GB2580392A

GB2580392A - Vehicle stability controller

Info

Publication number: GB2580392A
Application number: GB1900285.6A
Authority: GB
Inventors: Adrian Beever Paul
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2019-01-09
Filing date: 2019-01-09
Publication date: 2020-07-22
Anticipated expiration: 2039-01-09
Also published as: GB201900285D0; GB2580392B

Abstract

A controller for controlling vehicle stability, the controller having first and second drive modes and including a processor for switching between the drive modes, the processor being configured to: receive 610 steering angle, vehicle speed, yaw rate, vehicle direction, and brake input signals; determine 615, 620, 625 whether the steering angle, vehicle speed, and yaw rate signals exceed a predetermined threshold; determine 630 whether the direction of travel of the vehicle is backward, based on the vehicle direction signal or reverse gear being engaged; and switch the controller from the first drive mode to the second drive mode if the vehicle speed, steering angle, and yaw rate signals exceed their respective predetermined thresholds and the direction of travel of the vehicle is backward; and apply 640 a braking force at a front axle of the vehicle so as to substantially lock front wheels of the vehicle. This can provide the advantage that the vehicle may perform a j-turn. Also provided is a method of controlling vehicle stability.

Description

VEHICLE STABILITY CONTROLLER

TECHNICAL FIELD

The present disclosure relates to controlling vehicle stability during particular manoeuvres, and particularly, but not exclusively, to controlling vehicle stability whilst performing j-turns. Aspects of the invention relate to a method for controlling vehicle stability, a controller for controlling vehicle stability, a system including a controller for controlling vehicle stability, and to a vehicle including a system or controller for controlling vehicle stability.

BACKGROUND

Modern vehicles come fitted with various stability control systems (SCS') such as traction control ('TC') and anti-lock braking (ABS') systems. It is often possible for a vehicle user to partially or fully disable these systems, often through the selection of a "sport", "dynamic" or "race" setting, or through switching off the SCS in full.

It is therefore possible for a stability control system to be operating in a driver-selected mode which deliberately does not provide the highest-available possible stability by reducing or removing some or all of the restrictions that normal stability control may include. These driver-selected modes are typically selected using a stability control "off" switch or other control and typically causes the "stability control off" warning to be shown in the instrument pack/display.

In such driver-selected modes, it may be desired to perform particular manoeuvres in the vehicle, which would not usually be possible when in a non-driver-selected stability mode.

Such manoeuvres may include reverse j-turns. This function may also be desired to be active without the need for selecting a special mode since this function is actually a safety enhancement compared to previous technology.

Accordingly, it is an aim of the present invention to address this problem with the use of a controller which is adapted to recognise a demand for such manoeuvres, and to allow the driver of the vehicle to perform these manoeuvres without the stability control system preventing, or hindering, the manoeuvre.

SUMMARY OF THE INVENTION

Aspects and embodiments set out below provide a controller, a system, and a method for controlling vehicle stability, and a vehicle as claimed in the appended claims.

According to an aspect of the invention, there is provided a controller for controlling vehicle stability, the controller having first and second drive modes and including a processor for switching the controller between the drive modes, the processor being configured to receive a steering angle signal, a vehicle speed signal, a yaw rate sensor signal, a vehicle direction signal, and a brake input signal, determine whether the steering angle, vehicle speed, and yaw rate signals exceed a predetermined threshold, determine whether the direction of travel of the vehicle is backward, based on the vehicle direction signal, and switch the controller from the first drive mode to the second drive mode if the vehicle speed, steering angle and yaw rate signals exceed their respective predetermined thresholds and the direction of travel of the vehicle is backward, and apply a braking force at a front axle of the vehicle so as to substantially lock the front wheels of the vehicle.

This provides the advantage that the vehicle may perform a reverse j-turn more easily and successfully, without modification to the vehicle. It may enable a driver to rapidly move away from a threat and then drive forwards at speed. For this reason, this manoeuvre is also known as the terrorist escape manoeuvre.

Optionally in an embodiment of the invention, the controller is further configured to receive a wheel rotation speed and direction signal, and if the wheel rotation and direction signal is indicative that a rear roadwheel of the vehicle is accelerating in a forward direction, the braking force at the front axle of the vehicle is released and a forward gear in the transmission of the vehicle is engaged.

This provides the advantage that the controller may switch the transmission of the vehicle into a forward gear, without the intervention of the driver. This may make the manoeuvre easier and faster for the driver.

Optionally in an embodiment of the invention, the controller may be further configured to receive a signal from a sensor that the steering input is substantially straight ahead, and if the steering input is substantially straight ahead, the braking force on the front axle of the vehicle is released and a forward gear in the transmission of the vehicle is engaged.

Optionally in an embodiment of the invention, the drive angle sensor measures a yaw angle, body side slip angle, and/or a tyre side slip angle.

Optionally in an embodiment of the invention, if the vehicle direction is not backward, the braking force is not applied such that the wheels of the vehicle do not lock.

This provides the advantage that if the vehicle direction is not correct for the manoeuvre, the manoeuvre is not triggered.

Optionally in an embodiment of the invention, if the or each of the predetermined thresholds for vehicle speed, steering angle and yaw rate are not met, the braking force is applied at both axles of the vehicle such that the wheels of the vehicle do not lock.

Optionally in an embodiment of the invention if it is determined that the vehicle is travelling in a backwards direction and the park brake is applied, the front axles of the vehicle are locked.

