EP4713602A1

EP4713602A1 - Control systems for a vehicle powertrain

Info

Publication number: EP4713602A1
Application number: EP24727200.8A
Authority: EP
Inventors: Romain LACROISILLE; Olivier Roques; Matt Sullivan; Vladimir BARANCHIKOV
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2023-05-17
Filing date: 2024-05-14
Publication date: 2026-03-25
Also published as: GB2630087B; GB202307318D0; GB2630087A; CN121127698A; WO2024235977A1

Abstract

Aspects of the present invention relate to a control scheme for controlling a vehicle where an upshift of the vehicle is anticipated and where preparation for the upshift has begun. In cases where the torque demand on the vehicle reduces, the preparation for the upshift may be interrupted or cancelled in order to improve vehicle responsiveness.

Description

CONTROL SYSTEMS FOR A VEHICLE POWERTRAIN

TECHNICAL FIELD

The present disclosure relates to control systems for vehicle powertrains. Particularly but not exclusively, the disclosure relates to control of a powertrain during an upshift of a vehicle. Aspects of the invention relate to control systems, to vehicles and to methods.

BACKGROUND

It is known to provide a control system for a vehicle which processes a driver input in order to determine what torque should be produced by the power sources of the vehicle. Further, existing systems may attempt to manage torque during an upshift by increasing engine torque before the upshift occurs in order to maintain torque at the wheels relatively constant. However, where an upshift is cancelled after preparation forthe upshift has begun, such as due to a change in driver demand, existing systems may react slowly, resulting in undesirable acceleration of the vehicle.

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

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide control systems, vehicles, and methods as claimed in the appended claims.

According to an aspect of the invention, there is provided a control system for controlling a powertrain of a vehicle, the powertrain comprising a power source and a drivetrain arranged to receive torque from the power source, the drivetrain comprising a gearbox, the control system comprising one or more processors, the one or more processors being collectively configured to: receive a first input signal, the first input signal comprising information indicative of a torque demand; filter the torque demand to provide a filtered torque demand; determine a primary torque modulation value based at least partially on the torque demand; compare the filtered torque demand to the torque demand; determine an output torque modulation value in dependence on the comparison of the filtered torque demand to the torque demand and the primary torque modulation value; and output a first output signal, the first output signal being arranged to cause the power source to change a torque output in dependence on the output torque modulation value.

According to an aspect of the invention, there is provided a control system for controlling a powertrain of a vehicle, the powertrain comprising a power source and a drivetrain arranged to receive torque from the power source, the drivetrain comprising a gearbox, the control system comprising one or more processors, the one or more processors being collectively configured to: receive a gear change input signal indicative of an expected upshift of the gearbox; in response to receiving the gear change input signal: receive a first input signal, the first input signal comprising information indicative of a torque demand; filter the torque demand to provide a filtered torque demand; determine a primary torque modulation value based at least partially on the torque demand; compare the filtered torque demand to the torque demand; determine an output torque modulation value in dependence on the comparison of the filtered torque demand to the torque demand and the primary torque modulation value; and output a first output signal, the first output signal being arranged to cause the power source to change a torque output in dependence on the output torque modulation value.

Changing the torque output may comprise altering a torque split between a vehicle engine and electric machine.

In this way, the control system may prepare for an upshift, such as by increasing torque from a power source, and may interrupt the preparation in orderto respond more quickly if the torque demand changes, such as due to a sudden reduction in torque requirement from a driver reducing a pressure on an accelerator pedal or due to an advanced driver assistance system (ADAS) demanding less torque after detecting an obstruction.

According to a yet still further aspect of the invention, there is provided computer readable instructions which, when executed by a computer, are arranged to perform the method of the still further aspect of the invention.

The processors may be collectively configured to determine an arbitration value based on the comparison of the filtered torque demand to the torque demand, and determining the output torque modulation may comprise multiplying the primary torque modulation value by the arbitration value. In this way, there is provided a torque modulation scheme with efficient processing to manage variations in torque demand during an upshift.

