Control system and method for a vehicle

Abstract

A control system (200) is described for controlling a suspension system of a vehicle (1). The control system comprises one or more processors collectively configured to receive (A3) an angle of steer,

Description

TECHNICAL FIELD The present disclosure relates to a control system and method for a vehicle. Aspects of the invention relate to a control system, a control method, a vehicle and a computer program. BACKGROUND In development of vehicle architectures wheel size plays an important part of vehicle layout and has a number of design requirements. Some of these wheel-size based requirements relate to clearances required in specific events and or fitment of traction devices such as snow chains and socks. In particular, an initial architecture may specify a first wheel size prior to the architecture being “frozen”. During vehicle development there may be occasions where a request is made which deviates from original architecture parameters, resulting in additional work being required to mitigate. Depending on the level of change with respect to the original parameters this can require fundamental structural changes to the vehicle body to allow larger wheel fitment, which costs significant time and money. Examples of such significant architectural changes may include changes to physical parts such as a wheel arch liners, brake pipes, cooling pipes, and any other parts situated in the wheel houses. In particular, following the architecture freeze the wheel size may need to be increased. 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 control method, a vehicle and a computer program as claimed in the appended claims. According to an aspect of the present invention there is provided a control system for controlling a suspension system of a vehicle, the control system comprising one or more processors collectively configured to: receive an angle of steer; determine whether to adjust one or more suspension parameters of a wheel of the vehicle in dependence on the received angle of steer being greater than an angle threshold; and output a control signal to adjust the one or more suspension parameters in dependence on the determination. In this way, at or near full steering lock (when the angle of steer exceeds the angle threshold), the suspension system is adjusted via the control signal to avoid or at least reduce the likelihood of contact between over-size wheels and the body. The adjustment is not required at lower steering angles, when the risk of contact is lower. The specific mitigation applied (that is, the nature and magnitude of the adjustments made to the suspension system) may depend on the vehicle suspension type (for example coil spring or air spring, and the aspects of that suspension system which are adjustable) and the original architecture layout (that is, the geometry of the body / wheel arch and the wheel within it). For example, the proximity in some cases could be mitigated by use of the air suspension system and damper stiffness if electronically controlled to instantaneously raise the vehicle on that corner providing increased clearance between the wheel and the inside of the wheel well. With this strategy, the need for physical architectural changes to the body and wheel well to accommodate a larger wheel size can be avoided or at least ameliorated, resulting in a reduced cost to the manufacturer when considering larger wheel diameter for the vehicle. It will be appreciated that various suspension parameters of the suspension system may be adjusted to reduce the likelihood of a wheel ascending ordescending a kerb causing contact between the wheel and the inside of the wheel well. For example, the suspension height, its stiffness, and / or its coefficient of damping may be adjusted. In the case of suspension height, the adjustment would be to raise the ride height. In the case of the suspension stiffness, the adjustment would be to stiffen the suspension. In the case of the coefficient of damping, the adjustment would be to increase it. The angle of steer may be an angle of steer for an axle (generally the front axle) bearing the wheel being controlled by the method, or may be an angle of steer specifically for that wheel itself. The control system may be configured to: receive a speed of the vehicle, and adjust the one or more suspension parameters in dependence on the angle of steer being greater than the angle threshold and the vehicle speed being less than a speed threshold. That is, the present technique is most particularly concerned with climbing or descending a kerb, which will only typically be carried out at relatively low speeds. By carrying out the adjustment in a speed-dependent manner, the adjustment can be excluded (even at large steering angles) at higher speeds, at which the ascending or descending of a kerb is not expected, and at which speeds the suspension adjustments might impact of vehicle handling in an undesirable way. In some implementations, the control system may be configured to: determine if the wheel is being steered towards a kerb, and adjust the one or more suspension parameters in dependence on the wheel being steered towards a kerb, and the angle of steer being greater than the angle threshold. This makes it possible to further narrow