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Title:
REMOTE TRANSMITTER APPARATUS AND METHOD
Document Type and Number:
WIPO Patent Application WO/2018/041712
Kind Code:
A1
Abstract:
The present disclosure relates to a remote transmitter unit for controlling access to a vehicle. The remote transmitter unit has a transmitter for transmitting a wireless signal to the vehicle and movement sensing means for sensing movement of the remote transmitter unit. At least one processor is provided for receiving a signal (SXYZ) from the movement sensing means. A memory is connected to the at least one processor. In dependence on the signal (SXYZ) received from the movement sensing means, the at least one processor is configured to determine that the remote transmitter unit has been dropped and to generate a drop notification signal (SD). The present disclosure also relates to a method of monitoring a remote transmitter unit; and to the combination of a vehicle and a remote transmitter unit.

Inventors:
TALBOT, Kevin (Patents Department W/1/073 Abbey Road Whitley, Coventry Warwickshire CV3 4LF, CV3 4LF, GB)
Application Number:
EP2017/071338
Publication Date:
March 08, 2018
Filing Date:
August 24, 2017
Export Citation:
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Assignee:
JAGUAR LAND ROVER LIMITED (Abbey Road Whitley, Coventry Warwickshire CV3 4LF, CV3 4LF, GB)
International Classes:
G07C9/00
Foreign References:
US20150116078A12015-04-30
JP2012233328A2012-11-29
US20150291127A12015-10-15
CN201887837U2011-06-29
US20060187007A12006-08-24
US20150170491A12015-06-18
US20100188243A12010-07-29
Attorney, Agent or Firm:
CHANG, Seon-Hee (Jaguar Land Rover, Patents Department W/1/073 Abbey Road Whitley, Coventry Warwickshire CV3 4LF, CV3 4LF, GB)
Download PDF:
Claims:
CLAIMS :

1 . A remote transmitter unit for controlling access to a vehicle, the remote transmitter unit comprising:

a transmitter for transmitting a wireless signal to the vehicle;

means for sensing movement of the remote transmitter unit;

at least one processor for receiving a signal (SXYZ) from the movement sensing means; and

a memory connected to the at least one processor;

wherein, in dependence on the signal (SXYZ) received from the movement sensing means, the at least one processor is configured to determine that the remote transmitter unit has been dropped and to generate a drop notification signal (SD) .

2. A remote transmitter unit as claimed in claim 1 , wherein the movement sensing means comprises one or more accelerometers for measuring acceleration; and the signal

(SXYZ) received from the movement sensing means comprises an acceleration signal (SXYZ).

3. A remote transmitter as claimed in claim 2, wherein the movement sensing means comprises a three-axis accelerometer.

4. A remote transmitter unit as claimed in claim 2 or claim 3, wherein the at least one processor is configured to determine that the remote transmitter unit has been dropped by identifying a falling condition in dependence on said acceleration signal (SXYZ) . 5. A remote transmitter unit as claimed in claim 4, wherein the at least one processor is configured to identify said falling condition when the acceleration signal (SXYZ) is less than a predefined acceleration threshold.

6. A remote transmitter unit as claimed in claim 4, wherein the at least one processor is configured to identify said falling condition when the acceleration signal (SXYZ) is less than

9.81 m/s2.

7. A remote transmitter unit as claimed in any one of claims 2 to 6, wherein the at least one processor is configured to determine that the remote transmitter unit has been dropped by identifying a change in the acceleration signal (SXYZ) indicative of the remote transmitter unit contacting the ground after having been dropped.

8. A remote transmitter unit as claimed in any one of the preceding claims, wherein the movement sensing means comprises a trembler switch configured to detect a vibration of the remote transmitter unit. 9. A remote transmitter unit as claimed in claim 8, wherein the trembler switch is configured to detect a vibration indicative of the remote transmitter unit contacting the ground after having been dropped.

10. A remote transmitter unit as claimed in any one of the preceding claims, wherein the at least one processor is configured to output said drop notification signal (SD) if the movement sensing means determines that the remote transmitter unit is stationary for a predetermined period of time following determination that the remote transmitter unit has been dropped. 1 1 . A remote transmitter unit as claimed in any one of the preceding claims comprising at least one light emitting device, wherein the at least one light emitting device is configured to be illuminated in dependence on said drop notification signal (SD).

12. A remote transmitter unit as claimed in any one of the preceding claims comprising a timer for controlling a sample rate of the movement sensing means.

13. A remote transmitter unit as claimed in claim 12, wherein the timer comprises a crystal oscillator. 14. A remote transmitter unit as claimed in any one of the preceding claims, wherein the at least one processor is configured to generate a location signal (SL) for indicating a location of the remote transmitter unit relative to the vehicle, the at least one processor being configured to output the location signal (SL) upon determining that the remote transmitter unit has been dropped.

15. A combination of a remote transmitter unit as claimed in any one of the preceding claims and a vehicle.

16. A combination as claimed in claim 15, wherein the remote transmitter unit is configured to transmit the drop notification signal (SD) to the vehicle.

17. A combination as claimed in claim 16 wherein the vehicle is configured to illuminate at least one vehicle light in dependence on the drop notification signal (SD).

18. A combination as claimed in any one of claims 15, 16 or 17 when dependent directly or indirectly on any one of claims 1 to 13, the vehicle comprising an electronic control unit for receiving the drop notification signal (SD) ; wherein, in dependence on receipt of the drop notification signal (SD) , the electronic control unit is configured to determine a location of the remote transmitter unit relative to the vehicle. 19. A combination as claimed in claim 18, wherein the electronic control unit is configured to generate a location signal (SL) for indicating the determined location of the remote transmitter unit.

20. A combination as claimed in claim 19, wherein the location signal is operable to control one or more vehicle systems to provide an indication of the determined location of the remote transmitter unit relative to the vehicle.

