GB2527810A

GB2527810A - Vehicle diagnostic system and method

Info

Publication number: GB2527810A
Application number: GB1411854.1A
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: GB201411854D0

Abstract

The present disclosure relates to a vehicle diagnostic system (101) and method for diagnosing a vehicle. The vehicle diagnostic system (101) is configured to receive a first signal (S1) acquired by a first data acquisition device (103) and a second signal (S2) acquired by a second data acquisition device (105). The vehicle diagnostic system (101) comprises a component (123) for identifying a first time (T1) at which a reference event occurs in the first signal; a component (125) for identifying a second time (T2) at which said reference event occurs in the second signal; and a component (127) for determining a temporal offset (Î”T) between said first and second times. The temporal or time offset (Î”T) can be used to align the data signals so that the data signals can be displayed to a technician in such a manner that the signals are synchronised. The one of the signals can be acquired from a sensor (107) and the other of the signals can be acquired from a vehicle ECU (113) using a diagnostic tool (105). The reference event can be identified in the signals using known patterns. The reference event can be the cranking of an internal combustion engine.

Description

VEHICLE DIAGNOSTIC SYSTEM AND METHOD

TECHNICAL FIELD

The present disclosure relates to a vehicle diagnostic system and to a vehicle diagnostic method.

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 diagnostic system and to a vehicle diagnostic method.

According to a further aspect of the present invention, there is provided a vehicle diagnostic system comprising a first data acquisition device configured to receive a first signal and a second data acquisition device configured to receive a second signal, the vehicle diagnostic system comprising: means for identifying a first time at which a reference event occurs in the first signal; means for identifying a second time at which said reference event occurs in the second signal; and means for determining a temporal offset between said first and second times.

The occurrence of the same reference event is identified in said first and second signals.

The temporal offset can be determined based on the difference between the first and second time when said reference event is identified in said first and second signals respectively.

The vehicle diagnostic system can comprise means for synchronizing signals received from the first and second data acquisition devices based on the determined temporal offset. The synchronizing means can be configured to synchronize a signal received by one of the first and second data acquisition devices with another signal received by the other of said first and second data acquisition devices. The synchronizing means can be configured to synchronize at least the first and second signals using the determined temporal offset.

Moreover, the temporal offset can be used to synchronize other signals obtained from said first and second data acquisition devices. Alternatively, or in addition, third and fourth signals can be synchronized.

The means for identifying the first time at which the reference event occurs in the first signal can identify a first pattern in the first signal to identify the reference event. The first pattern can be predefined. The first pattern can comprise an increase or decrease greater than or equal to a predefined first threshold. The first pattern can comprise a rate of change substantially matching a first predefined rate or within upper and lower rate change thresholds. The means for identifying the second time at which the reference event occurs in the second signal can identify a second pattern in the second signal to identify the reference event. The second pattern can be predefined. The second pattern can comprise an increase or decrease greater than or equal to a predefined second threshold. The second pattern can comprise a rate of change substantially matching a second predefined rate or within upper and lower rate change thresholds. The first pattern and the second pattern both relate to the same reference event. The first pattern can be the same as the second pattern.

The first data acquisition device can comprise an acquisition system. The acquisition system can be configured to acquire said first signal from a sensor. In a variant, the first data acquisition device can comprise a first vehicle diagnostic tool for coupling to a vehicle to perform one or more diagnostic functions. The first vehicle diagnostic tool can be configured to receive said first signal from a first electronic control unit (ECU) of the vehicle.

The second data acquisition device can comprise a second vehicle diagnostic tool for coupling to a vehicle to perform one or more diagnostic functions. The second data acquisition device can be configured to receive said second signal from a second electronic control unit (ECU) of the vehicle.

The first vehicle diagnostic tool can acquire the first signal from the first ECU and the second vehicle diagnostic tool can acquire the second signal from the second ECU. The vehicle diagnostic system could comprise means for determining the temporal offset between the first and second signals acquired from said first and second ECU5. The vehicle diagnostic system can be configured to synchronize the first and second signals acquired from said first and second ECUs. In a modified arrangement, the vehicle diagnostic system can be configured to synchronize the signals from more than two ECUs.

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. For example, the reference event can result in a signal pattern comprising an identifiable positive gradient (rising signal) and/or a negative gradient (falling signal) in the first and second signals. The signal pattern could comprise one more identifiable peaks and/or troughs occurring within a prescribed timeframe. The identifiable pattern could comprise identifying a signal above or below a predefined threshold. In addition, or alternatively, the identifiable pattern could comprise a time component, for example identifying a signal above or below a predefined threshold, or within a predefined range for a defined time period. Alternatively, or in addition, the identifiable pattern can comprise a slope of the signal being above or below a threshold. Alternatively, or in addition, the identifiable pattern can comprise identifying a signal above or below a threshold during a first time period and then above or below a second threshold during a second time period. A still further alternative would be to identify a specific waveform 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 the reference event by the vehicle diagnostic system.

