Identification of an incompatible build condition of a vehicle

Abstract

Aspects of the present invention relate to a system (100) for identifying an incompatible build condition of a vehicle (400). The system (100) is configured to receive a first input signal (123) indic

Description

19 06 25 TECHNICAL FIELD The present disclosure relates to identification of an incompatible build condition of a vehicle. Aspects 5 of the invention relate to a system, to a control system, to a vehicle, to a method and to computer readable instructions. BACKGROUND Despite rigorous vehicle build and repair process controls, it remains possible that out of specification 10 component parts may be fitted to a vehicle during vehicle build or repair. This, in turn, may lead to reduced efficiency or sub-optimal dynamic performance. For example, installation of an out of specification rear differential may manifest as apparent reduced power train performance as a consequence of efforts by the dynamic stability control system to correct what it interprets as axle slip. In another example, an out of specification electric drive motor, or reduction gear attached to the electric 15 drive motor, may be interpreted by the vehicle control system as wheel slip resulting in inappropriate application of wheel slip mitigation protocols which may be perceived by the driver as reduced vehicle performance. It is against this background that the present invention has been devised. 20 SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a control system for controlling a system for identifying an incompatible build condition of a vehicle, a control system for controlling a warning device of a vehicle, a warning system for a vehicle, a vehicle, a method for identifying an incompatible build 25 condition of a vehicle, and computer readable instructions for performing the method as claimed in the appended claims. According to an aspect of the present invention there is provided a system for identifying an incompatible build condition of a vehicle, the system comprising one or more processors collectively 30 configured to: receive, at an input, a first input signal indicative of a wheel speed of a first axle of the vehicle; receive, at the input, a second input signal indicative of a wheel speed of a second axle of the vehicle; determine if the indicated wheel speeds satisfy a predetermined wheel speed criteria in dependence on the first and second input signals; if the indicated wheel speeds satisfy the predetermined wheel speed criteria, generate a fault code indicative of an incompatible build condition. 35 Optionally the system is configured to output, at an output, the generated fault code. The system of the present invention is advantageous as it facilitates rapid identification of drivetrain build incompatibilities. 19 06 25 The system comprises one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal; and at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute 5 the instructions thereon so as to: receive, at the input, a first input signal indicative of a wheel speed of a first axle of the vehicle; receive, at the input, a second input signal indicative of a wheel speed of a second axle of the vehicle; determine if the indicated wheel speeds satisfy a predetermined wheel speed criteria in dependence on the first and second input signals; if the indicated wheel speeds satisfy the predetermined wheel speed criteria, generate a fault code indicative of an incompatible build 10 condition; and output, at an output, the generated fault code. Optionally, the output generated fault code is configured to control operation of a warning device such as a warning light and / or display system and / or auditory warning which is configured to alert the driver and / or vehicle technician that an incompatible build condition has been identified. 15 Determining if the predetermined wheel speed criteria is satisfied comprises determining if the difference between the indicated wheel speeds falls outside a predetermined range. The use of a range to determine satisfaction of the wheel speed criteria is advantageous as it allows for variations in wheel speeds that might arise from user or operational variability to be accounted for. 20 The system may optionally be configured to: generate electronically modelled wheel speeds for the first and second axles; or receive, at the input, one or more third input signals indicative of electronically modelled wheel speeds for the first and second axles, wherein determining if the predetermined wheel speed criteria is satisfied comprises determining if the indicated wheel speeds match the electronically 25 modelled wheel speeds within a predetermined threshold. The use of electronically modelled wheel speeds is advantageous as it facilitates identification of an incompatible build condition without reliance on measured wheel speeds alone. The system may be configured to: receive, at the input, a fourth input signal indicative of an operational 30 state of the vehicle; and determine the electronically modelled wheel speeds in dependence on the indicated operational state of the vehicle thereby facilitating generation of more accurate electronically modelled wheel speeds. In one example, the system may be configured to: increment a count of satisfaction events following a 35 determination that the indicated wheel speeds satisfy the predetermined wheel speed criteria; and generate the fault code indicative of an incompatible build condition if the count of satisfaction events is greater than or equal to a predetermined minimum count. This is advantageous as it reduces the possibility of a false fault code being generated by the system. 19 06 25 Optionally, the system may be configured to decrement the count of satisfaction events following a determination that the indicated wheel speeds do not satisfy the predetermined wheel speed criteria. As above, this is advantageous as it reduces the possibility of a false fault code being generated by the system. 