21 . A combination as claimed in claim 20, wherein the one or more vehicle systems comprise one or more of the following: an internal vehicle light, an external vehicle light and a display screen.

22. An electronic control unit for receiving a drop notification signal (SD) from a remote transmitter unit; wherein, in dependence on receipt of the drop notification signal (SD), the electronic control unit is configured to determine a location of the remote transmitter unit relative to the vehicle.

23. An electronic control unit as claimed in claim 22, wherein the electronic control unit is configured to generate a location signal (SL) comprising the determined location of the remote transmitter unit.

24. An electronic control unit as claimed in claim 23, wherein the location signal is operable to control one or more vehicle systems to provide an indication of the determined location of the remote transmitter unit relative to the vehicle. 25. A vehicle comprising an electronic control unit as claimed in any one of claims 22 to 24.

26. A method of monitoring a remote transmitter unit to determine that it has been dropped, the remote transmitter unit being suitable for controlling access to a vehicle, wherein the method comprises:

obtaining a signal (SACC) from movement sensing means within the remote transmitter unit;

analysing the signal (SACC) to identify a steady-state condition when the signal is substantially constant;

analysing the signal (SACC) to identify a falling condition when the signal changes; and

determining that the remote transmitter unit has been dropped in dependence on identification of said falling condition.

27. A method as claimed in claim 26 wherein the signal from the movement sensing means comprises a measure of acceleration of the remote transmitter unit, and the method comprises identifying a falling condition when the measured acceleration decreases below a predefined acceleration threshold.

28. A method as claimed in claim 27 comprising identifying a falling condition when the measured acceleration is less than 9.81 m/s2.

29. A method as claimed in claim 27 or 28 comprising identifying the falling condition only after identifying the steady-state condition.

30. A method as claimed in any one of claims 27 to 29 comprising determining that the remote transmitter unit has been dropped in dependence on identifying a predefined change in the measured acceleration indicative of the remote transmitter unit contacting the ground after said falling condition.

31 . A method as claimed in any one of claims 26 to 30 comprising generating a drop notification signal (SD) in dependence on determination that the remote transmitter unit has been dropped.

32. A method as claimed in claim 31 comprising illuminating one or more light emitting device disposed on said remote transmitter unit in dependence on said drop notification signal (SD).

33. A method as claimed in claim 31 or 32 comprising transmitting the drop notification signal (SD) to a vehicle and receiving said drop notification signal (SD) by said vehicle.

34. A method as claimed in claim 33 comprising illuminating at least one of the lights of the vehicle in dependence on the drop notification signal (SD) received by the vehicle.

35. A method as claimed in any one of claims 26 to 34 comprising determining a location of the remote transmitter unit relative to the vehicle upon determining that the remote transmitter unit has been dropped.

36. A method as claimed in claim 35 comprising controlling one or more vehicle systems to provide an indication of the determined location of the remote transmitter unit relative to the vehicle. 37. A method as claimed in claim 36, wherein the one or more vehicle systems comprise one or more of the following: an internal vehicle light, an external vehicle light and a display screen.

38. A computer program comprising instructions that, when executed by one or more processors, cause a system to perform a method according to any of claims 26 to 37.

39. A non-transitory computer readable media comprising a computer program as claimed in claim 38. 40. A remote transmitter unit, a combination of a remote transmitter unit and a vehicle, a method of monitoring a remote transmitter unit, and computer software as described hereinbefore with reference to the accompanying drawings.

Description:
REMOTE TRANSMITTER APPARATUS AND METHOD

TECHNICAL FIELD

The present disclosure relates to a remote transmitter apparatus and method. Particularly, but not exclusively, the present disclosure relates to a remote transmitter unit for controlling access to a vehicle. Aspects of the invention relate to a remote transmitter unit; to a combination of a vehicle and a remote transmitter unit; to a method; and to a computer program. BACKGROUND

It is increasingly common to use a remote transmitter unit to control access to a vehicle. The remote transmitter unit may, for example, take the form of a key fob and may have a control interface including buttons operated by a user. The remote transmitter unit may provide keyless operation and may control the vehicle ignition. On occasion, a user may drop the remote transmitter unit and it may prove difficult to locate, particularly if it is dark. It is against this backdrop that the present invention has been conceived.

It is an aim of embodiments of the present invention to at least partially address disadvantages associated with conventional remote transmitter units.

SUMMARY OF THE INVENTION

Aspects of the present invention relate to a remote transmitter unit; to a combination of a vehicle and a remote transmitter unit; to a method; and to a computer program as claimed in the appended claims.

According to a further aspect of the present invention there is provided a remote transmitter unit for controlling access to a vehicle, the remote transmitter unit comprising:

a transmitter for transmitting a wireless signal to the vehicle;

means for sensing movement of the remote transmitter unit;

at least one processor for receiving a signal from the movement sensing means; and

a memory connected to the at least one processor;

wherein, in dependence on the signal received from the movement sensing means, the at least one processor is configured to determine that the remote transmitter unit has been dropped and to generate a drop notification signal. The drop notification signal is generated by the at least one processor and may be used to control other functions of the remote transmitter unit and/or the vehicle. For example, the drop notification signal can be used to trigger an alert or notification to help the user locate the remote transmitter unit.

The movement sensing means may comprise one or more accelerometer for measuring acceleration. The signal received from the movement sensing means may comprise an acceleration signal. The movement sensing means may comprise a three-axis accelerometer.

