GB2527811A

GB2527811A - Vehicle data acquisition device and method

Info

Publication number: GB2527811A
Application number: GB1411855.8A
Authority: GB
Inventors: Stephane Belsoeur; Guillaume Faber
Original assignee: Delphi International Operations Luxembourg SARL
Current assignee: Delphi International Operations Luxembourg SARL
Priority date: 2014-07-03
Filing date: 2014-07-03
Publication date: 2016-01-06
Also published as: GB201411855D0

Abstract

A vehicle data acquisition device (103; 105) for coupling to a vehicle to acquire data from the vehicle comprising a processor (111; 121) configured to receive a signal relating to a vehicle operating parameter. The processor (111, 121) is configured to identify a pattern in the received signal, the pattern being generated by a reference event performed by the vehicle. The processor may apply a timestamp to the signal based on the identified pattern in the received signal and output the timestamped signal to a vehicle diagnostic system. The pattern may be identified by comparing the received signal to one or more predefined signal parameters such as upper or lower thresholds, a change in magnitude, a rate of change, peaks, troughs, raising or falling edges, slopes, a pulse width, a DTC raising, a DTC status change or the absence of a response signal from an ECU and the like. The signal parameters may have to occur within a prescribed period of time. The reference event may relate to a vehicle operating condition, such as a cranking event of an internal combustion engine.

Description

VEHICLE DATA ACQUISITION DEVICE AND METHOD

TECHNICAL FIELD

The present disclosure relates to a vehicle data acquisition device and a method of processing data acquired from a vehicle.

BACKGROUND

Modern automotive vehicles are equipped with various networked electronic systems. A technician, for example in an automotive aftermarket workshop, can monitor the status of these electronic systems by connecting a diagnostic tool to an Electronic Control Unit (ECU), for example via a diagnostics port on the vehicle. The diagnostic tool can be connected to a diagnostics port on the vehicle to establish serial communication over a communication network, such as a CAN bus or a K line, provided on the vehicle. The ECU can provide an on-board diagnostics function to allow data relating to the vehicle to be output to the diagnostic tool. The data obtained by the diagnostic tool can provide a useful source of information when troubleshooting problems with a vehicle.

However, not all vehicle data is recorded or processed by the ECU or available via the diagnostic services of the ECU. For example, certain signals (voltage or current) and measured physical characteristics of the vehicle (such as exhaust gases, noise etc.) are not available from the ECU. In order to obtain this vehicle data, it is possible to use an acquisition system to measure the vehicle data directly, for example using one or more sensors, transducers, actuators or ECU pins. The ability to combine the data sets generated by the acquisition system and by the ECU would be useful to allow a direct comparison to be made of measured parameters with those derived from the ECU. However, it is not straightforward to make a direct comparison of the data derived from different sources.

One approach to synchronizing several acquisition systems is to define a master system that sends a trigger signal (or event) to a slave system(s). However, interconnecting the diagnostic tool (which reads data from the ECU) and the acquisition systems (which measures signals directly), or even having a single system performing both operations in parallel, doesn't guarantee a good synchronization of both sources of data because the acquisition chains are different. In particular, diagnostic tools and acquisition systems operate as separate systems which function independently of each other and acquire data through separate acquisition chains.

Figures 1 and 2 show a first acquisition chain 1 for acquiring a first data signal using an acquisition system 3, and a second acquisition chain 5 for acquiring a second data signal using a diagnostic tool 7. The first acquisition chain 1 (implemented by the acquisition system 3) comprises acquiring a signal from an actuator 9 of the vehicle (STEP 11) and converting the acquired signal into a digital signal through a first Analogue-to-Digital Converter 13 (STEP 15), and then processing the digital signal through a first processor 17 (STEP 19). The signal is then decoded for display (STEP 21) on a display screen 23. The second acquisition chain 5 (implemented by the diagnostic tool 7) differs from the first acquisition chain 1. The diagnostic tool 7 is connected to a diagnostic port to interrogate the ECU 25. The ECU 25 could monitor a drive signal, for example by acquiring a signal from the actuator 9 and/or from a sensor 27 of the vehicle (STEP 29). In particular, the diagnostic tool 7 can output a request to the ECU 25 which is received by a second processor 31. The signal is converted into a digital signal through a second Analogue-to-Digital Converter 33 (STEP 35), and then processed by the second processor 31 (STEP 37). The second processor 31 prepares a response for the diagnostic tool 7 (STEP 39), and the response containing the information requested by the diagnostic tool 7 is sent to the diagnostic tool 7 (STEP 41). The information is decoded for display (STEP 43) on a display screen 45. In an alternate implementation, the ECU 25 can output a command signal to the diagnostic tool 7 which corresponds to a command applied to the actuator 9. By way of example, the ECU 25 can return a value for the applied PWM (Pulse Width Modulation), such as 70%. However, in case of a failure, for instance an open circuit somewhere on the line, the drive command does not reach the actuator. It will be appreciated, therefore, that the information supplied by the ECU 25 to the diagnostic tool 7 can be the result of a computation performed by the ECU dependent on one or more parameters of the ECU, either internal parameters (which can be measured or computed) or external parameters (which are measured).

