GB2605418A

GB2605418A - Control system and method for providing end stop force

Info

Publication number: GB2605418A
Application number: GB2104580.2A
Authority: GB
Inventors: Michael Cull Adam
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2021-03-31
Filing date: 2021-03-31
Publication date: 2022-10-05
Anticipated expiration: 2041-03-31
Also published as: GB202104580D0; DE102022105299A1; GB2605418B

Abstract

A system is provided for controlling end stop force for a steering system of a vehicle (300, Figure 2). Steering data is received from a user steering input device 120, typically a steering wheel, indicating a requested steering angle. Driving style data indicating a driving style of the vehicle, such as changes in steering speed, tyre friction or the selection of a mode, is obtained. A steering end stop profile is determined based on the driving style data and an end stop force is determined based on the requested steering angle and the steering end stop profile. A control signal 155, 165 is output to control actuators 150, 160 to apply the determined end stop force to resist input at input device 120. Suitably, driving style data may comprise historic data, such as the number of previous approaches to the end stops. A corresponding steering system, vehicle, method and program are also provided.

Description

CONTROL SYSTEM AND METHOD FOR PROVIDING END STOP FORCE

TECHNICAL FIELD

The present disclosure relates to providing an end stop force for a steering system of a vehicle.

Aspects of the invention relate to a control system, to a steering system, to a vehicle, to a method and to computer software.

BACKGROUND

It is known to provide an "end of travel" stop, or end stop, on a steering system of a vehicle.

The end stop acts to prevent a driver of the vehicle articulating the steering system past a limit of movement of the steering system. In a traditional steering system, such as a non-power assisted steering system or a hydraulically assisted steering system, the end stop is a mechanical end stop which acts to prevent further range of motion of the steering system past its hardware limit.

In more recent power-assisted or steer-by-wire steering systems, a further electronically controlled (EC) end stop may be implemented. The EC end stop may be implemented to prevent the driver turning a steering wheel further before the mechanical end stop is reached by the steering system. The EC end stop thus acts to prevent damage to the mechanical end stops. The EC end stop may be implemented by controlling an assistive motor to reduce steering assistance force, or by actively controlling an actuator to apply a resistive force at the wheel to push against the driver turning the wheel further.

The EC end stop is programmed once for a particular steering system and has a predetermined profile, which defines the amount of resistive force provided by the end stop for a given requested steering angle, e.g. at a given rotation angle of the steering wheel. The shape of the profile of the end stop impacts the feel of steering the vehicle around the end stop, and as such the end stop characteristic can feel inappropriate depending on how the vehicle is being driven.

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 steering system, a vehicle, a method and a computer-readable medium as claimed in the appended claims.

According loan aspect of the present invention there is provided a control system for providing end stop force for a steering system of a vehicle, the control system comprising one or more controllers, the one or more controllers configured to: receive, from a user steering input device, steering data indicative of a requested steering angle; obtain driving style data indicative of a driving style of the vehicle; determine a steering end stop profile in dependence on the driving style data; determine an end stop force in dependence on the requested steering angle and the steering end stop profile; and output a control signal to control one or more actuators to apply the determined end stop force to resist input at the user steering input device. Advantageously, adjusting the end stop profile in dependence on the driving style facilitates a more use-specific end stop torque to be selected, which results in a more natural end stop feeling for the driver.

The end stop force may be an end stop torque. The end stop force is for implementing an electronically controlled (EC) end stop for the user steering input device, to prevent the steering system reaching a mechanical end stop. The steering end stop profile is indicative of a relationship between requested steering angle and the end stop force to be applied. The steering end stop profile may thus be dependent on a mechanical end stop of the steering system, in that the end stop force may be designed to increase as the requested steering angle approaches the mechanical end stop.

The driving style may be determined based on one or more user driving inputs. Optionally, the driving style data comprises an indication of a rate of change of one or more driver inputs to the vehicle. The rate of change of the one or more driver inputs may be indicative of a level of driving aggression. The steering end stop profile may be determined such that an end stop force is provided at a smaller steering angle in dependence on an increased rate of change of the one or more driver inputs. Additionally, or alternatively, a gradient of the end stop profile is reduced in dependence on an increased rate of change of the one or more driver inputs. Advantageously, implementing the end stop at a smaller requested steering angle with a lower gradient when the user is steering aggressively enables the mechanical end stop to be protected whilst feeling smoother for the driver, i.e. it avoids the provision of a sudden end stop force.