The at least one processor may be configured to determine that the remote transmitter unit has been dropped by identifying a falling condition in dependence on said acceleration signal. The at least one processor may be configured to identify said falling condition when the acceleration signal from the accelerometer decreases. The at least one processor may be configured to identify said falling condition when the acceleration signal is less than the acceleration signal for a steady-state condition, for example when the remote transmitter unit is stationary. When the remote transmitter unit is stationary, the steady-state accelerometer signal may, for example, be 9.81 m/s 2 . When the remote transmitter unit is in free fall, the measured acceleration signal may be substantially Om/s 2 . The at least one processor may be configured to identify the falling condition when the measured acceleration signal is substantially 0 m/s 2 or is less than a predefined acceleration threshold. The predefined acceleration threshold may, for example, be defined as 1 m/s 2 3m/s 2 , 5 m/s 2 or 7m/s 2 . Alternatively, the predefined acceleration threshold may be defined as a proportion of the acceleration signal for a steady-state condition, for example when the remote transmitter unit is stationary. The predefined acceleration threshold may, for example, be defined as the steady-state acceleration signal multiplied by a factor of 0.25, 0.5 or 0.75.

The at least one processor may be configured to determine that the remote transmitter unit has been dropped by identifying a predefined change in acceleration indicative of the remote transmitter unit contacting the ground after having been dropped. The at least one processor may be configured to identify an acceleration spike. The at least one processor may be configured to identify when the magnitude of the measured acceleration is greater than a predefined threshold. The predefined change in acceleration may comprise an increase in acceleration to a value greater than 9.81 m/s 2 .

Alternatively, or in addition, the movement sensing means may comprise a trembler switch configured to detect a vibration of the remote transmitter unit. The trembler switch may be configured to detect when the remote transmitter unit contacts the ground. The trembler switch is configured to detect a vibration indicative of the remote transmitter unit contacting the ground after having been dropped.

The at least one processor may be configured to output said drop detection signal if the movement sensing means determines that the remote transmitter unit is stationary for a predetermined period of time following determination that the remote transmitter unit has been dropped.

The remote transmitter unit may comprise at least one light emitting device, wherein the at least one light emitting device is configured to be illuminated in dependence on said drop notification signal. The at least one light emitting device may be illuminated to facilitate locating the remote transmitter unit, for example if it has been dropped inadvertently. The remote transmitter unit could include a light sensor. The at least one light emitting device may be illuminated only when light sensor determines that it is dark. The light sensor also could be activated in dependence on said drop notification signal.

The remote transmitter unit may comprise a sound generating device, such as a loud speaker or a buzzer. The sound generating device may be activated in dependence on said drop notification signal.

The remote transmitter unit may comprise a vibrating mechanism. The vibrating mechanism may be activated in dependence on said drop notification signal.

The remote transmitter unit may be configured to transmit a wireless signal in dependence on said drop notification signal. The wireless signal could be transmitted to the vehicle. The vehicle could be configured to illuminate internal and/or external lights in dependence on said wireless signal. For example, the vehicle could be configured to illuminate lights disposed in side mirrors (e.g. "puddle" lights) to facilitate locating the remote transmitter unit. Alternatively, or in addition, the wireless signal may be transmitted to a communication device, such as a cellular telephone. The wireless signal could be transmitted using Bluetooth (RTM), for example.

The remote transmitter unit may comprise a timer for controlling a sample rate of the movement sensing means. The timer may be used periodically to activate the movement sensing means to sample movement of the remote transmitter unit. The movement sensing means may be cycled between an active state and a dormant state. At least in certain embodiments this cycling may help to reduce power consumption compared to continuous operation of the movement sensing means. The timer may comprise a crystal oscillator.

To detect zero acceleration (free fall), the timer may be configured to implement a predetermined time interval between samples. The predetermined time interval may, for example, be 50ms, 100ms, 150ms or 200ms. The movement sensing means may be in said dormant state during this time interval. When the movement sensing means is activated, there may be a wake-up delay before the movement sensing means generates said signal. It will be appreciated that the wake-up delay may vary for different movement sensing means. The wake-up delay may, for example, be 1 ms. The timer may be configured to maintain the movement sensing means in said active state for a time period equal to or greater than said wake-up delay to enable the movement sensing means to complete a start-up procedure and to generate the signal. By way of example, the timer may be configured to maintain the movement sensing means in said active state for approximately 1 ms, 2ms, 3ms or 5ms. On detecting zero acceleration, the timer may be configured to maintain the movement sensing means in said active state for an extended time period. Upon detection of zero acceleration, the timer may, for example, maintain the movement sensing means in said active state for a time period equal to or longer than 250ms, 500ms, 750ms, 1 second, 3 seconds or 5 seconds. This time period may be specified to detect acceleration changes which are indicative of an impact.

The at least one processor may be configured to generate a location signal for indicating a location of the remote transmitter unit relative to the vehicle. The at least one processor may be configured to output the location signal upon determining that the remote transmitter unit has been dropped. For example, the at least one processor may be configured to determine the location of the remote transmitter unit in dependence on said drop notification signal.

According to a further aspect of the present invention there is provided a combination of a remote transmitter unit as described herein and a vehicle. The remote transmitter unit is configured to transmit the drop notification signal to the vehicle.

The vehicle may be configured to illuminate at least one vehicle light in dependence on the drop notification signal (SD). The vehicle may comprise an electronic control unit for receiving the drop notification signal. The electronic control unit may be configured to determine a location of the remote transmitter unit relative to the vehicle in dependence on receipt of the drop notification signal. Thus, upon detecting that the remote transmitter unit has been dropped, the electronic control unit may determine the location of the remote transmitter unit.

