A control system for determining an acceleration pedal progression of a vehicle

Abstract

Aspects of the present invention relate to a control system for controlling a powertrain system of a vehicle, the powertrain system comprising a power source and a drivetrain arranged to receive torque from the power source, the control system being arranged to control the power source to output torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold, the control system comprising one or more processors collectively configured to: receive a surface gradient signal indicative of a gradient of a surface on which the vehicle is located; receive a holding torque signal indicative of an output torque of the power source required for holding the vehicle stationary on the gradient; receive a pedal position signal indicative of the pedal position; determine, in dependence on the surface gradient signal and the holding torque signal, a torque range of the first portion of available torque to be delivered below the pedal position threshold; and output a control signal to the powertrain system to generate torque in dependence on the pedal position and the pedal progression logic.

Description

[0001] A CONTROL SYSTEM FOR DETERMINING AN ACCELERATION PEDAL PROGRESSION OF A VEHICLE

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a control system for determining an acceleration pedal progression of a vehicle. Aspects of the invention relate to a control system for controlling a powertrain system of a vehicle, to a powertrain system of a vehicle, to a vehicle, and to a method for controlling a powertrain system of a vehicle.

[0004] BACKGROUND

[0005] It is known to provide vehicles including systems for providing torque to drive the vehicle. Torque demand is conventionally based on a demand from a driver of the vehicle, such as by measuring the position of accelerator and brake pedals to determine whether the driver wishes to change an acceleration of the vehicle. It is also known to provide systems for vehicles which introduce or remove torque from a driver demand. It is important to ensure that the vehicle behaves in a way in which the user expects when the user applies pressure to the pedals on gradients, and particularly to the accelerator pedal on downhill gradients.

[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 for controlling a powertrain system of a vehicle, a powertrain system of a vehicle, a vehicle, and a method for controlling a powertrain system of 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 powertrain system of a vehicle, the powertrain system comprising a power source and a drivetrain arranged to receive torque from the power source, the control system being arranged to control the power source to output torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold, the control system comprising one or more processors collectively configured to: receive a surface gradient signal indicative of a gradient of a surface on which the vehicle is located; receive a holding torque signal indicative of an output torque of the power source required for holding the vehicle stationary on the gradient; receive a pedal position signal indicative of the pedal position; determine, in dependence on the surface gradient signal and the holding torque signal, a torque range of the first portion of available torque to be delivered below the pedal position threshold; and output a control signal to the powertrain system to generate torque in dependence on the pedal position and the pedal progression logic.

[0010] Advantageously, the surface gradient on which the vehicle is located is considered when determining a torque range of the first portion of available torque of a pedal progression logic. The pedal progression logic maps a pedal position to a torque demand, and by determining a torque range of a portion of the torque to be delivered below a pedal position threshold, the driver may have greater control of the vehicle on gradients when the pedal position is below the threshold. This is particularly advantageous on downhill gradients and at low speed. Further, a holding torque for holding the vehicle stationary is used to determine the pedal progression logic, and a torque output of a single pedal driving mode may be accounted for to provide the user with a smoother torque progression.

[0011] 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 the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon so as to carry out the disclosed function of the control system.

[0012] According to another aspect of the invention, there is provided a control system for controlling a powertrain system of a vehicle, the powertrain system comprising a power source and a drivetrain arranged to receive torque from the power source, the control system being arranged to control the power source to output torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold. The control system may comprise one or more processors collectively configured to receive a surface gradient signal indicative of a gradient of a surface on which the vehicle is located and to determine the pedal progression logic in dependence on the surface gradient signal.

[0013] In an embodiment, the one or more processors may be further collectively configured to determine the pedal progression logic in dependence on the gradient to reduce a first torque demand corresponding to a first pedal position when the gradient is negative.

[0014] In an embodiment, the pedal position threshold may comprise a pedal position above which a second portion of available torque of the power source is to be delivered.

[0015] In an embodiment, the one or more processors may be further collectively configured to determine, in dependence on the surface gradient, the pedal position threshold.

[0016] The user’s control at low speed may at least be partially dependent on a range of pedal position above and below the pedal position threshold. Advantageously, by adjusting the pedal progression threshold based on a gradient, the user is provided with greater control at low pedal positions on steep gradients where such control may be more beneficial. This combines synergistically with the adjustment to the torque range of the first portion of available torque. In addition to adjusting the torque range to be output below the pedal position threshold, the pedal position threshold is also adjusted to provide a greater range of pedal movement to output the first portion of torque, thereby providing greater user control.

[0017] In an embodiment, the one or more processors may be further collectively configured to determine a first threshold value for the pedal position threshold when the gradient is a negative gradient with respect to a direction of travel of the vehicle, and to determine a second threshold value for the pedal position threshold when the gradient is a flat or a positive gradient with respect to the direction of travel of the vehicle; and the first threshold value for the pedal position threshold corresponds to a greater depression of the pedal than that for the second threshold value for the pedal position threshold.

[0018] In an embodiment, the one or more processors may be further collectively configured to determine a pedal position threshold factor in dependence on the gradient, and to apply the pedal position threshold factor to a road load torque pedal position threshold to thereby determine the pedal position threshold.

[0019] An existing pedal progression logic may already determine the road load torque pedal position threshold based on the vehicle or its environment, such as based on vehicle speed. By applying a factor to the existing road load torque pedal position threshold, the existing logic can be adapted to accommodate the gradient. In an embodiment, the one or more processors may be further collectively configured to determine, in dependence on a speed of the vehicle, one or more of: the pedal position threshold factor and the road load torque pedal position threshold.

[0020] By determining the pedal position threshold factor based on the vehicle speed, the pedal position threshold may be determined differently depending on the vehicle speed. This may be advantageous in different situations. For example, at high speeds, the user may require less fine control of the torque output compared to at low speeds. The road load torque pedal position threshold may also be determined based on the vehicle speed.

[0021] In an embodiment, the road load torque pedal position threshold may comprise a pedal position corresponding to a road load torque of the vehicle on a flat gradient.

[0022] The existing first pedal progression logic may include a road load pedal position corresponding to a road load torque. The road load torque may already be determined based on the vehicle or its environment. Thus, by modifying the road load torque pedal position based on the gradient to determine the pedal position threshold for the pedal progression logic, the determined pedal position threshold is more appropriately determined for the environment where the vehicle is operating.

[0023] In an embodiment, the road load torque may be an opposing torque to a road load of the vehicle, wherein the road load of the vehicle may comprise a force opposing movement of the vehicle.

[0024] In an embodiment, determining the torque range of the first portion of available torque may comprise determining an upper limit of the torque range to be output when the pedal is depressed at the pedal position threshold.

