WO2017033014A2

WO2017033014A2 - Devices and methods for monitoring driver behaviour

Info

Publication number: WO2017033014A2
Application number: PCT/GB2016/052633
Authority: WO
Inventors: Paul Michael FELLOWS
Original assignee: E Touch Solutions Limited
Priority date: 2015-08-24
Filing date: 2016-08-24
Publication date: 2017-03-02
Also published as: GB201515025D0; GB2541668B; WO2017033014A3; GB2541668A

Abstract

Methods and devices for monitoring driver behaviour in a vehicle are disclosed. In one aspect, a method is provided for monitoring driver behaviour in a vehicle using a device comprising a three-axis accelerometer. The method comprises identifying a horizontal plane of the device when the vehicle is stationary repeatedly deriving, from an output of the accelerometer, an acceleration vector resolved in the horizontal plane, repeatedly comparing the magnitude of the resolved acceleration vector with an orientation- independent pre-determined threshold value during operation of the vehicle, and initiating a high-risk event response protocol of the device when the magnitude of the resolved acceleration vector exceeds the orientation-independent pre-determined threshold value. The device may include a connector arranged to mate with an accessory socket of the vehicle and to receive an electrical supply from the vehicle when the device is mated with the socket and a detector module configured to determine a connection state of the device and an engine running state of the vehicle based on voltage measurements at the connector.

Description

DEVICES AND METHODS FOR MONITORING DRIVER BEHAVIOUR

[0001 ] The present invention relates to devices and methods for monitoring driver behaviour in a vehicle. In particular, but not exclusively, the invention relates to methods for identifying high-risk events, and to an aftermarket plug-in telematics device suitable for connection to a vehicle accessory socket.

[0002] The use of telematics devices to monitor vehicle movement and driver behaviour is well known. Telematics devices for vehicle monitoring typically include one or more modules for determining data relating to various aspects of the status of the vehicle, and a communication function to allow transmission of the data to a remote server.

[0003] For example, some known telematics devices include a global positioning system (GPS) receiver to allow the position of the vehicle over time to be determined. Some devices also include one or more sensors, such as an accelerometer and/or a gyroscope, and data from these sensors can be interpreted to determine information about vehicle behaviour. It is also known to include an interface for receiving information from the vehicle's engine control computer to determine characteristics such as speed, distance driven, braking force, throttle application and so on. To record and analyse data from these features, a processor and a memory may be provided.

[0004] Telematics devices have applications in various fields, including vehicle tracking, vehicle security, emergency service call-out and so on. One increasingly popular application of telematics devices is in the auto or motor insurance industry, where the information provided by a device mounted in a customer's vehicle can be used to assess an individual risk-based premium to be applied to each particular customer's insurance policy. This has led to the introduction of several new insurance products.

[0005] For instance, information obtained from a telematics device relating to the distance driven in a given time period can be used to facilitate "pay-as-you-drive" insurance policies, in which an element of the insurance premium increases with the distance driven. The distance information can be supplemented with information relating to the corresponding time of day, allowing for example the greater risk of driving late at night to be charged at a higher rate. [0006] Devices that record additional information about the vehicle and the driver's behaviour can be used to assess a customer's insurance premium based on historical data relating to driver behaviour over a corresponding time period. Where the behaviour data is indicative of a low accident risk (such as gentle control inputs, modest speeds, driving during daylight hours, and driving on relatively safe roads), a relatively low insurance premium may be assessed. In contrast, when the behaviour data is indicative of a higher accident risk (exhibiting, for example, extreme control inputs, high speeds, driving at night and on more dangerous roads), the insurance premium may increase. Such schemes can be attractive to customers since they can allow access to reduced insurance premiums and further rewards for careful driving behaviour.

[0007] To be effective in such an application, a telematics device must be present in the customer's vehicle whenever the vehicle is in use, and it must be provided with a reliable source of power. Devices that include sensors such as accelerometers should ideally be mounted securely to the vehicle body, so that movement of the vehicle is picked up by the device and so that the data is not compromised by movement of the device that does not relate to driving behaviour. To this end, various practical solutions to providing telematics devices in vehicles for insurance monitoring purposes have been proposed.

[0008] One common approach is for the insurance provider to install a telematics device into a customer's vehicle. Typically, in such cases, the device is mounted under the bonnet or behind the dashboard of the vehicle and is secured to the vehicle body. The device can be connected to the vehicle battery to provide a permanent power supply, and connections to other vehicle systems may also be made, for example via the vehicle control area network (CAN) bus or to the on board diagnostics (OBD) port. With this approach, no intervention from the driver is required for operation of the device, and the device is always present in the customer's vehicle. However, installation of the device may require some modification of the vehicle (such as the drilling of mounting holes for the device and/or splicing of the wiring loom), which may not be desirable. Also, because professional installation of the device is required, the costs associated with this approach can be relatively high.

[0009] Another proposed approach is to provide a dedicated portable telematics device that can be easily installed and removed by the user. Conveniently, such a device may include a housing containing a GPS receiver, a processor, a cellular data transmitter and various sensors, and an integral connector for a conventional vehicle accessory socket or cigarette lighter receptacle. In this way, the device can be plugged into the vehicle accessory socket both to secure the device to the vehicle body while in use, and to provide a source of power to the device. Examples of such devices are described in UK Patent No. GB 2498793 and United States Patent Application Publication No. US 2013/0226369.

[0010] Unlike the above-described hard-wired, permanently installed devices, portable plug-in telematics devices of this type do not require professional installation or vehicle modification, and can therefore be more attractive to insurance providers and to customers. However, the data that can be provided by a portable, removable telematics device is typically limited compared with a hard-wired device, since there is no connection to the vehicle's CAN bus or OBD port. Furthermore, because the device can be removed from the accessory socket at any time by the user, there is an increased risk that relevant data may not be recorded or transmitted by the device.

[001 1 ] Calibration of user-installable devices of this type is also more challenging than for permanently installed devices. A typical vehicle accessory socket is of a cylindrical design, so that the corresponding connector can be fitted in substantially any angular orientation. Furthermore, the position of accessory sockets may differ between vehicles, and some vehicles have multiple sockets in different locations. Accordingly, it is not generally possible to predict the at-rest orientation of such a device for calibration purposes.

[0012] It would therefore be desirable to provide improved user-installable telematics devices which overcome or mitigate some of these problems.

[0013] From a first aspect, the present invention resides in a method for monitoring driver behaviour in a vehicle using a device comprising a three-axis accelerometer, the method comprising identifying a horizontal plane of the device when the vehicle is stationary, repeatedly deriving, from an output of the accelerometer, an acceleration vector resolved in the horizontal plane, repeatedly comparing the magnitude of the resolved acceleration vector with an orientation-independent pre-determined threshold value during operation of the vehicle, and initiating a high-risk event response protocol of the device when the magnitude of the resolved acceleration vector exceeds the orientation-independent pre-determined threshold value.

[0014] Because the method includes identifying a horizontal plane of the device when the vehicle is stationary, it is not necessary to know the orientation of the device in advance. Accordingly, the method is particularly useful when employed in removable aftermarket devices that are typically used in the cabin of the vehicle, such as devices that are plugged into an accessory socket of the vehicle. [0015] Furthermore, because the magnitude of the acceleration vector resolved in the horizontal plane is compared with an orientation-independent threshold value, it is not necessary to determine the orientation of the device or the vehicle in the horizontal plane. Said another way, the method does not require determination of the direction of forward motion of the vehicle. Accordingly, the method provides a simple way of identifying high-risk driving behaviour events without the need for complex statistical analysis.

[0016] The comparison of the magnitude of the resolved acceleration vector with the threshold value is advantageously performed in the device, so that a high-risk event protocol of the device can be triggered immediately on detection of a high-risk event. By performing the processing in the device, the need to store and transfer large quantities of data from the device to another device or computer for analysis can be avoided.

[0017] The high-risk event response protocol may comprise transmitting data from the device to a remote computer. The remote computer is preferably external to the vehicle. For example, the remote computer may be a remote server hosted by an insurance provider. Data transmission may be performed by a cellular modem or other transmitter of the device. [0018] The high-risk event response protocol may comprise recording data to a memory of the device. Data may be recorded to the memory of the device before transmission of the data to the remote computer.

[0019] The transmitted and/or recorded data may comprise event data. For example, the transmitted and/or recorded event data may comprise an indicator that a high-risk event has occurred, which may be referred to as a driving standards alert. The transmitted and/or recorded event data may comprise date, time, location, vehicle speed, and/or other relevant information that is associated with the high-risk event. The event data may therefore provide information about the occurrence of a high-risk event. The event data is preferably data generated by the processor in response to the identification of a high-risk event.

[0020] The transmitted and/or recorded data may comprise vehicle usage data. The vehicle usage data may provide information about the behaviour of the vehicle around the time of a high-risk event. The vehicle usage data is preferably data that is derived from the sensors, receivers and/or detectors of the device, and may comprise data that would be generated during normal data logging operations.

