GB2642329A - A control system and method for controlling a vehicle launch system - Google Patents

Abstract

A control system (100) for controlling a vehicle launch system (110), the vehicle launch system being configured to control acceleration of a vehicle (700) from a standstill in one of at least an off-road launch mode (210) and a standard launch mode (200), and the vehicle launch system comprising a traction control module (112), the control system comprising one or more processors (102) collectively configured to: receive an off-road launch request signal (120) indicative of an instruction to initiate the off-road launch mode; determine traction control values (412) for the traction control module in dependence on the off-road launch request signal, wherein the traction control values are configured to cause the traction control module to allow increased wheel slip relative to the standard launch mode; and output, to the traction control module, a control signal (130) in dependence on the traction control values.

Description

[0001] A CONTROL SYSTEM AND METHOD FOR CONTROLLING A VEHICLE LAUNCH SYSTEM

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a control system and method for controlling a vehicle launch system. Aspects of the invention relate to a control system, to a system, to a vehicle and to a method.

[0004] BACKGROUND

[0005] It is known to provide a vehicle with launch control, which is a feature that improves acceleration from a standstill. Launch control is typically found in many high-performance vehicles and allows the driver of the vehicle to achieve the fastest possible start from a standstill by managing torque delivery, minimising wheelspin and maximising traction. To activate launch control, a driver typically has to select that they wish to perform a launch using the launch control, by selecting launch control via a button within a vehicle control panel, infotainment display or other control. The user typically has to follow a specific input sequence, such as pressing the brake pedal while holding down the accelerator pedal to ready the vehicle for launch, and then releasing the brake pedal to initiate the launch.

[0006] It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

[0007] SUMMARY OF THE INVENTION

[0008] Aspects and embodiments of the invention provide a control system, a method, a system, and a vehicle as claimed in the appended claims.

[0009] According to an aspect of the present invention, there is provided a control system for controlling a vehicle launch system in an off-road launch mode and in a standard launch mode; the control system configured to: determine control values for a traction control module and/or a transmission control module of the vehicle launch system, in dependence on an off-road launch request signal indicative of an instruction to initiate a launch operation in off-road mode, wherein the control values for the traction control module are configured to allow increased wheel slip relative to the standard launch mode and/or the control values for the transmission control module are configured to increase rear axle utilization relative to the standard launch mode; and output the control values for the traction control module and the control values for the transmission control module.

[0010] Advantageously, the vehicle may perform an improved acceleration sprint when on a reduced friction driving surface such as loose gravel, sand, and loam soil surfaces.

[0011] According to an aspect of the present invention, there is provided a control system for controlling a vehicle launch system, the vehicle launch system being configured to control acceleration of a vehicle from a standstill in one of at least an off-road launch mode and a standard launch mode, and the vehicle launch system comprising a traction control module, the control system comprising one or more processors collectively configured to: receive an off-road launch request signal indicative of an instruction to initiate the off-road launch mode; determine traction control values for the traction control module in dependence on the off-road launch request signal, wherein the traction control values are configured to cause the traction control module to allow increased wheel slip relative to the standard launch mode; and output, to the traction control module, a control signal in dependence on the traction control values The control system may comprise 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 the instructions thereon so as to: receive the off-road launch request signal indicative of an instruction to initiate the off-road launch mode; determine the traction control values for the traction control module in dependence on the off-road launch request signal, wherein the traction control values are configured to cause the traction control module to allow increased wheel slip relative to the standard launch mode; and output, to the traction control module, the control signal in dependence on the traction control values.

[0012] Reference to "vehicle launch" refers to the initial vehicle movement from standstill (rest) and, typically, the first few seconds after a vehicle pulls away from a standstill (or rest position). A "launch mode" is a mode of operation of a vehicle in which at least one vehicle setting and/or at least one control module are managed to improve acceleration from standstill.

[0013] Advantageously a vehicle on a medium friction off-road surface such as sand, loose gravel, or loam soil may perform a launch operation to accelerate quickly to an operational vehicle speed. As well as reaching operational vehicle speed more quickly, the user may be pleased to experience a more dramatic acceleration experience. The control system may be particularly suited for an off-road surface having a friction coefficient in the range 0.4 to 0.6.

[0014] Optionally the vehicle launch system further comprises a transmission control module, the control system further configured to: determine transmission control values for the transmission control module in dependence on the off-road launch request signal; wherein the transmission control values for the transmission control module are configured to increase rear axle utilization relative to the standard launch mode; and output, to the transmission control module, a control signal in dependence on the transmission control values.

[0015] Advantageously, increasing the rear axle utilisation during an off-road launch compared to a standard launch improves the acceleration on an off-road surface which has a lower coefficient of friction compared to a tarmac road.

[0016] Optionally the control system is further configured to determine transmission control values for the transmission control module configured to cause the transmission control module to reduce time during gear shifts during the off-road launch mode relative to the standard launch mode. Advantageously the off-road launch operation may therefore be further improved by providing gear shifting which improves the traction of the vehicle on off-road surfaces which have a lower coefficient of friction.

[0017] Optionally the control system is further configured to determine traction control values configured to cause the traction control module to limit torque during the off-road launch mode relative to the standard launch mode.

[0018] Advantageously the off-road launch operation may therefore be further improved by limiting to the torque which can be provided to improve traction and/or stability on an off-road surface.

[0019] Optionally, the control system is further configured to determine the traction control values for the traction control module according to a vehicle speed. Advantageously, the off-road launch operation may be improved to provide traction control values appropriate for the speed the vehicle as the speed changes during the launch, thereby improving the launch.