Optionally in an embodiment of the invention the predetermined threshold for the steering angle sensor is a steering angle of at least 90 degrees.

This provides the advantage that the manoeuvre may not be triggered if a steering angle input is not sufficient, and therefore if the driver does not intend to trigger the manoeuvre.

Optionally in an embodiment of the invention the change in steering angle occurs in 0.5 seconds or less.

This also provides the advantage that the manoeuvre may not be triggered if a steering input is not sufficient, and therefore if the driver does not intend to trigger the manoeuvre.

Optionall in an embodiment of the invention y, the predetermined threshold for the steering angle sensor is a steering rate of greater than 180 degrees/sec.

Optionally in an embodiment of the invention, at least one of the steering angle sensor, vehicle speed sensor, and vehicle direction sensor comprises at least one of: an accelerometer, a gyroscope, a voltage sensor, an engine speed sensor, and a six-degree-of-freedom Inertial Measurement Unit.

This provides the advantage that the controller may be able to make an accurate estimation of the state of the vehicle.

Optionally in an embodiment of the invention, the braking force applied to the front axle of the vehicle is released when at least one of the following conditions are satisfied: a) the driver returns the steering input to substantially straight ahead; b) it is determined that the vehicle has completed substantially 180 degrees of rotation; and c) it is determined that the rear wheels are rotating in a forwards direction above a predetermined threshold of speed or accelerationr This steering input will usually reduce or reverse the steering direction, at least becoming a value somewhere near straight ahead (unless the vehicle has rotated through more than 180 degrees.) Optionally in an embodiment of the invention, the front axle brake may be released when it is detected that the driver has completed a steering input appropriate to completing this manoeuvre. This steering input will usually reduce or reverse the steering direction, at least becoming a value somewhere near straight ahead (unless the vehicle has rotated through more than 180 degrees.) Optionally in an embodiment of the invention, the second drive mode is configured to disable driver aids.

Optionally in an embodiment of the invention, the second drive mode is configured to disable a traction control system.

Optionally in an embodiment of the invention, the second drive mode is configured to disable an electronic stability programme.

Optionally in an embodiment of the invention, the front brakes may also be released based on having calculated that the vehicle has already rotated by sufficient angle to complete the manoeuvre and drive off forwards.

A further aspect of the invention provides a system including the controller of any preceding aspect.

A yet further aspect of the invention provides a vehicle including a controller or a system as described above.

An additional aspect of the invention provides a method of controlling vehicle stability, the method including: receiving a steering angle signal, a vehicle speed signal, a yaw rate signal, a vehicle direction signal, and a brake input signal; determining whether the steering angle, vehicle speed, and angle sensor signals exceed a predetermined threshold; determining whether the direction of travel of the vehicle is backward, based on the vehicle direction signal, and switching from the first drive mode to the second drive mode if the vehicle speed, steering angle, and yaw rate signals exceed their respective predetermined thresholds and the direction of travel of the vehicle is backward; and applying a braking force at the front axle of a vehicle so as to substantially lock front wheels of the vehicle, and the second drive mode is enabled.

No brake input is required from the driver. The braking of the front axle is provided to achieve two advantages: namely to increase the yaw rate of the vehicle so that it completes the turn is less time and to reduce the side forces on the vehicle.

This provides the advantage that the vehicle may perform a reverse j-turn, without modification to the vehicle. This may provide enjoyment for a driver. Or if the driver is in a hazardous situation, allows the driver to escape more quickly.

Optionally in an embodiment of the invention, the method further includes receiving a rear wheel rotation speed and direction signal and releasing the braking force at the front axle of the vehicle and engage a forward gear in the transmission of the vehicle, if the wheel rotation and direction signal is indicative that a rear roadwheel of the vehicle is accelerating in a forward direction.

This provides the advantage that the controller may switch the transmission of the vehicle into a forward gear, without the intervention of the driver. This may make the manoeuvre easier for the driver.

Optionally in an embodiment of the invention, the predetermined threshold for the steering angle sensor is a steering angle of between 80 to 100 degrees.

Optionally in an embodiment of the invention, the change in steering angle occurs in 0.5 seconds or less.

Optionally in an embodiment of the invention, the predetermined threshold for the steering angle sensor is a steering rate between 170 and 190 degrees/sec.

Optionally in an embodiment of the invention, the method further includes receiving a wheel rotation speed and direction signal from the rear wheels and releasing the braking force at the front axle of the vehicle and engage a forward gear in the transmission of the vehicle, if the wheel rotation and direction signal is indicative that a rear roadwheel of the vehicle is accelerating in a forward direction. Alternately, the front wheel braking may also be released based on a calculation that the vehicle will have rotated through 180 degrees or if the driver moves the steering wheel back to substantially straight ahead.

Optionally in an embodiment of the invention, if the or each of the predetermined thresholds for vehicle speed, steering angle and yaw angle sensor signal are not met, the braking force is applied at both axles of the vehicle such that the wheels of the vehicle do not lock.

Optionally in an embodiment of the invention, if the vehicle direction is not backward, the braking force is not applied.

As an alternative the front axle braking may be dependent on a driver input via the park brake switch, wherein, on the situation recognition similar to the hand brake turn logic, the application of the park brake switch by the driver may be interpreted as a demand to lock the front wheels instead of the rear wheels.

Optionally in an embodiment of the invention, the predetermined threshold for the steering angle sensor is a steering angle of at least 90 degrees.