The electronic control unit may be configured to generate a location signal for indicating the determined location of the remote transmitter unit. The location signal may be operable to control one or more vehicle systems to provide an indication of the determined location of the remote transmitter unit relative to the vehicle. The one or more vehicle systems may comprise one or more of the following: an internal vehicle light, an external vehicle light and a display screen. For example, the location of the remote transmitter unit may be indicated by illuminated an external vehicle light closest to the determined location. Alternatively, or in addition, the determined location may be displayed on the display screen in the vehicle. The display screen could, for example, be disposed on a centre console, a dashboard or an instrument cluster. In a variant, the electronic control unit may be configured to track the location of the remote transmitter unit, for example continuously or periodically. In this arrangement, the electronic control unit may be configured to record the location of the remote transmitter unit in dependence on receipt of the drop notification signal. The recorded location of the remote transmitter unit may subsequently be relayed to a user, for example by controlling one or more vehicle systems to provide a visual indication of the location of the remote transmitter unit when it was dropped. The one or more vehicle systems may comprise one or more of the following: an internal vehicle light, an external vehicle light and a display screen. For example, the location of the remote transmitter unit may be indicated by illuminated an external vehicle light closest to the determined location. Alternatively, or in addition, the determined location may be displayed on the display screen in the vehicle. Alternatively, or in addition, the recorded location may be output to a remote computational device, such as a personal computer or a cellular telephone, such as a smart phone.

According to a further aspect of the present invention there is provided an electronic control unit for receiving a drop notification signal from a remote transmitter unit. In dependence on receipt of the drop notification signal, the electronic control unit may be configured to determine a location of the remote transmitter unit relative to the vehicle. The remote transmitter unit may be of the type described herein. The electronic control unit may be configured to generate a location signal comprising the determined location of the remote transmitter unit relative to the vehicle. The location signal may comprise at least one of the following: a direction component and a distance component.

The direction component may define a direction of the remote transmitter unit relative to the vehicle when the drop notification signal is received. The direction of the remote transmitter unit relative to the vehicle may comprise one or more of the following: left hand side of the vehicle, right hand side of the vehicle, front of the vehicle, rear of the vehicle, front left of the vehicle, front right of the vehicle, rear right of the vehicle and rear left of the vehicle. Alternatively, or in addition, the direction may comprise a bearing or angular position of the remote transmitter unit relative to the vehicle, for example in relation to a reference axis, such as a longitudinal axis of the vehicle.

The distance component may define a distance between the vehicle and the remote transmitter unit when the drop notification signal is received. The distance may be defined with respect to a predefined reference point. The distance may, for example, be determined based on a comparison of the time-of-flight of the signals and/or a signal strength.

The location signal may be operable to control one or more vehicle systems to provide an indication of the determined location of the remote transmitter unit relative to the vehicle. The one or more vehicle systems may comprise one or more of the following: an internal vehicle light, an external vehicle light and a display screen. For example, the location of the remote transmitter unit may be indicated by illuminated an external vehicle light closest to the determined location. The location signal may be operable to control illumination of one or more external vehicle lights to provide an indication of the location of the remote transmitter unit. For example, the location signal may be used to selectively illuminate an external vehicle light disposed closest to the determined location of the remote transmitter unit. Alternatively, or in addition, the determined location may be displayed on the display screen in the vehicle. According to a further aspect of the present invention there is provided an electronic control unit as described herein.

According to a further aspect of the present invention there is provided a method of monitoring a remote transmitter unit to determine that it has been dropped, the remote transmitter unit being suitable for controlling access to a vehicle, wherein the method comprises:

measuring acceleration of the remote transmitter unit; analysing the measured acceleration to identify a steady-state condition when the measured acceleration is substantially constant;

analysing the measured acceleration to identify a falling condition when the measured acceleration decreases; and

determining that the remote transmitter unit has been dropped in dependence on identification of said falling condition.

According to another aspect of the present invention there is provided a method of monitoring a remote transmitter unit to determine that it has been dropped, the remote transmitter unit being suitable for controlling access to a vehicle, wherein the method comprises:

obtaining a signal from movement sensing means within the remote transmitter unit; analysing the signal to identify a steady-state condition when the signal is substantially constant;

analysing the signal to identify a falling condition when the signal decreases; and determining that the remote transmitter unit has been dropped in dependence on identification of said falling condition.

The signal from the movement sensing means may comprise a measure of acceleration of the remote transmitter unit, in which case the method may comprise identifying a falling condition when the measured acceleration decreases below a predefined acceleration threshold. Optionally, the method may comprise identifying a falling condition when the measured acceleration is less than 9.81 m/s 2 . The method may comprise determining that the remote transmitter unit has been dropped in dependence on identifying a predefined change in the measured acceleration indicative of the remote transmitter unit contacting the ground after said falling condition.

The method may comprise identifying the falling condition only after identifying the steady- state condition.

The method may comprise generating a drop notification signal in dependence on determination that the remote transmitter unit has been dropped. The method may comprise illuminating one or more light emitting device disposed on said remote transmitter unit in dependence on said drop notification signal. The method may comprise transmitting the drop notification signal to a vehicle and receiving said drop notification signal by said vehicle.

The method may comprise illuminating at least one of the lights of the vehicle in dependence on the drop notification signal received by the vehicle.

The method may comprise determining a location of the remote transmitter unit relative to the vehicle upon determining that the remote transmitter unit has been dropped. The method may comprise controlling one or more vehicle systems to provide an indication of the determined location of the remote transmitter unit relative to the vehicle. The one or more vehicle systems comprise one or more of the following: an internal vehicle light, an external vehicle light and a display screen. The method may comprise illuminating one or more external vehicle lights to provide an indication of the location of the remote transmitter unit. For example, the method may comprise selectively illuminating the external vehicle light disposed closest to the determined location of the remote transmitter unit. The method may comprise displaying the determined location on the display screen in the vehicle.

According to another aspect of the present invention there is provided a computer program comprising instructions that, when executed by one or more processors, cause a system to perform a method as described in the above aspect of the invention.

According to a further aspect of the invention there is provided a non-transitory computer readable media comprising a computer program as described in the preceding aspect.