[0025] In an embodiment, when the gradient is a negative gradient with respect to a direction of travel of the vehicle, the one or more processors may be further collectively configured to determine the upper limit of the torque range of the first portion of available torque of a pedal progression logic to be less than a road load torque of the vehicle on a flat gradient.

[0026] Advantageously, by determining, when the vehicle is on a negative gradient, the upper limit of the torque range of the first portion of available torque to be less than a road load torque of the vehicle on flat negative gradient, the user is provided with greater control of the vehicle at low speeds on negative gradients. This is achieved by reducing a difference between the torque applied to hold the vehicle stationary, which may be negative on a negative gradient, and a torque demand output when the user depresses the pedal.

[0027] In an embodiment, the one or more processors may be further collectively configured to apply, in dependence on the surface gradient signal, an offset to the output torque of the power source required for holding the vehicle stationary on the gradient to thereby determine the torque range of the first portion of available torque of the pedal progression logic.

[0028] By applying the offset to the torque for holding the vehicle stationary, a large difference in output torque between no pedal depression and initial pedal progression is avoided, as a torque corresponding to an initial pedal depression is reduced to be closer to the torque for holding the vehicle stationary. Thus, undesirable acceleration due to the gradient is avoided. By basing this torque demand on the torque for holding the vehicle stationary on the gradient, the gradient is taken into account and the pedal progression logic is suitable for all gradients. In an embodiment, the one or more processors may be further collectively configured to determine the offset in dependence on one or more of: a road load torque of the vehicle on a flat gradient or a positive gradient with respect to a direction of travel of the vehicle; the surface gradient signal; and a speed of the vehicle.

[0029] The torque range of the first portion of available torque may be determined by blending the road load torque of the vehicle on a flat gradient or positive gradient and the torque for holding the vehicle stationary on the gradient. Thereby, the pedal progression logic will output different mappings of torque to pedal position for different gradients to provide the user with greater control or greater responsiveness depending on the gradient.

[0030] In an embodiment, the one or more processors may be further collectively configured to determine a lower limit of the second portion of available torque of the pedal progression logic in response to determining the torque range of the first portion of available torque of the pedal progression logic.

[0031] In an embodiment, the torque for holding the vehicle stationary on the gradient may be determined in dependence on the surface gradient signal and a vehicle mass.

[0032] In an embodiment, the one or more processors may be further collectively configured to receive a first vehicle speed signal comprising information indicative of a first vehicle speed at a first time; receive a second vehicle speed signal comprising information indicative of a second vehicle speed at a second time; determine a vehicle acceleration based on the first vehicle speed and the second vehicle speed; and determine the road gradient based at least partially on the proper acceleration of the vehicle and the vehicle acceleration.

[0033] The proper acceleration of the vehicle is a physical acceleration relative to a free-fall or inertial observer, and may be measured by one or more accelerometers. The vehicle acceleration may be determined based on measurements of vehicle speed at different times (e.g., the first vehicle speed and the second vehicle speed).

[0034] In an embodiment, the one or more processors may be further collectively configured to receive a vehicle mass signal, the vehicle mass signal comprising information indicative of an estimated mass of the vehicle; and determine the output torque of the power source required for holding the vehicle stationary on the gradient based on the vehicle mass and the gradient signal.

[0035] In an embodiment, the one or more processors may be collectively configured to: receive a torque signal comprising information indicative of a torque generated by the power source; and determine, when the vehicle has been brought to rest by a torque generated by the power source, a corrected estimated vehicle mass based on the torque generated by the power source.

[0036] By using a proper acceleration value which accounts for acceleration due to gravity, the gradient and the mass of the vehicle may be determined more precisely, improving the accuracy of the determination of the output torque of the power source required for holding the vehicle stationary on the gradient.

[0037] In an embodiment, the one or more processors may be further collectively configured to: receive a single pedal driving mode signal indicative of a single pedal driving mode of the vehicle being active; and activate, in dependence on the single pedal driving mode signal, the pedal progression logic to determine a torque demand. The pedal progression logic may be used when the single pedal driving mode is active. The single pedal driving mode may apply a torque for holding the vehicle stationary on the gradient, which may then be used in the determination of the torque range of the pedal progression logic.

[0038] According to another aspect of the invention, there is provided a control system for controlling a powertrain system of a vehicle, the powertrain system comprising a power source and a drivetrain arranged to receive torque from the power source, the control system being arranged to control the power source to output torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold, the control system comprising one or more processors collectively configured to: receive a surface gradient signal indicative of a gradient of a surface on which the vehicle is located; receive a pedal position signal indicative of the pedal position; determine, in dependence on the surface gradient signal, the pedal position threshold; and output a control signal to the powertrain system to generate torque in dependence on the pedal position and the pedal progression logic.

[0039] By determining the pedal position threshold in dependence on the surface gradient on which the vehicle is located, the pedal progression logic can be adapted to better suit the driving environment of the vehicle. For example, when the gradient is negative, the pedal position threshold may be determined to correspond to a greater depression of the accelerator pedal compared to on a flat or positive gradient. This provides the driver with a greater range of pedal movement for requesting the first portion of torque, which allows the user greater control.

[0040] According to another aspect of the invention, there is provided a powertrain system of a vehicle, the powertrain system comprising: the control system of any preceding statement; the power source; and the drivetrain arranged to receive torque from the power source according to the pedal progression logic.

[0041] According to another aspect of the invention, there is provided a vehicle comprising the control system or the powertrain system of any preceding statement.

[0042] According to another aspect of the invention, there is provided a method for controlling a powertrain system of a vehicle, the powertrain system comprising a power source and a drivetrain arranged to receive torque from the power source, the control system being arranged to control the power source to output torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold, the method comprising: receiving a surface gradient signal indicative of a gradient of a surface on which the vehicle is located; receiving a holding torque signal indicative of an output torque of the power source required for holding the vehicle stationary on the gradient; receiving a pedal position signal indicative of the pedal position; determining, in dependence on the surface gradient signal and the holding torque signal, a torque range of the first portion of available torque to be delivered below the pedal position threshold; and outputting a control signal to the powertrain system to generate torque in dependence on the pedal position and the pedal progression logic.

[0043] According to another aspect of the present invention, there is provided computer readable instructions which, when executed by a computer, are arranged to perform the method. 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. 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.

[0044] BRIEF DESCRIPTION OF THE DRAWINGS

[0045] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0046] Figure 1 shows a block diagram illustrating a control system in accordance with an embodiment of the invention;

[0047] Figure 2 shows a block diagram illustrating a torque system in accordance with an embodiment of the invention;

[0048] Figures 3 and 4 show flowcharts illustrating methods of operating a control system in accordance with embodiments of the invention; Figure 5 shows a block diagram illustrating inputs into a pedal progression logic in accordance with an embodiment of the invention;

[0049] Figures 6A shows a graph illustrating pedal progression according to conventional approach;

[0050] Figure 6B shows a graph illustrating pedal progressions in accordance with an embodiment of the invention; and

[0051] Figure 7 shows a vehicle in accordance with an embodiment of the invention.