The vehicle diagnostics system can comprise means for applying a first timestamp to the first signal based on the identified first time. The vehicle diagnostics system can comprise means for applying a second timestamp to the second signal based on the identified second time. The first timestamp and the second timestamp can be used to synchronize the first and second signals with each other.

The means for identifying the first time at which the reference event occurs in the first signal can be configuied to apply a first timestamp to the first signal based on the identified first time. The means for identifying the second time at which said reference event occurs in the second signal can be configured to apply a second timestamp to the second signal based on the identified second time.

The first data acquisition device and/or the second data acquisition device could form part of the vehicle diagnostic system. In this arrangement, the first data acquisition device can comprise the means for identifying the first time at which the reference event occurs in the first signal.

The first data acquisition device can comprise the means for applying a first timestamp to the first signal. The second data acquisition device can comprise the means for identifying the second time at which the reference event occurs in the second signal. Moreover, the second data acquisition device can comprise the means for applying a second timestamp to the second signal.

Alternatively, the first data acquisition device and/or the second data acquisition device could be separate from the vehicle diagnostic system. The first data acquisition device can output said first signal to the vehicle diagnostic system. The second data acquisition device can output said second signal to the vehicle diagnostic apparatus.

The vehicle diagnostic system described herein is in the form of apparatus and can comprise one or more electronic processors. The one or more processors can be configured to receive said first signal and/or said second signal. The one or more processors can process said signal(s) to identify the reference event in said first signal and/or said second signal.

Accordingly, the one or more processors can be configured to identify the first time and/or the second time. The one or more processors can be configured to apply a first timestamp to identify when the reference event occurred in the first signal; and configured to apply a second timestamp to identify when the reference event occurred in the second signal.

Moreover, the one or more processors can be configured to determine the temporal offset between said first and second times.

The one or more processors can be configured to use the determined temporal offset to synchronize at least said first and second signals. The one or more processors can be configured to synchronize other signals (for example relating to other vehicle systems) acquired by said first and second data acquisition devices. For example, the one or more processors can be configured to synchronize third and fourth signals received from the first and second data acquisition devices respectively. The one or more processors can be configured to synchronize one of said first and second signals with another signal, for example a third signal. The one or more processors can be coupled to system memory storing computer software code. The computer software code, when executed, can cause the one or more processors to implement the function(s) described herein.

The vehicle diagnostic system can comprise means for displaying the first and second signals. The displaying means can be in the form of a display screen, such as a liquid crystal display. The first and second signals can be displayed simultaneously in a time-synchronized format based on the determined first and second times.

The first signal and/or the second signal can correspond to a vehicle battery voltage.

According to a yet further aspect of the present invention, there is provided a vehicle diagnostic method, the method comprising: identifying a first time at which a reference event occurs in a first signal acquired by a first data acquisition device; identifying a second time at which said reference event occurs in a second signal acquired by a second data acquisition device; and determining a temporal offset between said first and second times.

The method can comprise identifying a first pattern in the first signal to identify the reference event; and/or identifying a second pattern in the second signal to identify the reference event. The first pattern and the second pattern both relate to the same reference event. The first pattern can be the same as the second pattern.

The first pattern and/or the second pattern can be predefined. The first pattern can comprise a change in magnitude (increase or decrease) in the first signal which is greater than or equal to a predefined first threshold. The first pattern can comprise a rate of change in the first signal which substantially matches a predefined rate of change. The second pattern can comprise a change in magnitude (increase or decrease) in the second signal which is greater than or equal to a predefined second threshold. The second pattern can comprise a rate of change in the second signal which substantially matches a predefined rate of change.

The first pattern and/or the second pattern can comprise a signal above or below a predefined threshold. In addition, or alternatively, the first pattern and/or the second pattern can comprise a time component, for example identifying a signal above or below a predefined threshold, or within a predefined range for a defined time period. Alternatively, or in addition, the first pattern and/or the second pattern can comprise a slope of the signal being above or below a threshold. Alternatively, or in addition, the first pattern and/or the second pattern can comprise identifying a signal above or below a threshold during a first time period and then above or below a second threshold during a second time period. A still further alternative would be to identify a specific waveform shape in said first pattern and/or said second pattern.

The method can comprise using the determined temporal offset to synchronize at least the first and second signals. The temporal offset can be used to synchronize other signals (for example relating to other vehicle systems) obtained from said first and second data acquisition devices. For example, the temporal offset can be used to synchronize third and fourth signals received from the first and second data acquisition devices respectively. At least the first and second signals can be synchronized to enable a direct comparison. The synchronized first and second signals can optionally be output for display simultaneously on a display screen, such as a LCD screen.