The arbitration value may be between 0 and 1 .

Comparing the filtered torque demand to the torque demand may comprise determining whether the torque demand is reducing. By determining a reduction in drivertorque demand, the system may prepare for a change in powertrain behaviour, such as a cancellation of the expected upshift or a reduction in vehicle speed. This may provide a more responsive vehicle.

Filtering the torque demand to provide a filtered torque demand may comprise applying a low-pass filter. A low pass filter may filter out short-term changes torque demand. Therefore, a difference between a low-pass filtered torque demand and an unfiltered torque demand implies a sudden change in torque demand. In response, the control system may change the torque modulation scheme in order to account for the changing torque demand. Further, applying a low-pass filter or limiting a rate of change of torque is often required by vehicles in order to manage traction of the vehicle and comfort of the passengers. Therefore, the filtering step may be dual-purpose and so using a low pass filter may improve computational efficiency.

The processors may be collectively configured to: receive a predicted post-upshift torque demand, receive a current torque demand, and determine the primary torque modulation value based on a difference between the predicted post- upshift torque demand after the upshift and the current torque demand.

The predicted driver torque demand may be based at least one of an accelerator pedal input, a driving mode, a road gradient, a vehicle speed and a torque ratio of the drivetrain after the upshift. By using such a predicted driver torque demand and computing a difference between the predicted torque demand and the current torque demand, a primary torque modulation value may be determined, which may be used in downstream processing.

The processors may be collectively configured to: receive or determine an upshift cancellation signal indicative of a cancellation of the upshift, and determine the output torque modulation in dependence on the upshift cancellation. By considering the cancellation of an upshift and by modifying the torque modulation accordingly, the system may respond to changes in environment and/or changes in driver demand that may warrant a cancellation of the upshift more quickly. Further, the behaviour of the power source may be modified such as to avoid an undesirable acceleration due to excess torque where no upshift takes place.

The processors may be collectively configured to set the output torque modulation to 0 in response to the upshift cancellation. In this way, the torque modulation may effectively be cancelled, meaning that the vehicle may proceed without undesirable changes in speed in response to a cancelled upshift.

The processors may be collectively configured to determine the upshift cancellation signal based on the comparison of the filtered torque demand to the torque demand.

The first output signal may be arranged to cause the power source to change a torque output over time based on a limit on the rate of change of torque over time. In this way, severe changes in torque may be avoiding, providing a limit to the acceleration and deceleration of the vehicle. This may improve vehicle traction and passenger comfort.

The processors may be collectively configured to change the limit on the rate of change of torque over time in dependence on: receiving an upshift cancellation signal indicative of a cancellation of the upshift; or determining, in dependence on the comparison of the filtered torque demand to the torque demand and the primary torque modulation value, an upshift cancellation. By changing the limit on the rate of change of torque, the vehicle may react more quickly to a change in torque demand and may avoid unnecessary acceleration. Alternatively, the torque may be decreased more slowly, allowing a smoother driving experience.

The processors may be collectively configured to increase the limit on the rate of change of torque over time when the processors collectively receive or determine an upshift cancellation signal indicative of a cancellation of the upshift. By increasing the limit on the rate of change of torque, the vehicle may react more quickly to a change in torque demand and may avoid unnecessary acceleration.

According to a further aspect of the invention, there is provided a vehicle comprising the control system of the first-mentioned aspect.

According to a still further aspect of the invention, there is provided a method for controlling a powertrain of a vehicle, the powertrain comprising a power source and a drivetrain arranged to receive torque from the power source, the drivetrain comprising a gearbox, the method comprising: receiving a gear change input signal indicative of an upshift of the gearbox; receiving a first input signal, the first input signal including information indicative of a torque demand; filtering the torque demand provide a filtered torque demand; determining a primary torque modulation value based at least partially on the torque demand; comparing the filtered torque demand to the torque demand; determining an output torque modulation based on the comparison of the filtered torque demand to the torque demand and the primary torque modulation value; and outputting a first output signal, the first output signal causing the power source to change a torque output based on the output torque modulation value.