[0052] DETAILED DESCRIPTION

[0053] The present disclosure relates to a control system for controlling a powertrain system of a vehicle, a powertrain system of a vehicle, a vehicle, and to a method for controlling a powertrain system of a vehicle. The control system is provided to control the powertrain system to generate torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold. The present invention relates to methods for determining a torque range of the first portion of available torque to be delivered below the pedal position threshold and / or to determining a threshold value for the pedal position threshold, in dependence on a gradient of a surface on which the vehicle is located.

[0054] The present invention therefore provides a method for determining a pedal progression logic in which the torque range of the first portion of torque or the threshold value of the pedal position threshold is determined so as to take into account an impact of the surface gradient on vehicle acceleration. In one example, when the vehicle is travelling on a gradient downhill, the torque range of the first portion of available torque and / or the pedal position threshold are determined to provide the user with greater control of the vehicle. This may be achieved by reducing a difference between a torque for holding the vehicle stationary on the gradient and an output torque within the torque range of the first portion of torque. It should be understood that on a negative gradient with respect to the direction of travel of the vehicle, the torque for holding the vehicle stationary on the gradient may be negative. Conventionally, the torque corresponding to a pedal depression of the accelerator pedal may be positive. By reducing this torque difference between positive and negative torque, there is a smaller difference between the torque output when the user does not depress the pedal at all and when the user begins depressing the pedal, may provide better control to the user. In addition, the pedal position threshold may be increased (that is, to correspond to a greater depression of the accelerator pedal) on a downhill gradient so as to provide further improvements to vehicle control by increasing a pedal range over which the first portion of torque is applied. Thus, the present invention provides improvements for vehicle control on gradients, and particularly at low speed on downhill gradients, while maintaining a responsive pedal progression logic when the additional control is not needed.

[0055] A control system 100 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 1 and a powertrain system 240 of a vehicle 700 in accordance with an embodiment of the present invention is described herein with reference to accompanying Figure 2. As shown in Figure 7, the control system 100 and / or the powertrain system 240 (having components 210, 220 described further below) can be installed in a vehicle 700.

[0056] With reference to Figure 1, there is illustrated a control system 100 for controlling a powertrain system 240, such as the powertrain system 240 shown in Figure 2, which is described in detail below.

[0057] The control system 100 as illustrated in Figure 1 comprises one controller 110, although it will be appreciated that this is merely illustrative. The controller 110 comprises processing means 120 and memory means 130. The processing means 120 may be one or more electronic processing devices 120 which operably executes computer-readable instructions. The memory means 130 may be one or more memory devices 130. The memory means 130 is electrically coupled to the processing means 120. The memory means 130 is configured to store instructions, and the processing means 120 is configured to access the memory means 130 and execute the instructions stored thereon.

[0058] The controller 110 comprises an input means 140 and an output means 150. The input means 140 may comprise an electrical input of the controller 110. The output means 150 may comprise an electrical output of the controller 110. The input means 140 is arranged to receive one or more input signals. The input means 140 is arranged to receive at least a surface gradient signal 160 indicative of a gradient of a surface on which the vehicle is located. The input means 140 is further arranged to receive a holding torque signal 162 indicative of an output torque of the power source required for holding the vehicle stationary on the gradient, and a pedal position signal 164 indicative of a pedal position of an accelerator pedal of the vehicle.

[0059] The processing means 120 may be configured to determine a pedal progression logic mapping a pedal position to a torque demand. The pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold, and a second portion of available torque to be delivered above the pedal position threshold. The pedal progression logic may be determined by the processing means 120 or may be obtained via the input means 140 or stored in the memory means 130. The pedal progression logic may be configured to determine a torque output based on the torque range of the first portion of available torque and the pedal position threshold. That is, between no pedal depression and the pedal progression threshold, the pedal progression logic may describe how much torque should be output for different values of pedal depression. The pedal progression logic may further map a second portion of available torque to pedal position above the pedal position threshold. It should be understood that “below” the pedal position threshold means that the pedal is depressed to a lesser extent than at the pedal position threshold, while “above” the pedal position threshold means that the pedal is depressed to a greater extent than at the pedal position threshold. It should be understood that the mapping between the first or second portion of available torque to pedal position may be linear or may not be linear. It should also be understood that the mapping of the first portion of available torque to the pedal position may be different to the mapping of the second portion of available torque to the pedal position.

[0060] The processing means 120 is configured to determine, in dependence on the surface gradient signal 160 and the holding torque signal 162, a torque range of the first portion of available torque to be delivered below the pedal position threshold. In some examples, determining the torque range of the first portion of available torque comprises determining an upper limit of the torque range to be output when the pedal is depressed at the pedal position threshold. Further, when the gradient is a negative gradient with respect to a direction of travel of the vehicle, the processing means 120 may be configured to determine the upper limit of the torque range of the first portion of available torque of a pedal progression to be less than a road load torque of the vehicle on a flat gradient. It should be understood that the road load torque is an opposing torque to a road load of the vehicle, and the road load of the vehicle comprises a force opposing movement of the vehicle. The road load of the vehicle comprises the sum of forces opposing the movement of the vehicle, such as friction, drag or gravitation.

[0061] The processing means 120 may be configured to apply, in dependence on the surface gradient signal, an offset to the output torque of the power source required for holding the vehicle stationary on the gradient to thereby determine the torque range of the first portion of available torque of the pedal progression logic. The offset may be determined in dependence on the vehicle gradient and / or a speed of the vehicle. For example, a greater offset may be applied on steeper gradients, when the torque for holding the vehicle stationary will have a greater magnitude, in order to further reduce the difference between the torque for holding the vehicle stationary and a torque demand corresponding to a depression of the accelerator pedal, which would give the user greater control of the vehicle.

[0062] The processing means 120 may be configured to determine the offset in dependence on a road load torque of the vehicle on a flat gradient or a positive gradient with respect to a direction of travel of the vehicle. The road load torque of the vehicle may be received via the input means 140 or may be determined by the processing means 120 in dependence on a vehicle speed and the gradient. In some examples, the processing means 120 may be configured to determine the torque range of the first portion of available torque by blending the road load torque of the vehicle on the flat or positive gradient with the torque for holding the vehicle stationary on the gradient.