5 The system may optionally be configured to: receive, at the input, a fifth input signal indicative of an operational history of at least one system of the vehicle during a predetermined time interval or distance travelled; determine in dependence on the fifth input signal if a prespecified vehicle system event has occurred during the predetermined time interval or distance travelled; and if it is determined that the 10 specified vehicle system event has occurred during the predetermined time interval or distance travelled, set the count of satisfaction events to zero. By resetting the count of satisfaction events to zero after a prespecified vehicle system event has occurred during the predetermined time interval or distance travelled, the possibility of a false fault code being generated as a result of a particular system event taking place is reduced. 15 The system may be configured to set the count of satisfaction events to zero upon initiation of a drive cycle so that system data and events from previous drive cycles are not carried forward. As before, this is advantageous as it reduces the possibility of a false fault code being generated by the system. 20 In one example, the system may be configured to: receive, at the input, a sixth input signal indicative of the activation of a vehicle system flag; following receipt of the sixth input signal, generate a flag code indicative of the vehicle system flag having been activated; and output, at the output, the generated flag code. This is advantageous as it alerts the vehicle’s user that any fault code issued by the system may need to be interpreted in the context of activation of the vehicle system flag. 25 Optionally, the system may be configured to: receive, at the input, a seventh input signal indicative of an external environmental condition; and determine if the indicated external environmental condition satisfies a predetermined external environmental condition criteria in dependence on the seventh input signal; if the indicated external environmental condition satisfies the predetermined external 30 environmental condition criteria, either: prevent generation of the fault code indicative of an incompatible build condition; or generate an environmental condition code and output, at the output, the generated environmental condition code. This is advantageous as it either prevents issuance of the fault code I the external environmental conditions are not conducive to accurate identification of a build incompatibility, or alerts the vehicle’s user that any fault code issued by the system may need to be 35 interpreted in the context of the environmental conditions. In another aspect, embodiments of the invention provide a control system for controlling a warning device of a vehicle, the control system comprising one or more processors collectively configured to: receive, at an input, the fault code generated by the system described above; and operate a warning 19 06 25 device of the vehicle upon receipt of the fault code. Also, embodiments of the invention provide a warning system comprising the control system describe above and a warning device. In a further aspect, embodiments of the invention provide a method for identifying an incompatible build 5 condition of a vehicle, the method comprising: receiving a first input signal indicative of a wheel speed of a first axle of the vehicle; receiving a second input signal indicative of a wheel speed of a second axle of the vehicle; determining if the indicated wheel speeds satisfy a predetermined wheel speed criteria in dependence on the first and second input signals; if the indicated wheel speeds satisfy the predetermined wheel speed criteria, generating a fault code indicative of an incompatible build 10 condition; and outputting the generated fault code. In a still further aspect, embodiments of the invention provide a method for controlling a warning device of a vehicle, the method comprising: receiving the fault code generated using the method described above; and operating a warning device of the vehicle upon receipt of the fault code. 15 In a yet further aspect, embodiments of the invention provide a vehicle comprising the system, the control system, or the warning system described above. In another aspect, embodiments of the invention provide computer readable instructions which, when 20 executed by a computer, are arranged to perform a method as described above. 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 25 or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. 30 BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 35 Figure 1 shows a schematic representation of a four wheel drive vehicle drivetrain layout; Figure 2 shows a schematic representation of a control system such as may be adapted to implement a method in accordance with an embodiment of the invention; 19 06 25 Figure 3 shows a flow chart depicting a method such as may be adapted in accordance with an embodiment of the invention; Figure 4 shows a schematic representation of a rear wheel drive vehicle drivetrain layout; 5 Figure 5 shows a flow chart depicting another method such as may be adapted in accordance with an embodiment of the invention; Figure 6 shows a block diagram depicting a simplified example of a system such as may be adapted in 10 accordance with an embodiment of the invention; and Figure 7 shows a vehicle in accordance with an embodiment of the invention. DETAILED DESCRIPTION 15 A vehicle 400 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 7. As shown in Figure 7, a system 100 for identifying an incompatible build condition of the vehicle 400 is installed in the vehicle 400. The system 100 is configured to control operation of a warning device 140 of the vehicle 400. 20 With reference to Figure 2, there is illustrated a vehicle system 200 which comprises the system 100, a plurality of wheel speed sensors 120 (comprising individual wheel speed sensors 122, 124, 126, 128), steering angle indicator 130, braking indicator 132, vehicle warning flag indicator 134, environment sensor 136, and a warning device 140 and / or processing system as will be described in greater detail below. The system 100 comprises one or more controller 110. 