[0021 ] For example, the vehicle usage data may comprise acceleration data derived from the accelerometer and/or sensor data derived from one or more further sensors of the device. The further sensors may include a gyroscope, microphone, magnetometer (compass), or any other sensor useful for monitoring the behaviour of a vehicle and its driver. The device may comprise a positioning system receiver, and the vehicle usage data may comprise positional data derived from the positioning system receiver. The device may include a connection state detector for monitoring a connection state of the device and/or an engine running state detector for determining an engine running state of the vehicle, and the vehicle usage data may comprise the connection state and/or the engine running state derived from such detectors.

[0022] The high-risk event response protocol may comprise recording and/or transmitting vehicle usage data at an increased rate, to provide a more accurate indication of the behaviour of the vehicle around the time of a high-risk event.

[0023] The device may store vehicle usage data in a buffer memory during operation of the vehicle. When the buffer memory is full, the oldest entries in the buffer memory may be overwritten with newer data. The high-risk event response protocol may comprise transmitting the contents of the buffer memory to the remote computer and/or copying the contents of the buffer memory to an event log memory of the device. In this way, when a high-risk event is detected, the most recent vehicle usage data can be captured for further analysis by the device and/or the remote computer.

[0024] The magnitude of the resolved acceleration vector is preferably compared with the orientation-independent pre-determined threshold value at a frequency of at least 5 Hertz, and more preferably at a frequency of at least 10 Hertz. Accordingly, the device provides for "quasi-peak" monitoring of the accelerometer output, which is an improvement over prior art devices in which detection of high-risk events is based on data averaged over a GPS time segment (typically 1 -2 seconds).

[0025] The method may comprise monitoring a connection state of the device and a running state of an engine of the vehicle, and determining that the vehicle is stationary when the device is in a connected state and the engine is in an ignition-off state or a non-running state. In this way, the horizontal plane of the device can be determined when the device has been connected to the vehicle but before the engine has been started at the beginning of a driving session. If the vehicle is equipped with a start-stop function, the horizontal plane of the device could also be re-calibrated during an engine stop event in the course of a driving session.

[0026] The device may comprise a connector arranged to receive a voltage supply from an accessory socket of the vehicle, and the method may comprise determining the connection state of the device and the engine running state of the vehicle based on voltage measurements at the connector. Alternatively, or in addition, the method may comprise verifying that the vehicle is stationary using a positioning system receiver.

[0027] Identifying the horizontal plane of the device may comprise obtaining acceleration vector components from the output of the accelerometer, resolving the acceleration vector components into a vertical acceleration vector having a magnitude equal to gravitational acceleration, and identifying the horizontal plane as a plane normal to the vertical acceleration vector.

[0028] The invention extends to a device for monitoring driver behaviour in a vehicle, comprising a three-axis accelerometer, a processor configured to receive an output signal from the accelerometer and to process the output signal, and a transmitter configured to transmit data to a remote computer external to the vehicle. The device is arranged to perform the method of the first aspect of the invention. The device may further comprise a connector arranged to mate with an accessory socket of the vehicle and to receive an electrical supply from the vehicle when the device is mated with the socket, and a detector module configured to determine a connection state of the device and an engine running state of the vehicle based on voltage measurements at the connector. The detector module may be integrated with the processor.

[0029] The invention further extends to a computer program product comprising instructions that, when executed, implement the method of the first aspect of the invention, and to a non-transient storage medium comprising computer-executable instructions that, when executed, implement the method of the first aspect of the invention. [0030] According to a second aspect of the present invention, there is provided a telematics device for monitoring driver behaviour in a vehicle. The device comprises a connector arranged to mate with an accessory socket of the vehicle and to receive an electrical supply from the vehicle when the device is mated with the socket. The connector has a first electrical contact arranged to engage with a first supply terminal of the accessory socket and a second electrical contact arranged to engage with a second supply terminal of the accessory socket. The device also comprises an internal power source to provide power to the device when no electrical supply from the vehicle is received, a detector module configured to determine a connection state of the device and an engine running state of the vehicle based on voltage measurements at the connector, and a transmitter arranged to transmit data associated with the connection state and the engine running state to a remote computer. [0031 ] The device is preferably a plug-in, user-installable aftermarket device, which can be simply fitted to a vehicle without the need for modification of the vehicle or professional installation. However, by virtue of the detector module, the device is able to obtain information about the current operating mode or running state of the vehicle engine that would not otherwise be available from a user-installable, plug-in device. Such information can be useful in monitoring driver behaviour, since for example it allows identification of changes in the status of a vehicle during its operation, such as engine starting and engine stopping events.

[0032] The device is also able to determine, using the detector module, whether or not it is connected to the accessory socket of a vehicle. This information can be used for example to identify when the user has plugged the device into the accessory socket. The device may use the identification of this action as a trigger to begin initialisation and calibration procedures to ready the device for monitoring the driver behaviour when the journey starts. Similarly, the device may detect when the user has unplugged the device, which may trigger the device to transmit stored data to the remote computer.

[0033] The ability of the device to determine both the engine running state and the device connection state provides a particularly useful combination of data that can be used to identify and discriminate between certain events that might otherwise be indistinguishable without more complex analysis and inputs from other sensors. For instance, using information determined by the detector module, the device can distinguish between the disconnection of the device from the accessory socket mid- journey and the vehicle ignition being switched off at the end of a journey. [0034] The remote computer is preferably external to the vehicle. The transmitter may comprise a cellular modem. In these ways, the device can communicate directly with an external remote computer, without the need to rely on another device, such as a user's mobile telephone, to provide connectivity with the remote computer.

[0035] Preferably, the connector further comprises a third electrical contact arranged to connect electrically with the second electrical contact by way of the second supply terminal when the device is mated with the accessory socket. In other words, the second and third electrical contacts may be electrically isolated from one another except when the device is mated with the accessory socket, at which point the second and third electrical contacts are electrically short-circuited by the accessory socket. [0036] In one example, the connector may be generally elongate for insertion into an aperture of the accessory socket. The first electrical contact may be disposed at an end of the connector and the second and third electrical contacts may each be disposed on a side of the connector. In this way, the connector may be designed to mate with a vehicle accessory socket comprising a cigarette lighter receptacle.

[0037] When a third electrical contact is present, the detector module may be configured to check for a short-circuit between the second and third electrical contacts thereby to determine the connection state of the device. For example, if a short-circuit between the second and third electrical contacts is detected, the device may determine that the connector is mated with the accessory socket. The internal power source of the device may preferably be utilised when checking for a short-circuit.

[0038] Preferably, the detector module is configured to determine whether a vehicle supply voltage is present between the first electrical contact and the second electrical contact and, if no vehicle supply voltage is detected, to connect the second electrical contact to a ground potential of the internal power source by way of a pull-down load, connect the third electrical contact to a reference potential of the internal power source, and measure the voltage at the second electrical contact thereby to determine the connection state of the device.

[0039] The detector module may also be configured such that, when the measured voltage at the second electrical contact is substantially equal to the reference potential applied to the third electrical contact, the detector module determines that the device is in a connected state and that the engine is in an ignition-off state. In one embodiment, the detector module is configured such that, when the measured voltage at the second electrical contact is not substantially equal to the reference potential applied to the third electrical contact, the detector module determines that the device is in a non-connected state.

[0040] In these ways, the device can automatically sense when it has been mated with or removed from the vehicle accessory socket. Furthermore, because the connection state of the device is determined based on voltage measurements at the connector, a simple and robust solution is achieved compared with, for example, using a mechanical contact switch or similar device.

[0041 ] The detector module is preferably configured to measure the supply voltage between the first electrical contact and the second electrical contact, and to compare the measured supply voltage to a plurality of threshold voltages to determine the engine running state.

[0042] For example, in one embodiment, the detector module may be configured to determine that the engine is in a running state when the measured supply voltage is greater than a battery charging threshold voltage. The detector module may be configured to determine that the engine is in a non-running state when the measured supply voltage is between a lower base battery threshold voltage and an upper base battery threshold voltage. The detector module may also be configured to determine that the engine is in a cranking state when the measured supply voltage is between a lower cranking threshold voltage and an upper cranking threshold voltage.

[0043] In these ways, the device is able to gain information about the engine running state using voltage measurements at the connector, without the need for the device to interface with the vehicle control system.

[0044] The device may further comprise a processor for receiving an output from the detector module and/or a memory for storing data derived from the detector module and/or the processor. The processor may be configured to identify changes in the connection state of the device and/or the engine running state of the vehicle, and to write corresponding event data to the memory. The processor may be further configured to transmit the event data to the remote computer by way of the transmitter.