The method can comprise acquiring the first signal from a sensor. Alternatively, the method can comprise acquiring the first signal from a first electronic control unit.

The method can comprise acquiring the first signal from a second electronic control unit.

The vehicle diagnostic tool can be configured to be coupled to a diagnostics port provided on the vehicle, for example to establish communication with a vehicle ECU.

The method can comprise acquiring the first signal from a first ECU and acquiring the second signal from a second ECU. The method can comprise determining the temporal offset between the first and second signals acquired from said first and second ECUs. The method can comprise synchronizing the signals acquired from said first and second ECUs.

The method can comprise synchronizing said first and second signals, or other signals acquired from said first and second ECUs. For example, one of said first and second signals could be synchronized with a third signal. Alternatively, or in addition, the method could comprise synchronizing third and fourth signals with each other. In a modified arrangement, the method can comprise synchronizing signals from more than two ECUs.

The reference event can be any event which is identifiable in both said first and second signals. The reference event should be identifiable from those signals commonly found on an automotive ECU. In order to perform accurate synchronization, the reference event can be an event which passes through the complete acquisition chains associated with the first and second data acquisition devices should be used as the reference event. The reference event should result in an identifiable pattern in the first and second signals. For example, the reference event can result in a signal pattern comprising an identifiable positive gradient (rising signal) and/or a negative gradient (falling signal) in the first and second signals. The signal pattern could comprise an increase or a decrease greater than a predetermined threshold in said first signal or said second signal. Alternatively, or in addition, the signal pattern could comprise one more identifiable peaks and/or troughs occurring within a prescribed timeframe. 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 method could comprise identifying a pattern in the first signal and searching for a corresponding pattern in the second signal. A temporal offset be determined between the identified signals.

The signal pattern could comprise one more identifiable peaks and/or troughs occurring within a prescribed timeframe. The identifiable pattern could comprise identifying a signal above or below a predefined threshold. In addition, or alternatively, the identifiable pattern could comprise a time component, for example identifying a signal above or below a predefined threshold for a defined time period. Alternatively, or in addition, the identifiable pattern can comprise a slope of the signal being above or below a threshold. Alternatively, or in addition, the identifiable pattern can comprise identifying a signal above or below a threshold during a first time period and then above or below a second threshold during a second time period. A still further alternative would be to identify a specific waveform shape.

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.

A further alternative would be to detect a signal generated in dependence on a recovery trigger event performed by the user. The recovery trigger event could comprise one or more of the following: connecting/disconnecting a connector; shorting a signal to ground; operating a switch; depressing a pedal. The recovery trigger event would result in an identifiable pattern which could be identified in both said first and second signals.

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 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 oft-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, S2 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 ii 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 acouired 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 S2 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 S2, and a synchronizer 129 for synchronizing the first signal Si acquired by the acquisition system 103 and the second signal S2 acquired by the diagnostic tool 105. The apparatus further comprises a display screen 131 to display the acquired signals. The apparatus 1W 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 i2 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, S2. 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 iS 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 52, 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 iOi 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.

As shown in Figure 5, the acquisition system i03 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 i37. i3

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 51 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 51 is decoded and timestamped by the timestamping module 133 in dependence on the identified pattern (STEP i43). The timestamped first signal Si is output for display with reference to a virtual time origin (STEP i55).

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 i2i sends a request to the Vehicle Communication Interface 119, which then sends a request to the ECU 113 of the vehicle. The ECU 113 acquires a signal corresponding to the battery 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 transmitted 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 S2 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 51, 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 Si acquired by the acquisition system i03 is determined by the first signal decoder i23. A second time T2 at which the voltage drop occurs in the second signal 32 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-Ti) 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 31, 32.

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, 32 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 0), a first signal Si acquired respectively by the acquisition system 103 (curve E) and a second signal 32 acquired by the diagnostic tool 105 (curve F) and displayed on the display screen 131. The first signal 31 acquired respectively by the acquisition system 103 and the second signal S2 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 31, 32 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 103 and the diagnostic tool 105 can be synchronized. An example is monitoring fuel pressure. The diagnostic tool 105 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 105 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 S2 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, S2.

