GB2541668B

GB2541668B - Telematics device

Info

Publication number: GB2541668B
Application number: GB1515025.3A
Authority: GB
Inventors: Michael Fellows Paul
Original assignee: E Touch Solutions Ltd
Current assignee: E Touch Solutions Ltd
Priority date: 2015-08-25
Filing date: 2015-08-25
Publication date: 2019-06-26
Anticipated expiration: 2035-08-25
Also published as: WO2017033014A3; GB201515025D0; WO2017033014A2; GB2541668A

Description

TELEMATICS DEVICE

[001] The present invention relates to a telematics device for monitoring driver behaviour in a vehicle. In particular, but not exclusively, the invention relates to an aftermarket plug-in telematics device suitable for connection to a vehicle accessory socket.

[002] 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.

[003] 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.

[004] 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.

[005] 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.

[006] 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.

[007] 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.

[008] 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.

[009] 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.

[0011] 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] According to a first aspect of the present invention, there is provided 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, 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 to an orientation-independent pre-determined threshold value during movement of the vehicle and, when the magnitude of the resolved acceleration vector exceeds the orientation-independent pre-determined threshold value, recording that a high-risk event has occurred.

[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 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. The method may further comprise verifying that the vehicle is stationary using a positioning system receiver.

[0017] In one embodiment, the method includes 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.

[0018] 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, repeatedly derive, from the output signal, an acceleration vector resolved in the horizontal plane, repeatedly compare the magnitude of the resolved acceleration vector to an orientation-independent pre-determined threshold value during movement of the vehicle and, when the magnitude of the resolved acceleration vector exceeds the pre-determined threshold value, record that a high-risk event has occurred.

[0019] 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.

[0020] 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.

[0021] In one embodiment, 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 The transmitter is arranged to transmit data associated with the connection state and the engine running state to a remote computer.

[0022] 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 processor, 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.

[0023] The device is also able to determine, using the processor, 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.

[0024] 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 processor, the device can distinguish between the disconnection of the device from the accessory socket midjourney and the vehicle ignition being switched off at the end of a journey.

[0025] 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.

[0026] 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.

[0027] When a third electrical contact is present, the processor 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.

[0028] Preferably, the processor 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.

[0029] The processor 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 processor determines that the device is in a connected state and that the engine is in an ignition-off state. In one embodiment, the processor 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 processor determines that the device is in a non-connected state.

[0030] 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.

[0031] The processor 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.

[0032] For example, in one embodiment, the processor 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 processor 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 processor 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.

[0033] 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.

[0034] The device may further comprise a memory for storing data derived from 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.

[0035] 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 processor 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.

[0036] 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.

[0037] Preferably, the device comprises a housing for the internal power source, the transmitter, the processor 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.

[0038] 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.

[0039] 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 11 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; and

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

[0040] 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.

[0041] 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.

[0042] 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, 110 which are disposed on opposite sides of the connector 104. The contacts 104, 108, 110 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, 110 are spring-loaded, so that they each press against and connect with the second electrical terminal of the socket.

[0043] 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, 110 also serve to help retain the device 100 in the socket.

[0044] As shown in Figure 2, the first, second and third electrical contacts 106, 108, 110 are each connected to a detector module 112 of the device 100. As will be explained in more detail below, the detector module 112 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, 110.

[0045] The device 100 includes an internal power supply or battery 114, a processor 116, a transmitter module 118 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.

[0046] The internal battery 114 is of a rechargeable type, and is charged when the device 100 is receiving external power from the vehicle. The internal battery 114 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.

[0047] During operation of the device 100, the processor 116 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 (not shown) using the transmitter 118, as is generally known in the art. In this way, the telematics device 100 is able to communicate information to the remote server 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.

[0048] The processor 116 is also connected to the detector module 112. The detector module 112 performs a sequence of tests to provide additional information about the status of the device 100 and the vehicle. For example, the detector module 112 may operate in a sequence of steps as will now be described with reference to Figure 3.

[0049] Firstly, at step 201, the detector module 112 determines whether external power is being supplied to the device 100 through the connector 104. To do so, detector module 112 isolates the electrical contacts 106, 108, 110 of the connector 104 from the internal battery 114 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 110).