According to a yet still further aspect of the invention, there is provided computer readable instructions which, when executed by a computer, are arranged to perform a method according to the still further aspect.

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.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figure 1 shows a vehicle in accordance with embodiments of the invention;

Figure 2 shows a schematic diagram of a control system and powertrain of a vehicle in accordance with embodiments of the invention;

Figure 3 shows a flowchart illustrating a method in accordance with an embodiment of the invention;

Figure 4 shows a flowchart illustrating a method in accordance with an embodiment of the invention;

Figure 5 shows a flowchart illustrating a method in accordance with an embodiment of the invention;

Figure 6a shows a graph illustrating a filtered and un-filtered torque demand; and

Figure 6b shows a graph illustrating an engine torque modulation. DETAILED DESCRIPTION

Embodiments of this invention relate to a control system for determining required torque during an upshift of a vehicle. An upshift is a where a gearbox is actuated to alter the gear that is driven by a power source of a vehicle, such that a “higher” gear is selected, such that the drivetrain of the vehicle obtains a lower gear ratio. Generally, if a torque is not varied as an upshift takes place, then a torque on the wheels of the vehicle will reduce. Where a vehicle is accelerating, this will be felt by the driver as a reduction in the acceleration of the vehicle.

Figure 1 illustrates a vehicle according to an embodiment of the present invention to provide context for the invention.

The vehicle 10 includes a control system 100 and a powertrain 111. The control system 100 is arranged to control the powertrain 111. The vehicle 10 may be a hybrid electric vehicle having an electric machine and an internal combustion engine both arranged to drive the wheels of the vehicle. The vehicle 10 may be a mild hybrid electric vehicle (MHEV). An MHEV may be characterised by having no capacity to charge an electric battery using mains electricity and the electric battery may be charged by the internal combustion engine and regenerative braking only. Considered another way, the only primary energy source for an MHEV may be fossil fuels, for example petrol and diesel and the MHEV may have no electrical connection for charging the battery from an external source. The capacity of the battery of an MHEV may be less than 2 kWh. The battery voltage of an MHEV may be around 48 volts or less.

Alternatively, the vehicle 10 may be a plug-in hybrid electric vehicle (PHEV). A PHEV may be characterised by being arranged to receive electrical energy from an external source, such as via a connection to mains electricity. A PHEV may therefore comprise an external electrical connection for charging the battery.

Figure 2 shows a schematic diagram of the control system 100 and powertrain 111 of the vehicle 10.

The control system 100 is arranged to control the powertrain 11 1 of the vehicle. The term powertrain is intended to encompass a system comprising one or more power sources and a drivetrain coupled to the one or more power sources. The powertrain 111 comprises an internal combustion engine 110, an electric machine 120 and a battery 130, the battery 130 being arranged to supply electrical energy 137 to and receive electrical energy 137 from the electric machine 120. The internal combustion engine 110 and electric machine 120 may collectively be referred to as a single power source or as two power sources. Both of the internal combustion engine 110 and electric machine 120 transfer torque 117, 127 to a drivetrain 140 of the powertrain 111. The drivetrain 140 includes a gearbox and may also include further components such as a torque splitter, a torque converter, a differential and wheels of the vehicle 10.

It will be understood that this represents only one possible vehicle architecture according to embodiments of the invention and that other vehicle architectures are also within the scope of the invention, such as architectures with a separate electric motor and electric generator. The control system 100 as illustrated in Figure 2 comprises one controller, although it will be appreciated that this is merely illustrative. The controller comprises 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 is configured to access the memory means and execute the instructions stored thereon.

As shown in Figure 2, the control system 100 may provide signals 115, 125 to the internal combustion engine 110 and to the electric machine 120, such as signals 115, 125 to deliver a certain amount of torque or, in the case of the internal combustion engine 110, to advance or retard ignition timing or to increase or decrease a fuel/air mixture flow rate into the engine 110. The signal may comprise signals to change the torque split between the internal combustion engine 1 10 and electric machine 120. Signals may be outputted by publication on an in-vehicle network (e.g., CAN or FlexRay bus) and received or inputted by reading the published information. These signals may be described as a first output signal.