[0063] To provide an example, on a downhill gradient, a torque for holding the vehicle stationary on the gradient may be -2000Nm. The offset may be preconfigured or determined to be 100Nm. In an example, the pedal position threshold may be 0.5% depression of the accelerator pedal. In this example, the pedal progression is determined to output -1700Nm when the accelerator pedal is depressed by 0.5%. In a conventional pedal progression where the torque for holding the vehicle stationary on the gradient is not considered, a 0.5% pedal depression may correspond to, for example, 100Nm. The conventional approach would therefore result in an aggressive acceleration of the vehicle when the user depressed the accelerator pedal, due to the output torque going from -2000Nm to 100Nm. In contrast, when the torque range of the first portion of available torque is determined in dependence on the gradient and the torque for holding the vehicle stationary, the difference between the torque output when the pedal is not depressed (i.e., the torque for holding the vehicle stationary, -2000Nm in this example) and the torque output when the pedal is depressed is reduced to provide a less aggressive response to pedal depression (e.g., going from -2000Nm to -1700Nm). This provides the user with more control of the vehicle on the gradient. As will be discussed below, the pedal position threshold may also be determined to further improve the control of the vehicle on the gradient.

[0064] The processing means 120 in some examples may be further configured to determine, in dependence on the surface gradient, the pedal position threshold. That is, the processing means 120 may be configured to determine a value for the pedal position threshold below which the first portion of torque is delivered. The processing means 120 may determine to increase the value of the pedal position threshold when the gradient is a negative gradient with respect to the direction of travel of the vehicle. It should be understood that increasing the value of the pedal position threshold means setting the pedal position threshold to correspond to a greater depression of the accelerator pedal relative to the pedal position threshold on a flat gradient. By so doing, the user is provided with a greater range of pedal movement for requesting the first portion of torque, and the users control of the vehicle on downhill gradients is improved. It should be understood that the improvement in user control is achieved most effectively by determining both the pedal position threshold and the torque range of the first portion of torque in dependence on the gradient.

[0065] The processing means 120 may be configured to determine a first threshold value for the pedal position threshold when the gradient is a negative gradient with respect to a direction of travel of the vehicle, and to determine a second threshold value for the pedal position threshold when the gradient is a flat or a positive gradient with respect to the direction of travel of the vehicle. The first threshold value for the pedal position threshold may correspond to a greater depression of the pedal than that for the second threshold value for the pedal position threshold.

[0066] In some examples, the first threshold value may be predetermined. For example, the first threshold value may comprise 1%, 2%, 5% or 10% pedal depression, although it should be understood that the present disclosure is not limited thereto. The memory means 130 may store a plurality of threshold values for the pedal position threshold corresponding to a plurality of gradients. For example, the processing means 120 may determine a threshold value among the plurality of threshold values for the pedal position threshold according to the gradient.

[0067] The processing means 120 in some examples may be configured to determine a pedal position threshold factor in dependence on the gradient, and to apply the pedal position threshold factor to a road load torque pedal position threshold to thereby determine the pedal position threshold. The road load torque pedal position threshold is a pedal position at which the road load torque of the vehicle is to be delivered on a flat gradient. The road load pedal position threshold may be pre-determined, or may be determined by the processing means 120 based on a speed of the vehicle. The pedal position threshold factor may be applied by multiplying the road load pedal position threshold by the pedal position threshold factor to determine the pedal position threshold.

[0068] The input means 140 may be configured to receive a vehicle speed signal indicative of a speed of the vehicle. The processing means 120 may further be configured to determine the pedal position threshold factor in dependence on the vehicle speed. For example, the pedal position threshold factor may be determined based on the vehicle speed such that the pedal position threshold is determined to provide a greater range of pedal movement for delivering the first portion of torque at low vehicle speeds, where a user may prefer finer control of the vehicle.

[0069] To provide an example of how adjusting the pedal position threshold improves the user’s control of the vehicle, the example previously described above, where the torque for holding the vehicle stationary on the downhill gradient is -2000Nm, is continued. In this example, the torque range of the first portion of the available torque was determined such that the upper limit of the torque range of the first portion of available torque, i.e., the torque output at the pedal position threshold, was -1700Nm at 0.5% pedal depression. As set out above, the pedal position threshold may be additionally or alternatively determined based on the gradient. For example, the pedal progression factor may be preconfigured or determined based on a particular gradient to be 10. A value for the pedal position threshold may therefore be determined as 5% depression. In this example, compared to the conventional approach where a 0.5% depression may cause an output of 100Nm, a 5% depression may cause an output of -1700Nm, with a function mapping torque output within the torque range to pedal position up to the pedal position threshold. This provides the user with significant improvements to the vehicle control, by determining both the torque range and the pedal position range mapped to the torque range to provide the user with less aggressive acceleration compared to the conventional approach. This is achieved by reducing the difference between the torque for holding the vehicle stationary on the downhill gradient and the torque output according to the pedal progression logic, but it should be understood that the inverse may be applied on an uphill gradient.

[0070] The processing means 120 may be configured to determine a torque to be generated in dependence on the pedal position signal 164 and the pedal progression. The processing means 120 may therefore be configured to determine the torque to be generated in dependence on the determined torque range of the first portion of available torque and / or the determined pedal position threshold.

[0071] The output means 150 is configured to output a control signal 170 indicative of the determined torque to a powertrain system. In another example, the output means 150 may output a control signal 170 indicative of the pedal progression and / or the determined torque range of the first portion of available torque and / or the determined pedal position threshold, and the powertrain system may then determine a torque to be output in dependence on the pedal progression and the pedal position signal 164.

[0072] In some examples, the input means 140 may be configured to include other input signals in some examples. For example, the input means 140 may be configured to receive a single-pedal driving mode signal indicative of a single-pedal driving mode of the vehicle being active. The single-pedal driving mode may be a user-selectable mode of operation of the vehicle where the need for the user to depress the brake pedal is reduced by the introduction of positive or negative torque into the torque output of the powertrain system 240 by the single-pedal driving mode. Thus, the user may only need to use the accelerator pedal to operate the vehicle, and the singlepedal driving mode may bring the vehicle to rest by applying torque beyond torque requested by the user using the accelerator pedal. The single-pedal driving mode may determine the torque for holding the vehicle stationary on a gradient. In some examples, the pedal progression logic determined above may be applied only in dependence on receipt of a signal indicating that the single-pedal driving mode is active, and a conventional pedal progression logic may be otherwise used.