[0020] Optionally the determined traction control values are configured to cause the traction control module to apply wheel slip speed limits with respect to vehicle speed for each wheel of the vehicle, wherein for vehicle speeds between standstill and a first vehicle speed, the wheel slip speed limit either stays the same or increases. Advantageously, during the off-road launch, additional wheel slip from standstill, allowed for using increased wheel slip speed limits, is useful for providing improved acceleration from standstill on an off-road surface.

[0021] Optionally, the determined traction control values for the traction control module are configured to cause the traction control module to begin to reduce the wheel slip speed limit when the vehicle speed is between a first vehicle speed and a second vehicle speed. Advantageously, reducing the wheel slip when vehicle speed in this range is useful for providing improved acceleration on an off-road surface.

[0022] Optionally, the traction control values forthe traction control module are configured to cause the traction control module to allow at least double a level of wheel slip allowed in the standard launch mode for at least a first range of vehicle speed from standstill. Advantageously, during the off-road launch, the substantial additional wheel slip from standstill, allowed for using increased wheel slip speed limits, is useful for providing improved acceleration from standstill on an off-road surface.

[0023] Optionally, the control system is further configured to determine the transmission control values for the transmission control module in dependence upon the vehicle speed. Advantageously, the off-road launch operation may be improved to provide transmission control values appropriate for the speed the vehicle as the speed changes during the launch, thereby improving the launch.

[0024] Optionally, the determined transmission control values provide increased rear axle utilisation from standstill up to and including a predetermined vehicle speed. Advantageously, the transmission control values can be changed as the vehicle accelerates so as to provide improved operation of the transmission control module for the vehicle acceleration on the off-road surface.

[0025] Optionally, the control system is further configured to: receive a steering wheel position signal indicative of an angle of a steering wheel of the vehicle; determine a deviation value of the steering wheel indicative of the deviation of the steering wheel from the straight ahead position; and responsive to the deviation value being greater than a deviation threshold, output an off-road launch inhibit signal to prevent initiation of the off-road launch mode. Advantageously, the control system will not initiate the off-road launch mode if the steering wheel is turned too far to either side. The control system may also receive signals indicative of certain settings of the various other settings of the vehicle, and the an off-road launch inhibit signal may be determined in dependence on these signals According to an aspect of the present invention, there is provided a system comprising any control system disclosed herein and the vehicle launch system. Advantageously, a system is provided which can provide improved off-road launch by having an off-road launch mode, and controlling the vehicle launch system according to the off-road launch mode.

[0026] According to an aspect of the present invention, there is provided a vehicle comprising any system disclosed herein or any control system disclosed herein. Advantageously, a vehicle is provided which can provide improved off-road launch by having an off-road launch mode, and controlling the vehicle launch system according to the off-road launch mode.

[0027] According to an aspect of the present invention, there is provided a method for controlling a vehicle launch system, the vehicle launch system being configured to control acceleration of a vehicle from a standstill in one of at least an off-road launch mode and a standard launch mode, and the vehicle launch system comprising a traction control module; the method comprising: receiving an off-road launch request signal indicative of an instruction to initiate the off-road launch mode; determining traction control values for the traction control module in dependence on the off-road launch request signal, wherein the traction control values are configured to allow increased wheel slip relative to the standard launch mode; and outputting, to the traction control module, a control signal in dependence on the traction control values.

[0028] Advantageously a vehicle on a medium friction off-road surface such as sand, loose gravel, or loam soil may perform a launch operation using the method to accelerate quickly to an operational vehicle speed. As well as reaching operational vehicle speed more quickly, the user may be pleased to experience a more dramatic acceleration experience. The control system may be particularly suited for an off-road surface having a friction coefficient in the range 0.4 to 0.6.

[0029] Optionally, the vehicle launch system further comprises a transmission control module, and the method further comprises: determining transmission control values for the transmission control module in dependence on the off-road launch request signal; wherein the transmission control values for the transmission control module are configured to increase rear axle utilization relative to the standard launch mode; and outputting, to the transmission control module, a control signal in dependence on the transmission control values. Advantageously, increasing the rear axle utilisation during an off-road launch compared to a standard launch improves the acceleration on an off-road surface which has a lower coefficient of friction compared to a tarmac road.

[0030] According to examples, the method can comprise determining transmission control values for the transmission control module which are configured to cause the transmission control module to reduce time during gear shifts during the off-road launch mode relative to the standard launch mode. Advantageously the off-road launch operation may therefore be further improved by providing gear shifting which improves the traction of the vehicle on off-road surfaces which have a lower coefficient of friction.

[0031] According to examples, the method can comprise determining traction control values configured to cause the traction control module to limit torque during the off-road launch mode relative to the standard launch mode.

[0032] Advantageously the off-road launch operation may therefore be further improved by limiting to the torque which can be provided to improve traction and/or stability on an off-road surface.

[0033] According to examples, the method can additionally comprise determining the traction control values for the traction control module according to a vehicle speed. Advantageously, the off-road launch operation may be improved to provide traction control values appropriate for the speed the vehicle as the speed changes during the launch, thereby improving the launch.

[0034] According to examples, the method can additionally comprise determining the transmission control values for the transmission control module in dependence upon the vehicle speed. Advantageously, the off-road launch operation may be improved to provide transmission control values appropriate for the speed the vehicle as the speed changes during the launch, thereby improving the launch.

