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GB2633794A - Control system for controlling a powertrain and a foundation brake of a vehicle - Google Patents

Control system for controlling a powertrain and a foundation brake of a vehicle Download PDF

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Publication number
GB2633794A
GB2633794A GB2314470.2A GB202314470A GB2633794A GB 2633794 A GB2633794 A GB 2633794A GB 202314470 A GB202314470 A GB 202314470A GB 2633794 A GB2633794 A GB 2633794A
Authority
GB
United Kingdom
Prior art keywords
braking torque
electric machine
vehicle
foundation
control system
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
GB2314470.2A
Other versions
GB202314470D0 (en
Inventor
Jones Andy
Roques Olivier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Jaguar Land Rover Ltd
Original Assignee
Jaguar Land Rover Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jaguar Land Rover Ltd filed Critical Jaguar Land Rover Ltd
Priority to GB2314470.2A priority Critical patent/GB2633794A/en
Publication of GB202314470D0 publication Critical patent/GB202314470D0/en
Priority to PCT/EP2024/076493 priority patent/WO2025061984A1/en
Publication of GB2633794A publication Critical patent/GB2633794A/en
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L7/00—Electrodynamic brake systems for vehicles in general
    • B60L7/24—Electrodynamic brake systems for vehicles in general with additional mechanical or electromagnetic braking
    • B60L7/26—Controlling the braking effect
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L7/00—Electrodynamic brake systems for vehicles in general
    • B60L7/10—Dynamic electric regenerative braking
    • B60L7/18—Controlling the braking effect
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L7/00—Electrodynamic brake systems for vehicles in general
    • B60L7/22—Dynamic electric resistor braking, combined with dynamic electric regenerative braking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
    • B60T8/1761—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to wheel or brake dynamics, e.g. wheel slip, wheel acceleration or rate of change of brake fluid pressure
    • B60T8/17616—Microprocessor-based systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/60—Navigation input
    • B60L2240/64—Road conditions
    • B60L2240/642—Slope of road
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T2270/00—Further aspects of brake control systems not otherwise provided for
    • B60T2270/60—Regenerative braking
    • B60T2270/604—Merging friction therewith; Adjusting their repartition

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Fluid Mechanics (AREA)
  • Regulating Braking Force (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

A control system 110 for controlling a powertrain 120 and foundation (e.g. frictional) brake 134, the powertrain comprising an electric machine 122 and drivetrain 124, the electric machine being arranged to apply torque to the drivetrain, control system 110 comprising processor(s) configured to; receive a deceleration request of a specific deceleration; receive a surface signal indicating a condition of the surface on which the vehicle is located; determine a required braking torque based on the required deceleration; determine a threshold for the electric machine braking torque (aka the regenerative braking torque threshold); determine whether the required torque is over this threshold; and if it is, output a signal to engage the foundation brake also. Additionally the system is able to detect the converse, that the torque required from the foundation brake is beyond a threshold and use a secondary, greater threshold for the electric machine brake. Also claimed is a corresponding vehicle, method, and computer program.

Description

CONTROL SYSTEM FOR CONTROLLING A POWERTRAIN AND A FOUNDATION BRAKE OF A
VEHICLE
TECHNICAL FIELD
The present disclosure relates to a control system for controlling a powertrain and a foundation brake of a vehicle. Aspects of the invention relate to a control system, to a vehicle comprising the control system, to a method for controlling a powertrain and a foundation brake of a vehicle and to computer readable instructions which, when executed by a computer, are arranged to perform the method.
BACKGROUND
It is known to use an electric machine for providing a braking torque to decelerate a vehicle. However, in some cases there may be a loss of traction. In this case, the electric machine may cause rotation of the wheels, resulting in wheel slip and reducing vehicle stability.
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 a control system, a vehicle, a method and computer readable instructions as claimed in the appended claims.
This disclosure provides a technique for controlling a powertrain and a foundation brake of a vehicle. The technique determines the amount of braking torque needed to decelerate the vehicle and control a foundation brake based on a condition of a surface on which the vehicle is located and an expected level of traction between the vehicle and said surface.
According to an aspect of the present invention there is provided a control system for controlling a powertrain and a foundation brake of a vehicle, the powertrain comprising an electric machine and a drivetrain, the electric machine being arranged to apply a torque to the drivetrain, the control system comprising one or more processors collectively configured to: receive a deceleration request signal comprising information indicative of a requested deceleration of the vehicle; receive a surface signal, the surface signal comprising information indicative of a condition of a surface on which the vehicle is located; determine a required vehicle braking torque based at least partially on the requested deceleration of the vehicle; determine, in dependence on the information indicative of the condition of the surface, an electric machine braking torque threshold; determine whether the required vehicle braking torque is greater than the electric machine braking torque threshold; and output, in dependence on a determination that the required vehicle braking torque is greater than the electric machine braking torque threshold, a foundation brake signal to cause the foundation brakes to generate a foundation brake torque.