[0050] 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.

[0051] Accordingly, when external power is not detected, at step 202, the detector module 112 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 116 may write a data entry to the memory 120 and/or may transmit data to the remote server by way of the transmitter 118.

[0052] When external power is detected at step 201, the voltage measured between the first and second electrical contacts 106, 108 is the supply voltage Vs provided to the accessory socket by the vehicle electrical system. The supply voltage Vs supplied to an accessory socket is drawn from the vehicle battery and is not regulated, and therefore the supply voltage Vs varies substantially according to the running mode or state of the engine. At step 204, the detector module 112 attempts to determine the engine running state based on the supply voltage Vs. 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 118.

[0053] 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 112 makes use of the internal battery 114 and the second and third contacts 108, 110 of the connector 104. In the following description, the second contact 108 is referred to as side contact A and the third contact 110 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 110) 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), 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).

[0054] Figure 4 illustrates a possible sequence of steps for determining the device connection state. First, at step 301 in Figure 4, the detection module 112 applies a pull-down load to side contact A. In other words, side contact A is connected to a ground terminal 115 of the internal battery 114 through a high resistance. Then, at step 302, the detection module 112 applies internal battery power to side contact B (i.e. side contact B is connected to a reference, non-ground terminal 117 of the internal battery).

[0055] At step 303, the detection module 112 measures the voltages Va and Vb at side contact A and side contact B, respectively, relative to the ground terminal 117 of the internal battery 114. At step 304, the detection module 112 compares the measured voltages Va , Vb. If Va and Vb 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”.

[0056] If Va is not equal to Vb, and is instead equal to zero (i.e. the potential at side contact A is the same as the ground potential 115), 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”.

[0057] Referring back to Figure 3, determination of the engine running state at step 204is based on analysis by the detector module 112 of the supply voltage Vs 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 Vs 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 Vs 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 Vs typically drops to around 4 to 6 V whilst the engine is being started. By comparing the measured supply voltage Vs with suitable pre-set threshold voltages, each of these three engine running states can be identified and distinguished from one another.

[0058] Figure 5 shows a possible sequence of steps in which the detector module 112 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 112 measures the voltage at side contact A (or, equivalently, at side contact B) relative to the first contact 108 to determine the supply voltage Vs of the vehicle power supply.

[0059] Then, at step 402, the measured supply voltage Vs is compared with a battery charging threshold voltage, Verging. The battery charging threshold voltage Verging 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, Verging may be set at 13 V. If the supply voltage Vs is greater than the battery charging threshold voltage Verging, 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”.

[0060] If the supply voltage Vs is less than the battery charging threshold voltage Verging then, at step 404, the supply voltage Vs is compared with a lower base battery threshold voltage, Vbase. The lower base battery threshold voltage Vbase is set as the lowest expected voltage that a vehicle battery will deliver when it is not being charged. For example, Vbase may be set at 11 V. If the supply voltage Vs is greater than the lower base battery threshold voltage, Vbase (but lower than the battery charging threshold voltage Verging 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”.

[0061] It will be appreciated that, in this example, the battery charging threshold voltage Verging 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 Vs could also be compared with an upper base battery threshold voltage that differs from Verging and an “engine stopped” running state logged only if the supply voltage Vs is lower than the upper base battery threshold voltage.

[0062] If the supply voltage Vs is less than the lower base battery threshold voltage, Vbase, then, at step 406, the supply voltage Vs is compared with a lower cranking voltage threshold, Viow, and an upper cranking voltage threshold Vcranking. The cranking voltage thresholds Viow, Vcranking 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, Viow,may be set at 3 V and the upper cranking voltage threshold Vcranking may be set at8V.

[0063] If the supply voltage Vs is between the lower cranking voltage threshold, Viow, and the upper cranking voltage threshold Vcranking 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”.

[0064] If the supply voltage is not between the a lower cranking voltage threshold, Viow, and the upper cranking voltage threshold Vcranking 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.

[0065] In these ways, by virtue of the detector module 112, 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.

[0066] For example, in one embodiment of the device 100, the processor 116 looks for changes in the device connection state and engine running state information received from the detector module 112. 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.