The driving style data may, for example, comprise an indication of a rate of change of the requested steering angle, e.g. an indication of a rate of change of steering wheel angle. The rate of change of requested angle is one example of a rate of change of a driver input. Thus, the end stop profile may be determined such that end stop force is provided at a smaller steering angle and/or the gradient of the end stop profile may be reduced in dependence on an increased rate of change of the requested steering angle.

Optionally, the driving style data comprises an indication of one or more of a steering speed of the vehicle, an electric power assisted steering motor speed of the vehicle, an electric power assisted steering motor torque of the vehicle, a yaw rate of the vehicle, a steering acceleration of the vehicle, or a tyre friction of the vehicle. An increased value of each parameter may implicitly define a higher rate of change of requested steering angle, and thus indicate a more aggressive driving style. Thus, the end stop profile may be determined such that the end stop force is provided at a smaller steering angle and/or the gradient of the end stop profile is reduced in dependence on an increased value of each parameter.

In some embodiments, the driving style data comprises an indication of a user-selected configuration of the vehicle. For example, the user-selected configuration may be a configurable driving mode selected by the driver. The configurable driving mode may be selected from a plurality of options, e.g. from at least a first mode and a second mode. The first mode and the second mode may for example comprise a "sport" mode and a "comfort" mode. A first mode such as "sport" may define a quicker vehicle response in comparison to a second mode such as "comfort". The user selected configuration of "sport" may be indicative of a more aggressive desired driving style than a "comfort" mode, and thus the end stop force may be provided at a smaller steering angle and/or the gradient of the end stop profile may be reduced in dependence on a user-selected configuration indicative of a quicker vehicle response.

In some embodiments, the plurality of options may comprise an "off-road" mode or other mode indicative of low vehicle speed, for example for use on uneven terrain. The "off-road" mode may be selected, for example, by driving below a threshold vehicle speed. The threshold vehicle speed may be defined for example as 5km/h or 10kmp/h, though it will be appreciated that other threshold values may be used. The end stop force may be provided at a larger steering angle in dependence on the selection of a mode indicative of low vehicle speed. In this way, more larger steering angles which may be necessary in an off-road scenario may be readily facilitated.

Optionally, the driving style data comprises historic driving style data indicative of a previous driving style of the vehicle. Historic driving style data may be indicative of a recent driving style. The historic driving style data may be indicative of one or more of the above parameters over a predetermined period of time, such as 1 month or 1 week. In some embodiments, the historic driving style data may be indicative of one or more of the above parameters over a predetermined number of journeys, for example the last journey taken by the vehicle or the last three journeys.

In some embodiments, the historic driving style data may be defined in dependence on an identity of the driver. That is, a historic driving profile may be defined for each driver of the vehicle, and the historic driving style data may be obtained in dependence on the profile of the current driver of the vehicle. In this way, the steering end stop profile may be tailored differently for different drivers using the same vehicle. The identity of the driver may be determined for example by a user selection, though it will be appreciated that any identity determination means may be used, such as image recognition or audio recognition. The identity of the driver may be determined for example automatically by the identity determination means due to inputs received, such as a driver identity being associated with a vehicle access means for example a key that sends a wireless signal to unlock and/or activate the vehicle, or one or more signal associated with the ergonomic arrangement of one or more of: the driver's seat; steering column; and pedals.

The steering end stop profile may be determined in dependence on the historic driving style data. The end stop profile may be determined such that the end stop force is provided at a smaller steering angle and/or the gradient is decreased in dependence on a higher rate of change of one or more driver inputs to the vehicle in historic driving style data. Optionally, the historic driving style data comprises an indication of a number of instances of the steering system approaching a mechanical end stop. The end stop force may be provided at a smaller steering angle in dependence on higher instances of approaching mechanical end stop in the past. Advantageously, the end stop profile may be flexibly adjusted to account for a driver's tendency to approach the mechanical end stop, in order to mitigate the risk of such events occurring in the future.