The deceleration request may be received from a driver or ADAS. The surface signal may include an indication that the vehicle is being driven over loose terrain or may be a default value. By setting an electric machine braking torque threshold in dependence on the surface, and by applying a braking torque with foundation brakes, over-rotation of the wheels may be reduced. This may improve vehicle stability during deceleration.
According to an additional aspect of the present invention, there is provided a control system for controlling a powertrain and a foundation brake of a vehicle, the powertrain comprising an electric machine and a drivetrain, the electric machine being arranged to apply a torque to the drivetrain, the control system comprising one or more processors collectively configured to: receive a deceleration request signal comprising information indicative of a requested deceleration of the vehicle; determine a required vehicle braking torque based at least partially on the requested deceleration of the vehicle; determine an electric machine braking torque threshold; determine whether the required vehicle braking torque is greater than the electric machine braking torque threshold; and output, in dependence on a determination that the required vehicle braking torque is greater than the electric machine braking torque threshold, a foundation brake signal to cause the foundation brakes to generate a foundation brake torque.
The control system comprises one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal; and at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon so as to carry out the required functionality described herein.
The one or more processors may be collectively configured to output an electric machine torque signal to cause the electric machine to generate a required electric machine braking torque. In this way, the electric machine and the foundation brakes may work together to decelerate the vehicle. This may allow a faster deceleration and/or may allow kinetic energy to be converted into electrical energy such that vehicle efficiency may be improved.
The one or more processors may be collectively configured to, in dependence on the determination that the required vehicle braking torque is greater than the electric machine braking torque threshold, output the electric machine torque signal to cause the electric machine to generate the required electric machine braking torque, the required electric machine braking torque being equal to the electric machine braking torque threshold. This prioritises electric machine braking over foundation braking by applying the maximum allowable electric machine braking and using foundation brakes to the minimum required level, which may reduce the likelihood of skidding due to foundation brake locking. Kinetic energy recovery may also be improved.
The one or more processors may be collectively configured to determine a required foundation braking torque in dependence on a difference between the required electric machine braking torque or the electric machine braking torque threshold and the required vehicle braking torque, and output the foundation brake signal in dependence on the required foundation braking torque. The foundation brakes may therefore be used to supply further braking torque to allow a sufficient vehicle braking torque to be applied, so that the vehicle can be decelerated at the required rate.
The one or more processors may be collectively configured to, in dependence on the determination that the required vehicle braking torque is greater than the electric machine braking torque threshold, determine the required foundation braking torque in dependence on the difference between the required electric machine braking torque or the electric machine braking torque threshold and the required vehicle braking torque, determine a foundation braking torque threshold, determine whether the required foundation braking torque is greater than the foundation braking torque threshold, and output, in dependence on a determination that the required foundation braking torque is not greater than the foundation braking torque threshold, the electric machine torque signal to cause the electric machine to generate the required electric machine braking torque.
In the case that the foundation brakes can provide a sufficient braking torque to allow the vehicle to decelerate at the required rate, the electric machine may be commanded to generate the maximum allowable braking torque. This may improve kinetic energy recovery while maintaining good stability in braking. By comparing the foundation brake torque to a threshold, the prospect of damage to the brakes may also be reduced.
The one or more processors may be collectively configured to, in dependence on a determination that the required foundation braking torque is greater than the foundation braking torque threshold, set the required foundation braking torque to be equal to the foundation braking torque threshold. In this respect, the foundation brakes should not be controlled to exert too much braking torque. This can lead to brakes locking or overheating. Therefore, the control system may allow more stable braking and avoid damage to the foundation brakes.
The one or more processors may be collectively configured to, in dependence on a determination that the required foundation braking torque is greater than the foundation braking torque threshold, determine a further electric machine braking torque in dependence on a difference between the required vehicle braking torque and the foundation braking torque threshold. In this case, the electric machine may be used above capacity in order to reduce the likelihood of wheel locking and to prioritise deceleration of the vehicle.
The one or more processors may be collectively configured to, in dependence on a determination that the required foundation braking torque is greater than the foundation braking torque threshold: determine a further electric machine braking torque threshold, determine whether the further electric machine braking torque is greater than the further electric machine braking torque threshold, and in dependence on a determination that the further electric machine braking torque is greater than the further electric machine braking torque threshold, set the required electric machine braking torque to be equal to the further electric machine braking torque threshold, and reduce the required vehicle braking torque to equal the sum of the further electric machine braking torque and the foundation braking torque.