[0045] The determined connection state and engine running state information can be used to supplement other information relating to driver behaviour or vehicle use that may be generated by the device. For example, the device may include a positioning system receiver and/or a plurality of sensors. The device may include a memory, and a processor configured to write vehicle usage data derived from the detector module and, when present, the receiver and/or the sensors to the memory. The processor may be configured to identify changes in the connection state of the device and/or the engine running state of the vehicle, and to write corresponding event data to the memory, and the processor may be further configured to associate the event data with the vehicle usage data. The processor may be further configured to transmit the event data and the vehicle usage data to the remote computer by way of the transmitter.

[0046] The ability of the device to determine its connection state and the engine running state can be employed to facilitate calibration of a sensor of the device. For example, in one embodiment, the device includes a sensor comprising a three-axis accelerometer. In this case, the processor may be configured to determine the spatial orientation of the device based on an output of the accelerometer when the detector module determines that the device is in a connected state and the engine is in an ignition-off state or a non-running state.

[0047] Preferably, the device comprises a housing for the internal power source, the transmitter, the detector module and other optional or preferred device components. The connector may be integral with the housing, so that when the connector is mated with the vehicle accessory socket, the device is held in position within the vehicle. In this way, no other apparatus is required to mount the device in the vehicle. In an alternative embodiment, however, the connector is not integral with the housing and is instead connected or connectable to the housing by way of a cable. [0048] From a third aspect, the invention resides in a method for monitoring driver behaviour in a vehicle using a telematics device comprising a three-axis accelerometer. The method comprises identifying a horizontal plane of the device when the vehicle is stationary, deriving, from an output of the accelerometer, an acceleration vector resolved in the horizontal plane, monitoring the magnitude of the resolved acceleration vector during movement of the vehicle and, if the magnitude of the resolved acceleration vector exceeds an orientation-independent pre-determined threshold value, identifying that a high-risk event has occurred.

[0049] The device is preferably connectable to the vehicle, and the method may comprise monitoring a connection state of the device and a running state of an engine of the vehicle, and determining that the vehicle is stationary when the device is in a connected state and the engine is in an ignition-off state or a non-running state. In this way, the method may be used to monitor driver behaviour in a vehicle using a telematics device in accordance with the second aspect of the invention. The method may further comprise verifying that the vehicle is stationary using a positioning system receiver.

[0050] In one embodiment, the method includes identifying the horizontal plane of the device by obtaining acceleration vector components from the output of the accelerometer, resolving the acceleration vector components into a vertical acceleration vector having a magnitude equal to gravitational acceleration, and identifying the horizontal plane as a plane normal to the vertical acceleration vector.

[0051 ] The method may further comprise initiating a high-risk event protocol of the device upon identifying that a high-risk event has occurred. [0052] The present invention also extends to a telematics device for monitoring driver behaviour in a vehicle, comprising a three-axis accelerometer, a processor configured to receive an output signal from the accelerometer and to process the output signal to identify when high-risk events have occurred, and a transmitter configured to transmit data relating to the high-risk events to a remote computer. The processor is further configured to identify a horizontal plane of the device when the vehicle is stationary, derive, from the output signal, an acceleration vector resolved in the horizontal plane, compare the magnitude of the resolved acceleration vector to an orientation-independent pre-determined threshold value during movement of the vehicle and, if the magnitude of the resolved acceleration vector exceeds the pre-determined threshold value, record that a high-risk event has occurred.

[0053] The device may further comprise a connector arranged to mate with an accessory socket of the vehicle and to receive an electrical supply from the vehicle when the device is mated with the socket, and a detector module configured to determine a connection state of the device and an engine running state of the vehicle based on voltage measurements at the connector, and the processor may be configured to determine that the vehicle is stationary when the device is in a connected state and the engine is in an ignition-off state or a non-running state. The device may comprise a positioning system receiver, in which case the processor may be configured to verify that the vehicle is stationary using the positioning system receiver.

[0054] In one embodiment, the processor is configured to obtain acceleration vector components from the output of the accelerometer, resolve the acceleration vector components into a vertical acceleration vector having a magnitude equal to gravitational acceleration, and identify the horizontal plane as a plane normal to the vertical acceleration vector. The processor may be configured to initiate a high-risk event response protocol of the device upon identifying that a high-risk event has occurred.

[0055] Preferred and/or optional features of each aspect of the invention may be used, alone or in appropriate combination, in the other aspects of the invention also.

[0056] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which like reference signs are used for like features, and in which:

Figure 1 is a schematic drawing of a telematics device according to the invention;

Figure 2 is a block diagram of the telematics device of Figure 1 ; Figure 3 illustrates a method of operation of the telematics device of Figure 1 ;

Figure 4 illustrates a method of determining a connection state of the device of Figure 1 ; Figure 5 illustrates a method of determining an engine running state of a vehicle using the device of Figure 1 ;

Figure 6 is a schematic illustration of a tyre adhesion ellipse; Figure 7 provides schematic illustrations of acceleration vectors on the tyre adhesion ellipse of Figure 6;

Figure 8 is a schematic illustration of an acceleration vector and thresholds on the tyre adhesion ellipse of Figure 6;

Figure 9 illustrates different possible orientations of the device of Figure 1 ; Figure 10 illustrates further possible orientations of the device of Figure 1 ;

Figure 1 1 is a schematic illustration of the resolution of acceleration vectors; Figure 12 is a schematic illustration of a threshold boundary on the tyre adhesion ellipse of Figure 6;

Figure 13 is a schematic illustration of multiple threshold boundaries on the tyre adhesion ellipse of Figure 6;

Figure 14 illustrates a method for monitoring driver behaviour according to the present invention;

Figure 15 illustrates a protocol for calibrating a telematics device;

Figure 16 illustrates a method of execution of a high-risk event protocol;

Figure 17 illustrates a method of logging data to a buffer memory; and Figure 18 illustrates a further method of execution of a high-risk event protocol.

[0057] Figure 1 shows a telematics device 100 in accordance with a first embodiment of the present invention. The telematics device 100 comprises a housing 102 that contains internal components of the device, and a connector 104 for connecting the device to a vehicle. The connector 104 is integrated with the housing 102.

[0058] The connector 104 is designed to mate with a standard vehicle accessory socket, also known as a cigarette lighter receptacle (not shown). As is known in the art, a standard vehicle accessory socket of this type comprises a generally tubular or cup- shaped body that is open at one end to form a female socket for receiving a corresponding male connector. A first electrical terminal is disposed at a closed end of the body, opposite the open end. A second electrical terminal, which is normally ring- shaped, is provided on the inner side walls of the socket. The first and second electrical terminals receive power from the vehicle battery, with the first terminal typically connected to a positive feed of the vehicle electrical supply and the second terminal connected to the ground of the vehicle electrical supply. [0059] Referring back to Figure 1 , the connector 104 is generally elongate and cylindrical. The connector 104 includes a first electrical contact 106, disposed at the end of the connector 104, and second and third electrical contacts 108, 1 10 which are disposed on opposite sides of the connector 104. The contacts 106, 108, 1 10 are arranged to connect with the terminals of the socket when the connector 104 is inserted in the socket. The first electrical contact 106 is arranged to connect with the first electrical terminal of the accessory socket, and the second and third electrical contacts 108, 1 10 are spring-loaded, so that they each press against and connect with the second electrical terminal of the socket.

[0060] Because the connector 104 mates positively with the socket, the device 100 is retained relatively securely in the vehicle when connected. The spring-loaded second and third contacts 108, 1 10 also serve to help retain the device 100 in the socket.

[0061 ] As shown in Figure 2, the first, second and third electrical contacts 106, 108, 1 10 are each connected to a detector module 1 12 of the device 100. As will be explained in more detail below, the detector module 1 12 is arranged to determine both a connection state of the device 100 (for example whether the device 100 is physically inserted in the accessory socket) and an engine running state of the vehicle (for example whether the engine of the vehicle is running, not running, or being started) based on voltage measurements at the electrical contacts 106, 108, 1 10.

[0062] The device 100 includes an internal power supply or battery 1 14, a processor 1 16, a transmitter module 1 18 and a memory 120. In this example, the device 100 also includes a positioning system receiver 122, for example a GPS receiver, an accelerometer 124 and, optionally, one or more further sensors 126 as may be known in the art of telematics devices. Referring back to Figure 1 , the device 100 may also include a charging connector 128, such as a USB socket, and an associated transformer (not shown) to allow power to be supplied to portable devices. The device may also include one or more indicator lamps 130 and/or control buttons 132 to indicate and/or control various functions of the device.

[0063] The internal battery 1 14 is of a rechargeable type, and is charged when the device 100 is receiving external power from the vehicle. The internal battery 1 14 can be used to power the device 100 for a time when the external power source is disconnected, either by the ignition being switched off (which typically cuts power to the accessory socket) or by the device 100 being disconnected from the socket.