This provides the advantage that the manoeuvre may not be triggered if a steering input is not sufficient, and therefore if the driver does not intend to trigger the manoeuvre.

Optionally in an embodiment of the invention, the predetermined threshold for the steering angle sensor is a steering rate of greater than 180 degrees/sec.

Another additional aspect of the invention provides a controller configured to carry out such a method.

Another aspect of the invention provides a vehicle including a controller configured to carry out such a method.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

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 an example vehicle in which the described embodiments can be 35 implemented; Figure 2 shows a simplified diagram of some of the vehicle systems of the example vehicle of Figure 1; Figure 3 shows a more detailed block diagram of some of the control systems of the example vehicle of Figure 1; Figure 4 shows a flow diagram of an exemplary method for enabling a vehicle to carry out a burnout; Figure 5 shows a flow diagram of an exemplary method for enabling a vehicle to carry out a handbrake turn; and Figure 6 shows a flow diagram of an exemplary method for enabling a vehicle to carry out a reverse j-turn.

DETAILED DESCRIPTION

A method of controlling vehicle stability in accordance with an embodiment is described herein with reference to the accompanying Figures.

Modern vehicles equipped with advanced stability control systems and electronic parking brakes do not, in general, enable drivers to carry out more advanced driving manoeuvres, nor those which require a manually-operable handbrake to achieve. Such manoeuvres may include a 'burnout' (spinning the rear wheels), a handbrake turn, or a 'reverse j-turn' or 'reverse flick' (also known as an escape manoeuvre).

In the case of a burnout, it is necessary to allow the wheels at the rear axle of the vehicle to spin whilst braking the wheels at the front axle of the vehicle to either reduce the acceleration of the vehicle, slow the vehicle down or hold it stationary. This type of manoeuvre may be used to heat the rear tyres of the vehicle to improve traction in a subsequent "drag racing" start, or may be used for entertainment purposes, which may include generation of smoke from the spinning tyres.

Under normal operation, when a driver presses the brake pedal of a vehicle, the brakes are applied to both the front and rear axles of the vehicle, simultaneously. When attempting to perform a burnout manoeuvre, this is unhelpful, because a burnout is more effective if the rear brake pressure can be released. In addition to the brakes being applied to both the front and rear axle, in vehicles which are four-wheel drive, power is suppled to both the front and rear axles of the vehicle when the accelerator is applied. This can also hinder an attempt to spin only the wheels at the rear axle of the vehicle.

In the case of a handbrake turn, vehicles with electronic parking brakes ('EPBs') are not, in general, capable of executing a hand brake turn. Such a manoeuvre may be carried out very easily in a vehicle which is equipped with a mechanical hand brake. In general, in a vehicle equipped with an EPB, if the EPB is applied when the vehicle is in motion, the vehicle's hydraulic brakes are applied, with ABS control, to slow the vehicle in relative safety. This may prevent the driver of the vehicle from carrying out a handbrake turn, as the EPB will not lock the wheels at the rear axle of the vehicle if it is applied whilst the vehicle is in motion.

In a vehicle equipped with a stability control system, if a user attempts to carry out a handbrake turn manoeuvre, the stability control system may intervene in an attempt to reduce the yaw motion of the vehicle, thus reducing the effectiveness of the hand brake turn.

When a vehicle is in reverse it is more difficult to control and often incapable of reaching higher speeds. Because of this, drivers may make use of a 'reverse j-turn' or 'reverse flick' (also known as an escape manoeuvre). This type of turn is achieved by transferring the momentum of the car by reversing relatively quickly, in a straight line, and then turning the wheel sharply, with the vehicle rotating such that the front of the vehicle swings around, and the driver changes into a forward gear as the front of the vehicle comes about. It can be advantageous if braking is applied to the front wheels only.

This manoeuvre is relatively complex to execute, and if it is executed improperly, the manoeuvre may result in issues which may include: a) the vehicle may not be swinging around at a high enough rate for the direction of travel of the vehicle to be reversed; b) if the vehicle has a high centre of gravity, the vehicle may roll over; and c) the driver workload is made more complex by the requirement to control the gearshift to match the direction of vehicle travel.

Additionally, in vehicles equipped with stability control systems, such systems may intervene in an attempt to reduce the yaw motion of the vehicle, or the locking of the front wheels, thus reducing the effectiveness of the manoeuvre.

Figure 1 shows an example vehicle 100 according to an embodiment in which can be implemented one or more of the above described aspects.

In this embodiment, the vehicle 100 includes a control system and/or controller(s) configured to carry out a method of controlling vehicle stability. The vehicle 100 also include sensors configured to provide data to the controller. The vehicle 100 is provided with standard vehicle elements, such as wheels, a chassis, and a cabin body and interior.

Figure 2 shows a simplified diagram of some of the relevant vehicle systems of the vehicle 100, 200 of Figure 1 and it will be noted that these vehicle systems are typically present in most vehicles.

Specifically, Figure 2 shows a vehicle 200 having four wheels 202, 204, 206, 208 coupled to a chassis 210 via axles. Other vehicle components will typically be provided in addition of those described below, including: a propulsion means (for example, an internal combustion engine (ICE) or one or more electric motors or an engine powered by an alternative fuel such as a hydrogen-based fuel, or a hybrid arrangement of two or more of these); and a cabin.