Optionally, the one or more controllers are further configured to receive object detection data from a sensor unit associated with the vehicle, and the steering end stop profile is determined in dependence on the object detection data. Beneficially, the end stop force may be selectively used to alert a driver to proximal objects or prevent the steering of the vehicle towards the proximal objects.

Optionally, the user steering input device comprises a steering wheel, and the steering data comprises an indication of an angle of the steering wheel.

According to a further aspect, there is provided a steering system for a vehicle, comprising: a user steering input device; a control system as described above for determining an end stop force; and one or more actuators for applying the determined end stop force to resist input at the user steering input device. Optionally, one or more of the actuators comprise a feedback actuator (eg motor) configured to directly apply the end stop force at the steering input device.

In some embodiments, the steering system may thus facilitate implementing an EC end stop in a steer-by-wire system. Optionally, at least one of the actuators comprises an assist motor for applying assisfive torque to a steering rack of the vehicle. In power assisted steering systems, the end stop force may thus be applied to the steering input device indirectly via the steering rack and/or steering column. The end stop force may be applied to counter assistive torque applied by the assist motor.

According to a further aspect vehicle comprising a control system or a steering system as described above.

According to a further aspect of the invention there is provided a computer-implemented method for providing end stop force for a steering system of a vehicle, the method comprising: receiving, from a user steering input device, steering data indicative of a requested steering angle; obtaining driving style data indicative of a driving style of the vehicle; determining a steering end stop profile in dependence on the driving style data; determining an end stop force in dependence on the requested steering angle and the steering end stop profile; and outputting a control signal to control one or more actuators to apply the determined end stop force to resist input at the user steering input device.

Optionally, the driving style data comprises an indication of a rate of change of one or more driver inputs to the vehicle. Optionally, the steering end stop profile is determined such that an end stop force is provided at a smaller steering angle in dependence on an increased rate of change of the one or more driver inputs. Optionally, a gradient of the end stop profile is reduced in dependence on an increased rate of change of the one or more driver inputs.

Optionally, the driving style data comprises an indication of a rate of change of the requested steering angle. Optionally, the driving style data comprises an indication of one or more of: a steering speed of the vehicle, an electric power assisted steering motor speed of the vehicle, a yaw rate of the vehicle, a steering acceleration of the vehicle, or a tyre friction of the vehicle.

Optionally, the driving style data comprises an indication of a user-selected configuration of the vehicle According to a further aspect, there is provided a computer-readable medium comprising computer software which, when executed, is configured to cause performance of the method above.

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 schematic illustration of a steering system according to a first embodiment of the invention; Figure 2 shows a schematic illustration of a steering system according to a second embodiment of the invention; Figure 3 shows a vehicle in accordance with an embodiment of the invention; Figure 4 illustrates an example end stop profile for determining an end stop force; Figure 5 shows a flow chart for a method according to an embodiment of the invention; and Figure 6 shows a block diagram of a control system accordance with an embodiment of the invention.

DETAILED DESCRIPTION

A steering system in accordance with embodiments of the present invention will now be described with reference to Figures 1 and 2. As shown in Figure 3, the steering system is installed in a vehicle 300. The vehicle 300 in the present embodiment is an automobile, such as a wheeled vehicle, but it will be understood that the steering system 100, 200 may be used in other types of vehicle.

Figure 1 illustrates a steering system 100 according to an embodiment of the invention. A driver of the vehicle 300 can adjust a steering input device 120 such as a steering wheel 120 to indicate a requested steering angle for the vehicle 300. In a power assisted steering system such as the steering system 100, actuating the steering wheel 120 applies steering torque to a steering rack 140 via a steering column 132. The application of steering torque to the steering rack 140 adjusts one or more wheels 141, 142 of the vehicle in order to steer the vehicle at the requested steering angle. The steering system 100 comprises a steering sensor 130, such as an angle or angle sensor, associated with the steering input device 120. The steering sensor 130 is configured to detect a requested angle of the steering system, for example by detecting an angle of the steering wheel 120.

In the power assisted steering system 100, the steering torque is supplemented by an assistive torque generated by one or more assist actuator 150 associated with the steering system 100.

The assist actuator 150 may for example comprise one or more electric motor 150 or hydraulic mechanisms.