The further electric machine braking torque threshold may be determined in dependence on different criteria or with different coefficients from the first-mentioned electric machine braking torque threshold. Therefore, when the overall braking of the vehicle is required to be greater than can be achieved using the friction brakes at their limit and the electric machine at its preferred limit, the electric machine limit may be recalculated in order to prioritise braking speed of the vehicle. Further, the vehicle may be prevented from braking more quickly than can be achieved without risking damage to the foundation brakes or the electric machine, reducing the overall required vehicle braking.
The one or more processors are collectively configured to receive the deceleration request signal from an accelerator pedal. By detecting a lack of driver input to the accelerator pedal, the system may determine that a braking torque to decelerate the vehicle is required. By allowing a driver to command a deceleration using an accelerator pedal, a vehicle may be driven more easily.
The surface signal may comprise information indicative of a terrain on which the vehicle is located, and the one or more processors may be collectively configured to determine the electric machine braking torque threshold based at least partially on the terrain on which the vehicle is located. The driver of the vehicle may input the terrain mode. The electric machine braking torque threshold and likelihood of wheel slippage may therefore be determined more accurately based on a manual selection of the type of terrain the vehicle is on.
The surface signal may comprise information indicative of wheel slip during acceleration of the vehicle, and the one or more processors may be collectively configured to determine the electric machine braking torque threshold based at least partially on the wheel slip. A traction control signal may occur during a propulsive action of the vehicle, such as during acceleration where the wheels are slipping on the surface, which may indicate the surface is loose. The electric machine braking torque threshold may therefore be determined more accurately.
The surface signal may comprise information indicative of an anti-lock brake system being activated, and the one or more processors may be collectively configured to: determine the electric machine braking torque threshold based at least partially on the activation of the anti-lock braking system. Anti-lock braking systems may operate as a separate system to the control system herein. Loss of traction between the surface and the vehicle wheels due to a loose surface may result in brake lock-up which may be communicated to the control system via the anti-lock brake signal. This may indicate that the electric machine braking torque threshold should be reduced, as over-rotation of the wheels may be less preferable than lock-up of wheels.
The one or more processors may be collectively configured to: receive a vehicle mass signal comprising information indicative of the mass of the vehicle; and determine the electric machine braking torque threshold based at least partially on the information indicative of the mass of the vehicle. A vehicle having a greater mass may be less likely to lose traction when a given braking torque is generated. Therefore, by considering the mass of the vehicle, the electric machine braking torque threshold may be determined more accurately. The vehicle may therefore be decelerated with a lower risk of the brakes locking and with improved kinetic energy recovery.
The surface signal may comprise information indicative of the gradient of the surface on which the vehicle is located; wherein the one or more processors are collectively configured to determine the electric machine braking torque threshold based at least partially on the information indicative of the gradient of the surface on which the vehicle is located. At a steeper gradient, the normal reaction force between the car and the surface may be reduced, reducing the limiting friction between the wheels and the surface and thereby increasing the risk of slippage. By considering the gradient of the surface, the electric machine braking torque threshold may be determined more accurately.
According to a further aspect of the invention, there is provided a vehicle comprising: a powertrain, the powertrain comprising an electric machine and a drivetrain arranged to receive torque from the electric machine; a foundation brake; and the control system of any preceding claim.
According to a still further aspect of the invention, there is provided a method for controlling a powertrain and a foundation brake of a vehicle, the powertrain comprising an electric machine and a drivetrain, the electric machine being arranged to apply a torque to the drivetrain, the method comprising: receiving a deceleration request signal comprising information indicative of a requested deceleration of the vehicle; receiving a surface signal, the surface signal comprising information indicative of a condition of a surface on which the vehicle is located; determining a required vehicle braking torque based at least partially on the requested deceleration of the vehicle; determining, in dependence on the information indicative of the condition of the surface, an electric machine braking torque threshold; determining whether the required vehicle braking torque is greater than the electric machine braking torque threshold; and outputting, in dependence on a determination that the required vehicle braking torque is greater than the electric machine braking torque threshold, a foundation brake signal to cause the foundation brakes to generate a foundation brake torque.
According to a yet still further aspect of the invention, there is provided a computer readable instructions which, when executed by a computer, are arranged to perform a method according to the still further aspect of the invention.
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 an embodiment of the invention; Figure 2 shows a block diagram illustrating components of a vehicle in accordance with an embodiment of the invention; Figure 3 shows a block diagram illustrating components of a vehicle in accordance with a further embodiment of the invention; Figure 4 shows a flow chart illustrating a method in accordance with an embodiment of the invention; and Figure 5 shows a further flow chart illustrating a method in accordance with an embodiment of the invention.