[0035] According to examples, the method can additionally comprise receiving a steering wheel position signal indicative of an angle of a steering wheel of the vehicle; determining a deviation value of the steering wheel indicative of the deviation of the steering wheel from the straight ahead position; responsive to the deviation value being greater than a deviation threshold, outputting an off-road launch inhibit signal to prevent initiation of the off-road launch mode. Advantageously, the control system will not initiate the off-road launch mode if the steering wheel is turned too far to either side. The control system may also receive signals indicative of certain settings of the various other settings of the vehicle, and the an off-road launch inhibit signal may be determined in dependence on these signals.

[0036] According to examples, computer readable instructions are provided which, when executed by one or more processors, cause the one or more processors to perform the methods described herein. The computer readable instructions may be stored on a computer readable medium, e.g. a non-transitory computer readable medium.

[0037] Advantageously a vehicle on a medium friction off-road surface such as sand, loose gravel, or loam soil may perform a launch operation using the computer program instructions to accelerate quickly to an operational vehicle speed. As well as reaching operational vehicle speed more quickly, the user may be pleased to experience a more dramatic acceleration experience. The control system may be particularly suited for an off-road surface having a friction coefficient in the range 0.4 to 0.6.

[0038] 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.

[0039] 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.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1A shows a control system in accordance with an embodiment of the invention; Figure 1B shows a control system in accordance with an embodiment of the invention; Figure 1C shows a control system in accordance with an embodiment of the invention; Figure 2A shows a graphical representation of wheel slip values according to implementation of embodiments of the invention; Figure 2B shows another graphical representation of wheel slip values according to implementation of embodiments of the invention; Figure 3 shows a control system in accordance with an embodiment of the invention; Figure 4 shows a control system in accordance with an embodiment of the invention; Figure 5 shows a control system in accordance with an embodiment of the invention; Figure 6 shows a control system and a flowchart in accordance with an embodiment of the invention; Figure 7 shows a vehicle in accordance with an embodiment of the invention; and Figure 8 shows a method in accordance with an embodiment of the invention.

[0042] DETAILED DESCRIPTION

[0043] A control system 100 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 1k The control system 100 comprises one or more processor(s) 102.

[0044] The control system 100 is for controlling a vehicle launch system 110. The vehicle launch system 110 is configured to control acceleration of a vehicle from a standstill in one of at least an off-road launch mode and a standard launch mode. The vehicle launch system 110 comprises a traction control module 112.

[0045] The one or more processors 102 are collectively configured to: receive an off-road launch request signal 120 indicative of an instruction to initiate the off-road launch mode; determine traction control values for the traction control module 112 in dependence on the off-road launch request signal 120, wherein the traction control values are configured to cause the traction control module 112 to allow increased wheel slip relative to the standard launch mode; and output, to the traction control module 112, a control signal 130 in dependence on the traction control values.

[0046] Reference to "vehicle launch" refers to the initial vehicle movement from standstill (rest) and, typically, the first few seconds after a vehicle pulls away from a standstill (or rest position). A "launch mode" is a mode of operation of a vehicle in which at least one vehicle setting and/or at least one control module are managed to improve acceleration from standstill.

[0047] A launch mode for a vehicle launch system 110 specifies the vehicle operating parameters and sequences that the vehicle launch system 110 follows to improve acceleration from a standstill. According to examples disclosed herein, the vehicle launch system 110 is configured to perform a standard launch mode and an off-road launch mode. The standard launch mode can represent a launch mode typically used by high-performance vehicles in which traction is maximised and wheel slip is minimised in order to provide the fastest possible start on a road. It has been realised during the devising of this invention that a standard launch mode does not provide a desirable acceleration from standstill on an off-road setting, where the surface is looser than a road, i.e. the coefficient of friction of the surface is lower than that of tarmac road.

[0048] Advantageously, by providing a dedicated off-road launch mode in which increased wheel slip is allowed relative to a standard launch mode, a vehicle on a medium friction off-road surface such as sand, loose gravel, or loam soil may perform a launch operation to accelerate quickly to an operational vehicle speed. As well as reaching operational vehicle speed more quickly, the user may be pleased to experience a more dramatic acceleration experience. The control system 100 may be particularly suited for an off-road surface having a friction coefficient in the range 0.4 to 0.6.

[0049] Figure 1B illustrates a control system 100 in accordance with an embodiment of the invention. The control system 100 illustrated in Figure 1B is similar to the control system 100 illustrated in Figure 1A. The vehicle launch system 110 in Figure 1B further comprises a transmission control module 114. The control system 100 illustrated in Figure 1B is further configured to: determine transmission control values for the transmission control module 114 in dependence on the off-road launch request signal 120. The transmission control values for the transmission control module 114 are configured to increase rear axle utilization relative to the standard launch mode. The control system 100 is further configured to output, to the transmission control module 114, a control signal 140 in dependence on the traction control values.

[0050] According to examples, rear axle utilisation can refer to torque distribution between a front axle of the vehicle and a rear axle of the vehicle. Improving operation of the rear axle utilisation affects the acceleration of the vehicle during a launch, as factors such as weight transfer, stability and handling change during the course of a launch. For example as a vehicle accelerates, the weight transfer may shift towards the rear the vehicle, which gives the rear axle greater traction compared to the front axle. The vehicle can utilise this increased traction at the rear axle by sending more torque to the rear axle. During the devising of this invention it was discovered that increasing the rear axle utilisation during an off-road launch compared to a standard launch improves the acceleration on an off-road surface which has a lower coefficient of friction compared to a tarmac road.