To enable dynamic control, the vehicle 200 is typically provided with various sensors such as a yaw rate sensor, a steering wheel angle sensor, a lateral acceleration sensor, a longitudinal acceleration sensor and a roll rate sensor 220. These sensors are used to detect how much the vehicle is turning (rotating) or rolling, how much steering is being provided by the driver through the steering wheel, how much the car is accelerating. Further, wheel speed sensors 202', 204', 206', 208' are typically provided at each wheel 202, 204, 206, 208.

To provide dynamic control, a control system is provided where various options are possible for implementation of the control system including typically either providing a single computing device or processor 220' that acts as a master controller of the dynamics of the vehicle; or providing a distributed arrangement across multiple devices and/or processors that provides control of the dynamics of the vehicle. The computing device or processor 220' typically maintains a vehicle model and uses the received sensor data as inputs to the vehicle model to estimate or determine vehicle behaviour based on the vehicle model outputs. The computing device or processor 220' receives data from the wheel speed sensors 202', 204', 206', 208' and the other available sensors, typically any of the yaw rate sensor, steering wheel angle sensor, lateral acceleration sensor, longitudinal acceleration sensor and roll rate sensor 220'. Using the vehicle model, several estimations can be made as to vehicle behaviour based on the received sensor data. For example, the computing device or processor 220' can detect the speed of rotation of each wheel from the sensor data and determine any difference in wheel speed between the wheels 202, 204, 206, 208. The computing device or processor 220' can also detect any difference between the intended level of steering input by a driver using data from the steering wheel angle sensor 220 and how much the vehicle is actually turning from the sensor data from the yaw rate sensor 220. The computing device or processor 220' can also determine any relative values below or above predetermined thresholds between for example the lateral or longitudinal acceleration and the wheel speeds from the lateral acceleration sensor 220, longitudinal acceleration sensor 220 and the wheel speed sensors 202, 204', 206, 208'. The roll rate sensor 220 can be used by the computing device or processor 220' to improve the fidelity of its vehicle model and correct for errors when estimating vehicle behaviour from the other sensors alone.

From the estimated vehicle behaviour, including the examples described above, the computing device or processor then can provide corrective intervention and/or control. The computing device or processor 220 can operate various actuators such as the brakes on individual wheels 202, 204, 206, 208, the powertrain or the drivetrain. By actuating or controlling operation of one or more brakes, the speed of the wheels, or the amount the vehicle is turning can be adjusted by the amount determined necessary by the computing device or processor 220. By actuating or controlling operation of the power train, an increased amount of drive torque can be provided by an amount determined necessary by the computing device or processor 220. By actuating or controlling operation of the drive train, how drive torque is applied and/or distributed to the wheels 202, 204, 206, 208 by an amount determined necessary by the computing device or processor 220. A combination of these actuations/operations can be employed by the computing device or processor 220 as necessary.

It should be noted that various alternatives are possible in the embodiment described in relation to Figure 2. For example, rather than providing all of the control of the vehicle dynamics using a single computing device or processor to provide "master" control of the vehicle dynamics, the computing can be distributed around the vehicle for example using "smart" actuators. Another example is that the computing device or processor 220 can be provided in different forms and still provide the functionality described.

Figure 3 shows a more detailed implementation of the simplified embodiment described in relation to Figure 2, as per a further embodiment.

Figure 3 shows a vehicle 100 according to an embodiment of the present invention. The vehicle 100 has a powertrain 129 that includes an engine 121 that is connected to a driveline having an automatic transmission 124, and an accelerator pedal 161. A control system for the vehicle 100 includes a central controller 10, referred to as a vehicle control unit (VCU) 10, a powertrain controller 11, a brake controller 13 and a steering controller 1700 in communication with a steering wheel 171. It is to be understood that embodiments of the present invention are also suitable for use in vehicles with manual transmissions, continuously variable transmissions or any other suitable transmission. Moreover, embodiments of the invention are suitable for use in vehicles having other types of powertrain, such as battery electric vehicles, fuel cell powered vehicles, and hybrids.

In the embodiment of Figure 3, the transmission 124 may be set to one of a plurality of transmission operating modes, being a park mode P, a reverse mode R, a neutral mode N, a drive mode D or a sport mode S, by means of a transmission mode selector dial 124S. The selector dial 124S provides an output signal to the powertrain controller 11 in response to which the powertrain controller 11 causes the transmission 124 to operate in accordance with the selected transmission mode. Accordingly, in this embodiment a transmission controller (not shown) is incorporated into the powertrain controller 11. However, in other embodiments the transmission controller may be a separate element in operable communication with the central controller 10.

The brake controller 13 is an anti-lock braking system (ABS) controller 13 and forms part of a braking system 22 (FIG. 9), together with a brake pedal 163. The VCU 10 receives and outputs a plurality of signals to and from various sensors and subsystems (not shown) provided on the vehicle. The VCU 10 includes a low-speed progress ([SF) control system 12 shown in FIG. 9, a stability control system (SOS) 14S, a traction control system (TCS) 14T, a cruise control system 16 and a Hill Descent Control (HDC) system 12HD. The SOS 14S improves various levels of desired stability of the vehicle 100 by detecting and managing loss of traction when cornering. When a reduction in steering control is detected, the SOS 14S is configured automatically to command the brake controller 13 to apply one or more brakes 111B, 112B, 114B, 115B of the vehicle 100 to help to steer the vehicle 100 in the direction the user wishes to travel. If excessive wheel spin is detected, the TCS 14S is configured to reduce wheel spin by application of brake force in combination with a reduction in powertrain drive torque. In the embodiment shown the SOS 14S and TCS 14T are implemented by the VCU 10. In some alternative embodiments the SOS 14S and/or TCS 14T may be implemented by the brake controller 13. Further alternatively, the SOS 14S and/or TCS 14T may be implemented by one or more further controllers.