DETAILED DESCRIPTION
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 110, a powertrain 120 and a foundation braking system 130. The control system 110 is arranged to control the powertrain 120 and the foundation braking system 130. 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 or may be a battery electric vehicle powered by an electric machine only. The vehicle 10 may be a mild hybrid electric vehicle (MHEV) or a plug-in hybrid electric vehicle (PHEV).
Figure 2 shows a schematic diagram of components of the vehicle 10. The vehicle 10 has a control system 110, the control system 110 comprising one or more controllers. The one or more controllers are collectively configured to receive data from different sensors, systems, and input devices of the vehicle, to process the data and to output commands for controlling the vehicle. 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 110 is arranged to control a powertrain 120. The powertrain comprises a power source 122. The power source 122 may be an electric machine and in some cases the powertrain 120 may have two power sources 122 which are an electric machine and an internal combustion engine. The powertrain 120 also comprises a drivetrain 124 that is arranged to receive torque 125 from the power source 122, to convert the torque and to provide a converted torque 127 to the wheels 140. The drivetrain 124 may be a direct-drive drivetrain or may have a gearbox and a differential for increasing the torque 125 delivered from the power source 122 so that a higher torque 127 may be delivered to the wheels 140 of the vehicle.
The powertrain 120 is controlled by and monitored by the control system 110. The control system 110 is arranged to output an electric machine torque requirement signal 121 to the powertrain 120 to cause the power source 122 to generate a required amount of torque 125. The control system 110 is also arranged to receive data 123 from the powertrain 120. The received data 123 may include a rotational speed of the power source 122 and may include a torque generated by the power source 122. The control system 110 may also receive data 123 and transmit commands 121 related to the drivetrain 124. The control system 110 may transmit commands 123 to the powertrain 120, such as a gear change command to change a torque ratio of the drivetrain 124. The control system 110 may also receive data 123 that may include a rotational speed of one or more components of the drivetrain 124, or an amount of torque received by the drivetrain 124 or output by the drivetrain 124. The torque ratio of the drivetrain may be transmitted from the drivetrain 124 to the control system 110 as part of data 123 or may be stored as a value in the control system 110, as the control system 110 may command the drivetrain 124 in order to control the torque ratio of the drivetrain 124.
The vehicle 10 also has a foundation braking system 130. The foundation braking system 130 comprises a brake actuator 132 and a foundation brake 134. The brake actuator 132 may be a hydraulic pump or an electromechanical actuator for moving components of the foundation brake 134 that are arranged to engage frictionally in order to provide a braking torque. The brake actuator 132 may therefore apply a force 135 to the foundation brake 134. The foundation brake 134 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 134 into engagement, the foundation braking system 130 may provide a braking torque 137 to the wheels 140 to decelerate the vehicle.
The term "foundation brake" is generally used herein to mean any frictional brake that may decelerate the vehicle by converting kinetic energy into heat by friction, as opposed to a regenerative brake, such as may be provided by an electric machine.
The control system 110 is also arranged to receive further input signals. The control system 110 is arranged to receive an acceleration or deceleration request 103 from a speed control device 102. The speed control device 102 may be a drivers accelerator pedal or may be an autonomous driving system. An accelerator pedal is a device usually arranged in a footwell of a vehicle arranged to receive an input from a user indicating a desired speed, desired propulsive force, or change in speed of the vehicle. Usually, a higher pressure exerted by a user on the accelerator pedal indicates that a higher vehicle speed is required. The driver may exert no pressure on the accelerator pedal where no vehicle torque is required, to allow the vehicle to decelerate. The vehicle may decelerate due to aerodynamic drag and frictional forces alone or, in particular in a single pedal driving mode, the control system may command an electric machine to generate a braking torque to decelerate the vehicle.
The control system 110 is also arranged to receive a proper acceleration signal 105 from an inertial measurement unit 104. The proper acceleration signal may be used to determine a gradient of a road the vehicle is on and may be used in determination of a mass of the vehicle, in conjunction with a torque value received from the powertrain 120. The control system 110 may also receive a driving mode input value 107 from a driving mode selection switch 106. The driving mode may include information such as a desired driving style, or a terrain over which the vehicle is travelling. It will be understood that the inertial measurement unit 104 and/or the driving mode selection switch 106 may be omitted in some cases.
The driving mode selection switch 106 may indicate that a single pedal driving mode is to be effected. In a single pedal driving mode, the control system 110 may instruct the power source 122 to exert a braking torque to decelerate the vehicle based on an input from an accelerator pedal, without any input from a brake pedal.
It will be understood that the control system 110 may be formed of a plurality of separate controllers or processors, and that signals which are generally described as being received by the control system or output by the control system may be published on a central CAN bus or merely 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 110.
