rather than an MR fluid. Furthermore, appropriate alterations may be made to the electrical circuit  424  and/or the design of the cylinder and piston so that the mechanism may be adjusted to take into account changes in the viscosity of the fluid used and in the unlatching load of a particular latch mechanism. In particular, the resistance displacement of the piston may be adjusted to provide differing resistance in either direction of travel as required for the overall function of the mechanism. The mechanism may be fitted to a door surround portion of a vehicle rather than the door itself. It should be apparent that the mechanism may have applications in other fields such as locking mechanisms in buildings.  
     [0128] Turning to FIGS. 12A to  16 , a further aspect of the present invention relating to means for accessing a vehicle and engaging a vehicle door is disclosed.  
     [0129] Conventional vehicle door handles essentially serve two functions: firstly, they act as access means to unlatch the associated door and secondly as engagement means by providing a surface that a vehicle user may engage in order to open the door once unlatched. Thus, the terms “access means” and “engagement means” as used below should be understood as means whose primary function is access and engagement respectively, although the means may also perform a secondary function.  
     [0130] Referring back to FIG. 1A once the vehicle door(s) have been unlocked using AD  26  as described above, the vehicle user will then wish to open one or more vehicle doors in order to enter the vehicle.  
     [0131] Referring to FIG. 12A there is shown a perspective view of the passenger door  14  of a vehicle  12  which is a passenger car in this embodiment. In place of a conventional handle that both unlatches the vehicle and provides a surface by which a vehicle user may engage the door to open it, there is provided access means that is touch sensitive which, in this embodiment, is a touch pad  516 . The touch pad  516  is in turn connected to the controller  24  and communicates therewith as described below.  
     [0132] Although in this embodiment, the touch pad is shown in the position of a conventional door handle, in other embodiments the touch pad  516  or other touch-sensitive means may be positioned elsewhere on the vehicle such as the passenger door window, the wing mirrors or on another vehicle panel. The touch pad may be pressure sensitive or detect contact due to a change in its conductivity, but in either case there should be substantially no deflection of the surface being touched.  
     [0133] Turning to FIG. 12B, a strain gauge  32  is secured to the inner face of the outer skin  515  of door  14  resulting in the outer skin  515  being, in effect, the touch sensitive means. The strain gauge is in turn connected to the controller  24  and communicates therewith as described below. It can be seen that the strain gauge  32  is located in approximately the same position as touch pad  516  of the first embodiment, but because it is located on the inner face of the door skin, the door skin is uninterrupted, and does not require any apertures to be provided therein.  
     [0134] In use, when a user contacts the appropriate region of the door skin and exerts a pressure P, the (albeit small) deformation of the skin  515  causes the conductivity of the strain gauge  32  to change.  
     [0135] An alternative strain gauge arrangement is shown in FIG. 12C. In this embodiment, the gauge  32  is secured in a snaking arrangement to the inner face of the door skin  515 . Thus, in this embodiment, the user may touch substantially anywhere on the door skin for detection by the strain gauge to occur.  
     [0136] In other embodiments strain gauges could alternatively be arranged on the door hinge  517 , latch  16 , striker  521  or door seal (not shown) so as to detect pressure applied to the door  14 . Furthermore, force transducers may be used in place of the strain gauge. Additionally or alternatively, a strain gauge may be arranged on the window seal (not shown) to detect movement of the window glass  524  relative to the rest of the door  14 , or a transparent touch sensitive sheet of the type used on computer monitors and the like could be applied to the window to enable the user to gain entry by pressing on the window glass  524 .  
     [0137] Turning to FIG. 13 there is shown a foot operated access means such as a foot operated pedal  518  mounted to the sill area  519  of a vehicle. In this embodiment, actuation of the pedal  518  in the direction A signals the controller as described in more detail below. Alternatively, the pedal may be pressure sensitive, so that substantially no actual deflection occurs. In a preferred embodiment, the pedal is only deployed from a stowed position in the sill  519  when actuation thereof is required (eg once the latch  16  of door  14  has been unlocked), thus preventing the fouling of the pedal on foreign objects when the vehicle is in motion. One advantage of this arrangement is that the pedal  518  may be actuated when the user has no free hands.  