[0051] Figure 1C shows a control system 100 in accordance with an embodiment of the invention. The control system 100 illustrated in Figure 1C is similar to the control systems 100 illustrated in Figure 1A and Figure 1B. The control system 100 illustrated in Figure 1C is further configured to determine the traction control values for the traction control module according to vehicle speed.

[0052] As shown in Figure 10, the one or more processors 102 are arranged to receive a vehicle speed signal 150, which is indicative of a current speed of the vehicle. The control system 100 in some examples determines the traction control values in real-time as the vehicle is accelerating from standstill. The control signal 130 may provide traction control values for a given speed indicated by the vehicle speed signal 150, and the control signal 130 may be updated depending on the vehicle speed indicated by the vehicle speed signal 150. In other examples, the one or more processors 102 do not receive the vehicle speed signal 150 and the control system 100 determines the traction control values for a range of different vehicle speeds. The control signal 130 may provide the traction control values for the range of different vehicle speeds to the traction control module 112.

[0053] Figure 2A shows a first graphical representation of wheel slip values according to implementation of embodiments of the invention, and Figure 2B shows a second graphical representation of wheel slip values according to implementation of embodiments of the invention.

[0054] Figure 2A shows an example of vehicle speed in metres/second on the x-axis and wheel slip speed limits on the y-axis for the standard launch mode 200.

[0055] Figure 2B shows an example of vehicle speed in metres/second on the x-axis and wheel slip speed limits on the y-axis for the off-road launch mode 210.

[0056] As can be seen from Figure 2A and Figure 2B, the off-road launch mode 210 allows an increased level of wheel slip compared to the standard launch mode 200. Figures 2A and 2B also show that the profile of wheel slip speed limits for the off-road launch mode 210 is different to the profile of wheel sleep speed limits for the standard launch mode 200.

[0057] In examples, for the off-road launch mode 210, the determined traction control values are configured to cause the traction control module 112 to apply wheel slip speed limits with respect to vehicle speed for each wheel of the vehicle, wherein for vehicle speeds between standstill and a first vehicle speed 212, the slip speed limit either stays the same or increases, see Figure 2B. The first vehicle speed 212 can be, for example, 15 m/s. In contrast, wheel slip speed limits for the standard launch mode decrease from standstill up to a certain vehicle speed before increasing, see Figure 2A. In examples, the determined traction control values are configured to cause the traction control module 112 to apply wheel slip speed limits which stay the same from standstill to a vehicle speed before the first vehicle speed 112 (for example any speed between 3 m/s and 5 m/s), and then increases the wheel slip speed limits from that speed to the first vehicle speed 112.

[0058] During the devising of this invention, it was discovered that additional wheel slip from standstill is useful for providing improved acceleration from standstill on an off-road surface.

[0059] The determined traction control values for the traction control module 112 can be configured to cause the traction control module 112 to allow wheel slip limits with 0.5 m/s to 2.5 m/s of additional wheel slip relative to the standard launch mode 200.

[0060] As shown in Figure 2B, the determined traction control values forthe traction control module can be configured to cause the traction control module to begin to reduce the wheel slip speed limit when the vehicle speed is between the first vehicle speed 212 and a second vehicle speed 214. According to examples and as shown in Figure 2B, the first vehicle speed can be 15 m/s and the second vehicle speed can be 20 m/s.

[0061] During the devising of this invention, it was discovered that beginning to reduce wheel slip when vehicle speed in this range is useful for providing improved acceleration on an off-road surface.

[0062] As shown in Figures 2A and 2B, the traction control values for the traction control module 112 are configured to cause the traction control module 112 to allow an increased level of wheel slip compared to the standard launch mode 200. In examples, the traction control values for the traction control module 112 are configured to cause the traction control module 112 to allow at least double a level of wheel slip allowed in the standard launch mode 200 for at least a first range 216 of vehicle speed from standstill. The first range 216 can be from standstill (0 m/s) to 75 m/s. In examples the first range 216 can be from standstill to 100 km/h. During the devising of this invention it was discovered that additional wheel slip in this range is useful for providing improved acceleration from standstill on an off-road surface. In examples, the traction control values for the traction control module 112 are configured to cause the traction control module 112 to allow at least double a level of wheel slip allowed in the standard launch mode 200 from standstill to the top speed of the vehicle. The top speed being the highest speed the vehicle can achieve under ideal conditions, and is a metric often used to indicate the maximum performance capability of a vehicle.

[0063] As shown in Figure 2B, after the second speed 216, the wheel slip speed limit gradually increases with increasing vehicle speed, but less sharply than for the initial period between standstill and the first vehicle speed (e.g. 15 m/s).

[0064] According to examples, the wheel slip speed limit in the off-road launch mode 210 reaches a maximum of 2.5 m/s (at 15 m/s for example), and has a minimum of 1 m/s (at 20 m/s for example).

[0065] According to examples, wheel slip speed limits can also be determined based on lateral acceleration of the vehicle. For example, traction control signals can be dependent upon different amounts of lateral acceleration of the vehicle.

[0066] According to examples disclosed herein, the off-road launch mode 210 may operate up to a certain vehicle speed. For example the vehicle speed at which the off-road launch mode stops may be 100 km/h.

[0067] In examples, the control system 100 illustrated in Figure 1C is further configured to determine the transmission control values for the transmission control module 114 in dependence upon the vehicle speed.