To acquire a signal corresponding to information from the vehicle, the diagnostic tool 7 thereby performs additional operations compared to the acquisition system 3. Thus, acquiring information through the diagnosfic tool 7 takes longer than acquiring the information using the acquisition system 3. As shown in Figure 3, a temporal offset AT therefore exists between two signals corresponding to the same information, the two signals being respectively acquired by the diagnostic tool 7 and by the acquisition system 3. Figure 3 shows a graph representing, in addition to the signal in real time (curve A), the signal acquired respectively by the acquisition system 3 (curve B) and the signal by the diagnostic tool 7 (curve C). The temporal offset AT is visible between the two acquired signals. The temporal offset AT depends on each ECU type, and can depend on one or more of the following: the processor load, the diagnostics functions priority, the diagnostic communication priority on the communication network/bus and the volume of data transmitted at the same time as the requested data to be acquired. The difference between the sampling rate of the ECU and the sampling rate of the acquisition system can also result in a delay, thereby further increasing the temporal offset AT. In a worst case scenario, the temporal offset AT may reach an order of magnitude of up to 1 to 2 seconds. This temporal offset AT may cause a particular problem when the signals need to be read on a single interface and read against each other.

At least in certain embodiments, the present invention sets out to overcome or ameliorate at least some of the problems associated with known systems.

SUMMARY OF THE INVENTION

Aspects of the present invention relate to a vehicle data acquisition device and to a method of processing data acquired from a vehicle.

According to a further aspect of the present invention there is provided a vehicle data acquisition device for coupling to a vehicle to acquire data from the vehicle, the vehicle data acquisition device comprising a processor configured to: receive a signal relating to a vehicle operating parameter; and identify a pattern in the received signal, the pattern being generated in said signal in dependence on a reference event performed by the vehicle. The reference event corresponds to a predetermined event which can be selectively performed by the vehicle.

The processor can be configured to apply a timestamp to the signal based on the identified pattern in the received signal. The timestamp provides a time reference for the signal and can enable the signal to be compared directly with one or more other signals. The timestamp can be used to synchronise the signal with said one or more other signals. This can facilitate a direct comparison of the signals.

Alternatively, or in addition, the processor can be configured to output a control signal in dependence on identification of said pattern in said received signal. The control signal can, for example, initialize the recording of one or more signals. The one or more signals can be stored in memory or output to a storage device.

The pattern could be defined in more than one signal. The processor could be configured to receive a plurality of signals and to identify the pattern in said signals.

The pattern can be identified by comparing the received signal to one or more predefined signal parameters stored in system memory. The system memory can be coupled to the processor and can comprise at least one machine-readable storage device. A machine-executable instruction set can be stored on the system memory which, when executed by the processor, causes the processor to identify the pattern in the received signal and to apply the timestamp.

The one or more predefined signal parameters can comprise one or more of the following: an upper threshold; a lower threshold; a change in magnitude; a rate of change; an upper rate of change threshold; a lower rate of change threshold; one or more peaks; and one or more troughs; a raising edge; a falling edge; a slope, such as an instant slope going above or below an adjustable threshold; a pulse width, such as a pulse width going above or below a threshold during a minimum adjustable period, a serial bus frame, such as a Controller Area Network (CAN) frame, a Diagnostic Trouble Code (DTC) raising, a DTC status change (for example permanent state, historic state, age or counter); and an absence of an Electronic Control Unit (ECU) response signal.

The one or more predefined signal parameters can comprise a custom pattern. The custom pattern can be defined directly through a dedicated function of a Graphical User Interface (GUI) of the system, or through a file generated outside the data acquisition device such as a text file or a Microsoft® Excel® file.

The processor can be configured to identify said pattern when said one or more predefined signal parameters is identified in the received signal within a prescribed period of time.

The reference event can correspond to a vehicle operating condition. The reference event can be any event which is identifiable in the signal. A suitable reference event is a cranking event of an internal combustion engine. The vehicle starter motor operates to crank the engine and this typically results in a drop in the measured vehicle battery voltage, often over a short period of time. The voltage drop can be identified and, therefore, used as the reference event. The signal received by the processor can correspond to a vehicle battery voltage.

The vehicle data acquisition device can comprise means for receiving the signal from the vehicle. The receiving means can comprise a connector for connecting the data acquisition device to a vehicle diagnostics port. A vehicle diagnostics port is typically coupled to a vehicle communications network and this can enable the data acquisition device to acquire the signal from the vehicle systems. The vehicle systems can comprise one or more of the following: a sensor, a transducer and an actuator. One or more electronic control units can be coupled to, or integrated into the vehicle communications network.

The vehicle data acquisition device can comprise means for outputting the timestamped signal to a vehicle diagnostic system. The output means can comprise an output channel, a port or a transmitter for coupling to the vehicle diagnostic system. The output means can provide a wired connection or a wireless connection. Alternatively, the vehicle data acquisition device could be incorporated into a vehicle diagnostic system. The vehicle diagnostic system could be in the form of a vehicle diagnostic apparatus having a display screen for displaying the received signal.