Any control unit or controller described herein may suitably comprise a computational device having one or more electronic processors. The system may comprise a single control unit or electronic controller or alternatively different functions of the controller may be embodied in, or hosted in, different control units or controllers. As used herein the term "controller" or "control unit" will be understood to include both a single control unit or controller and a plurality of control units or controllers collectively operating to provide any stated control functionality. To configure a controller or control unit, a suitable set of instructions may be provided which, when executed, cause said control unit or computational device to implement the control techniques specified herein. The set of instructions may suitably be embedded in said one or more electronic processors. Alternatively, the set of instructions may be provided as software saved on one or more memory associated with said controller to be executed on said computational device. The control unit or controller may be implemented in software run on one or more processors. One or more other control unit or controller may be implemented in software run on one or more processors, optionally the same one or more processors as the first controller. Other suitable arrangements may also be used.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying Figures, in which:

Figure 1 shows a schematic representation of a vehicle and a remote transmitter unit in accordance with an embodiment of the present invention;

Figure 2 shows a schematic representation of the remote transmitter unit shown in

Figure 1 ;

Figure 3 is a graph illustrating the measured acceleration of the remote transmitter unit as it is dropped; and

Figure 4 shows a schematic representation of a vehicle and a remote transmitter unit in accordance with a further embodiment of the present invention.

DETAILED DESCRIPTION

A vehicle 1 and a remote transmitter unit 2 in accordance with an embodiment of the present invention will now be described with reference to the accompanying Figures.

The remote transmitter unit 2 is configured to communicate wirelessly with the vehicle 1 to control vehicle systems. In the present embodiment, the remote transmitter unit 2 is configured to provide remote control of one or more door locks 3 to control access to the vehicle 1 . The remote transmitter unit 2 may take the form of a key fob, for example. The remote transmitter unit 2 may provide additional functionality, for example to control a vehicle ignition. With reference to Figure 2, the remote transmitter unit 2 comprises a controller 4, a wireless transmitter 5, a three-axis accelerometer 6, two light emitting devices 7, a control interface 8 and a battery 9. The controller 4 comprises at least one processor 10 connected to a memory device 1 1 . The at least one processor 10 is an electronic processor configured to execute a set of computational instructions stored on a non-transitory computer readable media. In the present embodiment, the computational instructions are stored in the memory device 1 1 connected to the processor 10. The at least one processor 10 is configured to control operation of the wireless transmitter 5, the three-axis accelerometer 6 and the light emitting devices 7. In particular, the controller 4 is configured to identify that the remote transmitter unit 2 has been dropped and to activate the light emitting devices 7 to aid recovery thereof. The three-axis accelerometer 6 measures acceleration along X, Y and Z axes and is configured to output a signal to the controller 4. The signal comprises an acceleration signal SXYZ providing a substantially real-time measurement of acceleration along said X, Y and Z axes. The three-axis accelerometer 6 may comprise three micromechanical accelerometers arranged to measure acceleration along the X, Y and Z axes respectively. The micromechanical accelerators can, for example, each comprise a proof mass supported on a cantilever. Other types of accelerometer 6 can be used. The wireless transmitter 5 is a radio frequency (RF) transmitter and is configured to communicate with the vehicle 1 . In normal use, the wireless transmitter 5 is configured to transmit an access signal SACC to the vehicle 1 . The access signal SACC is typically generated in dependence on operation of the control interface 8 by a user and is unique for each remote transmitter unit 2. The control interface 8 may, for example, comprise two buttons 8A, 8B operative to control locking and unlocking of the door locks 3. The remote transmitter unit 2 comprises an antenna 12 connected to the wireless transmitter 5. With reference to Figure 1 , the vehicle 1 comprises a wireless receiver 13 for receiving the access signal SACC transmitted by the remote transmitter unit 2. The wireless receiver 13 may, for example, be connected to an electronic control unit 14 configured to control operation of the door locks 3. The door locks 3 may each comprise an electromechanical actuator, such as a solenoid, which is operated in dependence on a control signal from the electronic control unit 14. It will be understood that the remote transmitter unit 2 may optionally also comprise a receiver (not shown) and the vehicle 1 may comprise a wireless transmitter (not shown). This arrangement would enable two-way communication between the remote transmitter unit 2 and the vehicle 1 . For example, the vehicle 1 and the remote transmitter unit 2 may establish two-way communication and perform an authentication procedure (for example by performing an electronic "handshake" function). The controller 4 is a PIC microcontroller (supplied by Microchip Technology Inc.) having an internal oscillator 15. The oscillator 15 may, for example, be in the form of a 32,768Hz (often referred to as 32 kHz) crystal oscillator having low-power consumption. The mechanical oscillation of the oscillator 15 generates an electrical signal which is used by the controller 4 to implement a time module. The controller 4 uses the timer module to control a sample rate of the three-axis accelerometer 6. In order to reduce power consumption, the controller 4 periodically activates the three-axis accelerometer 6 and reads the acceleration signal SXYZ. The controller 4 deactivates the three-axis accelerometer 6 when not in use. The controller 4 can be configured to activate the three-axis accelerometer 6 for up to five (5) microseconds once every one hundred (100) microseconds. Other sample rates can usefully be implemented.

The acceleration measured by the three-axis accelerometer 6 corresponds to the proper acceleration of the remote transmitter unit 2. The controller 4 monitors the acceleration signal SXYZ to identify one or more predefined acceleration events indicative of one or more predetermined movements of the remote transmitter unit 2. In the present embodiment, the controller 4 is configured to identify a predefined acceleration event indicative of the remote transmitter unit 2 being in a falling condition, optionally followed by an acceleration spike when the remote transmitter unit 2 contacts the ground or another object. The controller 4 may be configured to monitor a return to a measured acceleration corresponding to a normal gravity acceleration reading.