[0068] The control system 100 in some examples is configured to determine the transmission control values for the transmission module 114 in real-time as the vehicle is accelerating from standstill. The control signal 140 may provide transmission control values for a given speed indicated by the vehicle speed signal 150, and the control signal 140 may be updated depending on the vehicle speed signal 150 indicated. In other examples, the one or more processors 102 do not receive the vehicle speed signal 150 and the control system 100 determines the transmission control values for a range of different vehicle speeds. The control signal 140 may provide the transmission control values for the range of different vehicle speeds to the transmission control module 114.

[0069] The transmission control values can therefore be changed as the vehicle accelerates so as to provide suitable operation of the transmission control module for the vehicle acceleration on the surface.

[0070] According to examples, the transmission control values for the transmission control module 114 are configured to increase a rear axle utilisation relative to the standard launch mode 200 and is dependent upon the vehicle speed. For example depending on the vehicle speed and the axle percentage, the transmission control values increase the rear axle utilisation (i.e. the percentage of the total torque requested to be provided by the rear axle) for one or more vehicle speed values relative to the standard launch mode 200. Table 1, Table 2 and Table 3 provide examples of rear axle utilisation, which in the tables below is presented as percentage of total torque provided to the rear axle. The values in Tables 1,2 and 3 can represent values for a torque on demand system.

[0071] Axle Percentage (%) Vehicle Velocity (m/s) 0 20 30 60 80 100 150 200 4 50 50 50 30 30 30 0 7 100 100 60 60 57 50 40 100 100 60 60 57 50 40 100 100 100 80 70 50 40 100 100 100 100 85 50 40 Table 1 -Percentage of total torque provided to rear axle (rear axle utilisation) for varying vehicle speed and varying axle percentage, for "standard launch mode" Axle Percentage (/0) Vehicle Velocity (m/s) 0 20 30 60 80 100 150 200 4 50 50 50 30 30 0 0 7 100 100 70 70 60 50 50 100 100 70 70 60 55 55 100 100 100 80 60 60 60 100 100 100 80 65 60 60 Table 2-Percentage of total torque provided to rear axle (rear axle utilisation) for varying vehicle speed and varying axle percentage, for "off-road launch mode" In Table 1 and Table 2, the first column, which has values of 0, 4, 7, 20, 35 and 60 values of different vehicle speeds in metres per second (m/s). The first row in each of Table 1 and Table 2, which has values of 0, 20, 30, 60, 80, 100, 150, 200 are values of percentages of different amounts of axle percentage. Axle percentage being the calculated or estimated maximum grip on the rear axle, 100% being where the axle is on its limit of grip, and over 100% representing when the wheels of the rear axles are sliding or the tyres are in slip. Below 100% the wheels of the rear axle are stable. For example in Table 1, when an axle percentage is 60%, and the velocity of the vehicle is 20 m/s, the percentage of the total torque provided to the rear axle is 60% of the torque requested. As another example, in Table 2 when the axle percentage is 30%, and the velocity of the vehicle is 60 m/s, the percentage of total torque provided to the rear axle is 100% of the torque requested. In other words all of the torque requested is provided by the rear axle.

[0072] 0 0 0 0 0 -30 0 0 0 10 10 3 0 10 0 0 10 10 3 5 15 0 0 0 0 -10 10 20 0 0 0 -20 -20 10 20 Table 3 -Differences between percentage of total torque provided to rear axle (rear axle utilisation) between

[0073] Table 1 and Table 2

[0074] As shown in Table 3, for the off-road launch mode 210, the percentage of total torque provided to the rear axle is mostly either the same or greater than that of the standard launch mode 200 with the exception of four values, thereby overall providing greater rear axle utilisation.

[0075] According to examples, the determined transmission control values provide increased rear axle utilisation from standstill up to and including a predetermined vehicle speed. The predetermined vehicle speed can be 20 m/s.

[0076] For example the predetermined vehicle speed can be the second speed 214 described herein.

[0077] When referring to increased rear axle utilisation, it is meant that for certain axle percentages and corresponding vehicle speeds that the percentage of torque provided to the rear axle remains the same or increases when comparing the off-road launch mode 210 to the standard launch mode 200.

[0078] Advantageously, the transmission control values are controlled in the first stages of the vehicle acceleration process in such a way that is beneficial for off-road launch. Improving operation of the rear axle utilisation affects the acceleration of the vehicle during a launch, as factors such as weight transfer, stability and handling change during the course of a launch. For example as a vehicle accelerates the weight transfer may shift towards the rear the vehicle. During the devising of this invention it was discovered that increasing the rear axle utilisation during an off-road launch compared to a standard launch improves the acceleration on an off-road surface which has a lower coefficient of friction compared to a tarmac road.

[0079] According to examples disclosed herein, in the off-road launch mode 210 the central differentiator may be locked, to provide increased stability.

[0080] Figure 3 shows a control system in accordance with an embodiment of the invention. The control system 100 comprises one or more controller 300. The control system 100 is configured to receive an off-road launch request signal 120 from a launch mode initiator controller 350 and determine traction control values for a traction control module 112 of a vehicle launch system 110. The control system 100 may then output a control signal 130 to control the traction control module 112.

[0081] The launch mode initiator controller 350 can be associated with at least one of a button within the vehicle; a control panel; an infotainment display or another controller.

[0082] The control system 100 as illustrated in Figure 3 comprises one controller 300, although it will be appreciated that this is merely illustrative. The controller 300 comprises processing means 310 (for example the one or more processors 102) and memory means 320. The processing means 310 may be one or more electronic processing device 310 which operably executes computer-readable instructions. The memory means 320 may be one or more memory device 320. The memory means 320 is electrically coupled to the processing means 310. The memory means 320 is configured to store instructions, and the processing means 310 is configured to access the memory means 320 and execute the instructions stored thereon. The instructions can include any of the methods described herein. The instructions can include the operations of any of the control systems 100 described herein.