[0067] 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 116 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 112.

[0068] Particular sequences of changes in the device connection state and/or the engine running state may trigger the processor 116 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.

[0069] 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 restarted 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 116 may record corresponding event data.

[0070] It will be understood that the detector module 112 may employ voltage sensing and switching methods that are generally known in the art. The detector module 112 may be embodied in software, hardware or in a combination of hardware and software. Elements or all of of the detector module 112 may be combined with the processor 116. The detector module 112 may continuously perform tests to determine the connection state and engine running state, or the detector module 112 may be instructed to perform a test or a sequence of tests by the processor 116 according to a timing schedule or in response to particular trigger events.

[0071] Referring back to Figure 1, in another embodiment 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 14.

[0072] 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 Ax and pure lateral acceleration is represented by vector Ay. Vector Axy represents the acceleration vector under a mixed load condition, in which the vehicle is both accelerating and turning.

[0073] Provided the acceleration vector Axy is within the boundary 500, as shown in Figure 6, the tyre should adhere to the road surface. When the acceleration vector Axy 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 Axy can provide information about driver behaviour.

[0074] By way of example, Figure 7 (a) illustrates the acceleration vector Axy 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 Axy 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).

[0075] Figure 7(c) illustrates the acceleration vector Axy for a vehicle accelerating at a modest rate. The acceleration vector Axy is well within the limits of adhesion represented by the boundary 500, whereas under harder acceleration the acceleration vector Axy 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 Axy 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.

[0076] Figure 8 illustrates another example of high-risk driving behaviour. In this case, the acceleration vector Axy is shown for a vehicle that is attempting to 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.

[0077] 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.

[0078] 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).

[0079] 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 11, 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 116 is configured to identify the horizontal X-Y plane 700 using the output from the accelerometer 124.

[0080] Firstly, the processor 116 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 112. For example, the processor 116 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 116 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.

[0081] 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 116 performs a calibration step, in which the horizontal X-Y plane is identified. This is achieved with reference to the acceleration due to gravity, Ag, which has a constant magnitude and a direction that will be approximately vertical with respect to the vehicle.

[0082] 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 Ag, 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.

[0083] After the calibration step, subsequent measurements from the accelerometer 124 are processed as follows to obtain the acceleration vector Axy 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 Ag 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 Axy in the X-Y plane.

[0084] 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 Axy 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.

[0085] 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.

[0086] Referring to Figure 12, the resolved acceleration vector in the X-Y plane, Axy, 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 Rmax, the processor 116 records that a high-risk driving behaviour event has occurred, for example by writing event data to the memory 120 and/or by transmitting data via the transmitter 118.

[0087] The threshold value Rmax 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 Axy with respect to the X and Y axes of the vehicle does not need to be determined. Accordingly, the threshold value Rmax 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 Rmax that lies within a conservative estimate of the adhesion limit 500 is appropriate.

[0088] 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 Ri, corresponding to a first orientation-independent threshold value for the magnitude of the acceleration vector Axy. 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 Axy. When the magnitude of the acceleration vector Axy exceeds the first threshold value Ri but not the second threshold value R2 (as illustrated by vector Axyi in Figure 13), the processor 116 records that a moderately high-risk driving behaviour event has occurred (such as, for example, rapid acceleration). When the magnitude of the acceleration vector Axy exceeds the second threshold value R2 (as illustrated by vector Axy2 in Figure 13), the processor 116 records that a very high-risk driving behaviour event has occurred.

[0089] 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.

[0090] 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 11. This completes a calibration process for the device.

[0091] 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 Rmax (i.e. the boundary 800 in Figure 12). If the magnitude of the resolved acceleration vector, Axy, is greater than the threshold value Rmax, a driving limits alert is logged 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.

[0092] In this context, logging a driving limits alert may be equivalent to recording that a high-risk event has occurred, and may for example comprise writing data to a memory or uploading 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 logging a driving limits alert, the process may restart from step 905 to allow continued monitoring of driver behaviour.

[0093] In another embodiment, at step 907, the magnitude of the resolved acceleration vector in the X-Y plane, Axy, is compared with first and second orientation-independent, pre-determined threshold values Ri, R2 (i.e. the boundaries 801, 802 in Figure 13), and first- and second-level driving limits alerts are logged accordingly.