[0064] During operation of the device 100, the processor 1 16 receives signals from the positioning system receiver 122, the accelerometer 124 and the other sensors 126. The processor is able to store data derived from these signals in the memory 120, and to periodically or continuously upload data to a remote computer or server (not shown) using the transmitter 1 18, as is generally known in the art. In this way, the telematics device 100 is able to communicate information to the remote computer that allows a determination of the behaviour of the driver of the vehicle, for example for use in insurance risk analysis, emergency calling, vehicle tracking, fleet management and so on.

[0065] In this example, the memory 120 includes a buffer memory 120a and an event log memory 120b. The buffer memory 120a is a circular buffer that can be used to record a continuous stream of vehicle usage data derived from the outputs of the positioning system receiver 122, the accelerometer 124 and the other sensors 126, with the contents of the buffer memory 120a being overwritten once the buffer memory 120a is full. In this way, the buffer memory 120a always contains the vehicle usage data most recently recorded by the device over a time period determined by the capacity of the buffer memory 120a and the recording resolution. For example, the buffer memory 120a preferably has capacity to store at least approximately 5 minutes, and more preferably at least approximately 10 minutes of vehicle usage data.

[0066] The event log memory 120b is a further area of memory that can be written to on a periodic or ad-hoc basis by the processor 1 16. The event log memory 120b is preferably not overwritten until the data in the event log memory 120b has been uploaded to the remote computer. The processor 1 16 may write event data to the event log memory 120b when the processor 1 16 detects that a particular event has occurred, such as the start of a driving session, the end of a driving session, or a high-risk driving event. The event data may include an indication of the type of event, along with further information associated with the event such as the time and date of the event, the location of the event and, if appropriate, the severity, duration and other quantifiable features of the event. When appropriate, vehicle usage data derived from the outputs of the positioning system receiver 122, the accelerometer 124 and the other sensors 126 may also be written directly to the event log memory 120b.

[0067] The processor 1 16 is also connected to the detector module 1 12. The detector module 1 12 performs a sequence of tests to provide additional information about the status of the device 100 and the vehicle. For example, the detector module 1 12 may operate in a sequence of steps as will now be described with reference to Figure 3.

[0068] Firstly, at step 201 , the detector module 1 12 determines whether external power is being supplied to the device 100 through the connector 104. To do so, the detector module 1 12 isolates the electrical contacts 106, 108, 1 10 of the connector 104 from the internal battery 1 14 and then the measures the voltage (potential difference) between the first electrical contact 106 and the second electrical contact 108 (or, equivalently, the third electrical contact 1 10).

[0069] If the measured voltage between the first and second electrical contacts 106, 108 is non-zero, it can be assumed that external power is being delivered to the device through the connector 104, and therefore that the device is connected to the socket. However, if a zero voltage is measured between the first and second electrical contacts 106, 108, i.e. no external power is detected, the connection state of the device cannot be determined without further information. In particular, no external power will be detected both when the device is physically installed in the socket but when the vehicle's ignition is switched off to cut power to the accessory socket, and when the device has been physically removed from the socket.

[0070] Accordingly, when external power is not detected, at step 202, the detector module 1 12 may attempt to determine the connection state of the device, as will be explained in more detail below. Once the connection state has been determined, it is logged by the device 100 at step 203. For example, the processor 1 16 may write a data entry to the memory 120 and/or may transmit data to the remote computer by way of the transmitter 1 18. [0071 ] When external power is detected at step 201 , the voltage measured between the first and second electrical contacts 106, 108 is the supply voltage V_s provided to the accessory socket by the vehicle electrical system. The supply voltage V_s supplied to an accessory socket is drawn from the vehicle battery and is not regulated, and therefore the supply voltage V_s varies substantially according to the running mode or state of the engine. At step 204, the detector module 1 12 attempts to determine the engine running state based on the supply voltage V_s. Once the engine running state has been determined, it is logged by the device 100 at step 205, again by writing a data entry to the memory 120 and/or by transmitting data thorough the transmitter 1 18. It is implicit that the device 100 must be in a connected state if the engine running mode can be determined, although step 205 may also include logging the device connection state.

[0072] Returning to the situation in which no external power is detected at step 201 , to determine the connection state of the device (step 202 in Figure 3), the detector module 1 12 makes use of the internal battery 1 14 and the second and third contacts 108, 1 10 of the connector 104. In the following description, the second contact 108 is referred to as side contact A and the third contact 1 10 is referred to as side contact B (see also Figure 2). There is no internal electrical connection within the device 100 between the side contacts A and B. However, when the connector 104 is inserted in the accessory socket, both the of the side contacts A, B come into contact with the second terminal of the socket. Therefore the side contacts A, B become electrically connected only when the device 100 is physically mounted in the socket. Stated another way, side contact B (i.e. the third contact 1 10) connects electrically with side contact A (the second contact 108) by way of the second supply terminal only when the device 100 is mated with the accessory socket. Accordingly, by checking for a short-circuit between the side contacts A, B the physical connection state of the device can be determined. When a short-circuit is present, the device can be assumed to be in a connected state (i.e. the connector 104 is mated with the socket) with the vehicle in an ignition-off state, and when no short-circuit is present, the device can be assumed to be in a not connected state (i.e. the connector is disconnected from the socket). [0073] Figure 4 illustrates a possible sequence of steps for determining the device connection state. First, at step 301 in Figure 4, the detection module 1 12 applies a pulldown load to side contact A. In other words, side contact A is connected to a ground terminal 1 15 of the internal battery 1 14 through a high resistance. Then, at step 302, the detection module 1 12 applies internal battery power to side contact B (i.e. side contact B is connected to a reference, non-ground terminal 1 17 of the internal battery).

[0074] At step 303, the detection module 1 12 measures the voltages V_A and V_B at side contact A and side contact B, respectively, relative to the ground terminal 1 17 of the internal battery 1 14. At step 304, the detection module 1 12 compares the measured voltages V_A, V_B. If V_A and V_B are equal, then it can be assumed that the device 100 is connected to the socket to allow an electrical connection between the contacts, and at step 305 the device state is logged as "connected". [0075] If V_A is not equal to V_B, and is instead equal to zero (i.e. the potential at side contact A is the same as the ground potential 1 15), then it can be assumed that the device 100 is unplugged from the socket. Accordingly, at step 306, the device state is logged as "not connected".

[0076] Referring back to Figure 3, determination of the engine running state at step 204 is based on analysis by the detector module 1 12 of the supply voltage V_s supplied to the accessory socket. The typical nominal supply voltage of a vehicle battery is around 12.6 V. However, during running of the engine, the vehicle battery is charged by an alternator at a regulated voltage which is higher than the nominal supply voltage. Typically, therefore, the supply voltage V_s supplied to the accessory socket when the engine is running is from around 13.2 V to around 14.6 V. When the engine is not running, the supply voltage V_s reduces to the nominal supply voltage of around 12.6 V. Finally, when the engine is being started, the starter motor applies a substantial load to the battery as it cranks the engine. Accordingly, the supply voltage V_s typically drops to around 4 to 6 V whilst the engine is being started. By comparing the measured supply voltage V_s with suitable pre-set threshold voltages, each of these three engine running states can be identified and distinguished from one another.

[0077] Figure 5 shows a possible sequence of steps in which the detector module 1 12 is used to determine the engine running state of the vehicle when the device 100 is connected to the socket and is receiving power from the vehicle. First, at step 401 , the detector module 1 12 measures the voltage at side contact A (or, equivalently, at side contact B) relative to the first contact 108 to determine the supply voltage V_s of the vehicle power supply.

[0078] Then, at step 402, the measured supply voltage V_s is compared with a battery charging threshold voltage, V_charg_ing. The battery charging threshold voltage Vcharging is set as the lowest expected voltage that will be measured when a typical vehicle engine, operating correctly, is running and the battery is being charged by the alternator. For example, V_cnarging may be set at 13 V. If the supply voltage V_s is greater than the battery charging threshold voltage V_cr,_arg_ing, then it can be assumed that the engine of the vehicle is running. Accordingly, at step 403, the engine running state is logged as "engine running".

[0079] If the supply voltage V_s is less than the battery charging threshold voltage Vcharging then, at step 404, the supply voltage V_s is compared with a lower base battery threshold voltage, V_base. The lower base battery threshold voltage V _ase is set as the lowest expected voltage that a vehicle battery will deliver when it is not being charged. For example, V_base may be set at 1 1 V. If the supply voltage V_s is greater than the lower base battery threshold voltage, V_base (but lower than the battery charging threshold voltage V_charg_ing as determined in step 402), then it is assumed that the engine of the vehicle is not running. Accordingly, at step 405, the engine running state is logged as "engine stopped". [0080] It will be appreciated that, in this example, the battery charging threshold voltage V_charging effectively also acts as an upper base battery threshold voltage (i.e. the highest expected voltage that a vehicle battery will deliver when it is not being charged). However, more generally, at step 404, the supply voltage V_s could also be compared with an upper base battery threshold voltage that differs from V_charging and an "engine stopped" running state logged only if the supply voltage V_s is lower than the upper base battery threshold voltage.