25 Figure 1 shows a schematic representation of a four wheel drive vehicle drivetrain layout 10. In one embodiment, the vehicle 400 comprises the drivetrain layout 10. The drivetrain layout 10 comprises a prime mover 11 which is attached to a gearbox 12. The gearbox 12 has a transfer case 13 which is operatively connected to a rear driveshaft 14 and a forward driveshaft 15. A front axle 20 of the drivetrain 30 10 comprises two half-shafts 21 connected by a front differential 22, and a rear axle 25 comprises two half-shafts 26 connected by a rear differential 27. The forward driveshaft 15 is operatively connected to the front differential 22 to provide drive to the front axle 20 via the front differential 22, and the rear driveshaft 14 is operatively connected to the rear differential 27 to provide drive to the rear axle 25 via the rear differential 27. A pairof front wheels 16 are driven by the front axle 20, and a pair of rear wheels 35 17 are driven by the rear axle 25. As a result of drive being provided to both the front and rear axles 20, 25 simultaneously, the final drive ratio of the front and rear differentials 22, 27 must be such that the front and rear axles 20, 25 rotate at the same speed (within a predetermined threshold) when the vehicle 400 is being driven along a straight 40 path. Even if the vehicle 400 is cornering, provided that the front and rear differentials 22, 27 are in 19 06 25 specification, the half-shafts 21,26 located on the same side of the vehicle 400 at the front and rear of the vehicle 400 respectively will rotate at the same speed (within a predetermined threshold), If either of the differentials 22, 27 are out of specification, this will not be the case and there will be a build incompatibility. It will be understood that the same situation would also arise in a vehicle drivetrain layout 5 in which the front axle comprises independent left and right axles, and the rear axle comprises independent left and right axles and the description which follows is equally applicable to such a vehicle drivetrain layout. The front wheels 16 and the rear wheels 17 are each provided with a wheel speed sensor 122, 124, 10 126, 128. The wheel speed sensors 122, 124, 126, 128 are configured to issue an input signal 123, 125, 127, 129 (see Figure 2) to the controller 110. In an alternative embodiment, only one of the front wheels 16 and one of the rear wheels 17 are provided with a wheel speed sensor. The vehicle system 200 comprises a steering angle indicator 130 for determining a steering angle and 15 issuing a steering angle input signal 131 to the controller 110. The vehicle system 200 also comprises a braking indicator 132 for determining if the vehicle’s brakes are applied and issuing a braking input signal 133 to the controller 110. The steering angle indicator 130 and / or the braking indicator 132 may be part of another control system of the vehicle 400 such as a steering control system or a braking system. The vehicle system 200 may additionally comprise a six degree of freedom multi-axis sensor 20 for measuring motion of the vehicle and issuing a vehicle motion input signal to the controller 110. The vehicle system 200 also comprises a vehicle warning flag indicator 134 for determining if a system or component of the vehicle 400 has issued a warning flag, and issuing a warning flag input signal 135 to the controller 110. The warning flag indicator 134 is configured to determine if a warning flag has 25 been issued by any vehicle system or component including, but not limited to, an anti-lock brake system (ABS), a dynamic stability control system (DSC), and / or the wheel speed sensors 122, 124, 126, 128. The vehicle system 200 also comprises an environment sensor 136 for sensing an external environmental condition in which the vehicle 400 is operating, and issuing an environment input signal 30 137 to the controller 110. The environment sensor 136 may comprise one or more of a temperature gauge, a camera, a water sensor or any other suitable device for sensing an external environment in which the vehicle 400 is operating. It will be understood that while the vehicle system 200 illustrated in Figure 2 shows only one environment sensor 136, more than one environment sensor 136 may be used to provide a plurality of separate environment input signals 137 to the controller 110. Alternatively, the 35 outputs from a plurality of environment sensors 136 may be received by an environment sensor system (not shown) which is configured to determine an environmental condition from the plurality of environment sensors 136, and issue a single environment input signal 137 to the controller 110. The controller 110 is configured to receive the various input signals at an input 440 (as shown in Figure 40 6) which may comprise a single electrical input which is configured to receive a plurality of input signals, 19 06 25 or which may comprise a plurality of separate electrical inputs which collectively form the input 440 of the controller 110. The system 100 is configured to receive at the input 440 of the controller 110 wheel speed data 121 5 from the wheel speed sensors 120 and determine, in dependence on the wheel speed data 121, if an incompatible build condition of the vehicle exists. If an incompatible build condition is identified, the system 100 is configured to generate a fault code 141 and output the fault code 141 at an output 450 (Figure 6) of the controller 110. The output of the fault code 141 may control operation of a warning device 140 such as a warning light and / or display system and / or auditory warning which is configured 10 to alert the driver and / or vehicle technician that an incompatible build condition has been identified. Alternatively or additionally, the fault code 141 may be provided to a processing system