Figure 3 shows a further possible architecture of a vehicle 10.
The control system 110, input devices 102, 104, 106, and signals 103, 105, 107 may be substantially similar to those described above with reference to Figure 2 and so their descriptions are not repeated here for brevity. 15 As can be seen in Figure 3, the vehicle 10 may have multiple powertrains 120a, 120b and multiple foundation braking systems 130a, 130b. The separate powertrains 120a, 120b and foundation braking systems 130a, 130b may control separate wheels or separate axles 140a, 140b. For example, a first powertrain 120a and a first braking system 130a may control a first pair of wheels 140a and a second powertrain 120b and a second braking system 130b may control a second set of wheels 140b. The first set of wheels 140a may be front wheels of a vehicle, and the second set of wheels 140b may be a rear set of wheels.
The first powertrain 120a has a first power source 122a arranged to transfer a first torque 125a to a first drivetrain 124a. The first drivetrain 124a is arranged to receive the first torque 125a, to convert the first torque 125a such as via a gearbox, and to transmit a first wheel torque 127a to the first wheels 140a. The vehicle 10 also has a first foundation braking system 130a comprising a first brake actuator 132a arranged to transfer a braking force 135a to a first foundation brake 134a, such that a first braking torque 137a is transmitted to the first wheels 140a.
The vehicle 10 has a second powertrain 120b and a second foundation braking system 130b arranged to transmit a second wheel torque 127b and a second braking torque 137b to the second wheels 140b respectively. The second powertrain 120b has a second power source 122b, arranged to transfer a second torque 125b to a second drivetrain 124b, and the second foundation braking system 130b has a second brake actuator 132b arranged to transfer a second braking force 135b to a second foundation brake 134b.
It will be understood that the powertrains 120a, 120b described with reference to Figure 3 may be substantially similar to the powertrain 120 described with reference to Figure 2 and that the braking systems 130a, 130b may be substantially similar to the braking system 130 of Figure 2.
The first and second powertrains 120a, 120b are also arranged to transfer data 123a, 123b to the control system 110 and to receive commands 121a, 121 b from the control system 110. Similarly, the braking systems 130a, 130b are arranged to transfer data 133a, 133b to the control system 110 and to receive commands 131a, 131 b from the control system 110.
By providing two separate power trains 120a, 120b and two separate braking systems 130a, 130b, the braking torques provided by the power trains and/or the braking systems may be selected for different wheels deliberately so as to improve traction of the vehicle. Stability of the vehicle may also be improved during a transition from a braking torque provided by the powertrains 120a, 120b to a braking torque provided by the foundation brakes 130a, 130b.
Figure 4 illustrates a method 200 according to an embodiment of the invention. The method 200 is a method of controlling a powertrain 120 and a foundation brake 130 of a vehicle 10, such as the vehicle 10 illustrated in Figures 1, 2 and 3. The method 200 may be performed by the control system 110 illustrated in Figures 1, 2 and 3. In particular, the control system 110 may comprise a memory, which may comprise computer-readable instructions which, when executed by a processor, perform the method 200 according to an embodiment of the invention.
At step 210, the control system 110 is arranged to receive a deceleration request signal (e.g., input signal 103). The deceleration request signal may be received from a driver input device, such as a brake pedal or an accelerator pedal, including a null signal from an accelerator pedal when the vehicle is in a single pedal driving mode or a high energy regeneration mode, indicating that the vehicle is to decelerate. Alternatively, the deceleration request signal may be received from an autonomous driving system, or an advanced driver assistance system (ADAS) such as emergency braking or adaptive cruise control. The deceleration request signal may include a desired deceleration rate for the vehicle, which is a rate at which the vehicle should decelerate.
At step 220, the control system 110 is arranged to receive a surface signal (e.g., input signals 105 and 107), the surface signal comprising information indicative of a condition of a surface on which the vehicle is located. The surface signal may be a signal indicating that the surface is loose or has a low frictional coefficient, or may pertain to a gradient of the surface and may be received from any range of different sensors and input devices.
For instance, the surface signal may be a signal from the braking system that anti-lock braking or ABS has been activated, indicating that the road surface is unable to provide a high level of traction for decelerating the vehicle, or may be a wheel slip signal from a powertrain, indicating that over-rotation of the wheels has occurred due to a loss of traction on the road surface.
Further, the surface signal may be an indication of a mass and/or a gradient of the vehicle, which may collectively be referred to as a vehicle load. The gradient and/or mass may be determined based on an acceleration value received from an inertial measurement unit and/or a torque output by the power train and/or suspension data indicating a pitch of the vehicle. The calculations necessary for determining a vehicle mass and a road gradient based on these data will be known to the skilled person and so are not repeated here for brevity.