The vehicle data acquisition device can be a measurement device for measuring one or more parameteis relating to the vehicle. The measurement device can be coupled to one or more of the following: a transducer, a sensor, and an actuator. Alternatively, the vehicle data acquisition device can be a vehicle diagnostic tool, for example for coupling to an electronic control unit disposed in the vehicle.

The signal could be a first signal. The processor could be configured also to receive a second signal. The first and second signals can be received from respective first and second data acquisition devices. The processor can be configured to analyse said first and second signals to identify respective first and second patterns. The first and second patterns can relate to the same reference event. The processor can be configured to determine a temporal offset between said first and second signals. The processor can be configured to synchronise said first and second signals based on the determined temporal offset.

According to a further aspect of the present invention there is provided a method of processing data acquired from a vehicle, the method comprising: receiving a signal relating to a vehicle operating parameter; and identifying a pattern in the received signal, the pattern being generated in said signal in dependence on a reference event performed by the vehicle.

The method can comprise applying a timestamp to the signal based on the identified pattern in the received signal. The timestamp provides a time reference for the signal and can enable the signal to be compared directly with one or more other signals.

Alternatively, or in addition, the method can comprise outputting a control signal in dependence of identification of said pattern in received signal. The control signal can, for example, initialize the recording of one or more signals.

The identification of the pattern in the received signal can comprise comparing the received signal to one or more predefined signal parameters. The one or more predefined signal parameters comprise one or more of the following: an upper threshold; a lower threshold; a change in magnitude; a rate of change; an upper rate of change threshold; a lower rate of change threshold; one or more peaks; one or more troughs; a raising edge; a falling edge; a slope, such as an instant slope going above or below an adjustable threshold; a pulse width, such as a pulse width going above or below a threshold during a minimum adjustable period; a serial bus frame, such as a Controller Area Network (CAN) frame, a Diagnostic Trouble Code (DTC) raising, a DTC status change (for example permanent state, historic state, age or counter); and an absence of an Electronic Control Unit (ECU) response signal.

The one or more predefined signal parameters can comprise a custom pattern. The custom pattern can be defined directly through a dedicated function of a Graphical User Interface (GUI) of the system; or through a file generated outside the data acquisition device, such as a text file or a Microsoft' Excel® file.

The signal can be acquired from a vehicle communications network. The vehicle communications network can be integrated into the vehicle and communicate with on-board apparatus, such as a sensor, a transducer or an actuators. The method can comprise interrogating the vehicle communications network to acquire the signal.

The reference event can correspond to a vehicle operating condition. The vehicle operating condition can comprise a cranking event of an internal combustion engine. The signal can correspond to a vehicle baftery voltage.

The method can comprise outputting the timestamped signal to a vehicle diagnostic system.

The method can comprise displaying the timestamped signal, for example on a liquid crystal display (LCD).

The received signal can be a first signal acquired from the vehicle. The method can be repeated for a second signal acquired from the vehicle. The method can comprise applying first and second timestamps to the respective first and second signals. The method can also comprise using said first and second timestamps to synchronise said first and second signals. The method could be applied to more than two signals acquired from the vehicle.

The reference event can be any event which is identifiable in both said first and second signals. The reference event should result in an identifiable pattern in the first and second signals. The method can comprise identifying the signal pattern in said first and second signals. At least in certain embodiments, the reference event can result in a unique signal pattern in said first and second signals.

The first signal and the second signal can correspond to the same parameter, such as a measured voltage or current. Alternatively, the first signal and the second signal can correspond to related parameters, such as voltage and current respectively. The first signal and the second signal can correspond to the vehicle battery voltage. The reference event can be identified in the measured voltage profile.

A suitable reference event is an engine cranking event. The vehicle starter motor operates to crank the engine and this typically results in a drop in the measured vehicle battery voltage, often over a short period of time. The voltage drop can be identified and, therefore, used as a suitable reference event in the method described herein. The battery voltage (or the ECU power voltage, if the ECU is supplied by the same power source or power circuit as the vehicle starter motor) is a common parameter which is generally readable by a vehicle diagnostics device.

In a variant, the reference event is selected within a signal generated by a sensor or switch connected to a pedal in the vehicle, for example a switch provided in the brake pedal or the clutch pedal. In a variant, the reference event is selected within a signal generated by a sensor connected to a switch in the vehicle, for example a switch on the dashboard of the vehicle. This approach may be appropriate on a hybrid vehicle whereby ignition of the internal combustion engine cannot be controlled directly by the operator. The presence of a voltage stabilizer on the on-board power supply network may inhibit monitoring of the battery pack voltage to identify the reference event. Equally, the presence of multiple batteries in the power supply, or an ECU sampling period which is too high to detect the voltage drop may render the cranking event unsuitable as a reference event.

The method can comprise applying a first timestamp to the first signal and/or a second timestamp to the second signal. The first and second timestamps can be based on the respective first and second times. The first and second signals can be synchronized using said first and second timestamps. A time shift function can be applied to data acquired by one of said first and second data acquisition systems to synchronize the first and second signals. The time shift function can be used to synchronize other signals received from the first and second data acquisition systems, for example to synchronize third and fourth signals.