for use in further vehicle diagnostics. In one embodiment, a front wheel speed sensor 122 senses the wheel speed of the front axle 20 and 15 issues an input signal 123 indicative of the wheel speed of the first axle 20 to the controller 110. Similarly, a rear wheel speed sensor 126 senses the wheel speed of the rear axle 25 and issues an input signal 127 indicative of the wheel speed of the rear axle 25 to the controller 110. In an alternative embodiment, both of the front wheel speed sensors 122, 124 may be used to sense 20 the wheel speed of the front axle 20 and issue input signals 123, 125 indicative of the wheel speed of the first axle 20 to the controller 110. Similarly, both of the rear wheel speed sensors 126,128 may be used to sense the wheel speed of the rear axle 25 and issue input signals 127, 129 indicative of the wheel speed of the first axle 25 to the controller 110. The controller 110 may be configured to use the wheel speed sensor signals 123, 125, 127, 129 independently to determine if the vehicle 400 is 25 cornering, the controller 110 may alternatively or additionally use the vehicle motion input signal from the multi-axis sensor (if present) to determine if the vehicle 400 is cornering. Figure 3 illustrates a method 50 according to an embodiment of the invention. The method 50 is a method of identifying an incompatible build condition of a vehicle 400, such as the vehicle 400 illustrated 30 in Figure 7. In particular, the method 50 is a method of determining if the indicated wheel speeds satisfy a predetermined wheel speed criteria. The method 50 may be performed by the controller 110 illustrated in Figures 2 and 6. In particular, with reference to Figure 6, the memory 430 may comprise computer-readable instructions which, when executed by the processor 420, perform the method 50 according to an embodiment of the invention. 35 The method 50 begins at step 51 with initiation of a drive cycle which may comprise the switching on of a power unit such as the prime mover 11, or the application of drive to the drivetrain 10 to initiate movement away from a stationary position. In step 53 a count of satisfaction events is set to zero before moving to step 55 in which the number of satisfaction events are totalled. The total number of 19 06 25 satisfaction events in step 55 is consequently always equal to zero immediately after initiation of a drive cycle. The method next moves to steps 57, 59, 61, and 63 which may be carried out in parallel (as shown) or 5 in series. In step 57 it is determined, in dependence on the wheel speed data input 121, if the speed of the vehicle 400 is above a predetermined speed (for example 5 kph). In step 59 it is determined, based on the steering angle input signal 131, if the steering angle is zero (within a predetermined tolerance -for example +1- 5 degrees). In step 61 it is determined, in dependence on the wheel speed data input 121, if the distance travelled by the vehicle 400 since the drive cycle was initiated is greater than a 10 predetermined distance (for example 100 metres). In step 63 it is determined, in dependence on the braking input signal 133, if the vehicle’s brakes have been applied since the drive cycle was initiated. If the speed of the vehicle 400 is below the predetermined speed in step 57, or if the steering angle is above zero (within a predetermined tolerance - for example within + / -2%) in step 59, or if the distance 15 travelled is greater than the predetermined distance in step 61, or if it is determined that the vehicle’s brakes have been applied since the drive cycle was initiated in step 63, the method returns to step 53 such that the count of satisfaction events is reset to zero (or remains at zero if it was already at zero). The method returns to step 53 even if only one of the conditions of steps 57, 59, 61, or 63 which causes a return to step 53 is identified. In other words, for the method to move on to step 67, none of the 20 conditions of steps 57, 59, 61, or 63 which cause a return to step 53 must be identified. If none of the conditions of steps 57, 59, 61, or 63 which cause a return to step 53 are identified, the method moves to step 67 where it is determined, in dependence on the wheel speed data input 121, if the wheel speed of the front axle 20 is the same as the wheel speed of the rear axle 25 (within a 25 predetermined tolerance - for example within + / -2%). If it is determined that the wheel speed of the front axle 20 is the same as the wheel speed of the rear axle 25 (within a predetermined tolerance - for example within + / -2%) in step 67, the method moves to step 75 which comprises an instruction to decrement the total count of satisfaction events by one. The 30 method then moves to step 55 where the total count of satisfaction events is calculated. The method then moves once again through steps 57 to 63 and so on. If it is determined that the wheel speed to the front axle 20 is not the same as the wheel speed of the rear axle 25 (within a predetermined tolerance - for example within + / -2%) in step 67, the method moves 35 to step 69 in which it is determined if the total count of satisfaction events in greater than a predetermined number (for example 5). If it is determined that the total count of satisfaction events is greater than the predetermined number in step 69, the method moves to step 71 where the fault code 141 is generated and issued as an output 40 control signal from the controller 110. If it is determined that the total count of satisfaction events is less 19 06 25 than the predetermined number, the method moves to step 73 which comprises an instruction to increment the total count of satisfaction events by one. The method then moves to step 55 where the total count of satisfaction events is calculated. The method then moves once again through steps 57 to 63 and so on. 5 The requirement for the wheel speeds of the front and rear axles 20, 25 to be non-equal (within a predetermined tolerance - for example within + / -2%) in step 67 