[0073] In some examples, the torque for holding the vehicle stationary on the gradient is determined in dependence on a vehicle mass and the gradient. The input means 140 may further be configured to receive a first vehicle speed signal comprising information indicative of a first vehicle speed at a first time and receive a second vehicle speed signal comprising information indicative of a second vehicle speed at a second time. The processing means 120 may be further configured to determine a vehicle acceleration based on the first vehicle speed and the second vehicle speed and determine the road gradient based at least partially on the proper acceleration of the vehicle and the vehicle acceleration. The proper acceleration of the vehicle is a physical acceleration relative to a free-fall or inertial observer, and may be measured by one or more accelerometers. The vehicle acceleration may be determined based on measurements of vehicle speed at different times (e.g., the first vehicle speed and the second vehicle speed).

[0074] The input means 140 in some examples may be further collectively configured to receive a vehicle mass signal, the vehicle mass signal comprising information indicative of an estimated mass of the vehicle; and the processing means 120 may be configured to determine the output torque of the power source required for holding the vehicle stationary on the gradient based on the vehicle mass and the gradient signal. In some examples, the input means 140 may be further configured to receive a torque signal comprising information indicative of a torque generated by the power source; and the processing means 120 may be configured to determine, when the vehicle has been brought to rest by a torque generated by the power source, a corrected estimated vehicle mass based on the torque generated by the power source. The corrected estimated vehicle mass may then be used for subsequent calculations of the torque for holding the vehicle at rest. Figure 2 shows a schematic diagram of components of a vehicle 700 including a powertrain system 240 in accordance with an embodiment of the invention. The vehicle 700 includes a control system 100, a powertrain 210 and a foundation braking system 220. The control system 100 is arranged to control the powertrain 210 and the foundation braking system 220, collectively referred to as the powertrain system 240.

[0075] The vehicle 700 has a control system 100, the control system 100 comprising a plurality of controllers. The controllers are collectively configured to receive data from different sensors, systems, and input devices of the vehicle 700, to process the data and to output commands for controlling the vehicle 700. The controllers may each or may communally comprise processing means and memory means. The processing means may be one or more electronic processing devices which operably execute computer readable instructions. The memory means may be one or more memory devices. The memory means is electrically coupled to the processing means. The memory means is configured to store instructions, and the processing means may be configured to access memory means and to execute the instructions stored thereon. The control system may be the control system 100 of Figure 1.

[0076] The control system 100 is arranged to control a powertrain 210. The powertrain comprises a power source 212. The power source 212 may be an electric machine and in some cases the powertrain 210 may have two power sources 212 which may be an electric machine and an internal combustion engine. In another example the powertrain 210 may comprise a single power source 212 being an internal combustion engine. The powertrain 210 also comprises a drivetrain 214 that is arranged to receive torque 215 from the power source 212, to convert the torque and to provide a converted torque to the wheels. The drivetrain 214 may be a direct-drive drivetrain or may have a gearbox and a differential for increasing the torque 215 delivered from the power source 212 so that a higher torque may be delivered to the wheels of the vehicle 700. The power train 210 may thereby output a positive torque.

[0077] The powertrain 210 is controlled by and monitored by the control system 100. The control system 100 is arranged to output an electric machine torque requirement signal 211, which may also be referred to as a required torque signal 211, to the powertrain 210 to cause the power source 212 to generate a required amount of torque 215. The control system 100 is also arranged to receive data 213, such as a torque generation signal 213, from the powertrain 210. The received data 213 may include a rotational speed of the power source 212 and may include a torque generated by the power source 212. The control system 100 may also receive data 213 and transmit commands 211 related to the drivetrain 214. The control system 100 may transmit commands 213 to the powertrain 210, such as a gear change command to change a torque ratio of the drivetrain 214. The control system 100 may also receive data 213 that may include a rotational speed of one or more components of the drivetrain 214, or an amount of torque received by the drivetrain 214 or output by the drivetrain 214. The torque ratio of the drivetrain may be transmitted from the drivetrain 214 to the control system 100 as part of data 213 or may be stored as a value in the control system 100, as the control system 100 may command the drivetrain 214 in order to control the torque ratio of the drivetrain 214.

[0078] The vehicle 700 also has a foundation braking system 220. The foundation braking system 220 comprises a brake actuator 222 and a foundation brake 224. The brake actuator 222 may be a hydraulic pump or an electromechanical actuator for moving components of the foundation brake 224 that are arranged to engage frictional ly in order to provide a braking torque (or a negative torque). The brake actuator 222 may therefore apply a force 225 to the foundation brake 224. The foundation brakes 224 may be any friction brake, such as brake discs with moveable brake callipers or drum brakes with moveable brake shoes. By moving components of the foundation brakes 224 into engagement, the foundation braking system 220 may provide a braking torque to the wheels to decelerate the vehicle. The term foundation brake is generally used herein to mean any frictional brake that may decelerate the vehicle by converting mechanical energy into heat by friction, as opposed to a regenerative brake, such as may be provided by an electric machine. It should be understood that in another example, the foundation braking system 220 may further comprise one or more regenerative braking systems.

[0079] The control system 100 is arranged to output brake command signals 221 to the foundation braking system 220. The brake command signals 221 include a foundation brake release signal that is arranged to cause the foundation brake actuator 222 to disengage the foundation brake 224, such that a braking torque is reduced. The brake command signals 221 also include a brake engagement signal that is arranged to cause the brake actuator 222 to engage the foundation brake 224 to cause an increase in braking torque applied to the wheels.

[0080] The control system 100 may receive brake data 223 from the foundation brake system 220. The foundation brake data 223 may include information of a generated brake torque, which may differ from the commanded brake torque due to a lag in the activation of the brake actuator 222. The data 223 may include data that a brake release has been affected, such that a negligible brake torque is being provided by the friction brake 224. This signal may also be referred to as a brake release signal.

[0081] The powertrain 210 and the foundation brake system 220 may together be considered a powertrain system 240, as indicated by the dashed line in Figure 2. The powertrain system 240 may be configured to output an output torque 231 to one or more wheels 230 of the vehicle. The output torque 231 may be based on positive torque associated with the powertrain 210 and negative torque associated with the foundation brake system 220. It should be understood that in some examples, the powertrain 210 may also be configured to output a negative torque. The output torque 231 is determined by the control system 100 as explained above in respect of Figure 1. The commands 211, 221 output by the control system 100 to the powertrain 210 and the foundation brake system 220 may be considered as part of the control signal 170 output by the control system 100 of Figure 1.

[0082] The control system 100 of Figure 1 may be configured to output the control signal 170 to control one or both of the powertrain 210 and the foundation braking system 220. For example, the control signal 170 may be configured to indicate a net torque to be output by the powertrain system 240 including by the powertrain 210 and / or the foundation braking system 220.

[0083] The control system 100 is also arranged to receive further input signals. The control system 100 is arranged to receive the surface gradient signal 160, the holding torque signal 162 and the pedal position signal 164 of Figure 1. The control system 100 in some examples may be configured to receive one or more signals indicative of an activation or deactivation of a single-pedal driving mode.