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, S2 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 iO implemented between the acquisition system 103 and the diagnostic tool 105 to determine a common time origin. The first and second signals Si, 52 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 i32 receives the first and second signals Si, S2 comprising said timestamps and the synchronized first and second signals Si, 52 can be displayed on the display screen 131. An alternative approach would be for the acquisition system i03 and the diagnostic tool 105 to output the raw data to the GUI i32 and a processor associated with the GUI i32 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, S2 generated in dependence on the performance of a reference event by the vehicle. In particular, the first and second signal decoders i23, i25 are configured to identify a pattern in the respective first and second signals 51, 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 i03: 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 i7 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 201 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 201 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 paftern 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 diagnostic system (101) comprising a first data acquisition device (103) configured to receive a first signal (Si) and a second data acquisition device (105) configured to receive a second signal (S2), the vehicle diagnostic system comprising: means (123) for identifying a first time (Ti) at which a reference event occurs in the first signal (Si); means (125) for identifying a second time (12) at which said reference event occurs in the second signal (S2); and means (127) for determining a temporal offset (AT) between said first and second times (Ti, 12).
2. A vehicle diagnostic system (101) as claimed in claim 1, wherein the means (123) for identifying the first time (Ti) is configured to identify a first pattern in the first signal (Si) to identify the reference event; and/or the means (125) for identifying the second time (T2) is configured to identify a second pattern in the second signal (S2) to identify the reference event.
3. A vehicle diagnostic system (101) as claimed in claim 1 or claim 2, wherein said first data acquisition device (103) comprises an acquisition system.
4. A vehicle diagnostic system (101) as claimed in claim 3, wherein said acquisition system is configured to acquire said first signal (Si) from a sensor.
5. A vehicle diagnostic system 001) as claimed in claim 1 or claim 2, wherein the first data acquisition device 003) comprises a first vehicle diagnostic tool for coupling to a vehicle to perform one or more diagnostic functions, the first vehicle diagnostic tool being configured to receive said first signal (Si) from a first electronic control unit of the vehicle.
6. A vehicle diagnostic system 001) as claimed in any one of the preceding claims, wherein the second data acquisition device 005) comprises a second vehicle diagnostic tool for coupling to a vehicle to perform one or more diagnostic functions, said second data acquisition device being configured to receive said second signal (S2) from a second electronic control unit of the vehicle.
7. A vehicle diagnostic system 001) as claimed in any one of the preceding claims, wherein the reference event corresponds to cranking an internal combustion engine.
8. A vehicle diagnostic system (101) as claimed in any one of the preceding claims comprising means (129) for synchronizing signals received by the first data acquisition device (103) and the second data acquisition device (105) using the determined temporal offset (AT).
9. A vehicle diagnostic system (101) as claimed in claim 8, wherein the synchronizing means is suitable for synchronizing at least said first and second signals (Si, 52) using the determined temporal offset (AT).
10. A vehicle diagnostic system (101) as claimed in any one of the preceding claims, wherein the means (123) for identifying the first time (Ti) is configured to apply a first timestamp to the first signal (Si); and/or the means (125) for identifying the second time (T2) is configured to apply a second timestamp to the second signal (52).
11. A vehicle diagnostic system 001) as claimed in any one of the preceding claims, wherein the first signal (Si) and/or the second signal (S2) correspond to a vehicle battery voltage.
12. A vehicle diagnostic method, the method comprising: identifying a first time (Ti) at which a reference event occurs in a first signal (Si) acquired by a first data acquisition device 003); identifying a second time (T2) at which said reference event occurs in a second signal (S2) acquired by a second data acquisition device 005); and determining a temporal offset (AT) between said first and second times (Ti, T2).
i3. A vehicle diagnostic method as claimed in claim 12 comprising identifying a first pattern in the first signal (Si) to identify the reference event; and/or identifying a second pattern in the second signal (S2) to identify the reference event.
i4. A vehicle diagnostic method as claimed in claim 12 or claim i3, wherein the first signal (Si) is acquired from a sensor or from a first electronic control unit.
15. A vehicle diagnostic method as claimed in any one of claims 12, 13 or 14, wherein the second signal (S2) is acquired from a second electronic control unit.
16. A vehicle diagnostic method as claimed in any one of claims 12 to 15, wherein the reference event corresponds to cranking an internal combustion engine.
17. A vehicle diagnostic method as claimed in any one of claims 12 to 16, comprising using the determined temporal offset (AT) to synchronize signals received by the first data acquisition device (103) and the second data acquisition device (105)
18. A vehicle diagnostic method as claimed in claim 17, comprising synchronizing at least said first and second signals (Si, S2) using the determined temporal offset (AT).
19. A vehicle diagnostic method as claimed in any one of claims 12 to 18 comprising applying a first timestamp to the first signal (Si) based on the first time (Ti); and/or applying a second timestamp to the second signal (S2) based on the second time (T2).
20. A vehicle diagnostic method as claimed in any one of claims 12 to 19, wherein the first signal (Si) and/or the second signal (S2) corresponds to a vehicle battery voltage.