to result in onward progression to step 69 constitutes a predetermined wheel speed criteria which is satisfied if the difference between the axle speeds falls outside a predetermined range. Satisfaction of the predetermined wheel speed criteria 10 results in an increment of the count of satisfaction events if it is also determined in step 69 that the total count of satisfaction events is less than the predetermined number. Non-satisfaction of the predetermined wheel speed criteria (i.e. the difference between the axle speeds falls within the predetermined range) results in a decrement of the count of satisfaction events. In an alternative example, non-satisfaction of the predetermined wheel speed criteria may result in no change of the 15 count of satisfaction events, or a reset of the count of satisfaction events to zero. It will be understood that one or more of steps 57 to 63, and / or the counting of satisfaction events, may be omitted from the method 50 such that, in its simplest form, method 50 comprises comparing the wheel speeds of the front and rear axles 20, 25 and generating a fault code 141 if the predetermined 20 wheel speed criteria is met. Nonetheless, it is advantageous to include steps 57 to 63 in the method as they help to prevent the generation of a false fault code. The minimum speed check of step 57 ensures that the axle speeds are sufficiently high to facilitate the detection of any difference between them. It is preferable to compare the axle speeds when the vehicle 25 400 is travelling in a straight path (zero steering angle within a tolerance) to avoid differences caused by different half-shaft speeds across the vehicle 400 as it travels around a corner. Similarly, it is preferable to compare the axle speeds when the vehicle 400 is not, or has not, braked as the application of the brakes can result in transient axle speed differences which may result in generation of a false fault code. 30 If the vehicle 400 has travelled over the predetermined distance, it is preferable to reset the count of satisfaction events to zero to prevent the count of satisfaction events from reaching the predetermined number of step 69 when no build incompatibility is actually present. It is to be expected that the predetermined wheel speed criteria will be satisfied on some occasions, and if no reset took place, 35 these events could accrue and result in generation of a false fault code. A predetermined time can be used instead of, or in addition to, a predetermined distance such that the count of satisfaction events is reset to zero if a predetermined amount of time has passed since the drive cycle was initiated in step 51. 19 06 25 The method 50 may include additional optional steps (not shown in Figure 3). For example, the method may include determining, in dependence on the warning flag input signal 135, if a warning flag has been issued by any vehicle system such as the anti-lock brake system (ABS), the dynamic stability control system (DSC), and / or the wheel speed sensors 120 (for example, to indicate a wheel speed sensor 5 fault). If it is determined that a warning flag has been issued, the controller may generate an associated flag code and output the generated flag code for use by the warning device 140 and / or another processing system for use in further vehicle diagnostics. The warning device 140 may be configured to indicate to the userthat both a fault code 141 indicative of a build incompatibility and flag code indicative of activation of another vehicle system have been generated. 10 Generation of a flag code together with a fault code 141 may indicate to a userthat further investigation is required. If the flag code indicates a wheel speed sensor error, the user must resolve the wheel speed sensor error before operating the vehicle 400 to establish if a build incompatibility truly exists, or if the fault code 141 was generated as a result of the wheel speed sensor error. If the flag code indicates 15 activation of the ABS or DSC, the user must operate the vehicle 400 in suitable conditions - such as on a dry straight road - to establish if a build incompatibility truly exists. To mitigate the uncertainty caused by generation of a flag code, the method may include determining, in dependence on the environment input signal 137, if the indicated external environmental condition 20 satisfies a predetermined external environmental condition criteria. For example, the environment input signal 137 may contain information concerning detection of water by water sensors located on the windscreen, detection of mud, ice or snow by an external camera, and / or detection of an external temperature at which ice is likely to form. Alternatively or additionally, environmental condition data may be provided to the controller as 110 from an external source such as a weather service or radar for 25 example. A GPS system of the vehicle may be used together with the external environmental data to determine if the vehicle 400 is located in an area of bad weather. If one or more predetermined environmental conditions are detected, the predetermined external environmental condition criteria may be satisfied, and the controller may either prevent generation of the fault code 141 until the predetermined external environmental condition criteria is no longer satisfied, or generate an 30 environmental condition code which is issued as an output to the warning device 140 and / or another processing system for use in further vehicle diagnostics. The warning device 140 may be configured to indicate to the userthat both a fault code 141 and an environmental condition code have been generated. The user must operate the vehicle 400 in suitable 35 conditions - such as on a dry, straight, surfaced road - when possible to establish if a build incompatibility truly exists. The uncertainty of detecting a build incompatibility in slippery conditions, and / or when operating the vehicle 400 in various use cases such as when cornering or ascending / descending a slope, may be 40 mitigated by comparing computer generated wheel speeds with measured wheel speeds as described 19 06 25 in greater detail below. The description is given in the context of a rear wheel drive vehicle. However, the method described below is equally applicable to a vehicle having a four wheel drivetrain, or a front wheel drivetrain. The method described below is also applicable to electric vehicles driven by one or more axle or wheel mounted electric motors which may include geared reduction drive units. 