The controller 4 may be configured to identify a steady-state condition which is followed by a falling condition. When the remote transmitter unit 2 is supported, the acceleration measured by the three-axis accelerometer 6 is approximately 9.81 m/s 2 (equivalent to 1 g). The controller 4 is configured to identify a steady-state condition over a series of consecutive samples, say for example three (3) consecutive samples. The steady-state condition may correspond to a measured acceleration of approximately 9.81 m/s 2 . The controller 4 is primed when this steady-state condition is identified and is configured to identify a falling condition. When the remote transmitter unit 2 is falling, the acceleration measured by the three-axis accelerometer 6 decreases to less than 9.81 m/s 2 (i.e. less than 1 g) while the remote transmitter unit 2 is falling. The measured acceleration may decrease to zero (0) m/s 2 during the falling condition since the remote transmitter unit is weightless while in free fall. By identifying a decrease in the measured acceleration, the controller 4 can identify a falling condition (i.e. when the remote transmitter unit 2 is falling). The controller 4 may be configured to identify the falling condition over a series of consecutive samples, say for example three (3) consecutive samples. The falling condition may correspond to a measured acceleration of approximately Om/s 2 . Alternatively, the falling condition may correspond to a measured acceleration less than a predefined lower acceleration threshold T L ow. The lower acceleration threshold T L ow may, for example, be predefined as 0.5g (approximately 4.9 m/s 2 ). The controller 4 is configured to generate a drop notification signal SD when a falling condition is identified.

As will be readily apparent to the skilled reader, in the case of a three-axis accelerometer the measured acceleration may be resolved into components in each of three mutually orthogonal axes (x, y and z) in dependence on the orientation or attitude of the remote transmitter unit during the steady-state condition and / or during a falling condition and / or during a stationary condition after a falling condition. Accordingly, in the case of a three-axis accelerometer, the identification of the steady state condition and / or a falling condition and / or a stationary condition may relate to one or more resolved components of the measured acceleration, or a combination (for example a summation) of one or more resolved components of the measured acceleration, optionally to a vector component of all of the resolved components of the measured acceleration.

The controller 4 in the present embodiment is configured to generate the drop notification signal SD upon detection of the falling condition. In accordance with an aspect of the present invention, the light emitting devices 7 are controlled in dependence on the drop notification signal SD generated by the controller 4. Specifically, the light emitting devices 7 are illuminated when said drop notification signal SD is generated by the controller 4. Thus, when the controller 4 determines that the remote transmitter unit 4 has been dropped, the light emitting devices 7 are illuminated. This can help a user to locate the remote transmitter unit 2, for example after it has been inadvertently dropped. At least in certain embodiments, the light emitting devices 7 may remain illuminated for a predetermined time period, for example one (1 ), three (3), five (5) or ten (10) seconds. The light emitting devices 7 in the present embodiment are light emitting diodes (LEDs). In normal use, the light emitting devices 7 may optionally provide an indication of the operating status of the remote transmitter unit 2. For example, the light emitting devices 7 may be illuminated when the control interface 8 is operated by a user. Alternatively, or in addition, the light emitting devices 7 may provide a backlight function for the control interface 8. The acceleration measured by the three-axis accelerometer 6 during a test scenario is illustrated in Figure 3. The controller 4 reads the acceleration signal SXYZ to monitor the acceleration of the remote transmitter unit 2. During a first time period T1 , the controller 4 identifies a steady-state condition when a consecutive series of four (4) samples are approximately 9.81 m/s 2 . The measured acceleration during the first time period T1 is indicative of the remote transmitter unit 2 being supported, for example in a user's hand or pocket. The controller 4 is then placed in a primed state in dependence on detection of said steady-state condition. During a second time period T2, the controller 4 identifies a steady- state condition when a consecutive series of four (4) consecutive samples are approximately Om/s 2 . The measured acceleration during the second time period T2 is indicative of the remote transmitter unit 2 being in a falling condition having been dropped. During a third time period T3, the controller 4 identifies an acceleration spike consisting of a single sample greater than 9.81 m/s 2 . The acceleration spike is indicative of the remote transmitter unit 2 coming into contact with the ground or another object. During a fourth time period T4, the controller 4 identifies a single sample substantially equal to 9.81 m/s 2 . The measured acceleration during the fourth time period T4 is indicative of the remote transmitter unit 2 being in a stationary condition, for example on the ground.

The controller 4 may optionally be configured to perform additional checks to identify that the remote transmitter unit 2 has been dropped. As outlined above, when the remote transmitter unit 2 is dropped, the decrease in the measured acceleration is typically followed by an acceleration spike when the remote transmitter unit 2 contacts the ground (or another object). The controller 4 may be configured to identify this spike from the measured acceleration. The controller 4 may be configured to identify that the remote transmitter unit 2 has been dropped when the measured acceleration increases to more than a predefined upper acceleration threshold Tup. The upper acceleration threshold TUP may, for example, be predefined as 1 .5g (approximately 14.7 m/s 2 ). The upper acceleration threshold TUP may be calibratable, for example to correspond to a drop from a predetermined height, say 0.5m. The controller 4 may be configured to output the drop notification signal SD only when this increase in the measured acceleration is detected. It will be appreciated that this check may be performed instead of, or in addition to the technique(s) described herein to identify the falling condition.

The controller 4 may optionally also be configured to continue monitoring the acceleration signal SXYZ after the remote transmitter unit 2 contacts the ground, for example to determine if the remote transmitter unit 2 is picked up by a user. If the remote transmitter unit 2 comes to rest and is not picked up, there will be little or no change in the measured acceleration (since it will remain stationary on the ground). The controller 4 may be configured to monitor the acceleration signal SXYZ to detect movement. If no movement is detected, the controller 4 may continue to output the drop notification signal SDRP. If movement is detected, the controller 4 may inhibit the output of the drop notification signal SDRP to deactivate the light emitting devices 7. This technique could be refined such that the controller 4 monitors the acceleration signal SXYZ to detect acceleration typically associated with picking up the remote transmitter unit 2. This functionality could be used automatically to switch off the light emitting devices 7 when the remote transmitter unit 2 is picked up again.