The battery 130 may supply electrical energy 137 to the electric machine 120 to generate a torque and may also supply electrical energy 139 to electric vehicle components, such as heaters and fans. The battery may also supply information regarding the electricity 139 supplied to other electrical devices 150 to the control system 100.

The control system 100 may also receive information 135 from the battery 130, such as a state of battery charge, a battery temperature and/or an indication of battery health. Overall, the information 135 received from the battery may be indicative of a battery discharge capability, which is the rate at which a battery may supply energy to the electric machine 120 and to other electrical devices 150 of the vehicle 10. Alternatively, the battery 130 may output a battery discharge capability directly to the control system 100. The battery 130 may also output information 135 to the control system 100 that is indicative of the power supplied to the electrical devices 150.

The control system 100 comprises an input means and an output means. The input means may comprise an electrical input of the controller 100. The output means may comprise an electrical output of the controller 100. The input is arranged to receive signals and the output is arranged to output a signal 115 for controlling the engine 110, including by increasing or decreasing the torque output by the engine and a signal 125 for controlling the electric machine 120, including by increasing or decreasing the torque output by the electric machine.

The control system 100 is arranged to receive torque demand data 102 from a torque demand input device 101 , such as an accelerator pedal and to determine a required torque to be generated by the engine 110 and electric machine 120 based at least partially on the received torque demand data 102. The torque demand data 102 may alternatively be received from an advanced driver assistance system (ADAS). The control system 110 may then output control signals 115, 125 to control the engine 110 and the electric machine 120 in order to generate the required torque. The torque demand data 102 may be referred to as a torque demand or, in embodiments when the driver is in manual control of the vehicle, a driver torque demand. The torque demand data may be a current torque demand.

An advanced driver assistance system (ADAS) is a system that provides assisted or autonomous driving modes such as a speed limiter, cruise control, adaptive cruise control. ADAS may provide a torque demand that is not correlated with the driver pedal input.

The control system 100 is also arranged to receive a driving mode signal 104 from a driving mode selector 103, which may take the form of a driving mode selector switch, or may be taken from a touch-screen, or other such input to a human-machine interface of the vehicle.. The driving mode may be selected by the driver depending on the desired behaviour of the vehicle. For example, when it is desired that a vehicle reacts quickly to a driver input and achieves high accelerations, a “sport” mode may be selected, whereas a “comfort” mode may be selected when a less reactive driving mode is desired. The control system 100 may determine a required torque based at least partially on the driving mode signal 104.

The control system 100 is also arranged to receive a vehicle condition signal 106 from a vehicle condition sensor 105. The vehicle condition sensor may determine properties such as a road gradient and a vehicle speed and the vehicle condition signal 106 may contain this information. The control system 100 may receive the vehicle condition signal 106 and may determine a required torque based at least partially on the information in the vehicle condition signal such as the road gradient and/or the vehicle speed.

The control system is also configured to receive drivetrain data 108 from a drivetrain management system 107. The drivetrain management system 107 may also be referred to as a transmission control system or a transmission management system. The drivetrain control system 107 may provide drivetrain data 108 and the drivetrain data 108 may include information such as a target gear following an upshift, a gear change signal indicating that an upshift is about to occur, a torque converter slip value, indicating a level of slip from a torque converter of the drivetrain 140, and a predicted post-upshift gearbox input shaft speed.

The control system 100 may also have values stored internally, such as transmission ratios of the different gears, a powertrain torque maximum capability, a blend rate for altering a torque output of the drivetrain 140, and a loss value indicative of torque losses in the powertrain.

The control system 100 may determine a predicted driver torque in a target gear based on any or all of the above-described data and may therefore determine a predicted torque required in a target gear more effectively. Further, the data included in the separate signals 102, 104, 106, 108 may be combined by a signal management system and received by the control system 100 as a single signal.