     [0138]FIG. 14 illustrates a fifth embodiment of this aspect of the invention in which a vehicle wing mirror  520  is used in the place of the conventional door handle as access means. In one class of embodiment, the mirror may be simply be provided with a switch or touch-sensitive means similar to the first embodiment in order to signal the controller. Alternatively, where a vehicle is provided with powered mirrors, physical movement of the mirror in a direction B may be converted into a signal that is sent to the controller  24  to initiate release as described in more detail below.  
     [0139] Turning to FIG. 15, there is illustrated an engagement means according to a sixth embodiment of this aspect of the present invention. In this embodiment the engagement means comprises a deployable handle  28  that in normal circumstances is retracted within the vehicle door. However, upon a signal from the vehicle controller  24 , (eg once the latch  16  of door  14  has been unlocked) the handle  28  is deployed from the “waistline” (the sill portion where the door panel meets the window)  523  of the vehicle. In one embodiment, the handle  28  is merely provided as a convenient surface that a vehicle user may engage to open the door  14 . However, in variant form, the handle may also be operably connected to the vehicle latch  16  such that engagement thereof causes the door to become unlatched. The interaction of the handle  28  and the controller is described in more detail below.  
     [0140] The engagement means according to a seventh embodiment of this aspect of the present invention is shown in FIG. 16. In this embodiment the engagement means is provided by the window sill  526  of the door  14 . Clearly, for reasons of security, the door window  524  will usually be left in a closed position when the vehicle  12  is left unattended. However, when a signal is received from the controller  24  (eg once latch  16  of door  14  has been unlocked) as described in more detail below, this causes the window regulator (not shown) to lower the window glass  524  and thus enable a vehicle user to grasp the sill or top of the window glass and open the door.  
     [0141] In installations where the authorisation device  26  causes just the unlocking of one or more door/closure latches  16 ,  20  the user then actuates either touch pad  516 , strain gauge  32 , door skin  515 , window  524  or wing mirror  520  by hand or foot pedal  518  by foot (for clarity, only strain gauge  32  is shown in FIG. 1A). Actuating the relevant access means signals the controller  24  which in turn signals the door latch actuator  36  to unlatch door latch  16 . Of course, the controller  24  will only permit those closures  14 , 18  that have been unlocked to be unlatched subsequently. The controller  24  preferably also signals the deployment of either handle  28  (if fitted) or the window regulator to drop the window glass  524  so that a surface is available for the user to engage by hand and open the door  14 . In its simplest form, however, specific engagement means may be dispensed with because the force exerted on the door by the door seals (not shown) is generally sufficient to cause the door to open enough when the door is unlatched for a user to engage an edge of the door by hand and open it. In some cases of embodiment the door hinge and/or door check may also exert an outward force that tends to cause the door to open.  
     [0142] In a preferred embodiment, when a touch pad  516  or strain gauge  32  is used as an access means and is mounted on the door  14 , the controller only signals the unlatching of the door once the user ceases to touch the touch pad, door skin or window. This avoids the possibility of the force due to contact between the user&#39;s hand and the touch pad, door skin or window counteracting the seal force and preventing the door opening by a sufficient amount, and also substantially avoids the risk of discomfort being caused to the users by the door opening against their fingers.  
     [0143] If the vehicle is fitted with a foot pedal  518 , the signal from the transceiver  44  or receiver  244  (FIG. 1B) to the controller  24  preferably causes the controller to signal the lowering of the foot pedal  518  from a retracted position in the sill  519  to a deployed position where it may be actuated by the foot of the vehicle user.  
     [0144] In embodiments where the controller  24  signals the door latch actuator  36  to unlatch the door latch  16  in response to signals from the transceiver  44 , the access means may be dispensed with. Similarly, in embodiments where the handle  28  is operably connected to the latch(es)  16 , the access means may be dispensed with.  