A further embodiment of the present invention will now be described with reference to Figure 4. The electronic control unit 14 provided in the vehicle is configured to determine a location of the remote transmitter unit 2 relative to the vehicle 1 when the remote transmitter unit 2 is dropped. In other words, the electronic control unit 14 is operable to determine a drop location of the remote transmitter unit 2. Like reference numerals are used for like components.

The electronic control unit 14 is operable to implement a location identification module 16 for determining the location of the remote transmitter unit 2. The location identification module 16 may be a dedicated module or may form part of an existing tracking system for the remote transmitter unit 2, such as an enhanced Passive Entry and Passive Start (ePEPS). As illustrated in Figure 4, the processor 10 is coupled to two or more vehicle transceivers 17- n for communicating with the remote transmitter unit 2. The vehicle transceivers 17-n each have an integrated antenna and are configured to transmit and receive radio frequency (RF) signals. In the present embodiment, the vehicle transceivers 17-n are ultra-wideband transceivers. The vehicle transceivers 17-n are disposed on the vehicle 1 . The vehicle transceivers 17-n are spaced apart from each other in a predefined configuration. In the present embodiment, there are three (3) of said vehicle transceivers 17-1 , 17-2, 17-3. The spatial positions of the first, second and third vehicle transceivers 17-1 , 17-2, 17-3 relative to each other are stored in system memory and may be accessed by the electronic control unit 14. A first vehicle transceiver 17-1 is located at the rear of the vehicle 1 ; and second and third vehicle transceivers 17-2, 17-3 are located on the right and left sides respectively of the vehicle 1 .

The vehicle transceivers 17-n are connected to the electronic control unit 14. The distance from each of the first, second and third vehicle transceivers 17-n to the remote transceiver 18 (which is disposed in the remote transmitter unit 2) may be determined by measuring a time-of-flight of at least one signal transmitted to and/or from the remote transmitter unit 2. In dependence on the known spatial positioning of the first, second and third vehicle transceivers 17-1 , 17-2, 17-3, the location identification module 16 implemented by the electronic control unit 14 may perform a triangulation calculation (in either two-dimensions or three-dimensions) to determine the location of the remote transmitter unit 2 in relation to the vehicle 1 . The use of ultra-wideband frequencies (typically greater than 3GHz) allows the location of the remote transmitter unit 2 to be tracked with a relatively high degree of accuracy.

The remote transmitter unit 2 is configured to generate a drop notification signal SD upon detection of a falling condition. The remote transmitter unit 2 comprises a controller 4 and a remote transceiver 18. The controller 4 is configured to measure acceleration to detect when the remote transmitter has been dropped. The operation of the controller 4 to detect a falling condition and to generate the drop notification signal SD is the same as the other embodiment(s) described herein. For the sake of brevity, the generation of the drop notification signal SD WIII not be described in relation to the present embodiment. The remote transceiver 18 comprises an integrated antenna and is configured to transmit and receive radio frequency (RF) signals. The remote transceiver 18 is an ultra-wideband transceiver. In use, the remote transceiver 18 is operable to communicate with the location identification module 16 implemented by the processor 10. The remote transmitter unit 2 is portable and is typically carried by the user. As described herein, the remote transmitter unit 2 communicates with the electronic control unit 14 to enable determination of a location of the remote transmitter unit 2 when the drop notification signal SD is received.

The drop notification signal SD is transmitted by the remote transceiver 18 as a wireless (RF) signal to the vehicle transceivers 17-1 , 17-2, 17-3. The electronic control unit 14 is configured to determine the location of the remote transmitter unit 2 in dependence on the drop notification signal SD. The vehicle transceivers 17-1 , 17-2, 17-3 may each record the time at which the drop notification signal SD is received, for example generating first, second and third timestamps. The electronic control unit 14 is operable to compare the time at which the drop notification signal SD is received by each of the vehicle transceivers 17-1 , 17-2, 17- 3. The location of each of the vehicle transceivers 17-1 , 17-2, 17-3 on the vehicle 1 is stored in system memory, for example as X, Y and Z coordinates. With reference to the stored position of each of the vehicle transceivers 17-1 , 17-2, 17-3, the location identification module 16 may use the differences in the time at which the signal is received by each of the vehicle transceivers 17-1 , 17-2, 17-3 to triangulate the location of the remote transmitter unit 2 in relation to the vehicle 1 . The electronic control unit 14 is configured to output a location signal SL to indicate the determined location of the remote transmitter unit 2. The location signal SL comprises a direction component representing a direction of the remote transmitter unit 2 relative to the vehicle 1 . The direction component of the location signal SL may, for example, indicate a bearing of the remote transmitter unit 2 with respect to the vehicle 1 . The location signal SL may optionally comprise a distance component representing a distance of the remote transmitter unit 2 from the vehicle 1 . The distance may be determined based on time-of-flight of a signal relayed between the remote transmitter unit 2 and one or more of the vehicle transceivers 17-1 , 17-2, 17-3. Alternatively, or in addition, the strength of a signal received from the remote transmitter unit 2 may provide an indication of the distance.

If required, the electronic control unit 14 may communicate with the remote transmitter unit 2, for example to perform a polling/authentication procedure. Alternatively, or in addition, the communication between the electronic control unit 14 and the remote transmitter unit 2 may be used to refine the location of the remote transmitter unit 2, for example by measuring a time-of-flight of a signal transmitted by said vehicle transceivers 17-1 , 17-2, 17-3 to the remote transmitter unit 2; and/or by measuring a time-of-flight of a signal transmitted by the remote transmitter unit 2 to the vehicle transceivers 17-1 , 17-2, 17-3. The communication with the remote transmitter unit 2 may be appropriate to identify the location of the remote transmitter unit 2 after detection of the falling condition, for example if the remote transmitter unit 2 travels after being dropped.