The steering system 100 comprises a control system 110 configured to determine an amount of assistive torque to be applied by the assist actuators 150. The control system 110 is configured to receive steering data 135 from the steering sensor 130 and determine an amount of assistive torque to be generated in dependence on the steering data 135. The control system 110 may then output a control signal 155 to control the one or more assist motors 150 to generate the assistive torque, to supplement the torque applied by the driver.

The control system 110 comprises processing means 111 and memory means 114. The processing means 111 may be one or more electronic processing device 111 which operably executes computer-readable instructions. The memory means 114 may be one or more memory device 114. The memory means 114 is electrically coupled to the processing means 111. The memory means 114 is configured to store instructions, and the processing means 111 is configured to access the memory means 114 and execute the instructions stored thereon.

The control system 110 is configured to determine an EC end stop force for the steering system 100. The end stop force may be determined as part of the assistive torque or may be determined separately. The EC end stop is implemented to prevent the driver actuating the steering input device 120 to an extent that a mechanical end stop is reached by the steering system 100. The EC end stop thus acts to prevent damage to the mechanical end stops. The EC end stop force may be determined as a reduction in the assistive torque or may be determined as an additional or separate resistive force to be applied to the steering input device 120. In particular, the EC end stop force may be applied in a direction opposed to the driver input at the steering input device 120.

Figure 2 illustrates a steering system 200 according to another embodiment of the invention. The steering system 200 is analogous to the steering system 100, with the difference that the steering system 200 is a "steer-by-wire" system. In the steering system 200, there is no mechanical connection between the steering input device 120 and the steering rack 140, and the assistive torque provided by the assist actuator(s) 150 fully replaces any steering torque that would have been applied via the steering column 132.

In a steer by wire steering system such as steering system 200, the lack of mechanical connection between the steering rack 140 and the steering input device 120 means that a driver of the vehicle does not feel any resistance implemented by the assist actuator(s) 150.

A feedback actuator 160 may be provided in order to provide haptic feedback to the driver to alert the driver to the EC end stop. The control system 110 may be configured to determine a level of haptic feedback and output a control signal 165 to the feedback actuator to provide the determined level of haptic feedback. The feedback actuator 160 may for example comprise one or more electric motor. The feedback actuator 160 may provide the EC end stop in the form of resistance at the steering input device 120, such that the driver must apply more force to the steering input device 120 towards the extremes of the range of motion of the steering system 200.

In this way, the EC end stop may be implemented by controlling the assist actuator(s) 150 to reduce the assistive torque (or apply negative assistive torque), or by controlling the force feedback actuator 160 to apply a resistive force at the steering input device 120 to push against the driver requesting more steering angle.

Previously, the EC end stop force has been determined for a steering system 100, 200 according to a predetermined end stop profile which defines the amount of resistive force provided by the end stop for a given requested steering angle.

An example end stop profile 400 is illustrated in Figure 4. Determined EC end stop force F (y axis) is plotted against requested steering angle A (x axis). Past a first threshold angle 410, end stop force is applied to provide feedback to the driver and prevent the requested steering angle reaching a second threshold angle 420 indicative of a mechanical end stop of the steering system. The shape of the end stop profile 400 determines the level of end stop force applied at the assist actuator 150 or the feedback actuator 160 for a given requested steering angle. The value of the first threshold angle 410 determines how soon in a steering manoeuvre the end stop force is implemented, and the gradient of the end stop profile 400 determines how sharply the end stop force is applied.

As a single end stop profile 400 is typically predefined and utilised by the control system 110 during use, no account is made for different use cases of the vehicle 300. As such, in some circumstances the end stop force may feel incongruous with the manner in which the vehicle is being driven. For example, if the first threshold angle 410 is large and thus the end stop profile has a high gradient, the end stop may feel overly harsh if the driver steers against it rapidly. If the first threshold angle 410 is small and thus the end stop force is applied early in a manoeuvre, the end stop may feel overly restrictive if the driver is steering gently. The present invention provides an alternative method in which the end stop profile may be effectively adjusted during use to facilitate a more natural and appropriate end stop feeling for the driver.

Figure 5 illustrates a method 500 for providing an end stop force for the steering system 100, 200. The method 500 may be performed at least in part by the control system 110.