The term control system may be used to describe a specific control module, or to describe a system of sensors and modules. For instance, the drivetrain control module 107, the torque demand input device 101 , the driving mode selection device 103, and the vehicle condition sensor 105 may be considered as within the same control system as the control system 100. Where a control system is described as arranged to receive a signal, it will also be understood that one part or program of the control system may receive the signal from a further part or program of the control system, and it is not essential that the signal is sent from a device that is external to the control system to a physically separated control system.

Figure 3 shows a flowchart illustrating a method 200 for controlling a powertrain during a change of mind of a driver, a change in torque demand from an ADAS, or a change in torque requirement from an autonomous driving program during an upshift may be detected and may affect the torque demand. In particular, the illustrated method relates to a reduction in torque demand.

At step 210 a gear change signal is received by the control system 100 indicating that an upshift is expected. In response, the control system 100 enters an upshift management mode for determining a torque required from the power source during the upshift.

At step 220, a first input signal comprising information indicative of a torque demand signal is received. The torque demand signal may be received from a torque input device such as a driver pedal, from ADAS, or from an autonomous driving program. The torque demand may also be pre-processed to some extent, such as by taking into account a driver mode or vehicle speed. The possible processing of the torque demand is described further below with reference to Figure 4.

The received torque demand is filtered at step 220 to provide a filtered torque demand. The filtering may also be referred to as “driveability shaping” and may comprise passing the torque demand through a low-pass filter or limiting a rate of change of torque over time. The filtering may improve traction of the vehicle by reducing high frequency variations in torque and may also provide a more comfortable experience for passengers. Figure 6 illustrates how the torque demand may be filtered.

At step 230, the filtered torque demand is compared to the unfiltered torque demand. A significant difference indicates that the torque demand is changing quickly, and that there may be a change of mind of the driver, or a change in the intention of an ADAS or autonomous driving program. In particular, if the unfiltered torque demand is significantly less than the filtered torque demand, then there is an implication that acceleration of the vehicle should cease or reduce.

In response to a determination as to whether the acceleration of the vehicle should reduce, the system may determine a torque modulation arbitration value at step 230. In the case that the acceleration should reduce, or in general that torque demand is reducing, the determined torque modulation arbitration value may be less than 1. In the case that no upshift should occur due to a significant reduction in torque demand, a torque modulation arbitration value of 0 may be selected. In the case that the torque demand matches the filtered torque demand, meaning that the upshift should occur as anticipated, a torque modulation arbitration value of 1 may be selected. The torque modulation arbitration value may be considered as a ratio of how much of the torque modulation value should be passed on to the downstream control logic. Further, in the case that it is determined that the torque demand has reduced such that no upshift should occur, an upshift cancellation signal may be output by the control system 100, to instruct a transmission control system not to actuate the gearbox to cause an upshift. The upshift cancellation signal may alternatively be output by the transmission control system, which may determine a reduction of torque demand. The control system 100 may therefore receive a upshift cancellation signal by way of publication on a CAN bus or by receiving a signal from a transmission control system.

In general, the control system may limit a rate of change of torque in order to improve vehicle driveability. In response to receiving the upshift cancellation signal or otherwise determining that an upshift cancellation is likely, the control system 100 may change a maximum torque decrease rate. This may include increasing a maximum torque decrease rate. In this way, the power source may have a higher rate of torque decrease than in a situation where no upshift cancellation signal is received or determined. The torque may be decreased more quickly in this case in order to match the determined torque modulation.

At step 240, a torque modulation value is determined by the control system 100. The torque modulation value may be determined using different torque modulation schemes based on the source of the torque demand. Where the torque demand is from a driver torque input device, such as an accelerator pedal, a predicted postupshift torque demand may be determined, as set out below in connection with Figure 4. A current torque demand may be subtracted from the predicted post- upshift torque demand in order to give a torque modulation value. Alternatively, where ADAS is the source of the torque demand, the torque modulation value may be determined on the basis of a current torque demand, a current torque ratio of the gearbox, and the post-upshift torque ratio of the gearbox. The torque modulation value may be determined such that the torque output from the gearbox does not change across the upshift.