     [0145] Once the vehicle user has entered the vehicle and closed the door, the controller signals the retraction of the pop-up handle  28  and/or of pedal  518  as appropriate, or signals the closure of the window  524 . Optionally, the vehicle motion sensor  42  may be connected to the controller  24  such that the controller may signal the locking of door/closure latches  16 ,  20  if the vehicle exceeds a certain predetermined speed such as 5 kilometres per hour, for example.  
     [0146] To summarise, the access means of FIGS. 12A to  14  may operate separately or in conjunction with the engagement means of FIGS. 15 and 16. Likewise, the engagement means of FIGS. 15 and 16 may operate separately from the access means of FIGS.  12 A and to  14 .  
     [0147] It should be understood that numerous changes may be made within the scope of this aspect of the present invention. For example, the system may be adapted for use with other vehicle doors such as sliding doors or rear doors and alternative types of scanner such as sonar, ultrasonic or infra-red type scanners may be used in place of a radio frequency scanner. The invention may be adapted for use with conventional remote keyless entry (RKE) “plip”-type locking devices rather than a passive entry system. Furthermore, touch sensitive means such as strain gauges may be employed as exit means on the inside of doors to permit exit from as well as entry to vehicles. Likewise, the engagement means described above may be deployed from the interior of the vehicle to assist in closing vehicle doors.  
     [0148] A further aspect of the present invention provides means for determining the appropriate locked state of the vehicle closures. Once a user is inside the vehicle  12 , the access control system  10  is capable of determining the locked state of the vehicle doors  14 . This is achieved by incorporating person sensing means which in this embodiment is an infra red (IR) sensor  54  in the vehicle passenger compartment  22  and which arranged to be in communication with the controller  24 .  
     [0149] An interior authorisation device detection means, preferably a short range radio frequency transceiver  52  is arranged to detect and interrogate the authorisation device  26  when inside the vehicle passenger compartment  22 . In alternative embodiments, the authorisation device may be a conventional ignition key and the detection means a conventional ignition lock system. The manual lock override  30 , preferably in the form of a switch, provides a further input into controller  24 .  
     [0150] In use, once one or more vehicle doors  14  have been unlocked, a delay is preferably provided to enable the user to enter the vehicle before the subsystem of this aspect of the present invention comes into operation. The subsystem  10  advantageously remains in a standby state up until this point to minimise battery drain.  
     [0151] Once the authorised user carrying AD  26  has entered the vehicle, the presence of the AD is detected by the interior transceiver  52  which signals the controller  24  to indicate the presence of the authorised user within the vehicle. Under normal circumstances, the controller  24  does not signal door lock actuators  38  such that the door latches  16  remain unlocked. However, in a preferred class of embodiments, the manual override  30  enables the authorised user to lock the vehicle doors, if for example they require protection from intruders whilst in the vehicle. Optionally, the controller  24  may signal the door lock actuators  38  when the motion sensor  42  signals that the vehicle has exceeded a certain speed such as 5 km/h, for example.  
     [0152] If the IR sensor  54  detects and signals the controller  24  of the presence of one or more people in the passenger compartment  22 , but no authorisation device  26  is detected, the controller determines that there are unauthorised people in the vehicle. Under normal circumstances the controller  24  signals the locking or superlocking of the vehicle doors in this situation. However, an alternative mode of operation may cause the vehicle to remain unlocked when unauthorised people are in the vehicle, either in response to a further manual override input e.g. by input means  56  (not shown), preferably in the form of a PIN or other code, or to pre-programmed instructions of the controller  24 .  
     [0153] Once one or more vehicle doors have been unlocked due to a detection of the authorisation device  26  by the external transceiver, and a predetermined period of time elapsed in which neither the authorised user nor any unauthorised people have entered the vehicle, the controller  24  signals the super locking of the vehicle door locks as a security measure. Alternatively, the vehicle will remain unlocked whilst the authorised user continues to be detected by the external transceiver  44  with super locking only occurring as a fail-safe measure once the user moves out of its range.  
     [0154] To exit the vehicle, the authorised user or unauthorised people may manually override the locking if single locked by pulling a sill button attached to the latch  16 , for example. However, only an authorised user may unlock the vehicle when superlocked.  