The method(s) described herein could be implemented on one or more processors, for example one or more electronic processors. According to a further aspect of the present invention there is provided a set of computational instructions which, when operating on a processor, cause the processor to perform the method(s) described herein. The computational instructions can be stored on memory associated with said one or more processors. The computational instructions can be provided on a machine-readable media or in a machine-readable signal, for example provided over a communications network.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying Figures, in which: Figure 1 shows a diagnostic tool and a measuring device for acquiring data through separate acquisition chains according to the prior art; Figure 2 shows a block diagram of the acquisition chains respectively of a diagnostic tool and of an acquisition system according to the prior art; Figure 3 shows a graph representing a signal respectively in real time and acquired by the acquisition system and the diagnostic tool as shown in Figure 1; Figure 4 shows a vehicle diagnostic apparatus in accordance with an embodiment of the present invention; Figure 5 shows a block diagram of a data synchronization implemented with the vehicle diagnostic apparatus shown in Figure 4; Figure 6 shows a graph representing a signal respectively in real time and acquired and synchronized by the vehicle diagnostic apparatus shown in Figure 4; Figure 7 shows a graph representing a vehicle battery voltage signal acquired and synchronized by the vehicle diagnostic apparatus in accordance with an embodiment of the present invention; and Figure 8 shows a vehicle diagnostic apparatus in accordance with a variant of the present invention; Figures 9 and 10 illustrate a first pattern in a control signal received by the vehicle data acquisition device; Figures 11 and 12 illustrate a second pattern in a control signal received by the vehicle data acquisition device; Figures 13 and 14 illustrate a third pattern in a control signal received by the vehicle data acquisition device; Figures 15 and 16 illustrate a fourth pattern in a control signal received by the vehicle data acquisition device; and Figures 17 and 18 illustrate a fifth pattern in a control signal received by the vehicle data acquisition device.

DETAILED DESCRIPTION

A vehicle diagnostic apparatus 101 in accordance with an embodiment of the present invention will now be described with reference to the accompanying Figures, and in particular with reference to Figures 4 to 7. The vehicle diagnostic apparatus 101 is suitable for performing diagnostic operations on a vehicle (not shown). The vehicle can, for example, be a light-duty vehicle, a medium-duty vehicle, a heavy-duty vehicle, or an off-road vehicle.

Figure 4 shows the apparatus 101 according to an embodiment of the present invention. The apparatus 101 comprises a first data acquisition device in the form of an acquisition system 103, and a second data acquisition device in the form of a vehicle diagnostic tool 105. The apparatus 101 is configured to determine a temporal offset between a first signal Si acquired from the vehicle by the acquisition system 103 and a second signal acquired from the vehicle by the diagnostic tool 105. At least in certain embodiments, the apparatus 101 can be used to synchronize the first and second signals Si, 52 acquired from the vehicle.

The acquisition system 103 is coupled to at least one sensor 107 which is configured to generate a signal corresponding to a parameter of the vehicle, such as a voltage, a current, a temperature (for example, exhaust gas temperature or engine temperature), composition of an exhaust gas, or the like. The acquisition system 103 is configured to acquire a first signal Si from the sensor 107. The acquisition system 103 includes a first Analogue-to-Digital Converter 109 connected to a first processor iii. The first processor ill includes a decoder (not shown) to decode the acquired data. The acquisition system 103 is adapted to provide data on the acquired signal, such as one or more of the following set: an instantaneous signal level, an instantaneous frequency, an instantaneous period, an instantaneous duty cycle and an average level (over a period defined by an operator or by default over a signal period). Moreover, conversion rules can be applied to the signal acquired by the acquisition system 103. The acquisition system 103 can measure one or more of the following: current (optionally in the form of a non-invasive device, such as an amp-clamp), voltage and impedance. The acquisition system 103 can, for example, be coupled to a transducer, an actuator or a probe.

The diagnostic tool 105 is configured to be connected to the Electronic Control Unit (ECU) 113 of the vehicle. The diagnostic tool 105 can, for example, be connected to a diagnostics port on the vehicle to communicate with the ECU 113 over a communications network. The diagnostic tool 105 is configured to acquire a signal corresponding to data acquired by the ECU 113, for example from a sensor 114 provided in the vehicle. The ECU 113 can additionally or alternatively acquire data from a vehicle actuator 116. The ECU 113 comprises a second Analogue-to-Digital Converter 115 and a second processor 117. The second processor 117 is connected to the second Analogue-to-Digital Converter 115. The diagnostic tool 105 comprises a Vehicle Communication Interface 119 coupled to a third processor 121. The Vehicle Communication Interface 119 is arranged to acquire a second signal 52 from the second processor 117 provided in the ECU 113 disposed in the vehicle.