5 Figure 4 shows a schematic representation of a rear wheel drive vehicle drivetrain layout 210. For simplicity, like reference numerals have been used to indicate like components. In one embodiment, the vehicle 400 comprises the drivetrain layout 210. 10 The drivetrain layout 210 comprises a prime mover 11 which is attached to a gearbox 12. The gearbox 12 has a transfer case 213 which is operatively connected to a rear driveshaft 214. A rear axle 225 of the drivetrain 210 comprises two half-shafts 226 connected by a rear differential 227. The rear driveshaft 214 is operatively connected to the rear differential 227 to provide drive to the half-shafts 226 via the rear differential 227. A pair of rear wheels 17 are driven by the half-shafts 226 of the rear axle 225. A 15 pairof front wheels 16 are operatively connected to the vehicle 400 but do not form part of the drivetrain 210. The front wheels 16 and the rear wheels 17 are each provided with a wheel speed sensor 122, 124, 126, 128 configured to issue an input signal 123, 125, 127, 129 to the controller 110. In an alternative 20 embodiment, only one of the front wheels 16 and / or one of the rear wheels 17 are provided with a wheel speed sensor. If the final drive ratio of the rear differential 227 is out of specification, the rear axle 225 will not rotate at the correct speed and will not perform correctly when the vehicle 400 is turning. There will 25 consequently be a build incompatibility. In this example, the vehicle system 200 for identifying a build incompatibility is largely the same as that described above with respect to Figure 2. However, the vehicle system 200 additionally comprises one or more additional data sources 300 which provide additional vehicle operational state data as a vehicle 30 operational state signal 301 to the input 440 of the controller 110. The additional operational state data may be provided by one or more of a number of vehicle control and / or monitoring systems 300 and may comprise data such as selected drive mode (Dynamic, Eco, Rain / lce / Snow etc.), slope angles, articulations, drive torque, lateral acceleration, brake torque, gearbox ratio, DSC mode selection, nominal rolling radius, diff lock status. It will be appreciated that this is a non-exhaustive list and that 35 other vehicle systems and devices may provide operational state data to the controller 110. The controller 110 is configured to use the vehicle operational state signal 301 to determine electronically modelled wheel speeds. The controller 110 may also be configured to use the steering angle input signal 131 and / or the braking input signal 133 to determine the electronically modelled 40 wheel speeds. 19 06 25 The electronically modelled wheel speeds may be generated by the controller 110 or by a separate modelling system 350 (as described below). Alternatively, the controller may determine the electronically modelled wheel speeds from a look up table stored within memory 430 of the system 100, 5 or stored in another electronic system of the vehicle 400, or stored in remote system and accessed via a wireless communication system. In another example, the vehicle system 200 may comprise a modelling system 350 for generating the electronically modelled wheel speeds. In this example the vehicle operational state input signal(s) 301, 10 131,133 are provided to the modelling system 350, and the modelled wheel speeds are provided to the controller input 440 as a modelled wheel speed signal 351. Figure 5 illustrates a method 550 according to an embodiment of the invention. The method 250 is a method of identifying an incompatible build condition of a vehicle 400, such as the vehicle 400 illustrated 15 in Figure 7. In particular, the method 250 is a method of determining if the indicated wheel speeds satisfy a predetermined wheel speed criteria. The method 250 may be performed by the controller 110 illustrated in Figures 2 and 6. In particular, with reference to Figure 6, the memory 430 may comprise computer-readable instructions which, when executed by the processor 420, perform the method 250 according to an embodiment of the invention. 20 The method 250 begins at step 251 with initiation of a drive cycle which may comprise the switching on of a power unit such as the prime mover 11, or the application of drive to the drivetrain 10 to initiate movement away from a stationary position. In step 253 a count of satisfaction events is set to zero before moving to step 255 in which the number of satisfaction events are totalled. The total number of 25 satisfaction events in step 255 is consequently always equal to zero immediately after initiation of a drive cycle. The method next moves to step 257 in which it is determined if the distance travelled by the vehicle 400 since the drive cycle was initiated is greater than a predetermined distance (for example 100 metres). 