     [0155] It can be seen that this aspect of the present invention provides enhanced security to both authorised vehicle users and vehicles themselves whilst operating in an unobtrusive and reliable manner.  
     [0156] Numerous changes may be made within the scope of this aspect of the present invention. For example, alternative means for detecting people in the vehicle may be used such as pressure sensors in the seats or barometric sensors. It should be appreciated that this aspect of the present invention has applications outside our vehicle access control and may be used in building access control, for example.  
     [0157] A further aspect of the present invention provides a subsystem of the access controls system that determines whether vehicle occupants may start the vehicle  12 .  
     [0158] In some classes of embodiments, the interior and external transceivers  52  and  44  may be combined. Referring to FIG. 1A, the vehicle  12  is fitted with transceivers operably connected to the vehicle engine starter  46  by an electrical circuit. In this embodiment, the operable connection is via controller  24 , but this need not necessarily be the case. Although transceivers  44 ,  52  and  53  are shown separately, all three could in practice be mounted within the same housing, for example. Input means, preferably in the form of switches  66  and  68  or touchpads is provided in the circuit connecting the controller to engine starter  46 .  
     [0159] As explained above, external transceiver  44  periodically scans for the existence of corresponding authorisation devices  26  outside the vehicle  12 . Once a compatible authorisation device  26  is detected, the transceiver  44  interrogates the authorisation device to obtain an identity code associated with that particular device.  
     [0160] In this aspect of the present invention, the external transceiver  44  then compares this code with codes held in a first block of memory  58  associated therewith to determine whether that AD  26  has the first level of authorisation required to permit access to the vehicle  12 . If this is the case, the controller  24  signals the unlocking of one or more door latches  16 . An authorised vehicle user may then unlatch a door latch and enter the vehicle as described above.  
     [0161] The driver&#39;s seat transceiver  53 , has a relatively low scanning power and/or is directional, being targeted specifically at driver&#39;s seat (not shown). In particularly preferred classes of embodiment, the driver&#39;s seat transceiver  53  is positioned under the driver&#39;s seat with the scanning directed upwardly, or is positioned above the driver&#39;s seat and directed downwardly. Both of the aforesaid arrangements mean that the scanning power of the driver&#39;s seat transceiver  53  is less crucial to the successful operation of the transceiver  53  within the immediate area of the driver&#39;s seat only.  
     [0162] If a vehicle user carrying authorisation device  26  is seated on the driver&#39;s seat, the authorisation device  26  will come into range of the driver&#39;s seat transceiver  53  and will be interrogated by the transceiver  53 . The interrogated data is passed to controller  24  which looks up the identity code of the authorisation device  26  in a second block of memory  58  to determine whether that particular authorisation device has the second level of authorisation required to start the vehicle. If this is the case, the driver&#39;s seat transceiver  53  energises/signals the engine starter  46 . However, unless switches  66  and  68  are closed/actuated, the signal will not reach the starter  46 .  
     [0163] Therefore, a user seated in the driver&#39;s seat and having authorisation device  26  with the second level of authorisation must close both switches  66  and  68  in order to start the vehicle.  
     [0164] In a preferred embodiment, the switches are mounted on a steering wheel of the vehicle and are sufficiently far apart to prevent their simultaneous closing by a single hand. Typically, a spacing of 250 mm is likely to be sufficient. Therefore, in order to start the vehicle, both switches must at the same time be actuated/in a closed state, meaning that both the user&#39;s hands must be in the region of the steering wheel. In a particularly preferred embodiment the switches  66 ,  68  are located such that when the steering wheel is grasped they fall easily to hand. Indeed, in some embodiments, no further action other than gripping the steering wheel is required to actuate the switches. The switches may be monostable (i.e. stable in only one position, such as in the off position) or bistable (i.e. stable in two positions, such as in both on and off positions), and in a preferred embodiment are touch sensors. A third switch/input (not shown) is preferably provided to enable the engine to be stopped once it is running.  
     [0165] However, if a vehicle user having the second authorisation level is not seated on the driver&#39;s seat, the authorisation device  26  will be out of the range of the driver&#39;s seat transceiver  53 . Therefore it is not possible for a non-driving user to start the vehicle even if they are seated in the driver&#39;s seat and carrying the authorisation device having the first level of authorisation, and even whilst a user having a second level of authorisation is seated outside the range of the driver&#39;s seat transceiver  53 .  