[0094] 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.

[0095] 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.

[0096] Several modifications and variations of the device and its operating methods are possible.

[0097] 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.

[0098] 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).

[0099] 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.

[00100] 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.

[00101] The transmitter may be a cellular modem to transmit data to a remote computer over a cellular wireless connection. In this case, the remote computer may be hosted by the insurance provider, so that the device sends information directly to the insurance provider. Alternatively, 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 (RTM) or NFC (near field communciation), which can serve to relay the data to another remote computer and/or to process the data.

[00102] 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

1. A method for monitoring driver behaviour in a vehicle using a telematics 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 to an orientation-independent pre-determined threshold value during movement of the vehicle; and, when the magnitude of the resolved acceleration vector exceeds the orientation-independent pre-determined threshold value, recording that a high-risk event has occurred.

2. A method according to claim 1, 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.

3. A method according to claim 1 or 2, further comprising verifying that the vehicle is stationary using a positioning system receiver.

4. A method according to any one of claims 1 to 3, 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.

5. 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; wherein the processor is further configured to: identify a horizontal plane of the device when the vehicle is stationary; repeatedly derive, from the output signal, an acceleration vector resolved in the horizontal plane; repeatedly compare the magnitude of the resolved acceleration vector to an orientation-independent pre-determined threshold value during movement of the vehicle; and, when the magnitude of the resolved acceleration vector exceeds the pre-determined threshold value, record that a high-risk event has occurred.

6. A telematics device according to claim 5, 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, and wherein the processor is 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.

7. A telematics device according to claim 6, further comprising a positioning system receiver, and wherein the processor is configured to verify that the vehicle is stationary using the positioning system receiver.

8. A telematics device according to any one of claims 5 to 7, 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.

9. A telematics device according to claim 6, : wherein 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; wherein the telematics device further comprises an internal power source to provide power to the device when no electrical supply from the vehicle is received; and wherein the transmitter is arranged to transmit data associated with the connection state and the engine running state to a remote computer.

10. A telematics device according to claim 9, 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.

11. A telematics device according to claim 10, 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.

12. A telematics device according to claim 10 or 11, wherein the processor is configured to check for a short circuit between the second and third electrical contacts thereby to determine the connection state of the device.

13. A telematics device according to any one of claims 10 to 12, wherein the processor is configured to determine whether a vehicle supply voltage Vs 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.

14. A telematics device according to claim 13, wherein the processor 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 processor determines that the device is in a connected state and that the engine is in an ignition-off state.

15. A telematics device according to claim 13 or 14, wherein the processor 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 processor determines that the device is in a non-connected state.

16. A telematics module according to any one of claims 9 to 15, wherein the processor is configured to measure the supply voltage Vs between the first electrical contact and the second electrical contact, and to compare the measured supply voltage Vs to a plurality of threshold voltages to determine the engine running state.

17. A telematics device according to claim 16, wherein the processor is configured to determine that the engine is in a running state when the measured supply voltage Vs is greater than a battery charging threshold voltage Verging.

18. A telematics device according to claim 16 or 17, wherein the processor is configured to determine that the engine is in a nonrunning state when the measured supply voltage Vs is between a lower base battery threshold voltage Vbase and an upper base battery threshold voltage.

19. A telematics device according to any one of claims 16 to 18, wherein the processor is configured to determine that the engine is in a cranking state when the measured supply voltage Vs is between a lower cranking threshold voltage Viow and an upper cranking threshold voltage Vcranking.

20. A telematics device according to any one of claims 9 to 19, further comprising a positioning system receiver and/or a plurality of sensors, and a memory, and wherein the processor is configured to write vehicle usage data derived from the receiver and/or the sensors to the memory.

21. A telematics device according to claim 20, 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.

22. A telematics device according to claim 21, wherein the processor is further configured to associate the event data with the vehicle usage data.

23. A telematics device according to claim 21 or 22, 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.

24. A telematics device according to any one of claims 9 to 23, comprising a housing for the internal power source, the transmitter, and the detector module, and wherein the connector is integral with the housing.