[0081 ] If the supply voltage V_s is less than the lower base battery threshold voltage, V_base, then, at step 406, the supply voltage V_s is compared with a lower cranking voltage threshold, V|_0W, and an upper cranking voltage threshold V_cranking. The cranking voltage thresholds V|_0W, V_cranking are set to correspond to the lower and upper bounds, respectively, of the voltage that will be delivered by the battery during operation of the starter motor. For example, the lower cranking voltage threshold, V|_0W, may be set at 3 V and the upper cranking voltage threshold V _anking may be set at 8 V.

[0082] If the supply voltage V_s is between the lower cranking voltage threshold V|_0W and the upper cranking voltage threshold V_cranking then it can be assumed that the starter motor is running to start the engine. Accordingly, at step 407, the engine running state is logged as "engine cranking".

[0083] If the supply voltage is not between the lower cranking voltage threshold V|_0W and the upper cranking voltage threshold V_cranking then, in this example, an engine running state of "not detected" is logged at step 408. In this case, it is not possible to identify unambiguously the running state of the engine. This may occur, for example, due to a fault with the vehicle electrical system or the vehicle battery. Although not shown in Figure 5, when the supply voltage V_s is zero, a engine status of "ignition-off" is determined and can be logged. [0084] In these ways, by virtue of the detector module 1 12, the device 100 of the present invention is able to determine additional information about the state of the device and the running mode of the engine that may not otherwise be available. This additional information can be used to influence the recording and transmission of data from the other sensors in the device and to provide direct or indirect data relating to driving behaviour.

[0085] For example, in one embodiment of the device 100, the processor 1 16 looks for changes in the device connection state and engine running state information received from the detector module 1 12. When the device connection state or the engine running state changes, the processor may write corresponding event data to the memory. The event data may be associated with vehicle usage data. For example, when the engine running state changes to "engine cranking", the processor may record the time, date and position of the vehicle at the time of the starting event.

[0086] To guard against false indications of changes in the device connection state and/or the engine running state, for example due to temporary disconnection of the device 100 from the accessory socket due to vibration, shock or other disturbances during use, the processor 1 16 may record a change in connection state or engine running state only if the change persists over a certain time period or over several successive tests by the detector module 1 12.

[0087] Particular sequences of changes in the device connection state and/or the engine running state may trigger the processor 1 16 to perform certain acts. For example, when the device 100 detects that the engine is running, then that the engine is stopped, and then that the device is disconnected from the socket, this may be indicative of a journey coming to an end and the device being removed from the accessory socket. This may trigger a burst of data storage and/or data transmission to allow certain data to be stored or uploaded before the internal battery is exhausted or before the data connection between the transmitter and the remote computer is lost.

[0088] In another example, when the device 100 detects that the engine is running, then that the engine is stopped, and then that the engine is re-started within a short period of time without the supply of power to the device from the vehicle being interrupted, this may be indicative of the vehicle performing an engine start/stop cycle for emissions control, and the processor 1 16 may record corresponding event data. [0089] It will be understood that the detector module 1 12 may employ voltage sensing and switching methods that are generally known in the art. The detector module 1 12 may be embodied in software, hardware or in a combination of hardware and software. Elements or all of the detector module 1 12 may be combined with the processor 1 16. The detector module 1 12 may continuously perform tests to determine the connection state and engine running state, or the detector module 1 12 may be instructed to perform a test or a sequence of tests by the processor 1 16 according to a timing schedule or in response to particular trigger events.

[0090] Referring back to Figure 1 , in another feature of the invention, data from the accelerometer 124 is used to identify high-risk driver behaviour, as will now be described with reference to Figures 6 to 18. [0091 ] As is generally known in the art, the limit of adhesion of a vehicle tyre can be approximated as an elliptical boundary when plotted as a function of acceleration (or, equivalently, force) in the horizontal (X-Y) plane. For example, Figure 6 illustrates schematically the elliptical boundary 500 representing the adhesion limit for a typical vehicle tyre. Pure linear acceleration is represented by vector A_x and pure lateral acceleration is represented by vector A_y. Vector Axy represents the acceleration vector under a mixed load condition, in which the vehicle is both accelerating and turning.

[0092] Provided the acceleration vector A^ is within the boundary 500, as shown in Figure 6, the tyre should adhere to the road surface. When the acceleration vector A_xy exceeds the boundary 500, the tyre is likely to lose grip and slip on the road, resulting in a skid. Accordingly, analysis of the acceleration vector A_xy can provide information about driver behaviour.

[0093] By way of example, Figure 7 (a) illustrates the acceleration vector A_xy for a vehicle cornering at constant speed well within the limits of adhesion represented by the boundary 500. Figure 7(b) illustrates the acceleration vector A_xy for a vehicle cornering at constant speed much closer to the limits of adhesion 500, which can be recognised as a higher-risk event than that illustrated in Figure 7(a). [0094] Figure 7(c) illustrates the acceleration vector A_xy for a vehicle accelerating at a modest rate. The acceleration vector A_xy is well within the limits of adhesion represented by the boundary 500, whereas under harder acceleration the acceleration vector A_xy would come closer to or exceed the boundary 500, resulting in wheelspin. In that case, a high-risk event would be recognised. Figure 7(d) illustrates the acceleration vector A_xy for a vehicle braking with a high brake force. Here, the acceleration vector is close to the limits of adhesion 500, at which point the tyre would skid. Accordingly, the situation in Figure 7(d) would also be recognised as a high-risk event.

[0095] Figure 8 illustrates another example of high-risk driving behaviour. In this case, the acceleration vector A_xy is shown for a vehicle that is attempting to accelerate out of a corner, but exceeding the limit of adhesion represented by the boundary 500. In this case, neither the linear adhesion limit 502 (i.e. the adhesion limit for pure linear acceleration), nor the lateral adhesion limit 504 (i.e. the adhesion limit for pure lateral acceleration) have been exceeded, but the combination of the linear and lateral loads leads to a loss of adhesion. [0096] Embodiments of the present invention address several practical difficulties in identifying high-risk behaviour from acceleration measurements in a device of the type shown in Figure 1 .

[0097] One such difficulty is that the device 100 may be installed in the vehicle in substantially any orientation, so that the orientation of the horizontal X-Y plane is not constant with respect to the device housing 102. For instance, as shown in Figures 9(a) to (c), in different vehicles 600, the vehicle accessory socket may be mounted at a different angle relative to the horizontal plane. Furthermore, because of the rotational symmetry of the vehicle accessory socket and the corresponding connector 104, the device can be inserted in the vehicle accessory socket in substantially any angular orientation, as illustrated in Figures 10(a) to (c).

[0098] As a result, when the device is installed in an initially-unknown orientation, the axes S1 , S2 and S3 of the three-axis accelerometer 124 are not aligned with the horizontal and vertical axes X, Y, Z of the vehicle, as illustrated in Figure 1 1 , and the orientation of the device will likely change each time the device is installed. To address this problem, in an embodiment of the invention, the processor 1 16 is configured to identify the horizontal X-Y plane 700 using the output from the accelerometer 124. [0099] Firstly, the processor 1 16 establishes that the vehicle is stationary and that the device is installed in the accessory socket. Conveniently, this can be done at least in part by reference to the device connection state and to the engine running state as determined by the detector module 1 12. For example, the processor 1 16 may check that the connection state of the device is "connected", and that the engine is not running (i.e. with the ignition off, or with an engine running state of "stopped" or "cranking"), since with this combination of states it can be assumed that the device has been installed in the vehicle accessory socket and that the vehicle is stationary. The processor 1 16 may use other inputs to establish or verify that the vehicle is stationary. For example, information from the positioning system receiver 122 can be used to check that the vehicle is not moving, and the signal from the accelerometer 124 can be monitored to establish that the device is in a stable position. It will be appreciated that any suitable method can be used to establish that the vehicle is stationary, and it is preferred that at least two different methods are used in combination to reduce the risk of errors.

[0100] Once it has been established that the vehicle is stationary and that the device is connected to the vehicle and is in a stable state, the processor 1 16 performs a calibration step, in which the horizontal X-Y plane is identified. This is achieved with reference to the acceleration due to gravity, A_g, which has a constant magnitude and a direction that will be approximately vertical with respect to the vehicle. [0101 ] Accordingly, during the calibration step, the accelerometer 124 measures the acceleration vector components along the three accelerometer axes S1 , S2, S3. Summation of these vector components yields the direction of the vector A_g, corresponding to the acceleration due to gravity. It is assumed that the upward vertical direction vector Z in the vehicle reference frame is in the opposite direction. The X-Y plane is then identified as the plane normal to the Z vector.