     [0166] The system preferably also operates in reverse, so that when the authorisation device moves out of range of the second and first scanning means, the vehicle is respectively stopped and locked, although this may be overridden by manual override  30 , as necessary.  
     [0167] It should be understood that numerous changes may be made within the scope of this aspect of the present invention. For example, the start system may also be used to store user preferences such as seat and steering wheel position, with the driver&#39;s seat only being adjusted when an appropriate authorisation device is detected in the immediate vicinity of the driver&#39;s seat. Individual sensors may be provided for one or more passenger seats so that personal preferences may be set for each passenger seat by the entry and start system. Alternative input means such as touch sensors may be provided. The scanning means may alternatively scan biometric data such as fingerprints or retinal data for use as an identity code for a particular user and may operate using alternatives to electromagnetic radiation such as ultrasonic or sonar sound waves. In other embodiments, more than two levels of authorisation may be used so as to control a user&#39;s use of other vehicle features. Furthermore, the subsystem may have applications in building entry control, for example  
     [0168] Another aspect of the present invention discloses one means for exiting a vehicle  12  once inside and is shown in FIG. 17. The vehicle side passenger door  14  is shown in FIG. 17 and comprises an interior trim panel  612  having an arm rest  614  mounted thereon. A handle portion  616  is integrally provided with the arm rest  614  and a strain gauge  34   a  (hereinafter referred to as the handle strain gauge) is provided to mount the front of the handle  616  to the trim panel  612  such that pulling on the handle  616  produces an output, as described in greater detail below. A further strain gauge  34   b  in the form of a panel (hereinafter referred to as the trim strain gauge) is mounted on the trim panel  612  above and towards the rear of the arm rest portion  614  such that pressing thereon produces an output. For clarity both strain gauges are designated by reference  34  on FIG. 1A.  
     [0169] Gauge  34   a  is located such that if a vehicle user grasps handle  616  and rests his/her arm on the upper face of arm rest  614  the elbow or lower arm will contact the strain gauge panel  34   b.  Although the gauges  34   a  and  34   b  are visible in FIG. 17, they may in alternative embodiments be hidden for aesthetic reasons. In this embodiment, the strain gauges  34   a,    34   b  comprise first and second input means of door inner release means.  
     [0170] A power door latch  16  (ie a latch that may be released by the use of an actuator motor or the like) is mounted on the rear face  623  of the door.  
     [0171] Referring to FIG. 1A, controller  24  receives inputs from the handle and trim strain gauges  34   a  and  34   b,  as well as retaining data on the current locking status of latch  16 , stored in this embodiment by memory  58 . The status value stored in the memory is altered when the controller  24  signals the door lock actuator  38  In other classes of embodiment, a separate lock status indicator (not shown) is supplied with status data by door lock actuator  38  and which may then be supplied to controller  24 .  
     [0172] The vehicle motion sensor  4  provides a further input signal to the controller  24  when the vehicle  12  is travelling in excess of a predetermined speed (e.g. 3 km/h).  
     [0173] In response to the inputs from the aforesaid components, the controller  24  determines the appropriate state of the door latch  16  and signals a power door latch actuator  36  and/or door lock actuator  38  accordingly. It should be appreciated that similar components and interconnections may be provided for each closure provided on the vehicle, and that individual controllers may be provided for each closure, or the single controller  24  may control the function of all closures as is illustrated.  
     [0174] For the avoidance of doubt, following terms relating to latch locking states are now defined:  
     [0175] A latch is in an unlocked security condition when operation of an inside release means or an outside release means causes unlatching of the latch.  
     [0176] A latch is in a locked security condition when operation of an outside release means does not unlatch the latch but operation of an inside release means does unlatch the latch.  
     [0177] A latch is in a superlocked security condition where operation of an outside or an inside release means does not unlatch the latch. In particular it should be noted that multiple operations of the inside and outside release means, in any sequence, does not unlatch the latch.  