The apparatus 101 is adapted to determine a temporal offset AT between the first signal Si acquired by the acquisition system 103 and the second signal 32 acquired by the diagnostic tool 105. This can be performed using a reference event as a trigger which is external to both the acquisition system 103 and the diagnostic tool 105. The apparatus 101 comprises means for identifying a first time at which the reference event occurs in the first signal Si, in the form of a first signal decoder 123. The apparatus 101 also comprises means for identifying a second time at which said reference event occurs in the second signal, in the form of a second signal decoder 125. The apparatus 101 further comprises an offset determining module 127 for determining the temporal offset AT between the first signal Si and the second signal 32, and a synchronizer 129 for synchronizing the first signal Si acquired by the acquisition system 103 and the second signal 32 acquired by the diagnostic tool 105. The apparatus further comprises a display screen 131 to display the acquired signals. The apparatus 101 implements a Graphical User Interface (GUI) 132 to enable a user to view the synchronised first and second signals Si, S2 on the display screen 131.

The GUI 132 allows the user to make inputs to the apparatus 101, for example to select the parameters to be displayed. At least in certain embodiments, the synchronizer 129 can be used to synchronize the first and second signals Si, S2 acquired from the vehicle.

Alternatively, or in addition, the synchronizer 129 can be used to synchronize one of said first and second signals Si, 52 with another signal, for example a third signal. Alternatively, or in addition, the synchronizer 129 can be used to synchronize third and fourth signals with each other.

In order to synchronize data read by the first and second data acquisition devices, a common time reference is applied to the first and second signals Si, 52. In the present embodiment, a timestamp is applied to the first signal Si and to the second signal S2. The offset determining module 127 comprises a timestamping module 133 for applying a first timestamp to the first signal Si and/or a second timestamp to the second signal S2. The first and second timestamps are applied respectively to the first signal Si and to the second signal S2, with respect to the reference event identified in the first signal Si and in the second signal 52.

The reference event in the present embodiment relates to a cranking event when an electric starter motor is activated to crank the internal combustion engine. The cranking event results in a drop in the vehicle battery voltage which results in an identifiable pattern in said first signal Si and said second signal S2. By identifying the voltage pattern in said first signal Si and said second signal S2, the time at which the reference event occurred in the respective first and second signals Si, S2 can be determined. In a variant, the reference event is identified within a signal acquired by a sensor of a pedal in the vehicle, for example the brake pedal or the clutch pedal. In a variant, the reference event is identified within a signal acquired by a sensor of a switch in the vehicle, for example a switch on the dashboard of the vehicle. The synchronizer 129 is configured to synchronize the first and second signals Si, S2 once the first and second signals Si, S2 have been timestamped.

The operation of the apparatus 101 according to an embodiment of the present invention will now be described with reference to Figures 4 to 7. The operation of the apparatus 101 will be described with reference to the acquisition of first and second signals Si, S2 corresponding to the voltage of the vehicle battery. ii

As shown in Figure 5, the acquisition system 103 is included in a first acquisition chain, namely a sensor acquisition chain 135, and the diagnostic tool 105 is included in a second acquisition chain, namely a diagnostic tool acquisition chain 137.

A first signal Si corresponding to the battery voltage is acquired by the acquisition system 103 (STEP 139). The first signal Si is converted into a digital signal through the first Analogue-to-Digital Converter 109 (STEP 140). The first signal Si is acquired by the first processor 111 at a predefined sample rate xms (STEP 141). The first signal Si is then analysed by the first signal decoder 123 to identify the pattern corresponding to the reference event (i.e. the engine cranking event). The first signal Si is decoded and timestamped by the timestamping module 133 in dependence on the identified pattern (STEP 143). The timestamped first signal Si is output for display with reference to a virtual time origin (STEP 155).

To acquire data corresponding to the battery voltage, the diagnostic tool 105 sends a request to the ECU 113 of the vehicle. More precisely, the third processor 121 sends a request to the Vehicle Communication Interlace 119, which then sends a request to the ECU 113 of the vehicle. The ECU 113 acquires a signal corresponding to the baftery voltage, for example from the sensor 114. The signal is converted into a digital signal by the second Analogue-to-Digital Converter 117 (STEP 145), and the digital signal is acquired by the second processor 117 at a predefined sample rate xms (STEP 147). The second processor 117 prepares a response to the request received from the diagnostic tool (STEP 149). The response is transmifted in the form of the second signal S2 to the diagnostic tool 105 (STEP 151) over a diagnostics network, for example the vehicle CAN network. The second signal S2 contains the information requested by the diagnostic tool 105. The second signal S2 is then analysed by the second signal decoder 125 to identify the pattern corresponding to the reference event (i.e. the engine cranking event). The second signal 52 is timestamped by the timestamping module 133 in dependence on the identified pattern (STEP 153). The timestamped second signal S2 is output to the GUI 132 for display with reference to a virtual time origin.

The first and second signals Si, S2 can be synchronized with each other using the respective timestamps (STEP 157). The synchronized first and second signals Si, S2 can be displayed together on the display screen 131 with reference to a common time axis. This synchronization is represented in Figure 5 as being performed by the diagnostic tool 105 (STEP 157), but in the present embodiment is performed by the GUI 132.

As outlined above, the first and second signals Si, S2 corresponding to the vehicle battery voltage are acquired by the diagnostic tool 105 and the acquisition system 103. The first and second signals are each analysed to identify the signal pattern associated with the same reference event (the cranking event in the present embodiment). The signal pattern comprises a voltage drop which can be identified in both the first and second signals Si, S2 by the respective first and second signal decoders 123, 125. The operation of the first and second signal decoders 123, 125 is described in more detail below.