[0102] After the calibration step, subsequent measurements from the accelerometer 124 are processed as follows to obtain the acceleration vector A_xy in the X-Y plane as the vehicle moves. First, the measured acceleration vector components along the three accelerometer axes S1 , S2, S3 are obtained from the accelerometer 124. The vector components are then summed, and the acceleration due to gravity A_g is subtracted to yield an acceleration vector that corresponds to acceleration due only to movement of the device (and therefore the vehicle). This acceleration vector is then resolved onto the X-Y plane to yield the acceleration vector A^ in the X-Y plane.

[0103] Referring back to Figure 8, it will be appreciated that, because the boundary 500 representing the limits of adhesion is elliptical, it would be necessary also to determine the linear direction X (i.e. the direction of forward travel of the vehicle) and the lateral direction Y, relative to the orientation of the device 100, to establish whether the acceleration vector A_xy has approached or exceeded the boundary 500. The situation is further complicated because the actual shape and size of the boundary 500 will vary according to the vehicle, the road conditions, the tyre properties and other factors.

[0104] However, embodiments of the present invention provide a useful indicator of high-risk driving behaviour without the need to determine the linear and lateral directions X, Y relative to the device 100 or the exact shape of the boundary 500, as will now be described.

[0105] Referring to Figure 12, the resolved acceleration vector in the X-Y plane, A^, is compared to a circular boundary 800. The circular boundary 800 has a radius Rmax, which represents a threshold value for the magnitude of the acceleration vector Axy. When the magnitude of the acceleration vector Axy exceeds the threshold value R_max, the processor 1 16 identifies that a high-risk event has occurred and initiates a suitable high-risk event protocol in the device. For example, the processor 1 16 may record that a high-risk driving behaviour event has occurred, for example by writing event data to the event log memory 120b and/or copying vehicle usage data from the buffer memory 120a to the event log memory 120b. Alternatively, or in addition, the high-risk event protocol may include transmitting data via the transmitter 1 18. The transmitted data may include all or part of the contents of the buffer memory 120a and/or all or part of the contents of the event log memory 120b.

[0106] The threshold value R_max is selected so that the circular boundary 800 lies wholly within the expected elliptical tyre adhesion boundary 500 for a typical vehicle. Because the boundary 800 is circular, the direction of the acceleration vector A_xy with respect to the X and Y axes of the vehicle does not need to be determined. Accordingly, the threshold value R_max is an orientation-independent threshold value. Also, since the device is intended to provide an indication of high-risk driving, it is not necessary to determine whether the limit of adhesion (i.e. the boundary 500) has actually been reached or exceeded, so the selection of a threshold value R_max that lies within a conservative estimate of the adhesion limit 500 is appropriate. It will also be appreciated that, because the threshold value R_max is orientation-independent and can be set to any suitable value, errors in the determination of the horizontal X-Y plane due to a tilted orientation of the vehicle during the calibration step do not substantially affect the assessment of driving behaviour.

[0107] A variant of this method provides a more refined assessment of driver behaviour. In this variant, the resolved acceleration vector in the X-Y plane, Axy, is compared to first and second circular boundaries 801 , 802, as shown in Figure 13. The first circular boundary 801 has a radius corresponding to a first orientation- independent threshold value for the magnitude of the acceleration vector A^. The first circular boundary 802 has a radius R₂, which corresponds to a second orientation- independent threshold value for the magnitude of the acceleration vector A^. When the magnitude of the acceleration vector A_xy exceeds the first threshold value but not the second threshold value R₂ (as illustrated by vector A^ in Figure 13), the processor 1 16 records that a moderately high-risk driving behaviour event has occurred (such as, for example, rapid acceleration). When the magnitude of the acceleration vector A^ exceeds the second threshold value R₂ (as illustrated by vector A^ in Figure 13), the processor 1 16 records that a very high-risk driving behaviour event has occurred.

[0108] In this way, the device 100 can provide information that gives a relatively refined indication of the driver's behaviour, which can be used for example to distinguish between a distracted driving style, which may show relatively few high-risk events in total but an unusually high proportion of very high-risk events, and a more aggressive driving style in which moderately high-risk events are frequently recorded with relatively few very high-risk events.

[0109] Furthermore, different high-risk event protocols may be initiated by the processor 1 16 depending on the severity of the driving behaviour event. For example, the identification of a moderately high-risk driving behaviour event may trigger the device 100 to write a driving limits alert as event data to the event log memory 120a. The identification of a very high-risk event may trigger the device 100 to copy all or part of the contents of the buffer memory 120a to the event log memory 120b, with associated event data, and to transmit the corresponding data to the remote computer immediately. It will be appreciated that several different grades of high-risk event protocols may be provided for initiation in response to the detection of events of corresponding levels of severity. [01 10] Figure 14 provides a summary of a method for monitoring driver behaviour in a vehicle using a telematics device having a three-axis accelerometer. First, at step 901 , a vehicle stationary condition is detected, for example by one of the techniques described above. Once it is established that the vehicle is stationary, at step 902, stationary acceleration vector components are obtained from the accelerometer. Then, at step 903, the orientation of the vertical Z direction and the horizontal X-Y plane are determined, for example as described above with reference to Figure 1 1 . This completes a calibration process for the device.

[01 1 1 ] After calibration, at step 904, the device waits for movement of the vehicle, for example by monitoring the accelerometer output for changes. When vehicle movement is detected, at step 905, a set of moving acceleration vector components is obtained from the accelerometer. At step 906, the acceleration due to gravity is subtracted and the moving acceleration vector components are resolved on the X-Y plane. At step 907, the magnitude of the resolved acceleration vector in the X-Y plane, Axy, is compared with an orientation-independent, pre-determined threshold value R_max (i.e. the boundary 800 in Figure 12). If the magnitude of the resolved acceleration vector, A_xy, is greater than the threshold value R_max, a high-risk event protocol of the device is initiated at step 908. Otherwise, the process re-starts from step 905, and a new set of moving acceleration vector components is obtained from the accelerometer to allow continued monitoring. [01 12] The rate at which steps 905, 906 and 907 are performed and repeated determines the time resolution of the detection of high-risk events. If these steps can be repeated at a greater frequency, the device 100 becomes more sensitive to high-risk events. [01 13] In one example, the moving acceleration vector components are retrieved from the accelerometer 124 at a frequency of approximately 100 Hz. Thus the moving acceleration vector components are updated 100 times per second.

[01 14] The output data from the accelerometer 124 may be filtered to reduce or eliminate spurious data, such as may arise from vibration of the device. For example, a low-pass filter may be applied to the output data to eliminate high-frequency elements of the data that are characteristic of vibrations, leaving only the low-frequency data that corresponds to movements of the vehicle itself. The resolved acceleration vector, A^, is then determined from the filtered moving acceleration vector components. After the filtering and resolving steps, the update frequency of the resolved acceleration vector, A_xy, may be approximately 10 Hz.

[01 15] The magnitude of the resolved acceleration vector, A^, can therefore be compared to the threshold value (step 907 in Figure 14) at a frequency of approximately 10 Hz. This relatively high comparison frequency allows relatively short-duration events that take place over a fraction of a second to be detected and identified as high-risk events. In other embodiments, the comparison frequency is between approximately 5 Hz and approximately 50 Hz.

[01 16] Initiating a high-risk event protocol at step 908 in Figure 14 may include logging a driving limits alert by recording that a high-risk event has occurred, and may for example comprise writing corresponding event data to a memory and/or uploading sensor and/or event data to a remote computer. A visual or audible indication may also be provided by the device (such as by the indicator lamp 130 of the device 100 of Figure 1 ). Although not shown in Figure 14, after initiating the high-risk event protocol, the process may re-start from step 905 to allow continued monitoring of driver behaviour.

[01 17] In another embodiment, at step 907, the magnitude of the resolved acceleration vector in the X-Y plane, A_xy, is compared with first and second orientation- independent, pre-determined threshold values R₂ (i.e. the boundaries 801 , 802 in Figure 13), and first- and second-level high-risk event protocols are initiated accordingly.

[01 18] It will be appreciated that, because the device 100 can detect that it is mounted in the vehicle accessory socket whilst the device 100 is running on internal battery power, the step of identifying the horizontal X-Y plane can be started before the vehicle ignition is switched on. In this way, the device can be readied for detection of high-risk behaviour before the start of a journey.

[01 19] Furthermore, as described above, the device 100 can detect that the engine has stopped during a stop-start event. In one embodiment of the invention, therefore, re-calibration of the X-Y plane is performed when the device detects that the engine has stopped during a stop-start event. In this way, the effect on the device performance of changes in the orientation of the device during the journey can be reduced.

[0120] Figure 15 provides a summary of a method that can be used by the device 100 to determine when to identify the horizontal X-Y plane. First, at step 1001 , the device connection state is determined, for example using the method described above with reference to Figure 4. At step 1002, if the connection state is not "connected", then the device 100 repeats the first step 1001.