30 Alternatively or additionally, it may be determined in step 257 if the time interval since the drive cycle was initiated is greater than a predetermined time (for example 30 seconds). If the distance travelled is greater than the predetermined distance, and / or if the time interval is greater than the predetermined time in step 257, the method returns to step 253 such that the count of 35 satisfaction events is reset to zero (or remains at zero if it was already at zero). If the distance travelled is less than the predetermined distance, and / or if the time interval is less than the predetermined time in step 257 the method moves to step 259 in which electronically modelled of wheel speeds of the vehicle 400 are determined in dependence on the vehicle operational state signal 40 301, the steering angle input signal 131, and / orthe braking input signal 133. The electronically modelled 19 06 25 vehicle wheel speeds are then compared to the indicated wheel speeds (from the wheel speed data 121) in step 263. If it is determined that the electronically modelled wheel speeds match the indicated wheel speeds 5 (within a predetermined tolerance - for example within + / -2%), the method moves to step 271 which comprises an instruction to decrement the total count of satisfaction events by one. The method then moves to step 255 where the total count of satisfaction events is calculated. The method then moves once again through steps 257 to 263 and so on. 10 If it is determined that the electronically modelled wheel speeds do not match the indicated wheel speeds (within a predetermined tolerance - for example within + / -2%), the method moves to step 265 in which it is determined if the total count of satisfaction events in greater than a predetermined number (for example 5). 15 If it is determined that the total count of satisfaction events is greater than the predetermined number in step 265, the method moves to step 267 where the fault code 141 is generated and issued as an output control signal from the controller 110. If it is determined that the total count of satisfaction events is less than the predetermined number, the method moves to step 269 which comprises an instruction to increment the total count of satisfaction events by one. The method then moves to step 255 where 20 the total count of satisfaction events is calculated. The method then moves once again through steps 257 to 263 and so on. The requirement for the electronically modelled wheel speeds to be non-equal to the indicated wheel speeds (within a predetermined tolerance - for example within + / -2%) in step 263 to result in onward 25 progression to step 265 constitutes a predetermined wheel speed criteria which is satisfied if the difference between the modelled wheel speeds and the indicated wheel speeds falls outside a predetermined range. Satisfaction of the predetermined wheel speed criteria results in an increment of the count of satisfaction events if it is also determined in step 265 that the total count of satisfaction events is less than the predetermined number. 30 Non-satisfaction of the predetermined wheel speed criteria (i.e. the difference between the modelled wheel speeds and the indicated wheel speeds within the predetermined range) results in a decrement of the count of satisfaction events. In an alternative example, non-satisfaction of the predetermined wheel speed criteria may result in no change of the count of satisfaction events, or a reset of the count 35 of satisfaction events to zero. It will be understood that the maximum distance / time criteria of step 257 and / or the counting and comparison of satisfaction events in steps 255, 265, may be omitted from the method 250 such that, in its simplest form, method 250 comprises comparing the electronically modelled and indicated wheel 40 speeds and generating a fault code 141 if the predetermined wheel speed criteria is met. Nonetheless, 19 06 25 it is advantageous to include steps 255, 257 and 265 in the method as it helps to prevent the generation of a false fault code for the same reasons as discussed above in respect of method 50. It will also be understood that in the method 250 it is not necessary to compare the electronically 5 modelled wheel speeds with the indicated wheel speeds for all of the vehicle’s wheels, and that the method may equally well be used with a comparison of only two, or only one of the wheels. In one example, the method 250 comprises comparing the modelled wheel speeds and the indicated wheels speeds of two wheels located on the same axle. 10 It will be appreciated that the exemplary speed, distance, time, angle, tolerance, count etc. criteria mentioned above are merely illustrative and that any suitable criteria may be selected in dependence on the specific implementation. The system 100 as illustrated in Figure 2 comprises one controller 110, although it will be appreciated 15 that this is merely illustrative. As shown in Figure 6, the controller 110 comprises processing means 420 and memory means 430. The processing means 420 may be one or more electronic processing device 420 which operably executes computer-readable instructions. The memory means 430 may be one or more memory device 430. The memory means 430 is electrically coupled to the processing means 420. The memory means 430 is configured to store instructions, and the processing means 420 20 is configured to access the memory means 430 and execute the instructions stored thereon. The controller 110 comprises an input means 440 and an output means 450. The input means 440 may comprise an electrical input 440 of the controller 110. The output means 450 may comprise an electrical output 450 of the controller 110. The input 440 is arranged to receive wheel speed signal(s) 121 from 25 the wheel speed sensors 120. The wheel speed signal(s) 121 is an electrical signal which is indicative of a wheel speed of one or more of the wheels 16, 17 of the vehicle 400. The output 450 is arranged to output a control signal 141 which is indicative of an incompatible build condition of the vehicle having been identified for controlling operation of the display system and / or processing system 140. 30 Figure 7 illustrates a vehicle 400 according to an embodiment of the present invention. The vehicle 400 comprises a system 100 for identifying an incompatible build condition of the vehicle 400. The system 100 is configured to control operation of a warning device 140 of the vehicle 400. It will be appreciated that various changes and modifications can be made to the present invention 35 without departing from the scope of the present application.