A first time Ti at which the voltage drop occurs in the first signal 51 acquired by the acquisition system 103 is determined by the first signal decoder 123. A second time 12 at which the voltage drop occurs in the second signal S2 acquired by the diagnostic tool 105 is determined by the second signal decoder 125. A temporal offset AT between the first and second times is determined (AT=T2-T1) by the offset determining module 127. The first time Ti is then defined as a virtual time reference origin for the first and second signals Si, 52.

The voltage drop in each signal is timestamped by the timestamping module 133 with reference to the time reference origin. Once the temporal offset AT has been determined and the virtual time reference identified, the first and second signals Si, 52 are synchronized by the synchronizer 129. The synchronized signals can be output for display on the display screen 131. Figure 6 shows, in addition to the signal in real time (curve D), a first signal Si acquired respectively by the acquisition system 103 (curve E) and a second signal 52 acquired by the diagnostic tool 105 (curve F) and displayed on the display screen 131. The first signal Si acquired respectively by the acquisition system 103 and the second signal 52 acquired by the diagnostic tool 105 have been synchronized, and the output signals time-matched.

Figure 7 shows an example of synchronized first and second signals for the vehicle battery voltage acquired by the acquisition system 103 (curve G) and by the diagnostic tool 105 (curve H). The first and second signals Si, S2 acquired respectively by the acquisition system 103 and by the diagnostic tool 105 have been synchronized. The battery voltage drop during the cranking event is measured by the acquisition system 103 at the battery terminals (a sample rate of 4000 samples per second) and at the ECU by the diagnostic tool over the CAN network (at a sample rate of 16 samples per second). At the beginning of the activation of the starter, a voltage drop occurs due to the current drawn by the electric motor in the starter. This is generally a 3-5V drop in less than lOms, and the battery voltage remains more than 2V below its nominal value during the starter activation, having a typical duration of 0.5 to 2 seconds. This is sufficient to be detected by a diagnostic tool (having a typical sampling period of between 50 and 250ms). The reference event in the present arrangement has been defined as a voltage drop of two (2) volts in the vehicle battery voltage and identification of this reference event in both the first and second signals Si, 52 is used to synchronize the signals acquired by the acquisition system 103 (curve G) and by the diagnostic tool 105 (curve H). The maximum synchronization error is equal to the highest sampling period of both acquisition systems, approximately 62ms in the present example, which is acceptable for a wide range of applications. Although the maximum synchronization error cannot be reduced, the average synchronization error over a number of trials can be significantly improved by linear interpolation of the time reference.

By determining the temporal offset AT, it is possible to synchronize other signals received by the acquisition system 103 and the diagnostic tool 105. Thus, a direct comparison can be made between the data acquired by the different data acquisition systems. The temporal offset AT can be used to synchronize one of said first and second signals Si, S2 with another signal acquired from the other of said acquisition system 103 and the diagnostic tool 105. Alternatively, or in addition, the temporal offset AT can be used to synchronize third and fourth signals acquired from said acquisition system 103 and the diagnostic tool 105. It will be appreciated that more than two signals could be synchronized.

The operation of the apparatus 101 has been described with reference to first and second signals Si, S2 associated with a measured voltage of a vehicle battery. By determining the temporal offset AT between the first and second signals Si, S2, other signals acquired by the acquisition system i03 and the diagnostic tool 105 can be synchronized. An example is monitoring fuel pressure. The diagnostic tool i05 can typically read the fuel pressure from an engine management system, but it is not always possible to read the command of the fuel pressure regulator. Accordingly, it would be useful to use the acquisition system 103 to measure the drive current or the PWM of the drive signal and to output this data in parallel with data acquired by the diagnostic tool 105 relating to one or more of the following: the fuel pressure, the engine speed and the acceleration pedal position. In this example, the battery voltage can be used to synchronize the signals acquired by the acquisition system 103 and the diagnostic tool 105, but the battery voltage signal is not required for diagnostic purposes.

The synchronization mechanism described herein provides a reference temporal offset for a particular diagnostic tool i05 and the acquisition system 103. By extension, this principle also applies to acquisition performed by one or more acquisition systems, and/or to one or more diagnostic tools acquiring data on one or more ECUs.

In a variant represented in Figure 8, the first and second signal decoders are incorporated into the acquisition system 103 and the diagnostic tool 105 respectively. The timestamping of the first signal Si and the second signal 32 is implemented within the acquisition system 103 and the diagnostic tool 105. Thus, the data output from the acquisition system 103 and the data output from the diagnostic tool 105 are timestamped with a common time reference to enable synchronization of the first and second signals Si, 32.