[0083] The controller 300 comprises an input means 330 and an output means 340. The input means 330 may comprise an electrical input 330 of the controller 300. The output means 340 may comprise an electrical output 340 of the controller 300. The input 330 is arranged to receive an off-road launch request signal 120 from a launch mode initiator controller 350. The off-road launch request signal 120 is an electrical signal which is indicative of an off-road launch mode 210 having been requested and/or selected. The output 340 is arranged to output a control signal 130 in dependence upon the traction control values for controlling a traction control module 112.

[0084] As will be appreciated, according to examples the control system 100 can receive the vehicle speed signal 150 or any other signal received by the one or more processors 102 described herein. In examples the control system 100 in Figure 3 can output control signal 140 in dependence upon transmission control values determined by the control system 100 to control a transmission control module 114 as described herein.

[0085] Figure 4 shows a control system 100 in accordance with an embodiment of the invention. According to examples, the determination of the traction control values and the determination of the transmission control values can depend on further factors and can provide additional changes to the operation of the traction control module 112 and the transmission control module 114.

[0086] In some examples, the control system 100 is further configured to determine transmission control values for the transmission control module 114 which are configured to cause the transmission control module 114 to reduce time between gear shifts during the off-road launch mode 210 relative to the standard launch mode 200. This can also be referred to as increasing the gear shifting rate in the transmission control module 114. The off-road launch operation may be further improved by providing gear shifting which improves the traction of the vehicle on off-road surfaces which have a lower coefficient of friction.

[0087] In some examples, the control system 100 is further configured to determine traction control values configured to cause the traction control module 112 to limit torque during the off-road launch mode 210 relative to the standard launch mode 200. For example the total torque requested by the engine may be limited to 3495 Nm.

[0088] In this way, the off-road launch operation may be further improved by limiting to the torque which can be provided to improve traction and/or stability on an off-road surface.

[0089] Figure 4 illustrates schematically the determination of the traction control values and the transmission control values. As shown in Figure 4, the one or more processors 102 receive the off-road launch request signal 120 and the vehicle speed signal 150. In a first traction control value determination block 410, traction control values for the traction control module 112 are determined that are configured to cause the traction control module 112 to allow increased wheel slip relative to the standard launch mode 200. First traction control values 412 are output from block 410 and are provided to second traction control value determination block 420. The second traction control value determination block 420 is shown in dotted lines to show that it is optional and that the traction control values may be determined without block 420. In particular the first traction control values 412 may instead be passed to block 430 and may form the traction control values 412. In the second traction control value determination block 420, traction control values are determined which are configured to cause the traction control module to limit torque during the off-road launch mode 210. Second traction control values 422 are output from the block 420 and provided to the traction control signal determination block 430.

[0090] In traction control signal determination block 430, one or more control signals 130 are determined and output, and each of the one or more control signals 130 can be referred to as one or more traction control signals 130. The control signals 130 determined based on the first traction control values 412 and the second traction control values 422 can either be determined separately or may be combined as one control signal.

[0091] In a first transmission control value determination block 440, transmission control values for the transmission control module 114 are determined that are configured to cause the transmission control module 114 to increase rear axle utilization relative to the standard launch mode 200. First transmission control values 442 are output from block 440 and are provided to second transmission control value determination block 450. The second transmission control value determination block 450 is shown in dotted lines to show that it is optional and that the transmission control values may be determined without block 450. In particular the first transmission control values 442 may instead be passed to block 460, and may form the transmission control values 442. In the second transmission control value determination block 450, transmission control values are determined which are configured to cause the transmission control module to reduce time between gear shifts during the off-road launch mode relative to the standard launch mode. Second transmission control values 446 are output from the lock 450 and are provided to the transmission control signal determination block 460. In transmission control signal determination block 460, one or more control signals 140 are determined and output, and each of the one or more control signals 140 can be referred to as one or more transmission control signals 140. The control signals 140 determined may be based on the first transmission control values 442 and the second transmission control values 446, and can either be determined separately or may be combined as one control signal.

[0092] According to examples disclosed herein, the traction control values 412, 422 and the transmission control values 442, 446 disclosed herein may be calculated based on look-up tables, mapping tables or functions which define relationships between different variables disclosed herein to provide the traction control values 412, 422 and the transmission control values 442, 446. The look-up tables, mapping tables or functions may be determined through experiment, or alternatively they may be self-taught via a machine-leaming algorithm stored in memory and executed by one or more processors, which may be the memory means 320 and the processing means 310 disclosed herein, or may be present on another controller of the vehicle 700 or elsewhere.

[0093] Figure 5 shows a control system 100 in accordance with an embodiment of the invention. The control system illustrated in Figure 5 is similar to the control systems 100 illustrated in Figures 1A, 1B and 1C.

[0094] As shown in Figure 5, the control system 100 is further configured to receive a steering wheel position signal 160 indicative of an angle of a steering wheel of the vehicle. The control system 100 is also configured to determine a deviation value of the steering wheel indicative of the deviation of the steering wheel from the straight ahead position; and responsive to the deviation value being greater than a deviation threshold, output an off-road launch inhibit signal 170 to prevent initiation of the off-road launch mode 210. Figure 5 shows the off-road launch inhibit signal 170 being output instead of control signals 130, 140. In other examples the control signals 130, 140 may still be output but the off-road launch inhibit signal 170 may override the control signals 130, 140 when received at the vehicle launch system 110.