[0084] The control system 100 may also receive further inputs from further input devices that are not shown. For example, a gear stick may provide an input signal to select a driving mode, a reversing mode or a parking mode. The control system 100 may also receive suspension loading data from suspension sensors, which may be strain sensors. The loading sensors may provide information about the pitch of the vehicle and / or the mass and mass distribution of the vehicle. This may be used in a determination of the mass of the vehicle and / or in the determination of the gradient of a surface the vehicle is located on.

[0085] It will be understood that the control system 100 may be formed of a plurality of separate controllers or processors, and that signals which are described as being received by the control system or output by the control system may be published on a central CAN bus or output by one portion of a computer program and received by a further portion of the computer program. Signals described as being received may also be retrieved from an internal memory or determined by a program within the control system 100.

[0086] Figure 3 illustrates a flowchart of a method 300 according to an embodiment of the invention. The method 300 of Figure 3 is a method for controlling a powertrain system of a vehicle, the powertrain system comprising a power source and a drivetrain arranged to receive torque from the power source, the control system being arranged to control the power source to output torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold. For example, the method 300 may be a method performed by the control system 100 of Figures 1 or 2, and the powertrain system 240 may be the powertrain system 240 of Figure 2.

[0087] The method 300 comprises, at step 310, receiving a surface gradient signal 160 indicative of a gradient of a surface on which the vehicle is located. The gradient may be a positive, a negative or a flat gradient with respect to a direction of travel of the vehicle. The surface gradient signal 160 may indicate a percentage gradient or an angle of the gradient. In some examples, the surface gradient may be determined based on a proper acceleration of the vehicle relative to free-fall and a vehicle acceleration determined based on measurements of vehicle speed, as discussed above.

[0088] The method 300 further comprises, at step 320, receiving a holding torque signal indicative 162 of an output torque of the power source required for holding the vehicle stationary on the gradient. The torque for holding the vehicle stationary on the gradient may be determined by and received from a single-pedal driving logic. In some examples, the torque for holding the vehicle stationary on the gradient may be determined in dependence on the gradient and a vehicle mass.

[0089] The method 300 further comprises, at step 330, receiving a pedal position signal 164 indicative of a pedal position. The pedal position signal 164 may be indicative of a pedal position of an accelerator pedal of the vehicle. For example, the pedal position signal 164 may indicate a degree of depression of the accelerator pedal, for example indicated as a percentage of maximum depression.

[0090] The method 300 further comprises, at step 340, determining, in dependence on the surface gradient signal and the holding torque signal, a torque range of the first portion of available torque to be delivered below the pedal position threshold.

[0091] The torque range of the first portion of available torque may be determined as explained above in respect of Figure 1. For example, determining the torque range of the first portion of available torque may comprise determining an upper limit of the torque range to be output when the pedal is depressed at the pedal position threshold. In an example, when the gradient is a negative gradient with respect to a direction of travel of the vehicle, the upper limit of the torque range of the first portion of available torque of a pedal progression may be determined to be less than a road load torque of the vehicle on a flat gradient.

[0092] In some examples, the method 300 may comprise applying, in dependence on the surface gradient signal, an offset to the output torque of the power source required for holding the vehicle stationary on the gradient to thereby determine the torque range of the first portion of available torque of the pedal progression logic. The method 300 may comprise determining the offset in dependence on one or more of a road load torque of the vehicle on a flat gradient or a positive gradient with respect to a direction of travel of the vehicle; the surface gradient signal; and a speed of the vehicle. In another example, the offset may be predetermined. The offset may be applied to the output torque of the power source required for holding the vehicle stationary on the gradient to determine the upper limit of the torque range of the first portion of available torque. The method 300 further comprises, at step 350, outputting a control signal 170 to the powertrain system 240 to generate torque 231 in dependence on the pedal position and the pedal progression logic.

[0093] The method 300 may further comprise receiving a road load torque estimate on a flat or a positive gradient. The road load torque estimate is indicative of a road load torque of the vehicle. As has been explained above, the road load torque is a torque corresponding to a road load of the vehicle, and the road load of the vehicle comprises a force opposing movement of the vehicle. The road load torque estimate may be received or may be determined in dependence on a vehicle speed and the surface gradient signal 160.

[0094] The method 300 may further comprise determining the torque range of the first portion of available torque in dependence on the road load torque estimate and the holding torque signal 162. The torque range may be determined by applying an offset to the torque for holding the vehicle stationary on the gradient. The offset may be determined based on the road load torque estimate, or may be predetermined. In one example, a function describing the torque for holding the vehicle stationary and a function describing the road load torque estimate may be blended to determine the torque range of the first portion of torque.

[0095] It should be understood that the illustration of a particular order to the steps illustrated in Figure 3 does not necessarily imply that there is a required or preferred order for the steps and the order and arrangement of the steps may be varied. Further, the method 300 of Figure 3 may include further steps, or may omit one or more of the steps illustrated. For example, instead of receiving the pedal position signal 164 and outputting a control signal 170 indicative of a torque to be output, the method 300 may instead comprise outputting a control signal to update the pedal progression logic with the determined torque range of the first portion of available torque. The method 300 also further comprise determining the torque range of the first portion of available torque as explained above in respect of Figure 1, and may also comprise determining the pedal position threshold as explained in Figures 1 and 4.

[0096] Figure 4 is a flowchart illustrating another method 400 for controlling a powertrain system of a vehicle in accordance with an embodiment of the invention. The powertrain system comprising a power source and a drivetrain arranged to receive torque from the power source, the control system being arranged to control the power source to output torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold. For example, the method 400 may be a method performed by the control system 100 of Figures 1 or 2, and the powertrain system 240 may be the powertrain system 240 of Figure 2.

[0097] As has been discussed above, alternatively or in addition to determining the torque range of the first portion of torque to be delivered below the pedal position threshold in dependence on a surface gradient, the pedal position threshold may also be determined to account for the gradient. Figure 4 is a method 400 for determining the pedal position threshold in dependence on the gradient.

[0098] The method 400 comprises receiving, at step 410, a surface gradient signal indicative of a gradient of a surface on which the vehicle is located. Step 410 of Figure 4 may be considered the same as step 310 of Figure 3.