As described herein, the time reference is based on identification of a common reference event in the first and second signals Si, S2. In particular, a reference event is detected and the timestamp applied to each of the first and second signals Si, 32 based on identification of the reference event in that signal. The reference event in the present embodiment is an engine cranking event, but a recovery trigger event could be used in place of, or in addition to the engine cranking event. As shown in Figure 8, a synchronization mechanism is implemented between the acquisition system 103 and the diagnostic tool 105 to determine a common time origin. The first and second signals Si, S2 are output respectively from the acquisition system 103 and the diagnostic tool 105 and each comprise a timestamp (to enable identification of the common time origin). The GUI 132 receives the first and second signals Si, S2 comprising said timestamps and the synchronized first and second signals Si, S2 can be displayed on the display screen 131. An alternative approach would be for the acquisition system 103 and the diagnostic tool 105 to output the raw data to the GUI 132 and a processor associated with the GUI 132 to identify the reference event in each signal and to apply the appropriate timestamp.

The apparatus 101 has been described with reference to identifying a pattern in the first and second signals Si, 32 generated in dependence on the performance of a reference event by the vehicle. In particular, the first and second signal decoders 123, 125 are configured to identify a pattern in the respective first and second signals Si, S2. The techniques implemented by the first and second signal decoders 123 to identify a signal pattern in the first signal Si which corresponds to a reference event will now be described in greater detail with reference to Figures 9 to iS.

The first signal decoder 123 can be configured to identify one or more of the following patterns in the first signal output from the acquisition system 103: Threshold -a magnitude of the signal increases above (raising edge) or falls below (falling edge) a predefined threshold; Gradient -a determined gradient (slope) of the signal increases above or falls below a predefined threshold; Pulse width -a pulse is detected in the signal having a width which is greater than or less than a threshold during a predefined time period; and Custom pattern -identification of a predefined pattern in the signal which is defined directly through a dedicated function of the GUI 132, or through an externally generated file (for example, a text file, an excel file etc.).

In addition, the second signal decoder 125 can be configured to identify one or more of the following patterns in the second signal output from the diagnostic tool 105: Diagnostic Trouble Code (DTC) raising -a trouble code raised by the ECU 113; Diagnostic Trouble Code (DTC) status change -the status of a DTC changes, for example state (permanent, historic etc.), age, counter etc.; Frame detection -a frame is detected on the CAN bur or other serial bus; and ECU stops responding -the ECU 113 does not respond to a request made by the diagnostic tool 105.

The techniques described herein can be expanded using operators to define a composite pattern which is identifiable in the first and second signals Si, S2. The composite pattern comprises a plurality of functions and each function can correspond to one of the aforementioned patterns transmitted to the acquisition system 103 and the diagnostic tool 105.

The operators are described with reference to Figures 9 to 18 which illustrate a sample signal 2W for input to the first signal decoder 123. The sample signal 201 is a waveform (illustrated as a square wave) comprising a series of functions 203 combined using one or more operators to form an identifiable composite pattern 205. The identification of the composite pattern 205 can be used to trigger a function, for example to initialize a recording function to record one or more signals. Alternatively, or in addition, the identification of the composite pattern 205 can be used to synchronize one or more signals, as described herein.

The composite pattern 205 can be defined to correspond to a reference event performed by the vehicle. The function of the operators will now be described.

Repetition: Detection of a repeated function 203 in the sample signal 2W a predetermined number of times (X). The number of times (X) that the function 203 must be detected in order for the first signal decoder 123 to identify the composite pattern 205 can be adjusted.

Also, a timeout period can be defined for detection of each function 203 making up the composite pattern 205. In the example illustrated in Figure 9, the first signal decoder 123 is configured to identify the pattern when the function 203 occurs three times (X=3) within a prescribed time period tl. The first signal decoder 123 identifies the composite pattern upon identification of the third function 203. The operation of the timeout feature is illustrated in Figure 10 in which the third function 203 does not occur until after the timeout period ti has expired. The defined sequence of the functions 203 does not correspond to the defined composite pattern 205.

Period: An operator to define a minimum or maximum time period between successive functions 203 in the composite pattern 205. The operator can be used to require that the time elapsed between two successive functions 203 is less than, or greater than a defined time period. The time period can be specified depending on the application.

In the example illustrated in Figures 11 and 12, two successive functions 203 must be identified in the signal 201 within a defined maximum timeout period t2. As shown in Figure 11, the first signal decoder 123 identifies the composite signal 205 when the successive functions 203 are identified within the maximum timeout period t2. The first signal decoder 123 does not identify the composite signal 205 when the second function 203 occurs after the maximum timeout period t2 has elapsed, as shown in Figure 12.

In the example illustrated in Figures 13 and 14, the successive functions 203 must be identified in the signal 201 with a minimum timeout period t3 elapsing between them. As shown in Figure 13, the first signal decoder 123 identifies the composite pattern 205 when the second function 203 is identified after the minimum timeout period t3 has elapsed. The first signal decoder 123 does not identify the composite signal 205 when the second function 203 occurs before the minimum timeout period t3 has elapsed, as shown in Figure 14.

A period timeout function can be implemented to require that a function 203 is detected over a defined function period t4. The first signal decoder 123 is configured to output a trigger when the function period t4 elapses. As shown in Figure 15, the first signal decoder 123 identifies the pattern 205 when the function 203 is maintained for the duration of the function period t4. The first signal decoder 123 does not identify the pattern 205 when the function 203 ends before the function period t4 has elapsed, as shown in Figure 16.