Steps 220 and 230 may be carried out in parallel with step 240, as shown in Figure 3. Alternatively, step 240 may be performed before or after steps 220 and 230. This may be advantageous where determined values such as the filtered torque demand may be used in both processes.

The torque modulation value and torque arbitration values may be combined at step 250, such as by multiplication, in order to output a final torque modulation value.

At step 260, the torque modulation value may be output to a power source in order to change the torque generated by the power source. Alternatively, the torque modulation may be added to a current torque demand in orderto determine an absolute torque demand. The absolute torque demand may then be output to a power source to cause the power source to generate a torque equal to the absolute torque demand.

Figure 4 shows a further flowchart, illustrating how data received by the control system may be processed for determining the predicted driver torque after the upshift. A first processing step 310 may receive inputs from the various sources. Specifically, the process 310 may receive an accelerator pedal input 301 , a previous driver or terrain mode 302, a current driver or terrain mode 303, a road gradient 304, a vehicle speed 305, a high or low range requirement 306, a target gear transmission ratio excluding torque converter slip 307, drive or sport selection 308, and a predicted gearbox input shaft speed in the target gear 309. Based on the inputs 301-309, the process 310 generates a normalised torque demand 315. A second process 320 calculates a predicted torque demand in the target gear based on the normalised torque demand 315. The second process 320 calculates the predicted torque demand in the target gear 330 based on the losses known within the powertrain, 321 , the transmission ratio in the target gear 322, and the maximum torque capability of the powertrain 323.

By following the process 300, a more accurately predicted torque demand in the target gear 330 may be determined.

Figure 5 shows a further flowchart illustrating a method 400 of determining a torque modulation value 445. The control system receives a torque demand 401 . At step 410, the torque demand is filtered in order to provide a filtered torque demand 415. Step 420 receives the raw, unfiltered torque demand 401 and the filtered torque demand 415 in order to determine whether the torque demand is decreasing. The comparison may be performed as described with reference to Figure 6 below. Based on the comparison, a torque modulation arbitration value 425 is determined.

At step 430, a torque modulation value 435 is determined. The torque modulation value 435 is, in the illustrated method of Figure 5, determined based on the predicted post-upshift torque demand 403, which may be determined as described above with reference to Figure 4, and the current torque demand 405. The raw, unfiltered torque demand 401 may be the same as the current torque demand 405. The torque modulation 435 may be determined based on a difference between the predicted post-upshift torque demand 403 and the current torque demand 405.

At step 440, a final torque modulation value 445 is determined based on the torque modulation value 435 and the torque modulation arbitration value 425. The final torque modulation value 445 may be determined by multiplying the torque modulation value 435 by the torque modulation arbitration value 425.

Figure 6 shows a graph 500 of a raw torque demand 510 and a filtered torque demand 520. It can be seen that the raw torque demand 510 may change abruptly. This may be due to a driver lifting their foot off the accelerator pedal or due to ADAS detecting an obstruction in the path of the vehicle and instructing a deceleration. In order to improve traction and passenger comfort, the raw torque demand 510 may be filtered. The filtering may comprise removing high frequency components of the raw torque demand and/or limiting a rate of change of the torque demand. In this way, a filtered torque demand 520 is determined.

As can be seen from Figure 6a, due to the high rate of change of the raw torque demand 510, the filtered torque demand 520 deviates from the raw torque demand 510 significantly. By comparing contemporaneous values of the filtered torque demand 520 and the raw torque demand 510, it may be determined whether the raw torque demand 510 includes a high rate of change of torque. Further, in the case that the filtered torque demand 520 is greater than the raw torque demand 510, it may be determined that the raw torque demand 510 is decreasing. Figure 6b shows that the logic comprises a detection whether the shift is in progress 531 or has been interrupted 530, which will result in different decreasing selectable rates for the filtered upshift torque modulation, respectively 541 and 540.