[0099] The method 400 further comprises receiving, at step 420, a pedal position signal indicative of a position of an accelerator pedal. Step 420 of Figure 4 may be considered the same as step 330 of Figure 3. The method 400 further comprises determining, at 430, the pedal position threshold in dependence on the gradient of the surface on which the vehicle is located. In some examples, the method 400 may comprises determining a first threshold value for the pedal position threshold when the gradient is a negative gradient with respect to a direction of travel of the vehicle, and a second threshold value for the pedal position threshold when the gradient is a flat or a positive gradient with respect to the direction of travel of the vehicle. The first threshold value for the pedal position threshold may correspond to a greater depression of the pedal than that for the second threshold value for the pedal position threshold. In other words, when the vehicle is on a downhill gradient, the threshold pedal position may be increased to provide a greater range of pedal movement for requesting torque within the torque range of the first portion of available torque.

[0100] In some examples, the method 400 may further comprise determining a pedal position threshold factor in dependence on the gradient, and applying the pedal position threshold factor to a road load torque pedal position threshold to thereby determine the pedal position threshold. The method may further comprise receiving a vehicle speed signal indicative of a speed of the vehicle, and determining the pedal position threshold and / or the road load torque pedal position threshold in dependence on a speed of the vehicle.

[0101] The method 400 may further comprise, at step 440, outputting a control signal 170 to the powertrain system 240 to generate torque 231 in dependence on the pedal position and the pedal progression logic. That is, the method 400 may comprise outputting a control signal 170 to the powertrain system 240 to generate torque 231 in dependence on the pedal position and the determined pedal position threshold.

[0102] It should be understood that the illustration of a particular order to the steps illustrated in Figure 3 does not necessarily imply that there is a required or preferred order for the steps and the order and arrangement of the steps may be varied. Further, the method 400 of Figure 4 may include further steps, or may omit one or more of the steps illustrated. For example, instead of receiving the pedal position signal 164 and outputting a control signal 170 indicative of a torque to be output, the method 300 may instead comprise outputting a control signal to update the pedal progression logic with the determined torque range of the first portion of available torque. The method 400 may also further comprise determining the pedal position threshold as explained above in respect of Figure 1, and may also comprise determining the torque range of the first portion of available torque as explained in Figures 1 and 3. That is, it should be understood that the methods 300, 400 of Figures 3 and 4 may be combined.

[0103] Figure 5 is a block diagram illustrating inputs into a pedal progression logic 590 according to an embodiment of the invention. The pedal progression logic 590 may process the inputs to determine a torque 231 to be output by the powertrain system 240.

[0104] An accelerator pedal position 510 may be input into the pedal progression logic 590. The accelerator pedal position 510 is indicative of a live position of the accelerator pedal, and may be understood to be the same as the pedal position signal 164 of Figure 1.

[0105] A vehicle speed 520 may be input into the pedal progression logic 590. The vehicle speed 520 is indicative of a live speed of the vehicle. The pedal progression logic 590 may be configured to output a torque in dependence on the vehicle speed 520. That is, for a constant accelerator pedal position 510, the pedal progression logic 590 may output varying torque depending on the vehicle speed 520.

[0106] The pedal position threshold 550 may be input into the pedal progression logic 590. The pedal position threshold 550 may be determined as explained above, particularly in respect of Figures 1 and 4. The pedal position threshold 550 may be determined based on its inputs of a road load torque pedal position threshold 530 and a pedal position threshold factor 540. The road load torque pedal position threshold 530 may be determined based on a vehicle speed 520. As explained above, the road load torque may vary in dependence on vehicle speed 520, and the road load torque pedal position threshold 530 may be determined according to the vehicle speed 520 to provide an intuitive pedal position for outputting the road load torque. The pedal position threshold factor 540 may be determined in dependence on the vehicle speed 520 and the gradient of the surface on which the vehicle is located, as is explained above in respect of Figures 1 and 4. The pedal position threshold 550 may be determined by multiplying the road load torque pedal position threshold 530 by the pedal position threshold factor 540.

[0107] The pedal progression logic 590 is configured as explained above to map the accelerator pedal position 510 to a torque demand, and to map a first portion of available torque to be delivered by the pedal position threshold 550 to the accelerator pedal position 510. Therefore, when the pedal position threshold 550 is determined according to the road load torque pedal position threshold 530 and the pedal position threshold factor 540, the pedal progression logic 590 may be determined or updated with the pedal position threshold 550 to account for the gradient of the surface on which the vehicle is located.

[0108] The torque range 580 of the first portion of available torque may also be input into the pedal progression logic 590. The torque range 580 of the first portion of available torque may be determined as explained above, particularly in respect of Figures 1 and 3. The torque range 580 of the first portion of available torque may be determined based on its inputs of a road load torque of the vehicle on a flat or a positive gradient 560 and a torque for holding the vehicle stationary on the gradient 570. The torque range 580 of the first portion of available torque may be determined by blending the road load torque of the vehicle on a flat or a positive gradient 560 and the torque for holding the vehicle stationary on the gradient 570. It should be understood that “blending” these inputs may mean to apply the offset to the torque for holding the vehicle stationary on the gradient 570, where the offset is determined according to the road load torque of the vehicle on a flat or a positive gradient 560. The road load torque of the vehicle on a flat or a positive gradient 560 may be determined based on the vehicle speed 510 and the gradient of the surface on which the vehicle is located. The torque for holding the vehicle stationary on the gradient 570 may be determined based on a vehicle mass and the gradient of the surface on which the vehicle is located.

[0109] The pedal progression logic 590 is configured as explained above to map the accelerator pedal position 510 to a torque demand, and to map a first portion of available torque to be delivered by the pedal position threshold 550 to the accelerator pedal position 510. Therefore, when the torque range 580 of the first portion of available torque is determined according to the road load torque of the vehicle on a flat or a positive gradient 560 and the torque for holding the vehicle stationary on the gradient 570, the pedal progression logic 590 may be determined or updated with the torque range 580 of the first portion of available torque to account for the gradient of the surface on which the vehicle is located.

[0110] It should be understood that the pedal progression logic 590 may be continuously or periodically determined during operation of the vehicle or a command to use the pedal progression logic may be received by the user, and each of the inputs illustrated in Figure 5 may be continuously or periodically received. The pedal progression logic 590 may thereby adjust a mapping between the accelerator pedal position 510 and a torque output 231 to provide an improved driving style for the user, where the user is provided with a greater control of the vehicle on gradients, and a more response to pedal progression where such additional control is not needed.

[0111] In Figure 6A, a conventional pedal progression is illustrated which does not account for a gradient. In Figure 6B, a pedal progression logic such as the pedal progression logic 590 of Figure 5 is shown, where a negative gradient is considered when determining a torque range of the first portion of available torque to be output below the pedal position threshold, and when determining the pedal position threshold.