The method 500 comprises a block 510 of receiving steering data 135 from the steering input device 120 or associated steering sensor 130. The steering data 135 is indicative of a requested steering angle. The requested steering angle may be derived from an angle of a steering wheel, as discussed.

The method 500 comprises a block 520 of obtaining driving style data indicative of a driving style of the vehicle. The driving style may be used to select an appropriate end stop force, as will be explained. As the driving style varies, different end stop response profiles may be appropriate. The driving style may be determined based on one or more user driving inputs and/or one or more user selected configurations.

For example, the driving style may be determined based on a driver input to the steering input device 120, or a driver input to one or more further vehicle controls such as an accelerator, a brake, or a gear selector. The driving style may be determined in particular embodiments in dependence on a rate of change of the one or more driver inputs. The rate of change of each of the one or more driver inputs may indicate a level of driving aggression, or urgency.

In some embodiments, the driving style data comprises an indication of a rate of change of the requested steering angle by the driver. That is, an input rate at which the driver makes an input at the steering input device 120. In the case of a steering wheel 120, the input rate may be expressed as a rate of change of wheel angle. An increased rate of change of wheel angle may be indicative of an aggressive or urgent driving style, as the driver rapidly steers the vehicle 300. The input rate may be received by the control system from the sensor 130 or may be derived by the control system 110 in dependence on the steering data 135. That is, the input rate may be calculated from steering data indicative of the requested steering angle over time.

The driving style data may comprise one or more parameters which implicitly define the input rate at the steering input device 120. Such parameters may include, for example, a steering speed of the vehicle, an electric power assisted steering motor speed of the vehicle, a yaw rate of the vehicle, a steering acceleration of the vehicle, or a tyre friction of the vehicle. Each parameter may be received from further control systems associated with the vehicle 300, or directly from one or more sensors arranged on the vehicle 300. In each case, an increased value of the parameter may be indicative of an increased input rate at the steering input device 120, and thus a more aggressive driving style.

The driving style may be determined in dependence on one or more user selected configurations, such as a configurable driving mode selected by the driver. The configurable driving mode may be selected from a plurality of options, e.g. from at least a first mode and a second mode. The configurable driving mode may define a responsiveness of the vehicle to driver input. For example, a vehicle 300 may facilitate the user selecting a comfort configuration or a sports configuration, wherein in the sports configuration aspects of the vehicle are more rapidly responsive to driver input, e.g. at an accelerator, in comparison to the comfort configuration. In this way, the driving style data may comprise the user selected configuration. A first user selected configuration such as "sport" may thus define a quicker vehicle response than a second user selected configuration such as "comfort". The first user selected configuration may thus be indicative of a more aggressive desired driving style than the second user selected configuration. It will be appreciated that although in this example only two configurations are illustrated, vehicles may have alternative or further configurations defining a range of vehicle response profiles. In each case, the configuration may be utilised to define a respective driving style in the driving style data. For example, in some embodiments, the one or more user selected configurations may comprise an "off-road" mode or other mode indicative of low vehicle speed, for example for use on uneven terrain. The "off-road" mode may be selected, for example, by driving below a threshold vehicle speed. The threshold vehicle speed may be defined for example as 5km/h or 10kmp/h, though it will be appreciated that other threshold values may be used.

The driving style data may thus in some embodiments comprise one of the above parameters, such as an input rate at the steering input device 120. In other embodiments, the driving style data may comprise a plurality of parameters, such as a user-selected configuration and a tyre friction at a tyre 141, 142 of the vehicle 300. In some embodiments, the driving style data may comprise historic driving style data indicative of a previous driving style of the vehicle. The historic driving style data may comprise values for one or more of the driving style parameters within a recent time window, i.e. within a predetermined period of time. In this way, the end stop force may be determined to account for recent driving behaviour.

The method 500 comprises a block 530 of determining an end stop profile in dependence on the driving style data. That is, the driving style data is utilised to impact the relationship between the requested steering angle A and the end stop force F, such as illustrated by the end stop profile 400. Thus, the control system 110 is configured to calculate the end stop force differently depending on the driving style data.

In some embodiments, the control system 110 may be configured to store a plurality of different end stop profiles in memory, for example in the form of a plurality of look-up tables.