Still further, the surface signal may include an indication of a road surface from a driver input device, such as a driving mode switch. The driving mode may be set to an off-road mode or a sport mode for example and the level of traction that may be expected from the surface may be inferred based on these inputs.
It will generally be understood that the surface signal may include all or any combinations of the above-described inputs and an overall value for the tractional force that may be provided by the surface may be determined using heuristics based on the received data.
At step 230, the control system 110 is arranged to determine a required vehicle braking torque based at least partially on the requested deceleration of the vehicle received at step 210. The required vehicle braking torque may be determined based on the vehicle load or vehicle mass as well as the desired deceleration such that the vehicle may be brought to rest in the required time or at the desired rate. The vehicle mass may be known or estimated or may be determined based on received signals, such as an acceleration of the vehicle. The steps 220 and 230 may therefore be performed in any order or simultaneously.
At step 240, the control system 110 is arranged to determine, based on the surface signal, an electric machine braking torque threshold. The electric machine braking torque threshold may be based on an expected level of traction between the vehicle tyres and the surface on which the vehicle is travelling, such as a road surface. The electric machine providing a high braking torque may increase the prospect of the wheels losing traction with the surface on which the vehicle is braking, with the possible consequence of over rotation of the wheels, which may reduce vehicle stability. It is therefore desirable to avoid an excessively high electric machine braking torque when considering the surface to which the braking torque is being applied.
The electric machine braking torque threshold may also be referred to as an electric machine braking torque limit, since, under normal conditions, the electric machine should not be requested to produce a braking torque above the electric machine braking torque threshold.
Step 240 may be performed at any time after step 220 and may be performed before, after or simultaneously with step 230.
At step 250, the control system 110 is arranged to determine whether the required vehicle braking torque is greater than the electric machine braking torque threshold. A purpose of the determination is to avoid the electric machine being requested to provide a braking torque greater than the electric machine braking torque threshold. In this way, the stability of the vehicle may be improved and the prospect of over rotation of the wheels is reduced. If the required vehicle braking torque is greater that the electric machine braking torque threshold, the method 200 moves to step 260.
At step 260, a foundation braking torque, which may also be referred to as a friction braking torque, is applied to the wheels in order to provide a deceleration. In this case an electric machine braking torque may still be applied to the wheels, at a level at or below the electric machine braking torque threshold. Together the foundation braking torque and the electric machine braking torque may sum to the required braking torque, such that the vehicle decelerates as required according to the deceleration request received at step 210.
Alternatively, if it is found at step 250 that the required braking torque is below the electric machine braking torque threshold then the method may move to step 270, and the entirety of the required braking torque may be provided by the electric machine. In this case, there may be no foundation braking torque used to decelerate the vehicle and the vehicle may be decelerated using the electric machine exclusively. The electric machine braking torque may be set to be equal to the required braking torque.
In some cases, it may be sufficient to provide braking torque using both of the electric machine and the foundation brakes. However, in other cases a further determination as to the braking torque provided by the foundation brakes and the electric machine may be made.
Figure 5 is a flowchart illustrating such a method 265. The method 265 of Figure 5 may take place at the end of method 200 of Figure 4, at the step indicated at 260. The methods 200, 265 shown in the respective flowcharts may therefore be combined.
The control system 110 may also receive or determine a foundation brake torque threshold at step 310. The foundation brake torque threshold may be the maximum brake torque that the foundation brakes should exert.
The foundation brake torque threshold may be determined by the size of the foundation brakes and/or the heat dissipation of the foundation brakes.
The control system 110 may determine a required foundation brake torque at step 320. The required foundation brake torque may be determined based on a difference between the electric machine brake torque threshold and the required brake torque.
The required foundation brake torque may then be compared to the foundation brake torque threshold at step 330. If the required foundation brake torque is less than the foundation brake torque threshold, then the control system 110 may output brake signals to the electric machine and the foundation brakes to exert the required respective brake torques at step 340.
However, if the required foundation brake torque exceeds the foundation brake torque threshold, then the control system 110 may carry out steps 350, 360 and 370. Steps 350, 360 and 370 may be carried out in any order or simultaneously. At step 360, the electric machine braking torque threshold may be recalculated and/or may be increased to provide a recalculated electric machine braking torque threshold. The recalculation may involve using a less conservative estimate of the traction with the road surface.
The foundation brake torque may be set to be equal to the foundation brake torque threshold at step 350.
At step 370, the required electric machine braking torque may be recalculated based on the required vehicle braking torque and the updated foundation brake torque (i.e., the foundation brake torque threshold) to determine a further required electric machine braking torque. The further required electric machine braking torque is an updated value for the required electric machine braking torque, At step 380, the further required electric machine braking torque may be compared to the recalculated electric machine braking torque threshold. If the further required electric machine braking torque is less than the recalculated electric machine braking torque threshold, then the control system 110 may output a braking signal at step 390 to cause the electric machine and the foundation brakes to output the required respective braking torques.