The driveline 130 is arranged to drive a pair of front vehicle wheels 111,112 by means of a front differential 137 and a pair of front drive shafts 118. The driveline 130 also comprises an auxiliary driveline portion 131 arranged to drive a pair of rear wheels 114, 115 by means of an auxiliary driveshaft or prop-shaft 132, a rear differential 135 and a pair of rear driveshafts 139. The front wheels 111, 112 in combination with the front drive shafts 118 and front differential 137 may be referred to as a front axle 136F. The rear wheels 114, 115 in combination with rear drive shafts 139 and rear differential 135 may be referred to as a rear axle 136R.

The wheels 111, 112, 114, 115 each have a respective brake 111B, 112B, 114B, 115B. Respective speed sensors 111S, 1125, 1145, 1155 are associated with each wheel 111, 112, 114, 115 of the vehicle 100. The sensors 111S, 1128, 114S, 115S are mounted to the vehicle 100 and arranged to measure a speed of the corresponding wheel.

Embodiments of the invention are suitable for use with vehicles in which the transmission is arranged to drive only a pair of front wheels or only a pair of rear wheels (i.e. front wheel drive vehicles or rear wheel drive vehicles) or selectable two-wheel drive/four-wheel drive vehicles. In the embodiment of FIG. 8, the transmission 124 is releasably connectable to the auxiliary driveline portion 131 by means of a power transfer unit (PTU) 131P, allowing operation in a two-wheel drive mode or a four-wheel drive mode. It is to be understood that embodiments of the invention may be suitable for vehicles having more than four wheels or where only two wheels are driven, for example two wheels of a three-wheeled vehicle or four-wheeled vehicle or a vehicle with more than four wheels.

One or more of the controllers 10, 11, 13, 1700 may be implemented in software run on a respective one or more computing devices such as one or more electronic control units (ECUs). In some embodiments two or more of the controllers 10, 11, 13, 1700 may be implemented in software run on one or more common computing devices. Two or more controllers 10, 11, 13, 1700 may be implemented in software in the form of a combined software module.

It is to be understood that one or more computing devices may be configured to permit a plurality of software modules to be run on the same computing device without interference between the modules. For example, the computing devices may be configured to allow the modules to run such that if execution of software code embodying a first controller terminates erroneously, or the computing device enters an unintended endless loop in respect of one of the modules, it does not affect execution of software code comprised by a software module embodying a second controller.

It is to be understood that one or more of the controllers 10, 11, 13, 1700 may be configured to have substantially no single point failure modes, i.e. one or more of the controllers may have dual or multiple redundancy. It is to be understood that robust partitioning technologies are known for enabling redundancy to be introduced, such as technologies enabling isolation of software modules being executed on a common computing device. It is to be understood that the common computing device will typically comprise at least one microprocessor, optionally a plurality of processors, which may operate in parallel with one another. In some embodiments a monitor may be provided, the monitor being optionally implemented in software code and configured to raise an alert in the event a software module is determined to have malfunctioned.

The SCS 145, ICS 14T, ABS controller 22C and HDC system 12HD provide outputs indicative of, for example, SCS activity, TCS activity and ABS activity including brake interventions on individual wheels and engine torque requests from the VCU 10 to the engine 121, for example in the event a wheel slip event occurs. Each of the aforementioned events indicate that a wheel slip event has occurred. Other vehicle sub-systems such as a roll stability control system or the like may also be present.

It is to be understood that the VCU 10 is configured to implement a Terrain Response (TR) (RIM) System of the kind described above in which the VCU 10 controls settings of one or more vehicle systems or sub-systems such as the powertrain controller 11 in dependence on a selected driving mode. The driving mode may be selected by a user by means of a driving mode selector 141S (FIG. 8). The driving modes may also be referred to as terrain modes, terrain response modes, or control modes. In the embodiment of FIG. 8, four driving modes are provided: an 'on-highway' driving mode or 'special programs off' (SPO) mode suitable for driving on a relatively hard, smooth driving surface where a relatively high surface coefficient of friction exists between the driving surface and wheels of the vehicle; a 'sand' driving mode (SAND) suitable for driving over sandy terrain; a 'grass, gravel or snow' (GGS) driving mode suitable for driving over grass, gravel or snow, a 'rock crawl' (RC) driving mode suitable for driving slowly over a rocky surface; and a 'mud and ruts' (MR) driving mode suitable for driving in muddy, rutted terrain. Other driving modes may be provided in addition or instead.

The sensors on the vehicle 100 include sensors which provide continuous sensor outputs to the VCU 10, including wheel speed sensors 111S, 112S, 114S, 1155. as mentioned previously and as shown in FIG. 8, and other sensors (not shown) such as an ambient temperature sensor, an atmospheric pressure sensor, tyre pressure sensors, wheel articulation sensors, gyroscopic sensors to detect vehicular yaw, roll and pitch angle and rate, a vehicle speed sensor, a longitudinal acceleration sensor, an engine torque sensor (or engine torque estimator), a steering angle sensor, a steering wheel speed sensor, a gradient sensor (or gradient estimator), a lateral acceleration sensor which may be part of the SOS 145, a brake pedal position sensor, a brake pressure sensor, an accelerator pedal position sensor, longitudinal, lateral and vertical motion sensors, an inertial measurement unit (IMU) 220", and water detection sensors forming part of a vehicle wading assistance system (not shown). In other embodiments, only a selection of the aforementioned sensors may be used. Other sensors may be useful in addition or instead in some embodiments.