[0121 ] If the connection state is determined as "connected" then, at step 1003, the device 100 proceeds to determine the engine running state, for example using the method described above with reference to Figure 5. At step 1004, if the engine running state is not "ignition off" or "engine stopped", then the device 100 re-starts the process at step 1001 . If, however, the engine running state is "ignition off" or "engine stopped", then the device 100 proceeds to step 1006 to identify the horizontal plane, as described above.

[0122] In other embodiments of the invention, identification of the horizontal plane at step 1006 may be performed only when the engine running state is "ignition off", or only when the engine running state is "engine stopped". An engine running state of "engine cranking" could also (or instead) be used to trigger identification of the horizontal plane.

[0123] The high-risk event protocol of the device can take the form of any suitable actions or set of actions. Figure 16 provides examples of the basic actions that may occur upon initiation of a high-risk event protocol. When a high-risk event protocol is initiated, at step 1 101 , the device 100 may transmit data to the remote server, at step 1 102. Alternatively, or in addition, the device 100 may record data to the device memory 120, at step 1 103. The device 100 may also transmit the data after recording the data to the memory. [0124] The data recorded and/or transmitted may include event data (e.g. data created by the processor 1 16 in response to the detection of certain conditions and events), vehicle usage data (e.g. sensor data derived from the output of the positioning system receiver 122, the accelerometer 124 and/or the other sensors 126), or any suitable combination of event and vehicle usage data.

[0125] A high-risk event protocol may involve data operations to read and write data to and from the buffer memory 120a and the event log memory 120b. Figure 17 illustrates how data may be written to the buffer memory 120a during a normal data logging operation of the device. At step 1201 , the logging operation starts, for example once the device has established that the device is connected to the vehicle, the engine mode is "running", and the calibration step has been performed to establish the horizontal plane of the device 100. [0126] At step 1202, vehicle usage data is obtained from the positioning system receiver 122, the accelerometer 124 and/or the other sensors 126 of the device 100. At step 1203, a check is performed to determine if the buffer memory 120a is full. If the buffer memory 120a is not full, the vehicle usage data is written to the buffer memory 120a, at step 1204. If the buffer memory 120a is full, then the oldest entry in the buffer memory 120a is deleted at step 1205, and the new vehicle usage data is written in its place at step 1204. Further vehicle usage data can then be obtained and stored by repeating steps 1202 to 1205 until data logging stops. [0127] The vehicle usage data may comprise raw sensor output data and/or processed data derived from the output of the sensors. For example, the positioning system receiver 122 may output GPS coordinates in a format that can be written directly to the buffer memory 120a as vehicle usage data. However, the resolved acceleration vector in the horizontal plane determined by the processor 1 16 (as described above with reference to Figure 1 1 ) may be written to the buffer memory 120a instead of the raw output of the accelerometer 124,

[0128] The data written to the buffer memory 120a and the event log memory 120b and/or transmitted to the remote computer may be accompanied by a time/date stamp. Conveniently, the time and date information can be obtained from the positioning system receiver 122.

[0129] In one example of a high-risk event protocol, illustrated in Figure 18, the high-risk event protocol is initiated at step 1301 . At step 1302, the processor 1 16 writes a driving standards alert to the event log memory 120b. The driving standards alert may indicate that a high-risk event has occurred, the time and date of the event, the location of the vehicle at the time of the event, and the speed of the vehicle at the time of the event. The time and date, location and speed can be derived from the positioning system receiver 122.

[0130] At step 1303, the vehicle usage data stored in the buffer memory 120a is copied to the event log memory 120b to preserve the vehicle usage data from a time period immediately before and during the occurrence of the high-risk event. The copied vehicle usage data may be associated in the event log memory 120b with the driving standards alert created in step 1302.

[0131 ] At step 1304, the device 100 also attempts to connect to the remote computer via the transmitter 1 18 and, if a connection can be established, the event data associated with that high-risk event and the corresponding vehicle usage data are read from the event log memory 120b and transmitted to the remote computer. If a connection cannot be established at that time, the event data and vehicle usage data are preserved in the event log memory 120b for retrieval and transmission at a later time when a connection can be established.

[0132] A high-risk event protocol may include increasing the rate at which data is sampled, recorded and/or transmitted. For example, under normal circumstances, the device 100 may record positional data at a relatively low frequency, say once every two minutes, which is sufficient to allow the route taken by the vehicle to be determined whilst maintaining economy of data. However, when a high-risk event is detected, the corresponding high-risk event protocol may include increasing the recording frequency of the positional data to its maximum possible level, for example once every second, to allow the circumstances of the high-risk event to be more readily understood in subsequent analysis.

[0133] In another example, under normal conditions, positional data may be transmitted to the remote computer at a frequency of once every ten minutes. Upon detection of a high-risk event, the high-risk event protocol may increase the transmission rate to once every minute for a period of 10 minutes, to allow the remote computer to determine quickly whether the vehicle has continued its journey after the detection of a high-risk event or come to a standstill, with the latter case indicating a potential accident and allowing a suitable response to be initiated.

[0134] Several modifications and variations of the device and its operating methods are possible.

[0135] For example, the device may be capable of receiving data from the remote computer by way of a receiver, which may be integrated with the transmitter. Conveniently, this may allow re-programming of the device to improve performance without user intervention.

[0136] For instance, if the device is used to detect an engine running state using voltage thresholds (as described with reference to Figure 5, for example), the voltage thresholds stored on the device may be updated by the remote computer to improve the detection of changes in the engine running state in a particular user's vehicle. Such updates may be triggered, for example, if data obtained from the determination of the engine running state does not match other data obtained by the device (for example, if an engine starting state is repeatedly not detected even though positioning system receiver data indicates that the vehicle has moved on several occasions).

[0137] Similarly, if the device is used to detect high-risk driving events using acceleration threshold values, the acceleration threshold values may be updated to tailor the performance of the device to a particular vehicle, based for example on a statistical analysis of the data from the device or a knowledge of the type of vehicle in which the device is to be used.

[0138] In the above-described examples, the device includes an integral connector for a vehicle accessory socket of the conventional cigarette lighter receptacle type. However, it will be appreciated that aspects of the invention could equally be applied to devices with other types of connectors, such as USB connectors. It is also conceivable that aspects of the invention could be applied to devices with non-integrated connectors.

[0139] The transmitter (and receiver, where provided) may be a cellular modem to transmit data to a remote computer over a cellular wireless connection using any suitable data service. In this case, the remote computer may be hosted by the insurance provider, so that the device sends information directly to the insurance provider. The transmitter could also (or instead) incorporate an SMS sender. By allowing the device to communicate directly with the external remote computer, operation of the device is not dependent on another device, such as a smartphone, to deliver information to the insurance provider. Alternatively, however, the transmitter could be configured to communicate with a remote computer comprising the user's mobile telephone or smartphone, for example by way of a short-distance wireless communication protocol such as Bluetooth or NFC (near field communication), which can serve to relay the data to another remote computer and/or to process the data.

[0140] Although the invention has been explained with reference to a dedicated plug-in telematics device, it will be appreciated that aspects of the methods and apparatus could find application in other devices, including but not limited to smartphones, mobile telephones, portable computing devices, hard-wired telematics devices, vehicle on-board computers, navigation devices, entertainment devices and so on.

[0141 ] Further modifications and variations of the invention are also possible without departing from the scope of the invention as defined in the appended claims.

Claims

A method for monitoring driver behaviour in a vehicle using a device comprising a three-axis accelerometer, the method comprising:

identifying a horizontal plane of the device when the vehicle is stationary;

repeatedly deriving, from an output of the accelerometer, an acceleration vector resolved in the horizontal plane;

repeatedly comparing the magnitude of the resolved acceleration vector with an orientation-independent pre-determined threshold value during operation of the vehicle; and

initiating a high-risk event response protocol of the device when the magnitude of the resolved acceleration vector exceeds the orientation- independent pre-determined threshold value.

A method according to Claim 1 , wherein the high-risk event response protocol comprises transmitting data from the device to a remote computer.

A method according to Claim 1 or Claim 2, wherein the high-risk event response protocol comprises recording data to a memory of the device.

A method according to Claim 2 or Claim 3, wherein the transmitted and/or recorded data comprises event data.

A method according to any of Claims 2 to 4, wherein the transmitted and/or recorded data comprises vehicle usage data.

A method according to Claim 5, wherein the high-risk event response protocol comprises recording and/or transmitting vehicle usage data at an increased rate.

A method according to Claim 5 or Claim 6, wherein the device stores vehicle usage data in a buffer memory during operation of the vehicle, and wherein the high-risk event response protocol comprises transmitting the contents of the buffer memory to the remote computer and/or copying the contents of the buffer memory to an event log memory of the device.

A method according to any of Claims 5 to 7, wherein the vehicle usage data comprises acceleration data derived from the accelerometer and/or sensor data derived from one or more further sensors of the device.

A method according to any of Claims 5 to 8, wherein the device comprises a positioning system receiver, and wherein the vehicle usage data comprises positional data derived from the positioning system receiver.