As illustrated in Figures 17 and 18, a positive or negative time delay function can be applied to implement a control function in dependence on identification of the function 203. As shown in Figure 17, a positive delay can be used to implement the control function after identification of the function 203. As shown in Figure 18, a negative delay can be used to implement the control function before identification of the function 203. A time period t5 can be defined for the time delay function. The control function can, for example, initialize recording of one or more signals. A positive or negative delay can be applied so that the recording of the signal 201 is initialized a certain adjustable time period after that the pattern 203 occurs in the signal, so that useless data are not recorded. Alternatively, the control function could be used to specify a reference time in the signal which is offset temporally from the identified pattern 205.

The operators described herein can be combined with logic operators. The following logic operators allow the composite pattern 205 to be identified in one or more than one signals: OR (Disjunction): One event or the other event or both events occur.

XOR (Exclusive Or): One event or the other event but not both occurs.

XNOR (Exclusive Nor): Both events occur or do not occur at the same time.

AND (Conjunction): Both events occur.

NOT (Negation): The event does not occur (for example to monitor disappearance of a fault code, or communications stop on CAN Bus etc.).

It will be appreciated that various changes and modifications can be made to the method(s) and apparatus described herein.

An engine cranking event has been described herein as a suitable reference event to identify in the first and second signals Si, S2. However, it will be appreciated that other reference events could be used. Moreover, the embodiment described herein refers to the identification of patterns in the signals corresponding to the battery voltage, but it will be appreciated that other signals could be used.

Claims

CLAIMS: 1. A vehicle data acquisition device (103; 105) for coupling to a vehicle to acquire data from the vehicle, the vehicle data acquisition device (103; 105) comprising a processor (ill; 121) configured to: receive a signal relating to a vehicle operating parameter; and identify a pattern in the received signal, the pattern being generated in said signal in dependence on a reference event performed by the vehicle.
2. A vehicle data acquisition device (103; 105) as claimed in claim 1, wherein the processor (111; 121) is configured to apply a timestamp to the signal based on the identified pattern in the received signal.
3. A vehicle data acquisition device (103; 105) as claimed in claim 2, comprising means for outputting the timestamped signal to a vehicle diagnostic system (101).
4. A vehicle data acquisition device (103; 105) as claimed in any one of claims 1, 2 or 3, wherein the processor (111; 121) is configured to initialize the recording of the received signal based on identification of the pattern in the received signal.
5. A vehicle data acquisition device (103; 105) as claimed in any one of the preceding claims, wherein the pattern is identified by comparing the received signal to one or more predefined signal parameters stored in a system memory.
6. A vehicle data acquisition device (103; 105) as claimed in claim 5, wherein the one or more predefined signal parameters comprise one or more of the following: an upper threshold; a lower threshold; a change in magnitude; a rate of change; an upper rate of change threshold; a lower rate of change threshold; one or more peaks; one or more troughs; a raising edge; a falling edge; a slope; a pulse width; a serial bus frame; a Diagnostic Trouble Code raising, a Diagnostic Trouble Code status change; and an absence of a response signal of an Electronic Control Unit of the vehicle.
7. A vehicle data acquisition device (103; 105) as claimed in claim 5 or claim 6, wherein the processor (111; 121) is configured to identify said pattern when said one or more predefined signal parameters is identified in the received signal within a prescribed period of time.
8. A vehicle data acquisition device (103; 105) as claimed in any one of the preceding claims, wherein the reference event corresponds to a vehicle operating condition.
9. A vehicle data acquisition device (103; 105) as claimed in claim 8, wherein the vehicle operating condition comprises a cranking event of an internal combustion engine.
10. A method of processing data acquired from a vehicle, the method comprising: receiving a signal relating to a vehicle operating parameter; and identifying a pattern in the received signal, the pattern being generated in said signal in dependence on a reference event performed by the vehicle.
11. A method as claimed in claim 10 comprising applying a timestamp to the signal based on the identified pattern in the received signal.
12. A method as claimed in claim 10 or claim 11 comprising initializing the recording of the received signal based on the identified pattern in the received signal.
13. A method as claimed in any one of claims 10, 11 or 12, wherein identifying the pattern comprises comparing the received signal to one or more predefined signal parameters.
14. A method as claimed in claim 13, wherein the one or more predefined signal parameters comprise one or more of the following: an upper threshold; a lower threshold; a change in magnitude; a rate of change; an upper rate of change threshold; a lowel rate of change threshold; one or more peaks; one or more troughs; a raising edge; a falling edge; a slope; a pulse width; a serial bus frame; a Diagnostic Trouble Code raising, a Diagnostic Trouble Code status change; and an absence of a response signal of an Electronic Control Unit of the vehicle.
15. A method as claimed in claim 13 or claim 14, wherein said pattern is identified when said one or more predefined signal parameters is identified in the received signal within a prescribed period of time.
16. A method as claimed in any one of claims 10 to 15, wherein the reference event corresponds to a vehicle operating condition.
17. A method as claimed in claim 16, wherein the vehicle operating condition comprises a cranking event of an internal combustion engine.
18. A method as claimed in any one of claims 11 to 17 comprising outputting the timestamped signal to a vehicle diagnostic system (101).