With reference to Figure 4, there is illustrated a method 400 for enabling a stability control system to recognise a demand for the vehicle 100, 200 to carry out a burnout.

When starting 410 of the method of Figure 4, a step 420 is performed to establish whether vehicle 100, 200 is in a driver-selected mode which does not provide the highest available stability or maximum level of desired stability (known as 'Mode 11'). If the vehicle 100, 200 is not in Mode 11, then the method stops 490 and repeats 410 to provide continuous monitoring should the vehicle 100, 200 settings be changed. If the vehicle 100, 200 is in such a mode, the method continues in order to monitor for a demand for the vehicle 100, 200 to carry out a burnout.

The driver-selected mode may disable a driver aid, a traction control system, and/or an electronic stability programme. The method 400 is configured to detect 430 whether a control switch for EPB of the vehicle 100, 200 has been switched into the 'release' position (the position normally required to release the EPB). If the control switch for the EPB is switched into the release position, the method may detect an input from a vehicle speed sensor to ensure that the vehicle 100, 200 is travelling at a speed below a maximum threshold for carrying out the manoeuvre 440, whilst monitoring a brake input 450 and an accelerator input 445 to determine whether the brake and accelerator inputs are above a predetermined threshold 445, 450.

If these thresholds are met 460, the method releases the brakes 465 at the rear axle of the vehicle 100, 200, whilst maintaining the braking force at the front axle, so that the rear wheels 114, 115, 206, 208 of the vehicle slip whilst the vehicle 100, 200 stays substantially stationary. The brake pressure at the rear axle may be released to zero.

In the case that the vehicle 100, 200 is a four-wheel-drive vehicle, the method may also disengage drive to the front wheels 111, 112, 202, 204 or front axle of the vehicle 100, 200 and may route all drive torque to the rear wheels 114, 115, 206, 208. This may be achieved by opening a central differential of the vehicle 100, 200, or in the case of an EV, power only the motor or motors configured to drive the rear axle.

lithe thresholds for accelerator input and brake input are not exceeded, the method may apply a braking force to the axles of the vehicle 100, 200 such that the rear wheels 114, 115, 206, 208 of the vehicle 100, 200 do not slip.

The method may also be configured to apply the braking force at the front axle of the vehicle 100, 200 for a longer duration than power is applied to the rear axle.

In use, the method recognises a demand for the rear brake pressure to be released (to zero) if the driver has selected a special stability control operating mode to enable the function, and then simultaneously applies enough accelerator pedal input to spin the rear wheels 114, 115, 206, 208 and enough brake pressure to stop the vehicle 100, 200 or reduce vehicle acceleration significantly.

These inputs may be recognised as a demand for spinning the rear wheels 114, 115, 206, 208 without any rear wheel braking and also, where the vehicle 100, 200 is four-wheel drive, to direct the driving torque to the rear wheels 114, 115, 206, 208 and not the front wheels 111, 112, 202, 204. The brake pressure at the rear wheels 114, 115, 206, 208 is released to zero even though the driver is providing a significant braking input.

If the activation criteria are not met 460, then the rear brakes can be activated or re-activated 480. lithe control switch for the EPB is pressed, 470 then this can be another trigger to activate or re-activate the rear brakes 480.

The present invention also provides a controller which includes a processor configured to carry out the steps of Figure 4, and a system including such a controller.

With reference to Figure 5, there is illustrated a method 500 for enabling a stability control system to recognise a demand for the vehicle 100, 200 to carry out a handbrake turn.

The start 510 method 500 of Figure 5 then performs the step of establishing whether vehicle 100, 200 is in a driver-selected mode which does not provide the maximum possible stability or maximum level of desired stability ('Mode 11'), and if the vehicle 100, 200 is in such a mode, monitoring for a demand for the vehicle 100, 200 to carry out a handbrake turn 520.

The driver-selected mode may disable a driver aid, a traction control system, and/or an electronic stability programme.

The method is configured to detect whether vehicle 100, 200 speed is above a predetermined threshold 530, and whether the steering input angle is above a predetermined threshold 540.

If these two thresholds are exceeded 550, and the control switch for the EPB of the vehicle 100, 200 has been switched into the 'active' position (the position normally required to activate the EPB) 560, a braking force is applied to the rear axle of the vehicle 100, 200 in order to lock the rear wheels 570. If the control switch for the EPB is released, the braking force at the rear axle of the vehicle 100, 200 is released 580 and the method ends 590 and resets 510 to restart monitoring 520. The method 500 may optionally also determine whether the vehicle 100, 200 is travelling in a forward direction.

If the thresholds for accelerator input and steering angle input are not exceeded 550, the method may apply a braking force to the axles of the vehicle 100, 200 such that the wheels 111, 112, 114, 115, 202, 204, 206, 208 of the vehicle 100, 200 do not lock. The method may also apply a braking force to the axles of the vehicle 100, 200 such that the wheels 111, 112, 114, 115, 202, 204, 206, 208 do not lock if the vehicle 100, 200 is travelling in a backward direction.