     [0178] A latch is in a child safety on security condition when operation of an inside release means does not unlatch the latch but operation of an outside release means may or may not unlatch the latch depending on whether the latch is an unlocked or locked condition.  
     [0179] Override unlocking is a function whereby operation of an inside release means, with the latch in a locked condition, causes unlocking of the latch.  
     [0180] Note that override unlocking is applicable to a latch in a locked child safety off condition, and is also applicable to a latch in a locked child safety on condition. In particular starting from a locked child safety on condition of a latch having override unlocking, an actuation of the inside release means will unlock the door, but this operation or any subsequent operation of the inside release means will not unlatch the door since the child safety feature is on. Nevertheless, once the latch has been unlocked by actuation of the inside release means, a subsequent operation of the outside release means will unlatch the latch. In particular it should be noted that this situation is different from a superlocked latch since in the former case a particular sequence of release means operations, i.e. operation of the inside release means followed by operation of the outside release means, will unlatch the latch. This is not the case for superlocking.  
     [0181] One pull override unlocking is a function whereby with the latch in a locked child safety off condition a single actuation of the inside release means results in unlocking of the door and also unlatching of the door.  
     [0182] Two pull override unlocking is a function, whereby with the latch in a locked child safety off condition a first actuation of the inside release means results in unlocking of the latch but does not result in unlatching of the latch. However, a further operation of the inside release means will then cause the latch to unlatch.  
     [0183] This embodiment, the latch  16  has a child safety function and one a pull override unlocking function, although in other embodiments, the child safety function may be omitted (e.g. for front driver doors) and the latch may have two pull override unlocking.  
     [0184] The operation of the mechanism is as illustrated by the flow chart of FIG. 18. In use, a user seated in the vehicle grasps handle  616  and rests his/her forearm along arm rest  614 . Then, by applying an inwardly directed tensile force to handle  616  and an outwardly directed compression force to strain gauge  34   b,  output signals from both gauges are simultaneously sent to controller  24 . If both signals exceed a predetermined threshold value, the controller  24  then goes on to determine the locked state of latch  16  from memory  58 . If the latch is superlocked, no unlatching signal is sent to door latch actuator  38 . If child safety is on and the latch is locked, the controller  24  signals the door lock actuator  38  to unlock the latch  16  but not to unlatch it. The controller simultaneously rewrites the appropriate portion of memory  58  to update the lock status of latch  16 . Only if the latch  16  is locked or unlocked and the output from the motion sensor  42  is low will unlatching occur. The controller  24  sends the appropriate signal to the door latch actuator  36  in order to achieve this.  
     [0185] Thus, is apparent that the arrangement of the strain gauges  34   a  and  34   b  substantially prevents the accidental unlatching of latch  16  and that in a preferred embodiment, vehicle occupant safety is further enhanced by integrating a motion sensor into the mechanism so as to prevent accidental unlatching whilst the vehicle is in motion.  
     [0186] It is envisaged that numerous changes may be made within the scope of this aspect of the present invention. For example, alternative input means, such as switches, force transducers or even a mechanical linkage but may be provided in place of the strain gauges. The positioning of the input means may be altered. For example, one gauge may be provided on the handle so that an output is generates when it is squeezed.  
     [0187] Referring to FIGS.  19  to  22 , an alternative exit means according to another aspect of the present invention for exiting vehicle  12  is disclosed.  
     [0188] Turning to FIG. 19, a door  14  comprises an interior trim panel  712  having an arm rest portion  714  provided thereon. Integral with the arm rest is a handle  716  that has the dual function of unlatching a latch  16  provided on the door  14  when the door is closed so as to enable the user to exit the vehicle  12  to which the door is fitted, and also to pull the door into a closed position when it is ajar (not closed). Generally, the simple combination of these function would not work since pulling on a single handle to close the door would prevent the corresponding latch  16  from being latched at precisely the moment when latching should occur, since a pawl of the latch would be lifted away from the latch bolt.  