[0095] According to some examples the deviation threshold is 45 degrees. In some examples, the off-road launch inhibit signal 170 is output before the launch is initiated. For example after the vehicle has started moving from standstill when the launch has been initiated, the deviation threshold of the steering wheel position may no longer apply and the off-road launch inhibit signal 170 may no longer apply.

[0096] In this way, the control system 100 may not initiate the off-road launch mode 210 if the steering wheel is turned too far to either side. The control system 100 may also receive signals indicative of certain settings of the various other settings of the vehicle, and the an off-road launch inhibit signal 170 may be determined in dependence on these signals.

[0097] Figure 6 shows a control system 100 and a flowchart 600 in accordance with an embodiment of the invention. In particular Figure 6 shows operations which can be performed by the one or more processors 102. Figure 6 shows a sequence for initiating an off-road launch mode 210 according to examples disclosed herein. In a preconditions block 610 of the flowchart, in dependence upon receiving the off-road launch request signal 120, the control system 100 is configured to determine whether one or more preconditions are met. If the one or more preconditions are met, the sequence progresses to trigger block 610. If the one or more preconditions are not met, the off-road launch is aborted 612.

[0098] The one or more preconditions can comprise determining a deviation value of the steering wheel indicative of the deviation of the steering wheel from the straight ahead position and determining whether or not the deviation value is greater than a deviation threshold as described herein. Other preconditions comprise: determining that the vehicle is in a particular power mode; determining that the off-road launch mode 210 is installed within the vehicle; determining an all surface drive mode is active; determining that the transmission is in automatic shift control; determining that the transmission is in a sport mode; determining that vehicle towing has not been detected; determining that the number of recorded completed off-road launch events is less than a threshold; determining that brake pedal pressure to hold the vehicle stationary has been detected; determining that powertrain settings associated with the off-road launch mode 210 are available; determining that the dynamic stability control (DSC) is set to a mid-DSC setting part way between DSC operation and no DSC operation On some examples this may be referred to as "TracDSC"; this setting may provide improved traction compared with standard or usual DSC); determining that high range is selected. The preconditions block 610 may require that all of the preconditions are met to proceed with the off-road launch, or it may determine that a subset of the preconditions disclosed herein have been met in order to proceed with the off-road launch.

[0099] In trigger block 610, it is determined whether one or more trigger conditions have been met. For example if it is determined that the driver is fully depressing the accelerator pedal and is depressing the brake pedal to hold the vehicle stationary then the trigger condition has been met and the sequence progresses to the activate block 630. If the trigger conditions are not met for a predetermined amount of time, or for example the driver stops holding the brake pedal or presses the accelerator pedal without the brake pedal being depressed, then the off-road launch is aborted 622.

[0100] In the activate block 630, if it is determined that the driver releases the brake pedal while still maintaining the depression of the accelerator pedal, then the off-road launch is initiated and the sequence progresses to stop block 630. However if it is determined that a predetermined amount of time has elapsed without the driver activating the off-road launch sequence by releasing the brake pedal, or if the driver releases the accelerator pedal, then the off-road launch is aborted 632.

[0101] In the stop block 640, the control system 100 determines whether a stop condition has been met. For example the stop condition may comprise a particular vehicle speed and/or whether a predetermined time has elapsed after the initiation of the off-road launch. The stop block 640 can also determine whether one or more abort conditions have been met which would lead to aborting 642 the off-road launch. For example the off-road launch may be aborted if the accelerator pedal is released or if the brake pedal is reapplied. Other abort conditions are envisaged.

[0102] Any of the aborts 612, 622, 632, 642 can be provided as off-road launch inhibit signals 170 as described herein. Advantageously the off-road launch according to examples is initiated according to various conditions to ensure that an improved launch is achieved.

[0103] According to examples disclosed herein, a system comprising the control system 100 as described herein and the vehicle launch system 110 can be provided.

[0104] Figure 7 illustrates a vehicle 700 according to an embodiment of the present invention. The vehicle 700 comprises a system 710 which comprises the control system 100 and vehicle launch system 110 as described herein. According to examples a vehicle 700 comprising the control system 100 as described herein is provided.

[0105] In some of the Figures, the control system 100 is shown as being separate to the vehicle launch system 110. According to examples disclosed herein, the vehicle launch system 110 can comprise the control system 100.

[0106] Figure 8 illustrates a method 800 according to an embodiment of the invention. The method 800 is a method of controlling a vehicle launch system 110 of a vehicle, such as the vehicle 700 illustrated in Figure 7. The method 800 may be performed by the control system 100 illustrated in Figure 3, or any other control system 100 as described herein. In particular, the memory 320 may comprise computer-readable instructions which, when executed by the processor 310, perform the method 800 according to an embodiment of the invention.

[0107] Method 800 is for controlling a vehicle launch system 110 of a vehicle 700, the vehicle launch system 110 being configured to control acceleration of a vehicle 700 from a standstill in one of at least an off-road launch mode 210 and a standard launch mode 200. The vehicle launch system 110 comprises a traction control module 112.

[0108] The method comprises: receiving 810 an off-road launch request signal 120 indicative of an instruction to initiate the off-road launch mode 210; determining 820 traction control values 412 for the traction control module 112 in dependence on the off-road launch request signal 120, wherein the traction control values 412 for the traction control module 112 are configured to allow increased wheel slip relative to the standard launch mode 200; and outputting 830, to the traction control module 112, a control signal 130 in dependence on the traction control values 412.