Block 530 may thus comprise selecting an appropriate end stop profile in dependence on the driving style data.

In other embodiments, the control system 110 may be configured to receive the driving style data as an input to a model for determining the end stop force dynamically. Thus, the end-stop profiles may not be explicitly stored, but rather the end stop profile may represent the mathematical relationship by which the end-stop force is calculated for a given set of input parameters. It will be appreciated that the specific implementation of the calculation does not conceptually impact the invention.

The end stop profile 400 is determined to reflect the driving style parameterised by the driving style data. In general, a more "aggressive" driving style, exemplified by an increased rate of change of driver input to the vehicle, may be reflected in block 530 by adjusting the end stop profile to reduce the threshold 410 and/or reduce the gradient of the profile 400. In this way, the end stop force may interject earlier in the manoeuvre and ramp up more smoothly, such that if the driver rapidly turns the steering wheel 120, the angle is smoothly damped, and the mechanical end stop is protected. Conversely, for a less aggressive driving style, or a lower rate of change of driver input to the vehicle, the EC end stop may be unnecessary at lower steering, and the resistive force may be irritating to the driver. Thus, the end stop profile may be adapted to increase the threshold 410 and/or increase the gradient such that the EC end stop provides damping closer to the mechanical end stop of the steering system.

As discussed, the driving style data may comprise historic driving style data. The historic driving style data may be used to adjust the end stop profile analogously to current driving style data, e.g. historically increased rate of driver input may be reflected by reducing the threshold 410 and/or reducing the gradient of the profile 400.

In some embodiments, the historic driving style data may comprise an indication of a number or frequency of instances of the steering system approaching its mechanical end stop. The end stop profile may be adjusted to reduce the threshold 410 or increase the gradient of the profile if historically the mechanical end stop has been frequently reached by the driver, in order to increase the distance between the EC end stop and mechanical end stop to better protect the mechanical end stop from engagement in future.

In particular embodiments, the parameters included in the driving style data may be configured to have one or more of the following effects on the end stop profile as they increase in value: Driving style parameter Effect on threshold Effect on gradient Input rate (at steering input Decrease Decrease device, accelerator, brake etc) User configuration defining Decrease Decrease increased speed of vehicle response User configuration defining Increase Increase lower/damped speed of vehicle response Steering speed of the Decrease Decrease vehicle, electric power assisted steering motor speed of the vehicle, yaw rate of the vehicle, steering acceleration of the vehicle, tyre friction Historic parameter Same as respective current parameter Same as respective current parameter Frequency of engaging Decrease Decrease mechanical end stop It will be appreciated that the above effects are merely illustrative, and in some other embodiments the parameters of the driving style data may be utilised differently. For example, in some embodiments only a subset of the parameters may be used. Further, in some embodiments the gradient may be adapted without adapting the first threshold angle, and vice versa.

In some embodiments, the control system 110 may be configured to receive object detection data from one or more sensor units associated with the vehicle 300. The object detection data may be indicative of a location of one or more objects proximal to the vehicle. In block 530, the end stop profile may be determined further in dependence on the object detection data. In particular, the end stop profile may be modified to alert a driver to the presence of the one or more objects or otherwise prevent the driver steering the vehicle 300 towards the one or more objects. For example, if the object detection data is indicative that an object is located directly to the left of the vehicle, the end stop profile may be modified asymmetrically to provide a decreased threshold and/or an increased gradient of the end stop profile for requested steering angles to the left.

The method 500 comprises a block 540 of determining an end stop force in dependence on the requested steering angle and the steering end stop profile. The end stop force may be determined by inputting the requested steering angle and the driving style data into a model which incorporates the steering end stop profile, and calculating the respective end stop force, as discussed. In other embodiments, the end stop profile may have been selected as a look up table or other data structure in block 530, and block 540 may comprise selecting a value of end stop force corresponding to the requested steering angle in the look up table.

The method 500 comprises a block 550 of outputting a signal 155, 165 to control one or more actuators to apply the determined end stop force to resist input at the user steering input device. The signal may be output to one or both of the assist actuator(s) 150 and the feedback actuator 160. The end stop force may be determined as part of the determination of the assisfive torque, and a single control signal may be output to the assist actuator 150. In other embodiments, the end stop force may be determined independently, in particular for steer by wire implementations such as the steering system 200.