Alternatively, if the further required electric machine braking torque is greater than the recalculated electric machine braking torque threshold, the further required electric machine braking torque may be set to be equal to the recalculated electric machine braking torque threshold at step 410 and the required vehicle braking torque may be reduced at step 420. At step 430, the control system 110 may output a braking signal to cause the electric machine and the foundation brakes to output the required respective braking torques.
In an alternative control method, the foundation brake torque threshold and the electric machine braking torque threshold may be recalculated alternatingly and the foundation brake torque and required electric machine braking torque may be set to the recalculated maximum foundation brake torque and the recalculated electric machine braking torque threshold respectively in order to increase each so as to share the required vehicle braking torque between the electric machine and the foundation brakes.
It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims (15)

  1. CLAIMS1. A control system for controlling a powertrain and a foundation brake of a vehicle, the powertrain comprising an electric machine and a drivetrain, the electric machine being arranged to apply a torque to the drivetrain, the control system comprising one or more processors collectively configured to: receive a deceleration request signal comprising information indicative of a requested deceleration of the vehicle; receive a surface signal, the surface signal comprising information indicative of a condition of a surface on which the vehicle is located; determine a required vehicle braking torque based at least partially on the requested deceleration of the vehicle; determine, in dependence on the information indictive of the condition of the surface, an electric machine braking torque threshold; determine whether the required vehicle braking torque is greater than the electric machine braking torque threshold; and output, in dependence on a determination that the required vehicle braking torque is greater than the electric machine braking torque threshold, a foundation brake signal to cause the foundation brakes to generate a foundation brake torque.
  2. 2. The control system of claim 1, wherein the one or more processors are collectively configured to output an electric machine torque signal to cause the electric machine to generate a required electric machine braking torque.
  3. 3. The control system of claim 2, wherein the one or more processors are collectively configured to, in dependence on the determination that the required vehicle braking torque is greater than the electric machine braking torque threshold, output the electric machine torque signal to cause the electric machine to generate the required electric machine braking torque, the required electric machine braking torque being equal to the electric machine braking torque threshold.
  4. 4. The control system of claim 2 or 3, wherein the one or more processors are collectively configured to: determine a required foundation braking torque in dependence on a difference between the required electric machine braking torque or the electric machine braking torque threshold and the required vehicle braking torque; and output the foundation brake signal in dependence on the required foundation braking torque.
  5. 5. The control system of claim 4, wherein the one or more processors are collectively configured to, in dependence on the determination that the required vehicle braking torque is greater than the electric machine braking torque threshold: determine the required foundation braking torque in dependence on the difference between the required electric machine braking torque or the electric machine braking torque threshold and the required vehicle braking torque; determine a foundation braking torque threshold; determine whether the required foundation braking torque is greater than the foundation braking torque threshold; and output, in dependence on a determination that the required foundation braking torque is not greater than the foundation braking torque threshold, the electric machine torque signal to cause the electric machine to generate the required electric machine braking torque.
  6. 6. The control system of claim 5, wherein the one or more processors are collectively configured to, in dependence on a determination that the required foundation braking torque is greater than the foundation braking torque threshold, set the required foundation braking torque to be equal to the foundation braking torque threshold.
  7. 7. The control system of claim 5 or 6, wherein the one or more processors are collectively configured to, in dependence on a determination that the required foundation braking torque is greater than the foundation braking torque threshold: determine a further electric machine braking torque in dependence on a difference between the required vehicle braking torque and the foundation braking torque threshold.
  8. 8. The control system of claim 7 when dependent on claim 6, wherein the one or more processors are collectively configured to, in dependence on a determination that the required foundation braking torque is greater than the foundation braking torque threshold: determine a further electric machine braking torque threshold; determine whether the further electric machine braking torque is greater than the further electric machine braking torque threshold; and in dependence on a determination that the further electric machine braking torque is greater than the further electric machine braking torque threshold: set the required electric machine braking torque to be equal to the further electric machine braking torque threshold; and reduce the required vehicle braking torque to equal the sum of the further electric machine braking torque and the foundation braking torque.
  9. 9. The control system of any preceding claim, wherein the one or more processors are collectively configured to receive the deceleration request signal from an accelerator pedal.