[0109] According to examples, the vehicle launch system 110 comprises a transmission control module 114, and the method 800 additionally comprises: determining transmission control values 442 for the transmission control module 114 in dependence on the off-road launch request signal 120; wherein the transmission control values 442 for the transmission control module 114 are configured to increase rear axle utilization relative to the standard launch mode 200; outputting, to the transmission control module 114, a control signal 140 in dependence on the transmission control values 442. According to examples, the method 800 can include any of the operations described herein which are performed by the control systems 100 described herein.

[0110] According to examples, computer readable instructions are provided which, when executed by one or more processors, cause the one or more processors to perform the methods 800 described herein.

[0111] According to examples, the method 800 can comprise determining transmission control values 446 for the transmission control module 114 which are configured to cause the transmission control module 114 to reduce time during gear shifts during the off-road launch mode 210 relative to the standard launch mode 200.

[0112] According to examples, the method 800 can comprise determining traction control values 422 configured to cause the traction control module 112 to limit torque during the off-road launch mode 210 relative to the standard launch mode 200. According to examples, the method 800 can additionally comprise determining the traction control values 412 for the traction control module 112 according to a vehicle speed. According to examples, the method 800 can additionally comprise determining the transmission control values 442 for the transmission control module 114 in dependence upon the vehicle speed. According to examples, the method 800 can additionally comprise receiving a steering wheel position signal 160 indicative of an angle of a steering wheel of the vehicle 700; determining a deviation value of the steering wheel indicative of the deviation of the steering wheel from the straight ahead position; responsive to the deviation value being greater than a deviation threshold, outputting an off-road launch inhibit signal 170 to prevent initiation of the off-road launch mode 210.

[0113] It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims (15)

1. CLAIMS1. A control system for controlling a vehicle launch system, the vehicle launch system being configured to control acceleration of a vehicle from a standstill in one of at least an off-road launch mode and a standard launch mode, and the vehicle launch system comprising a traction control module, the control system comprising one or more processors collectively configured to: receive an off-road launch request signal indicative of an instruction to initiate the off-road launch mode; determine traction control values forthe traction control module in dependence on the off-road launch request signal, wherein the traction control values are configured to cause the traction control module to allow increased wheel slip relative to the standard launch mode; and output, to the traction control module, a control signal in dependence on the traction control values.

2. A control system as claimed in claim 1, wherein the vehicle launch system further comprises a transmission control module, the control system further configured to: determine transmission control values for the transmission control module in dependence on the off-road launch request signal; wherein the transmission control values for the transmission control module are configured to increase rear axle utilization relative to the standard launch mode; and output, to the transmission control module, a control signal in dependence on the transmission control values.

3. A control system as claimed in claim 1, further configured to determine transmission control values for the transmission control module configured to cause the transmission control module to reduce time during gear shifts during the off-road launch mode relative to the standard launch mode.

4. A control system as claimed in any preceding claim, further configured to determine traction control values configured to cause the traction control module to limit torque during the off-road launch mode relative to the standard launch mode.

5. A control system as claimed in any preceding claim, further configured to determine the traction control values for the traction control module according to a vehicle speed.

6. A control system as claimed in claim 5, wherein the determined traction control values are configured to cause the traction control module to apply wheel slip speed limits with respect to vehicle speed for each wheel of the vehicle, wherein for vehicle speeds between standstill and a first vehicle speed, the wheel slip speed limit either stays the same or increases.

7. A control system as claimed in any preceding claim, wherein the determined traction control values for the traction control module are configured to cause the traction control module to begin to reduce the wheel slip speed limit when the vehicle speed is between a first vehicle speed and a second vehicle speed.

8. A control system as claimed in any preceding claim, wherein the traction control values for the traction control module are configured to cause the traction control module to allow at least double a level of wheel slip allowed in the standard launch mode for at least a first range of vehicle speed from standstill.

9. A control system as claimed in any preceding claim, when dependent upon claim 2, further configured to determine the transmission control values for the transmission control module in dependence upon the vehicle speed.

10. A control system as claimed in claim 9, wherein the determined transmission control values provide increased rear axle utilisation from standstill up to and including a predetermined vehicle speed. 15

11. A control system as claimed in any preceding claim further configured to: receive a steering wheel position signal indicative of an angle of a steering wheel of the vehicle; determine a deviation value of the steering wheel indicative of the deviation of the steering wheel from the straight ahead position; and responsive to the deviation value being greater than a deviation threshold, output an off-road launch inhibit signal to prevent initiation of the off-road launch mode.

12. A system comprising the control system of any preceding claim and the vehicle launch system.

13. A vehicle comprising the system of claim 12 or the control system of any of claims 1 -11.

14. A method for controlling a vehicle launch system, the vehicle launch system being configured to control acceleration of a vehicle from a standstill in one of at least an off-road launch mode and a standard launch mode, and the vehicle launch system comprising a traction control module; the method comprising: receiving an off-road launch request signal indicative of an instruction to initiate the off-road launch mode; determining traction control values for the traction control module in dependence on the off-road launch request signal, wherein the traction control values are configured to allow increased wheel slip relative to the standard launch mode; and outputting, to the traction control module, a control signal in dependence on the traction control values.

15. A method as claimed in claim 14, wherein the vehicle launch system further comprises a transmission control module, the method comprising: determining transmission control values for the transmission control module in dependence on the off-road launch request signal; wherein the transmission control values for the transmission control module are configured to increase rear axle utilization relative to the standard launch mode; and outputting, to the transmission control module, a control signal in dependence on the transmission control values.