It can therefore be seen that the present invention provides a method and system for flexibly determining the end stop force felt by a driver of the vehicle to reflect the driving style. In this way, the end stop force may more accurately reflect the current use case of the vehicle, leading to an end stop feeling which is more natural and appropriate for the driver.

With reference to Figure 8, there is illustrated a simplified example of a control system 110 such as may be adapted to implement the method described herein. The control system 110 comprises one or more controller 1000 and is configured to receive 510, from a user steering input device 120, steering data indicative of a requested steering angle; obtain 520 driving style data indicative of a driving style of the vehicle; determine 530 a steering end stop profile in dependence on the driving style data; determine 540 an end stop force in dependence on the requested steering angle and the steering end stop profile; and output 550 a control signal to control one or more actuators 150, 160 to apply the determined end stop force to resist input at the user steering input device 120.

It is to be understood that the or each controller 1000 can comprise a control unit or computational device having one or more electronic processors (e.g., a microprocessor, a microcontroller, an application specific integrated circuit (ASIC), etc.), and may comprise a single control unit or computational device, or alternatively different functions of the or each controller 1000 may be embodied in, or hosted in, different control units or computational devices. As used herein, the term "controller," "control unit," or "computational device" will be understood to include a single controller, control unit, or computational device, and a plurality of controllers, control units, or computational devices collectively operating to provide the required control functionality. A set of instructions could be provided which, when executed, cause the controller 1000 to implement the control techniques described herein (including some or all of the functionality required for the method described herein). The set of instructions could be embedded in said one or more electronic processors of the controller 1000; or alternatively, the set of instructions could be provided as software to be executed in the controller 1000. A first controller or control unit may be implemented in software run on one or more processors. One or more other controllers or control units may be implemented in software run on one or more processors, optionally the same one or more processors as the first controller or control unit. Other arrangements are also useful.

In the example illustrated in Figure 6, the or each controller 1000 comprises at least one electronic processor 111 having one or more electrical input(s) 112 for receiving one or more input signals, and one or more electrical output(s) 113 for outputting one or more output signals. The or each controller 1000 further comprises at least one memory device 114 electrically coupled to the at least one electronic processor 111 and having instructions 115 stored therein. The at least one electronic processor 111 is configured to access the at least one memory device 114 and execute the instructions 115 thereon.

The, or each, electronic processor 111 may comprise any suitable electronic processor (e.g., a microprocessor, a microcontroller, an ASIC, etc.) that is configured to execute electronic instructions. The, or each, electronic memory device 114 may comprise any suitable memory device and may store a variety of data, information, threshold value(s), lookup tables or other data structures, and/or instructions therein or thereon. In an embodiment, the memory device 114 has information and instructions for software, firmware, programs, algorithms, scripts, applications, etc. stored therein or thereon that may govern all or part of the methodology described herein. The processor, or each, electronic processor 111 may access the memory device 114 and execute and/or use that or those instructions and information to carry out or perform some or all of the functionality and methodology describe herein.

The at least one memory device 114 may comprise a computer-readable storage medium (e.g. a non-transitory or non-transient storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational devices, including, without limitation: a magnetic storage medium (e.g. floppy diskette); optical storage medium (e.g. CD-ROM); magneto optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g. EPROM ad EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

Example controllers 1000 have been described comprising at least one electronic processor 111 configured to execute electronic instructions stored within at least one memory device 114, which when executed causes the electronic processor(s) 111 to carry out the method as hereinbefore described. However, it is contemplated that the present invention is not limited to being implemented by way of programmable processing devices, and that at least some of, and in some embodiments all of, the functionality and or method steps of the present invention may equally be implemented by way of non-programmable hardware, such as by way of non-programmable ASIC, Boolean logic circuitry, etc. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