The rate of change of torque for the filtered torque demand 620 may be selectable, such that the filtering may be performed in order to provide vehicle stability and avoid a sudden change in vehicle behaviour.

Based on a determination that the raw torque demand 510 is reducing at a high rate, a torque modulation arbitration value 425 may be selected accordingly, providing an appropriate final torque modulation value 445. In this way, torque generated by a power source may be managed effectively during an upshift in the case that the demanded torque changes significantly during the upshift.

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

1 . A control system for controlling a powertrain of a vehicle, the powertrain comprising a power source and a drivetrain arranged to receive torque from the power source, the drivetrain comprising a gearbox, the control system comprising one or more processors, the one or more processors being collectively configured to: receive a gear change input signal indicative of an expected upshift of the gearbox; in response to receiving the gear change input signal, enter an upshift management mode, and in the upshift management mode: receive a first input signal, the first input signal comprising information indicative of a torque demand; filter the torque demand to provide a filtered torque demand; determine a primary torque modulation value based at least partially on the torque demand; compare the filtered torque demand to the torque demand; determine an output torque modulation value in dependence on the comparison of the filtered torque demand to the torque demand and the primary torque modulation value; and output a first output signal, the first output signal being arranged to cause the power source to change a torque output in dependence on the output torque modulation value.

2. The control system according to claim 1 , wherein the processors are collectively configured to determine an arbitration value based on the comparison of the filtered torque demand to the torque demand, and wherein determining the output torque modulation comprises multiplying the primary torque modulation value by the arbitration value.

3. The control system according to claim 2, wherein the arbitration value is between 0 and 1 .

4. The control system according to claim 1 , 2 or 3, wherein comparing the filtered torque demand to the torque demand comprises determining whether the torque demand is reducing.

5. The control system according to any preceding claim, wherein filtering the torque demand to provide a filtered torque demand comprises applying a low-pass filter.

6. The control system according to any preceding claim, wherein the processors are collectively configured to: receive a predicted post- upshift torque demand, receive a current torque demand, and determine the primary torque modulation value based on a difference between the predicted postupshift torque demand after the upshift and the current torque demand.

7. The control system according to any preceding claim, wherein the processors are collectively configured to: receive or determine an upshift cancellation signal indicative of a cancellation of the upshift, and determine the output torque modulation in dependence on the upshift cancellation.

8. The control system according to claim 7, wherein the processors are collectively configured to set the output torque modulation to 0 in response to the upshift cancellation.

9. The control system according to claim 7 or 8, wherein the processors are collectively configured to determine the upshift cancellation signal based on the comparison of the filtered torque demand to the torque demand.

10. The control system according to any preceding claim, wherein the first output signal is arranged to cause the power source to change a torque output over time based on a limit on the rate of change of torque over time.

11. The control system according to claim 10, wherein the processors are collectively configured to change the limit on the rate of change of torque over time, in dependence on: receiving an upshift cancellation signal indicative of a cancellation of the upshift; or determining, in dependence on the comparison of the filtered torque demand to the torque demand and the primary torque modulation value, an upshift cancellation.

12. The control system according to claim 11 , wherein the processors are collectively configured to increase the limit on the rate of change of torque over time.

13. A vehicle comprising the control system of any preceding claim.

14. A method for controlling a powertrain of a vehicle, the powertrain comprising a power source and a drivetrain arranged to receive torque from the power source, the drivetrain comprising a gearbox, the method comprising: receiving a gear change input signal indicative of an upshift of the gearbox; in response to receiving the gear change input signal, enter an upshift management mode, and in the upshift management mode: receiving a first input signal, the first input signal including information indicative of a torque demand; filtering the torque demand provide a filtered torque demand; determining a primary torque modulation value based at least partially on the torque demand; comparing the filtered torque demand to the torque demand; determining an output torque modulation based on the comparison of the filtered torque demand to the torque demand and the primary torque modulation value; and outputting a first output signal, the first output signal causing the power source to change a torque output based on the output torque modulation value.

15. Computer readable instructions which, when executed by a computer, are arranged to perform a method according to claim 14.