[0112] In Figures 6A and 6B, the y-axis is a torque output, and the x-axis is a vehicle speed. An upper horizontal line 610 is shown to represent the peak torque output in each graph. A lower horizontal line 620 is shown to represent the torque for holding the vehicle stationary on the gradient. Each of the non-straight horizontal lines between the peak torque output 610 and the torque 620 for holding the vehicle stationary represent different depressions of the accelerator pedal. In the examples of Figures 6A and 6B, the pedal positions are illustrated between 0% pedal depression (which corresponds to the torque for holding the vehicle stationary 620) and 100% pedal depression, at 5% increments. It should be understood that the pedal progression logic may be configured to map any pedal position to an output torque, and that the 5% increments used in Figures 6A and 6B are to illustrate an example only.

[0113] As can be seen in Figure 6A, when the gradient is not taken into account, particularly at low speeds, there is a large difference between the torque for holding the vehicle stationary on the gradient 620 and a torque output even at low accelerator pedal depression. The result of this is that when the user depresses the accelerator pedal to begin moving, the user may perceive that the vehicle begins to move more aggressively than desired due to this large difference in torque. In comparison, in Figure 6B, the torque outputs for different pedal positions are shifted downwards, due to being determined in dependence on the torque for holding the vehicle stationary on the gradient 620, as explained above. For example, these torque outputs may be determined at least in part by applying an offset to the torque for holding the vehicle stationary on the gradient 620. As can be seen in Figure 6B, the pedal progressions are determined to reduce the difference between the torque for holding the vehicle stationary on the gradient 620 and the torque output, particularly at low speeds and low pedal depression. Thus, the vehicle acceleration is more controllable for the user on the downhill gradient. The pedal position threshold is also adjusted to provide a greater range of pedal movement to provide further control to the user. Meanwhile, the maximum torque output 610 is not reduced.

[0114] Figure 7 illustrates a vehicle 700 according to an embodiment of the present invention. The vehicle 700 may comprise the control system 100 of Figure 1, and the powertrain system 240 of Figure 2. The vehicle 700 may also comprise the powertrain 210 and the foundation braking system 220 of Figure 2 as illustrated. The vehicle 700 may be a hybrid electric vehicle having an electric machine and an internal combustion engine both arranged to drive the wheels of the vehicle 700, or may be a battery electric vehicle powered by an electric machine only, or may be a vehicle powered by an internal combustion engine only. In some cases, the vehicle 700 may have multiple electric machines arranged to drive the wheels. The vehicle 700 may also be a mild hybrid electric vehicle (MHEV) or a plug-in hybrid electric vehicle (PHEV). It should be understood that the location of the control system 100 and the powertrain system 240 shown in Figure 7 is purely illustrative.

[0115] 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

CLAIMS1. A control system for controlling a powertrain system of a vehicle, the powertrain system comprising a power source and a drivetrain arranged to receive torque from the power source, the control system being arranged to control the power source to output torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold, the control system comprising one or more processors collectively configured to: receive a surface gradient signal indicative of a gradient of a surface on which the vehicle is located; receive a holding torque signal indicative of an output torque of the power source required for holding the vehicle stationary on the gradient; receive a pedal position signal indicative of the pedal position; determine, in dependence on the surface gradient signal and the holding torque signal, a torque range of the first portion of available torque to be delivered below the pedal position threshold; and output a control signal to the powertrain system to generate torque in dependence on the pedal position and the pedal progression logic.

2. The control system of claim 1, wherein the one or more processors are further collectively configured to determine, in dependence on the surface gradient, the pedal position threshold.

3. The control system of claim 2, wherein the one or more processors are collectively further configured to determine a first threshold value for the pedal position threshold when the gradient is a negative gradient with respect to a direction of travel of the vehicle, and to determine a second threshold value for the pedal position threshold when the gradient is a flat or a positive gradient with respect to the direction of travel of the vehicle; and wherein the first threshold value for the pedal position threshold corresponds to a greater depression of the pedal than that for the second threshold value for the pedal position threshold.

4. The control system of claim 2 or 3, wherein the one or more processors are further collectively configured to determine a pedal position threshold factor in dependence on the gradient, and to apply the pedal position threshold factor to a road load torque pedal position threshold to thereby determine the pedal position threshold.

5. The control system of claim 4, wherein the one or more processors are further collectively configured to determine, in dependence on a speed of the vehicle, one or more of: the pedal position threshold factor and the road load torque pedal position threshold.

6. The control system of any preceding claim, wherein determining the torque range of the first portion of available torque comprises determining an upper limit of the torque range to be output when the pedal is depressed at the pedal position threshold.

7. The control system of claim 6, wherein when the gradient is a negative gradient with respect to a direction of travel of the vehicle, the one or more processors are further collectively configured to determine the upper limit of the torque range of the first portion of available torque of a pedal progression to be less than a road load torque of the vehicle on a flat gradient.

8. The control system of any preceding claim, wherein the one or more processors are further collectively configured to:apply, in dependence on the surface gradient signal, an offset to the output torque of the power source required for holding the vehicle stationary on the gradient to thereby determine the torque range of the first portion of available torque of the pedal progression logic.

9. The control system of claim 8, wherein the one or more processors are further collectively configured to determine the offset in dependence on one or more of: a road load torque of the vehicle on a flat gradient or a positive gradient with respect to a direction of travel of the vehicle; the surface gradient signal; and a speed of the vehicle.

10. The control system of any preceding claim, wherein the torque for holding the vehicle stationary on the gradient is determined in dependence on the surface gradient signal of any preceding claim, wherein the one or more processors are further collectively configured to: receive a single pedal driving mode signal indicative of a single pedal driving mode of the vehicle being active; and activate, in dependence on the single pedal driving mode signal, the pedal progression logic to determine a torque demand.

11. A powertrain system of a vehicle, the powertrain system comprising: the control system of any preceding claim; the power source; and the drivetrain arranged to receive torque from the power source according to the pedal progression logic.

12. A vehicle comprising the control system of any of claims 1 to 10 or the powertrain system of claim 11.

13. A method for controlling a powertrain system of a vehicle, the powertrain system comprising a power source and a drivetrain arranged to receive torque from the power source, the control system being arranged to control the power source to output torque according to a pedal progression logic mapping a pedal position to a torque demand, wherein the pedal progression logic maps a first portion of available torque to be delivered below a pedal position threshold, the method comprising: receiving a surface gradient signal indicative of a gradient of a surface on which the vehicle is located; receiving a holding torque signal indicative of an output torque of the power source required for holding the vehicle stationary on the gradient; receiving a pedal position signal indicative of the pedal position; determining, in dependence on the surface gradient signal and the holding torque signal, a torque range of the first portion of available torque to be delivered below the pedal position threshold; and outputting a control signal to the powertrain system to generate torque in dependence on the pedal position and the pedal progression logic.

14. The method of claim 13, further comprising determining, in dependence on the surface gradient, the pedal position threshold.

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