The threshold for the steering angle input may be at least 90 degrees, and the method may require that the steering input be applied in a duration of 0.5 seconds or less, giving a steering rate of at least 180 degrees/second.

The steering angle, vehicle speed, and vehicle direction inputs may alternatively or in combination be provided by one of an accelerometer, a gyroscope, a voltage sensor, an engine speed sensor, and/or an Inertial Measurement Unit (IMU') 220". The IMU 220" used may be a six degree-of-freedom (i6D0F') IMU.

The output from the IMU 220" may be used to detect the vehicle speed and/or the vehicle direction as part of the vehicle state estimation, as the IMU 220" sensors including the accelerometer may be used to determine the behaviour of the wider vehicle 100, 200.

The present method may monitor the vehicle state, and the six-degree-of-freedom IMU 220" may enable a vehicle state estimation to be carried out in substantially real-time and allow for rapid estimation of the behaviour of the vehicle 100, 200 at any point in time.

In use, the method recognises a demand for a hand brake turn if the driver has selected a special stability control operating mode to enable the function, and switches the EPB to an active position, whilst applying a large amount of steering lock rapidly. The method applies pressure to the brakes at the rear axle of the vehicle 100, 200 to lock the rear wheels 114, 115, 206, 208. The method would release the pressure to the brakes at the rear axle if the driver releases the EPB, allowing the rear wheels 114, 115, 206, 208 to rotate.

The present invention also provides a controller which includes a processor configured to carry out the steps of Figure 5, and a system including such a controller.

With reference to Figure 6, there is illustrated a method for enabling a stability control system to recognise a demand for the vehicle 100, 200 to carry out a reverse j-turn.

Following the start 605 of method 600 of Figure 6, there is performed the step 610 of establishing whether vehicle 100, 200 is in a driver-selected mode which does not provide the maximum possible stability ('Mode 11 or Dynamic stability control "DSC" off mode), and if the vehicle 100, 200 is in such a mode, monitoring for a demand for the vehicle 100, 200 to carry out a reverse j-turn.

The method is configured to detect whether vehicle speed is above a predetermined threshold 615, whether the steering input angle is above a predetermined threshold 620, and whether the driving angle of the vehicle 100, 200 is above a predetermined threshold 625. If these three thresholds are exceeded 630, and the vehicle 100, 200 is travelling in a backward direction, the function is started 635 and a braking force is applied to the front axle of the vehicle 100, 200 in order to lock the front wheels 640. Further, the method may also detect the rotation speed and rotation direction of the rear roadwheels of the vehicle 100, 200. If the rotation speed and direction are indicative a rear roadwheel of the vehicle 100, 200 accelerating in a forward direction, the method may release the braking force at the front axle of the vehicle 100, 200 and engage a forward gear in the transmission of the vehicle 100, 200.

If the thresholds for vehicle speed, steering angle input and driving angle input are not exceeded 630, the method may apply a braking force to the axles of the vehicle 100, 200 such that the wheels of the vehicle 100, 200 do not lock. The method may also apply a braking force to the axles of the vehicle 100, 200 such that the wheels do not lock if the vehicle 100, 200 is travelling in a forward direction.

The method may release the pressure to the brakes at the front axle if the vehicle speed falls below a predetermined threshold, allowing the front wheels 111, 112, 202, 204 to rotate.

The driving angle sensor may measure the yaw angle of the vehicle 100, 200, the body side slip angle of the vehicle 100, 200, or the tyre side slip of the vehicle 100, 200.

The steering angle, vehicle speed, vehicle direction, and driving angle inputs may alternatively or in combination be provided by one of an accelerometer, a gyroscope, a voltage sensor, an engine speed sensor, and/or an Inertial Measurement Unit (IMU') 220". The IMU 220" used may be a six degree-of-freedom (6D0F') IMU.

The output from the IMU 220" may be used to detect the vehicle speed and/or the vehicle direction as part of the vehicle state estimation, as the IMU sensors including the accelerometer may be used to determine the behaviour of the wider vehicle 100, 200.

In use, the method recognises a demand for a reverse j-turn if the driver has selected a special stability control operating mode to enable the function, and is travelling in reverse, whilst applying a large amount of steering lock and braking, rapidly. The method applies pressure to the brakes at the front axle of the vehicle 100, 200 to lock the front wheels 640. Once the method detects that the vehicle speed has reached nearly zero 645, that the vehicle 100, 200 has rotated and is travelling in a generally forward direction, the method releases the pressure to the brakes at the front axle 650 and engages a forward gear in the vehicle transmission 655. The function then ends 660 and the method 600 recommences 605 to monitor for further similar manoeuvres.

These embodiments provide an improved controller and method for controlling vehicle stability which may recognise a demand for a particular manoeuvre.

Figure 1 shows an example vehicle 100 which may include a controller according to embodiments of the invention. The vehicle 100 may also include sensors configured to provide data to the controller.

The vehicle 100 may include a controller configured to carry out a method according to an embodiment of the invention.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

Any control system, controller or controllers described herein may suitably comprise a control unit or computational device having one or more electronic processors. Thus, the system may comprise a single control unit or electronic controller or alternatively different functions of the controller may be embodied in, or hosted in, different control units or controllers. As used herein the term "controller" or "control unit" will be understood to include both a single control unit or controller and a plurality of control units or controllers collectively operating to provide any stated control functionality. To configure a controller, a suitable set of instructions may be provided which, when executed, cause said control unit or computational device to implement the control techniques specified herein. The set of instructions may suitably be embedded in said one or more electronic processors. Alternatively, the set of instructions may be provided as software saved on one or more memory associated with said controller to be executed on said computational device. A first controller may be implemented in software run on one or more processors. One or more other controllers may be implemented in software run on one or more processors, optionally the same one or more processors as the first controller. Other suitable arrangements may also be used.