     [0189] As described in further detail below, in this embodiment the handle  716  is operably connected to the latch by a mechanical connection and an electrical connection. In normal use, actuating the handle  716  closes a switch (not shown) and thereby sends an electrical signal to latch power actuator  36  that causes the latch to unlatch. Further, if the electrical power in the vehicle fails due to a flat battery, for example, a mechanical connection enables the latch  16  to be manually unlatched.  
     [0190] Considering first the mechanical connection, FIGS. 20A and 20B illustrate the latch  16  in a latched condition and in particular those parts constituting the mechanical connection between handle  716  and the latch. The latch comprises a latch bolt in the form of a claw  720  rotatably mounted about a pivot  722  to a latch chassis (not shown) and having a recess  724  which retains a striker  732  when the latch is latched. The claw  20  further comprises a first abutment surface  726  for a first safety latched position and a second abutment surface  728  against which pawl  730  abuts to retain the claw in a fully latched condition. Pawl  730  is resiliently biased into contact with claw  720 . The latch further comprises an inside release lever  742  rotatably mounted to the latch chassis about a pivot  744 .  
     [0191] The lever  742  is connected to the handle  716  by a rod or cable (not shown) mounted to a pivot  746  such that actuating the handle  716  pulls the cable or rod in a direction X thereby causing the lever to pivot clockwise in a direction Y as shown in FIG. 20B as is well known. The inside release lever  742  is in turn connected by a linkage (not shown) of known type to the pawl such that when the lever pivots in direction Y the pawl  730  lifts.  
     [0192] A block link  736  is mounted for slidable movement in a vertical plane only intermediate claw  720  and lever  742 . The link  736  comprises a substantially vertically arranged bar  737  having a substantially horizontally positioned claw abutment projection  738  formed integrally therewith at the upper end of the bar. A substantially horizontally arranged lever abutment projection  740  is formed integrally with the lower end of the bar  737 . When viewed along the longitudinal axis of the bar  737 , projections  738  and  740  are angled at substantially 90° to each other. As can be seen most clearly from FIG. 20B, when the latch  16  is in a latched condition, the block link is arranged such that it does not impede rotation of lever  742 .  
     [0193] Turning now to FIGS. 21A and 21B, the latch  16  is shown in an unlatched condition with the door open (note striker  732  is no longer retained in recess  724 ). Unlatching occurs via a user actuating either the inside handle  716  or outside release handle (not shown) thereby causing pawl  730  to lift out of abutment with either of surfaces  726  or  728 . Because claw  720  is biased in an anti-clockwise direction as shown in FIG. 21A, anti-clockwise rotation of the claw occurs, thereby releasing striker  732 . This simultaneously causes block link  736  to be engaged by an abutment surface  734  of the claw and thus to be lifted. As can be seen most clearly from FIG. 21B, in this position it is not possible for lever  742  to further actuate pawl  730  since rotation of lever  742  is prevented by projection  740 . Therefore, when the user pulls handle  716  in order to close and latch the door  14 , this pulling action is prevented from causing the latching action to fail due to the pawl being lifted out of contact with the claw  720  as the claw rotates during contact with the striker.  
     [0194] Referring to FIG. 1A, the electrical connection comprises an inside handle switch (not shown) provided in the place of inside strain gauges  34  and arranged so as to signal controller  24  when the handle  716  is actuated and a door ajar sensor  40  arranged so as to signal the controller  24  when the door is ajar (open). In response to the input signals from switch and sensor  40 , the controller  24  determines whether door latch power actuator  36  is to cause the unlatching of the latch  16  and signals the actuator accordingly. The power actuator  36  is arranged so as to lift pawl  730  when an unlatching signal is sent by controller  24 . In use, the controller  24  does not send an unlatching signal to the actuator  36  when sensor  40  indicates that the door  16  is ajar.  
     [0195] The operational sequence of the mechanism is illustrated by the flow chart of FIG. 22. In order to determine whether the latch is to be operated electrically, in one embodiment a small force applied to handle  716  is sufficient to cause the latch to be unlatched electrically, but that if electrical operation is not possible, a larger force must be exerted on the handle  716  to cause mechanical unlatching. Thus, electrical unlatching takes precedence.  