  10. 10. The control system of any preceding claim, wherein the surface signal comprises information indicative of at least one of: a terrain on which the vehicle is located, and wherein the one or more processors are configured to determine the electric machine braking torque threshold based at least partially on the terrain on which the vehicle is located; wheel slip of the vehicle, and wherein the one or more processors are configured to determine the electric machine braking torque threshold based at least partially on the wheel slip; an anti-lock brake system being activated, and wherein the one or more processors are configured to: determine the electric machine braking torque threshold based at least partially on the activation of the anti-lock braking system.
  11. 11. The control system of any preceding claim, wherein the one or more processors are collectively configured to: receive a vehicle mass signal comprising information indicative of the mass of the vehicle; and determine the electric machine braking torque threshold based at least partially on the information indicative of the mass of the vehicle.
  12. 12. The control system of any preceding claim, wherein the surface signal comprises information indicative of the gradient of the surface on which the vehicle is located; and wherein the one or more processors are collectively configured to: determine the electric machine braking torque threshold based at least partially on the information indicative of the gradient of the surface on which the vehicle is located.
  13. 13. A vehicle comprising: a powertrain, the powertrain comprising an electric machine and a drivetrain arranged to receive torque from the electric machine; a foundation brake; and the control system of any preceding claim.
  14. 14. A method for controlling a powertrain and a foundation brake of a vehicle, the powertrain comprising an electric machine and a drivetrain, the electric machine being arranged to apply a torque to the drivetrain, the method comprising: receiving a deceleration request signal comprising information indicative of a requested deceleration of the vehicle; receiving a surface signal, the surface signal comprising information indicative of a condition of a surface on which the vehicle is located; determining a required vehicle braking torque based at least partially on the requested deceleration of the vehicle; determining, in dependence on the information indicative of the condition of the surface, an electric machine braking torque threshold; determining whether the required vehicle braking torque is greater than the electric machine braking torque threshold; and outputting, in dependence on a determination that the required vehicle braking torque is greater than the electric machine braking torque threshold, a foundation brake signal to cause the foundation brakes to generate a foundation brake torque.
  15. 15. Computer readable instructions which, when executed by a computer, are arranged to perform a method according to claim 14.
GB2314470.2A 2023-09-21 2023-09-21 Control system for controlling a powertrain and a foundation brake of a vehicle Pending GB2633794A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB2314470.2A GB2633794A (en) 2023-09-21 2023-09-21 Control system for controlling a powertrain and a foundation brake of a vehicle
PCT/EP2024/076493 WO2025061984A1 (en) 2023-09-21 2024-09-20 Control system for controlling a powertrain and a foundation brake of a vehicle

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2314470.2A GB2633794A (en) 2023-09-21 2023-09-21 Control system for controlling a powertrain and a foundation brake of a vehicle

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GB2633794A true GB2633794A (en) 2025-03-26

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US20030168266A1 (en) * 2002-03-06 2003-09-11 Nissan Motor Co., Ltd. Brake control apparatus
US20090222156A1 (en) * 2008-02-29 2009-09-03 Gm Global Technology Operations, Inc. Methods, program products, and systems for controlling braking in a hybrid vehicle
US20160167519A1 (en) * 2014-12-10 2016-06-16 Gogoro Inc. Systems and methods of adaptive regenerative braking and collision avoidance for electrically powered vehicles
EP3173283A1 (en) * 2014-07-23 2017-05-31 Hitachi Construction Machinery Co., Ltd. Braking distance suppression device
GB2559376A (en) * 2017-02-03 2018-08-08 Bentley Motors Ltd Regenerative braking system

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JP4134706B2 (en) * 2002-12-10 2008-08-20 日産自動車株式会社 Braking device for vehicle
JP2007030631A (en) * 2005-07-25 2007-02-08 Advics:Kk Brake control device for vehicle
US8645040B2 (en) * 2010-05-06 2014-02-04 GM Global Technology Operations LLC Method for operating a vehicle brake system
US11498429B2 (en) * 2020-09-28 2022-11-15 Ford Global Technologies, Llc Aggregating braking torque during one-pedal drive mode

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Publication number Priority date Publication date Assignee Title
US20030168266A1 (en) * 2002-03-06 2003-09-11 Nissan Motor Co., Ltd. Brake control apparatus
US20090222156A1 (en) * 2008-02-29 2009-09-03 Gm Global Technology Operations, Inc. Methods, program products, and systems for controlling braking in a hybrid vehicle
EP3173283A1 (en) * 2014-07-23 2017-05-31 Hitachi Construction Machinery Co., Ltd. Braking distance suppression device
US20160167519A1 (en) * 2014-12-10 2016-06-16 Gogoro Inc. Systems and methods of adaptive regenerative braking and collision avoidance for electrically powered vehicles
GB2559376A (en) * 2017-02-03 2018-08-08 Bentley Motors Ltd Regenerative braking system

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WO2025061984A1 (en) 2025-03-27

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