CLAIMS1. A control system for providing end stop force for a steering system of a vehicle, the control system comprising one or more controllers, the one or more controllers configured to: receive, from a user steering input device, steering data indicative of a requested steering angle; obtain driving style data indicative of a driving style of the vehicle; determine a steering end stop profile in dependence on the driving style data; determine an end stop force in dependence on the requested steering angle and the steering end stop profile; and output a control signal to control one or more actuators to apply the determined end stop force to resist input at the user steering input device.
2. A control system as claimed in claim 1, wherein the driving style data comprises an indication of a rate of change of one or more driver inputs to the vehicle.
3. A control system as claimed in claim 2, wherein the steering end stop profile is determined such that an end stop force is provided at a smaller steering angle in dependence on an increased rate of change of the one or more driver inputs.
4. A control system as claimed in claim 2 or 3, wherein a gradient of the end stop profile is reduced in dependence on an increased rate of change of the one or more driver inputs.
5. A control system as claimed in any preceding claim, wherein the driving style data comprises an indication of a rate of change of the requested steering angle.
6. A control system as claimed in any preceding claim, wherein the driving style data comprises an indication of one or more of: a steering speed of the vehicle, an electric power assisted steering motor speed of the vehicle, a yaw rate of the vehicle, a steering acceleration of the vehicle, or a tyre friction of the vehicle.
7. A control system as claimed in any preceding claim, wherein the driving style data comprises an indication of a user-selected configuration of the vehicle.
8. A control system as claimed in any preceding claim, wherein the driving style data comprises historic driving style data indicative of a previous driving style of the vehicle.
9. A control system as claimed in claim 8, wherein the steering end stop profile is determined in dependence on the historic driving style data.
10. A control system as claimed in claim 8 or 9, wherein the historic driving style data comprises an indication of a number of instances of the steering system approaching a mechanical end stop.
11. A control system as claimed in any preceding claim, wherein the one or more controllers are further configured to receive object detection data from a sensor unit associated with the vehicle, and wherein the steering end stop profile is determined in dependence on the object detection data.
12. A control system as claimed in any preceding claim, wherein the user steering input device comprises a steering wheel, and wherein the steering data comprises an indication of an angle of the steering wheel.
13. A steering system for a vehicle, comprising: a user steering input device; a control system as claimed in any preceding claim for determining an end stop force; and one or more actuators for applying the determined end stop force to resist input at the user steering input device.
14. A steering system as claimed in claim 13, wherein one or more of actuators comprise a force feedback motor configured to directly apply the end stop force at the steering input device.
15. A steering system as claimed in claim 13 or 14, wherein at least one of the actuators comprises an assist motor for applying assistive torque to a steering rack of the vehicle.
16. A steering system as claimed in claim 15, wherein the end stop force is applied to counter assisfive torque applied by the assist motor.
17. A vehicle comprising a control system as claimed in any of claims 1 to 12 or a steering system as claimed in claims 13 to 16.
18. A computer-implemented method for providing end stop force for a steering system of a vehicle, the method comprising: Receiving, from a user steering input device, steering data indicative of a requested steering angle; obtaining driving style data indicative of a driving style of the vehicle; determining a steering end stop profile in dependence on the driving style data; determining an end stop force in dependence on the requested steering angle and the steering end stop profile; and outputting a control signal to control one or more actuators to apply the determined end stop force to resist input at the user steering input device.
19. A method as claimed in claim 18, wherein the driving style data comprises an indication of a rate of change of one or more driver inputs to the vehicle.
20. A method as claimed in claim 19, wherein the steering end stop profile is determined such that an end stop force is provided at a smaller steering angle in dependence on an increased rate of change of the one or more driver inputs.
21. A method as claimed in claim 19 or 20, wherein a gradient of the end stop profile is reduced in dependence on an increased rate of change of the one or more driver inputs.
22. A method as claimed in any of claims 18 to 21, wherein the driving style data comprises an indication of a rate of change of the requested steering angle.
23. A method as claimed in any of claims 18 to 22, wherein the driving style data comprises an indication of one or more of: a steering speed of the vehicle, an electric power assisted steering motor speed of the vehicle, a yaw rate of the vehicle, a steering acceleration of the vehicle, or a tyre friction of the vehicle.
24. A method as claimed in any of claims 18 to 23, wherein the driving style data comprises an indication of a user-selected configuration of the vehicle.
25. A computer-readable medium comprising computer software which, when executed, is configured to cause performance of the method of claims 18 to 23.