     [0196] It is therefore apparent that both the electrical and mechanical connections are provided with safeguards to prevent the latch being mis-set when the door is being pulled to a closed position, enabling a single handle  716  to act as door engagement means and inside release means.  
     [0197] It should be understood that numerous changes may be made within the scope of this aspect of the present invention. For example, a break rather than a block may be provided in the latch linkage to prevent the latch being mis-set and the mechanism may be adapted for use with other known types of latches. The choice between electrical and mechanical unlatching may be left to the vehicle user by, for example, electrical unlatching being initiated by pulling handle  16  inwardly and mechanical actuation by lifting the handle upwardly. In this embodiment, the block link may be dispensed with since mechanical unlatching would not be caused by pulling the door into a closed position under normal operational circumstances. Rather than the electrical connection comprising a door ajar sensor, a sensor to determine the state of the latch could be employed. The door ajar sensor may be provided in series with the inside handle switch and in which case, a controller may be dispensed with.  
     [0198] Note that the orientations such an “inner” “outer”, “vertical” and “horizontal” and directions such as anticlockwise as referred to herein, relate to orientations of components when installed in a vehicle. Nevertheless, such terms should not be construed as limiting.  
     [0199] Turning to the flowchart of FIG. 23, this illustrates the various procedural steps taken when a vehicle user approaches a vehicle whose doors are locked, in order to enter the vehicle and start the vehicle engine. The illustrated steps assume that the vehicle is fitted with a passive entry system which has all of the possible subsystems described above included therein.  
     [0200] As a vehicle user carrying authorisation device  26  approaches the vehicle whether a user is permitted access to the vehicle is determined using the subsystem of the embodiment disclosed by FIGS.  2  to  5  and is summarised by processes  810  and  812  of FIG. 23. The user may then attempt to unlatch one of the vehicle closures using access means of the embodiments of FIGS. 12A to  14  and subsequently open the closure using engagement means disclosed in FIG. 15 or  16 . If no access attempt occurs within a predetermined period or the authorisation device  26  moves out of range of the transceiver the closures are relocked by the controller  24  unless manual override  30  has been actuated. This sequence is summarised by steps  814 ,  815 ,  816  and  822  of FIG. 23.  
     [0201] Once a closure has been unlatched, the interior short range transceiver  52  and interior infrared sensor  54  determine the appropriate lock state of the vehicle closures as summarised by steps  818 ,  820 ,  822  and  824 . Thereafter, whether a particular user is permitted to start the vehicle is determined by using the driver&#39;s seat transceiver  53  and is summarised in steps  826  and  828 . Only if the user actuates the start inputs on the steering wheel will the engine start, as summarised by steps  830  and  832 . The access and start procedure is then complete and the user may drive off in the vehicle. Optionally, once the vehicle speed exceeds a predetermined value, the closures may be locked for reasons of safety.  
     [0202]FIG. 24 illustrates the engine switch off and vehicle exit procedure incorporating all of the potential sub-systems of the present invention.  
     [0203] At steps  910  and  912  it can be seen that only if vehicle motion sensor  42  output is low and the user signals the switching off of the vehicle engine, will the controller  24  signal the turning off of the engine as illustrated by steps  910 ,  912  and  914 . Only then may the user exit the vehicle by using the strain gauge arrangement of the embodiment of FIGS. 17 and 18 or the handle arrangement of FIGS.  19  to  22  (as represented by step  916 ). Thereafter, only once the authorisation device has left the vehicle, the door has been relatched and the authorisation device has moved out of range of the external directional transceiver  44  or a predetermined delay has elapsed, will the controller signal the locking of the vehicle closures  14  and  18  as illustrated by steps  918 ,  920 ,  922  and  924 .  
     [0204] It should be appreciated that the present invention provides a complete system for controlling vehicle access and security. It will further be appreciated that the invention does not depend on the various sub-systems all being fitted to a vehicle and that two or more sub-systems may be combined.  
     [0205] It should further be appreciated that numerous changes may be made within the scope of the present invention. For example, although the invention has been described in relation to a vehicle having a conventional internal combustion engine, the invention may equally be applied to electric, fuel cell or other alternatively powered vehicles.