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

Claims

CLAIMS1. A controller for controlling vehicle stability, the controller having first and second drive modes and including a processor for switching the controller between the drive modes, the processor being configured to: receive a steering angle signal, a vehicle speed signal, a yaw rate signal, a vehicle direction signal, and a brake input signal; determine whether the steering angle, vehicle speed, and yaw rate signals exceed a predetermined threshold; determine whether the direction of travel of the vehicle is backward, based on the wheel speed signal or reverse gear being engaged, and switch the controller from the first drive mode to the second drive mode if the vehicle speed, steering angle, and yaw rate signals exceed their respective predetermined thresholds and the direction of travel of the vehicle is backward; and apply a braking force at a front axle of the vehicle so as to substantially lock the front wheels of the vehicle.
2. A controller according to claim 1, wherein the controller is further configured to receive a wheel rotation speed and direction signal, and if the wheel rotation and direction signal is indicative that a rear roadwheel of the vehicle is accelerating in a forward direction, the braking force at the front axle of the vehicle is released and a forward gear in the transmission of the vehicle is engaged.
3. A controller according to claim 1, wherein the controller is further configured to receive a signal from a sensor that the steering input is substantially straight ahead, and if the steering input is substantially straight ahead, the braking force at the front axle of the vehicle is released and a forward gear in the transmission of the vehicle is engaged.
4. A controller according to any preceding claim, wherein the yaw rate sensor measures a yaw angle, body side slip angle, and/or a tyre side slip angle.
5. A controller according to any preceding claim, wherein if the or each of the predetermined thresholds for vehicle speed, steering angle and yaw rate are not met, the braking force is applied at both axles of the vehicle such that the wheels of the vehicle do not 35 lock.
6. A controller according to any preceding claim, wherein if it is determined that the vehicle is travelling in a backwards direction and the park brake is applied, the front axles of the vehicle are locked.
7. A controller according to any preceding claim wherein the predetermined threshold for the steering angle sensor is a steering angle of at least 90 degrees.
8. A controller according to claim 7 wherein the change in steering angle occurs in 0.5 seconds or less.
9. A controller according to claims 1 to 6 wherein the predetermined threshold for the steering angle sensor is a steering rate of greater than 180 degrees/sec.
10. A controller according to any preceding claim wherein at least one of the steering angle sensor, vehicle speed sensor, vehicle direction sensor, and yaw rate sensor comprises at least one of: an accelerometer, a gyroscope, a voltage sensor, an engine speed sensor, and a six-degree-of-freedom Inertial Measurement Unit.
11. A controller according to any preceding claim wherein the braking force applied to the front axle of the vehicle is released when at least one of the following conditions are satisfied: a) the driver returns the steering input to substantially straight ahead; b) it is determined that the vehicle has completed substantially 180 degrees of rotation; and c) it is determined that the rear wheels are rotating in a forwards direction above a predetermined threshold of speed or acceleration.
12. A controller according to any preceding claim, wherein the second drive mode is configured to disable driver aids.
13. A controller according to any preceding claim, wherein the second drive mode is configured to disable a traction control system.
14. A controller according to any preceding claim, wherein the second drive mode is configured to disable an electronic stability programme.
15. A system including the controller of any preceding claim.
16. A vehicle including a controller according to any one of claims 1 to 14 or the system of claim 15.
17. A method of controlling vehicle stability, the method including: receiving a steering angle signal, a vehicle speed signal, a yaw rate signal, a vehicle direction signal, and a brake input signal; determining whether the steering angle, vehicle speed, and angle sensor signals exceed a predetermined threshold; determining whether the direction of travel of the vehicle is backward, based on the vehicle direction signal, and switching from the first drive mode to the second drive mode if the vehicle speed, steering angle, and yaw rate signals exceed their respective predetermined thresholds and the direction of travel of the vehicle is backward; and applying a braking force at the front axle of a vehicle so as to substantially lock front wheels of the vehicle, and the second drive mode is enabled.
18. A method according to claim 17, further including receiving a rear wheel rotation speed and direction signal and releasing the braking force at the front axle of the vehicle and engage a forward gear in the transmission of the vehicle, if the wheel rotation and direction signal is indicative that a rear roadwheel of the vehicle is accelerating in a forward direction.
19. A method according to any one of claims 17 or 18, wherein if the or each of the predetermined thresholds for vehicle speed, steering angle and yaw rate are not met, the braking force is applied at both axles of the vehicle such that the wheels of the vehicle do not 25 lock.
20. A method according to any one of claims 17 to 19, wherein the predetermined threshold for the steering angle sensor is a steering angle of between 80 to 100 degrees.
21. A method according to claim 20 wherein the change in steering angle occurs in 0.5 seconds or less.
22. A method according to any one of claims 17 to 19 wherein the predetermined threshold for the steering angle sensor is a steering rate between 170 and 190 degrees/sec.
23. A controller configured to carry out the method steps of claims 17 to 22.
24. A vehicle including a controller according to claim 23.