Claims

19 06 251. A system for identifying an incompatible build condition of a vehicle, the systemcomprising one or more processors collectively configured to:5 receive, at an input, a first input signal indicative of a wheel speed of a first axle of thevehicle;receive, at the input, a second input signal indicative of a wheel speed of a second axle of the vehicle;determine if the indicated wheel speeds satisfy a predetermined wheel speed criteria10 in dependence on the first and second input signals, wherein determining if the predetermined wheel speed criteria is satisfied comprises determining if the difference between the indicated wheel speeds falls outside a predetermined range;if the indicated wheel speeds satisfy the predetermined wheel speed criteria, generate a fault code indicative of an incompatible build condition; and15 output, at an output, the generated fault code.

2. The system of claim 1, configured to:generate electronically modelled wheel speeds for the first and second axles; orreceive, at the input, one or more third input signals indicative of electronically modelled 20 wheel speeds for the first and second axles,wherein determining if the predetermined wheel speed criteria is satisfied comprises determining if the indicated wheel speeds match the electronically modelled wheel speeds within a predetermined threshold.25 3. The system of claim 2, configured to:receive, at the input, a fourth input signal indicative of an operational state of the vehicle; anddetermine the electronically modelled wheel speeds in dependence on the indicated operational state of the vehicle.

304. The system of any preceding claim, configured to:increment a count of satisfaction events following a determination that the indicated wheel speeds satisfy the predetermined wheel speed criteria; andgenerate the fault code indicative of an incompatible build condition if the count of 35 satisfaction events is greater than or equal to a predetermined minimum count.

5. The system of claim 4, configured to decrement the count of satisfaction eventsfollowing a determination that the indicated wheel speeds do not satisfy the predetermined wheel speed criteria.

406. The system of claim 4 or 5, configured to:19 06 25receive, at the input, a fifth input signal indicative of an operational history of at least one system of the vehicle during a predetermined time interval or distance travelled;determine in dependence on the fifth input signal if a prespecified vehicle system event has occurred during the predetermined time interval or distance travelled; and5 if it is determined that the specified vehicle system event has occurred during thepredetermined time interval or distance travelled, set the count of satisfaction events to zero.

7. The system of any of claims 4 to 6, configured to set the count of satisfaction events tozero upon initiation of a drive cycle.

108. The system of any preceding claim, configured to:receive, at the input, a sixth input signal indicative of the activation of a vehicle system flag;following receipt of the sixth input signal, generate a flag code indicative of the vehicle15 system flag having been activated; andoutput, at the output, the generated flag code.

9. The system of any preceding claim, configured to:receive, at the input, a seventh input signal indicative of an external environmental20 condition; anddetermine if the indicated external environmental condition satisfies a predetermined external environmental condition criteria in dependence on the seventh input signal;if the indicated external environmental condition satisfies the predetermined external environmental condition criteria, either:25 prevent generation of the fault code indicative of an incompatible buildcondition; orgenerate an environmental condition code and output, at the output, the generated environmental condition code.30 10. A control system for controlling a warning device of a vehicle, the control systemcomprising one or more processors collectively configured to:receive, at an input, the fault code generated by the system of any of claims 1 to 9; and operate a warning device of the vehicle upon receipt of the fault code.35 11. A method for identifying an incompatible build condition of a vehicle, the methodcomprising:receiving a first input signal indicative of a wheel speed of a first axle of the vehicle;receiving a second input signal indicative of a wheel speed of a second axle of the vehicle;determining if the indicated wheel speeds satisfy a predetermined wheel speed criteria in dependence on the first and second input signals, wherein determining if the predetermined wheel speed criteria is satisfied comprises determining if the difference between the indicated wheel speeds falls outside a predetermined range;5 if the indicated wheel speeds satisfy the predetermined wheel speed criteria, generatinga fault code indicative of an incompatible build condition; andoutputting the generated fault code.

12. A method for controlling a warning device of a vehicle, the method comprising:10 receiving the fault code generated using the method of claim 11; andoperating a warning device of the vehicle upon receipt of the fault code.

13. A vehicle comprising the system of any of claims 1 to 9, or the control system of claim10.1514. Computer readable instructions which, when executed by a computer, are arranged toperform a method according to claim 11 or 12.19 06 25

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