The location signal SL is output to a communication bus (not shown) on the vehicle 1 and may be read by other vehicle systems. The location signal SL in the present embodiment is used to control operation of one or more external vehicle lights 19 provided on the vehicle 1 to provide an indication of the location of the remote transmitter unit 2. In use, the location signal SL is used selectively to illuminate the external vehicle light 19 disposed closest to the determined location of the remote transmitter unit 2. The external vehicle light 19 may thereby provide a visual indication of the determined location of the remote transmitter unit 2, for example indicating a quadrant or sector corresponding to the determined direction of the remote transmitter unit 2 to the vehicle 1 . The external vehicle lights 19 may, for example, comprise one or more of the following: head lamps, side lights, signalling (indicator) lights, brake lights, reversing lights, puddle lights, and fog lights. In the arrangement illustrated in Figure 4, the location signal SL indicates that the remote transmitter unit 2 has been dropped in a rear right-hand quadrant and, in dependence on the location signal SL, a rear signalling light 19 on the right hand side of the vehicle 1 is illuminated, thereby providing a user with an indication of the location of the remote transmitter unit 2. In arrangements in which the external vehicle light 19 comprises a plurality of light sources, such as light emitting diodes (LEDs), only some of the light sources may be illuminated to provide a more accurate indication of the determined location of the remote transmitter unit 2. In a variant, the location signal SL may be output to a display screen 20 provided in the vehicle 1 , for example disposed in a centre console, a dashboard or an instrument cluster. The display screen 20 could, for example, provide a graphical indication of a determined direction of the remote transmitter unit 2 in relation to the vehicle 1 . Alternatively, or in addition, the display screen may provide a graphical indication of a distance of the remote transmitter unit 2 from the vehicle 1 . The determined location of the remote transmitter unit 2 may be output to a remote computational device 21 , such as a personal computer or a cellular telephone, such as a smart phone. A graphical representation of the determined location of the remote transmitter unit 2 with respect to the vehicle 1 may be displayed on the remote computational device 21 . The location signal may be sent (either directly or indirectly, for example via a vehicle/cloud server) to the remote computational device 21 .

In the present embodiment, the electronic control unit 14 determines the location of the remote transmitter unit 2. In a variant, the controller 4 provided on-board the remote transmitter unit 2 may be operable to determine the location of the remote transmitter unit 2. By way of example, the controller 4 may be configured to output a drop notification signal SD when a measured acceleration indicates that the remote transmitter unit 2 has been dropped. The remote transceiver 18 transmits the drop notification signal SD as a wireless (RF) signal to the vehicle transceivers 17-1 , 17-2, 17-3. A response is transmitted back to the remote transmitter unit 2 upon receipt of the drop notification signal SD. The vehicle transceivers 17-1 , 17-2, 17-3 may, for example, each transmit a unique signal which is received by the remote transceiver 18. The differences in the time-of-flight of the signals from each of the vehicle transceivers 17-1 , 17-2, 17-3 may be determined and may be used to triangulate the location of the remote transmitter unit 2. The determined location of the remote transmitter unit 2 may then be transmitted to the electronic control unit 14 or to a remote computational device, such as a personal computer or a cellular telephone.

The electronic control unit 14 may determine the location of the remote transmitter unit 2 in two-dimensions, for example in a horizontal plane. The location of the remote transmitter unit 2 may be determined in two-dimensions using at least first and second vehicle transceivers 17-1 , 17-2. Alternatively, the electronic control unit 14 may determine the location of the remote transmitter unit 2 in three-dimensions, for example to indicate a vertical position of the remote transmitter unit 2. The location of the remote transmitter unit 2 may be determined in three-dimensions using three or more vehicle transceivers 17-n.

The drop notification signal SD may be transmitted periodically to facilitate determination of the location of the remote transmitter unit 2. For example, the controller 4 may be configured to transmit the drop notification signal SD for a predetermined time period, say two (2) minutes, following detection of a falling condition. The remote transceiver 18 may be used to communicate with the electronic control unit 14 to perform polling/authentication functions. In a modified arrangement, the remote transceiver 18 may be replaced with a transmitter.

It will be appreciated that various modifications may be made to the embodiment(s) described herein without departing from the scope of the appended claims.

The remote transmitter unit 2 could be modified to transmit a wireless signal to the vehicle 1 upon determining that the remote transmitter unit 2 has been dropped. The vehicle 1 could be configured to illuminate an internal light and/or an external light in dependence on said receipt of said wireless signal from the remote transmitter unit 2. For example, the vehicle could be configured to illuminate "puddle" lights disposed in side mirrors. The remote transmitter unit 2 has been described herein as comprising a three-axis accelerometer 6. In alternative arrangements, the three-axis accelerometer 6 may be replaced with a trembler switch (not shown) configured to generate an actuation signal when the remote transmitter unit 2 experiences a shock, for example when it contacts a surface after having been dropped. A change in state of the trembler switch could be detected by the remote transmitter unit 2 which could generate the drop notification signal SD to activate the light emitting devices 7. An advantage of the use of a trembler switch is that the current drawn is zero when not in use.

It will be appreciated that the sampling rate of the three-axis accelerometer 6 could be changed, for example to increase the sampling frequency or to provide continuous sampling.

The controller 4 described herein is configured to determine that the remote transmitter unit 4 has been dropped. Alternatively, or in addition, the controller 4 may be configured to identify other predefined acceleration events. For example, the controller 4 may be configured to identify when the remote transmitter unit 2 has been shaken.

In a further variant, the three-axis accelerometer 6 could be used to implement an additional security feature. For example, the controller 4 may be configured to transmit said access signal SACC only when movement of the remote transmitter unit 2 is detected. This could protect against possible scenarios where the remote transmitter unit 2 is not in use, for example inside a home, and the access signal SACC is boosted to gain unauthorised access to the vehicle 1 .