A method according to any preceding claim, wherein the magnitude of the resolved acceleration vector is compared with the orientation-independent pre-determined threshold value at a frequency of at least 5 Hertz.

A method according to Claim 10, wherein the magnitude of the resolved acceleration vector is compared with the orientation-independent predetermined threshold value at a frequency of at least 10 Hertz.

A method according to any preceding claim, comprising monitoring a connection state of the device and a running state of an engine of the vehicle, and determining that the vehicle is stationary when the device is in a connected state and the engine is in an ignition-off state or a non-running state.

A method according to Claim 12, wherein the device comprises a connector arranged to receive a voltage supply from an accessory socket of the vehicle, and wherein the method comprises determining the connection state of the device and the engine running state of the vehicle based on voltage measurements at the connector

A method according to any preceding claim, further comprising verifying that the vehicle is stationary using a positioning system receiver.

A method according to any preceding claim, wherein identifying the horizontal plane of the device comprises obtaining acceleration vector components from the output of the accelerometer, resolving the acceleration vector components into a vertical acceleration vector having a magnitude equal to gravitational acceleration, and identifying the horizontal plane as a plane normal to the vertical acceleration vector.

A device for monitoring driver behaviour in a vehicle, comprising a three-axis accelerometer, a processor configured to receive an output signal from the accelerometer and to process the output signal, and a transmitter configured to transmit data to a remote computer external to the vehicle;

wherein the device is arranged to perform the method of any of Claims 1 to 15.

A device according to Claim 16, further comprising a connector arranged to mate with an accessory socket of the vehicle and to receive an electrical supply from the vehicle when the device is mated with the socket, and a detector module configured to determine a connection state of the device and an engine running state of the vehicle based on voltage measurements at the connector.

A computer program product comprising instructions that, when executed, implement the method of any of Claims 1 to 15.

A non-transient storage medium comprising computer-executable instructions that, when executed, implement the method of any of Claims 1 to 14.

A telematics device for monitoring driver behaviour in a vehicle, comprising: a connector arranged to mate with an accessory socket of the vehicle and to receive an electrical supply from the vehicle when the device is mated with the socket, the connector having a first electrical contact arranged to engage with a first supply terminal of the accessory socket and a second electrical contact arranged to engage with a second supply terminal of the accessory socket;

an internal power source to provide power to the device when no electrical supply from the vehicle is received;

a detector module configured to determine a connection state of the device and an engine running state of the vehicle based on voltage measurements at the connector; and

a transmitter arranged to transmit data associated with the connection state and the engine running state to a remote computer external to the vehicle.

A telematics device according to Claim 20, wherein the transmitter comprises a cellular modem.

A telematics device according to Claim 20 or Claim 21 , wherein the connector further comprises a third electrical contact arranged to connect electrically with the second electrical contact by way of the second supply terminal when the device is mated with the accessory socket.

A telematics device according to Claim 22, wherein the connector is generally elongate for insertion into an aperture of the accessory socket, and wherein the first electrical contact is disposed at an end of the connector and the second and third electrical contacts are each disposed on a side of the connector.

A telematics device according to Claim 22 or Claim 23, wherein the detector module is configured to check for a short circuit between the second and third electrical contacts thereby to determine the connection state of the device.

A telematics device according to any of Claims 20 to 24, wherein the detector module is configured to determine whether a vehicle supply voltage V_s is present between the first electrical contact and the second electrical contact and, if no vehicle supply voltage is detected, to connect the second electrical contact to a ground potential of the internal power source by way of a pull-down load, connect the third electrical contact to a reference potential of the internal power source, and measure the voltage at the second electrical contact thereby to determine the connection state of the device.

A telematics device according to Claim 25, wherein the detector module is configured such that, when the measured voltage at the second electrical contact is substantially equal to the reference potential applied to the third electrical contact, the detector module determines that the device is in a connected state and that the engine is in an ignition-off state.

A telematics device according to Claim 25 or Claim 26, wherein the detector module is configured such that, when the measured voltage at the second electrical contact is not substantially equal to the reference potential applied to the third electrical contact, the detector module determines that the device is in a non-connected state.

A telematics device according to any of Claims 20 to 27, wherein the detector module is configured to measure the supply voltage V_s between the first electrical contact and the second electrical contact, and to compare the measured supply voltage V_s to a plurality of threshold voltages to determine the engine running state.

A telematics device according to Claim 28, wherein the detector module is configured to determine that the engine is in a running state when the measured supply voltage V_s is greater than a battery charging threshold voltage V_charging.

A telematics device according to Claim 28 or Claim 29, wherein the detector module is configured to determine that the engine is in a non-running state when the measured supply voltage V_s is between a lower base battery threshold voltage V _ase and an upper base battery threshold voltage.

A telematics device according to any of Claims 28 to 30, wherein the detector module is configured to determine that the engine is in a cranking state when the measured supply voltage V_s is between a lower cranking threshold voltage V|_0W and an upper cranking threshold voltage V_cranking.

A telematics device according to any of Claims 20 to 31 , further comprising a positioning system receiver and/or a plurality of sensors, a memory, and a processor configured to write vehicle usage data derived from the receiver and/or the sensors to the memory.

A telematics device according to Claim 32, wherein the processor is configured to identify changes in the connection state of the device and/or the engine running state of the vehicle, and to write corresponding event data to the memory.

A telematics device according to Claim 33, wherein the processor is further configured to associate the event data with the vehicle usage data.

A telematics device according to Claims 33 or Claim 34, wherein the processor is further configured to transmit the event data and the vehicle usage data to the remote computer by way of the transmitter.

A telematics device according to any of Claims 20 to 35, including a sensor comprising a three-axis accelerometer.

A telematics device according to Claim 36, wherein the processor is configured to determine the spatial orientation of the device based on an output of the accelerometer when the detector module determines that the device is in a connected state and the engine is in an ignition-off state or a non-running state.

A telematics device according to any of Claims 20 to 37, comprising a housing for the internal power source, the transmitter, and the detector module, and wherein the connector is integral with the housing.

A method for monitoring driver behaviour in a vehicle using a telematics device comprising a three-axis accelerometer, the device being connectable to the vehicle, and the method comprising:

monitoring a connection state of the device and a running state of an engine of the vehicle;

determining that the vehicle is stationary when the device is in a connected state and the engine is in an ignition-off state or a non-running state;

identifying a horizontal plane of the device when the vehicle is stationary;

deriving, from an output of the accelerometer, an acceleration vector resolved in the horizontal plane;

monitoring the magnitude of the resolved acceleration vector during movement of the vehicle;

and, if the magnitude of the resolved acceleration vector exceeds an orientation-independent pre-determined threshold value, identifying that a high-risk event has occurred.

A method according to Claim 39, further comprising initiating a high-risk event response protocol of the device upon identifying that a high-risk event has occurred.

A method according to Claim 39 or Claim 40, further comprising verifying that the vehicle is stationary using a positioning system receiver.

A method according to any of Claims 39 to 41 , wherein identifying the horizontal plane of the device comprises obtaining acceleration vector components from the output of the accelerometer, resolving the acceleration vector components into a vertical acceleration vector having a magnitude equal to gravitational acceleration, and identifying the horizontal plane as a plane normal to the vertical acceleration vector.

A telematics device for monitoring driver behaviour in a vehicle, comprising a three-axis accelerometer, a connector arranged to mate with an accessory socket of the vehicle and to receive an electrical supply from the vehicle when the device is mated with the socket, a detector module configured to determine a connection state of the device and an engine running state of the vehicle based on voltage measurements at the connector, a processor configured to receive an output signal from the accelerometer and to process the output signal to identify when high-risk events have occurred, and a transmitter configured to transmit data relating to the high-risk events to a remote computer;

wherein the processor is further configured to:

determine that the vehicle is stationary when the device is in a connected state and the engine is in an ignition-off state or a non-running state;

identify a horizontal plane of the device when the vehicle is stationary; derive, from the output signal, an acceleration vector resolved in the horizontal plane;

compare the magnitude of the resolved acceleration vector to an orientation-independent pre-determined threshold value during movement of the vehicle;

and, if the magnitude of the resolved acceleration vector exceeds the pre-determined threshold value, identify that a high-risk event has occurred.

44. A telematics device according to Claim 43, wherein the processor is configured to initiate a high-risk event response protocol of the device upon identifying that a high-risk event has occurred.

45. A telematics device according to Claim 43 or Claim 44, further comprising a positioning system receiver, and wherein the processor is configured to verify that the vehicle is stationary using the positioning system receiver.

46. A telematics device according to any of Claims 43 to 45, wherein the processor is configured to obtain acceleration vector components from the output of the accelerometer, resolve the acceleration vector components into a vertical acceleration vector having a magnitude equal to gravitational acceleration, and identify the horizontal plane as a plane normal to the vertical acceleration vector.

47. A telematics device substantially as hereinbefore described with reference to the accompanying drawings.