the circumstances in which the suspension is adjusted to prepare for kerb ascent / descent, based on a direction of steer and a location of the kerb, thereby reducing the instances in which the suspension is needlessly adjusted. Similarly, the control system may be configured to: receive one or more sensor signals indicative of the proximity of the wheel to a kerb, and adjust the one or more suspension parameters in dependence on the wheel being steered towards the kerb, and the angle of steer being greater than the angle threshold. In this case, the proximity of the kerb (rather than a direction of steer in combination with a general location of the kerb) is used to narrow down the circumstances in which the suspension adjustment is carried out. It will be appreciated that both proximity and direction of steer could be used in conjunction with each other. One of the one or more sensor signals may measure a distance to ground from a fixed point on the vehicle. For example, a wading sensor, typically disposed on a vehicle wing mirror and used to measure the distance to a road or water surface (to infer water depth), could be used to determine the presence or absence of a kerb to a particular side of the vehicle. One of the one or more sensor signals may be an image signal having a field of view which includes an area proximate the wheel. In this case, the captured image may be processed to automatically detect the presence and / or location of a kerb relative to the vehicle. In some embodiments the control system is configured to: determine an applied torque, and adjust the one or more suspension parameters in dependence on the determined torque, and the angle of steer being greater than the angle threshold. In this case, the applied I measured torque is used as an indicator that kerb is being climbed (or descended). For example, it may be determined that a wheel is climbing a kerb if the applied torque (being applied to cause the wheel to climb the kerb) exceeds a first predetermined threshold. It may be determined that a wheel is descending a kerb if the applied torque drops below a second predetermined threshold. The control system may be configured to adjust the one or more parameters only for one wheel of the vehicle in response to the angle of steer being greater than the angle threshold. That is, it is only necessary to adjust the suspension for the wheel which is actually climbing the kerb. The suspension for other wheels of the vehicle could be left unadjusted. However, in other embodiments both the suspension may concurrently be adjusted for both front wheels, or for all wheels, or for both wheels on the side of the vehicle encountering the kerb. A rationale for only adjusting the front suspension is that the rear wheels (in the absence of rear wheel steering) are not angled within the wheel well, and so are less likely to contact it, even when encountering a kerb. Even if rear wheel steering is provided, the rear wheel steering angle is typically much less than a full lock angle on the front wheels. The control system may be configured to adjust the one or more suspension parameters for the suspension of both wheels on one side of the vehicle and not adjust the one or more suspension parameters for the suspension of the wheels on the other side of the vehicle in response to the angle of steer being greater than the angle threshold. The one side in this case is the side of the vehicle predicted to ascend or descend the kerb. The one side of the vehicle may be identified based on one of the techniques described above. A rationale for only adjusting the suspension of wheels to one side of the vehicle is that the wheels to the other side of the vehicle would typically not be expected to encounter the kerb. The control system may be configured to raise the suspension of the wheel to a maximum height of the suspension system in response to the angle of steer being greater than the angle threshold. Alternatively, the suspension may be raised by a fixed amount. The vehicle may be operable in a plurality of terrain modes, each terrain mode being generally optimised for dealing with a particular type or terrain or environmental conditions. In this case, the control system may be configured to adjust the one or more parameters in dependence on the angle of steer being above the angle threshold in only one or more of a subset of the plurality of terrain modes. The control system may be configured to provide a suspension lowering function on all wheels of the vehicle in response to the vehicle reducing below a first predetermined speed. This suspension lowering function provides a kneel mode in which entry to or exit from the vehicle is facilitated by lowering the suspension. It will be appreciated that there is a potentially conflict between the lowering of the suspension for a kneel mode, and the raising of the suspension (as an option for kerb bump mitigation) when encountering a kerb. With the present technique the suspension is raised by an amount greater than that applied by the lowering function in response to the angle of steer being above the angle threshold. According to another aspect of the invention, there is provided a system comprising the control system of any preceding claim and a vehicle suspension system. According to another aspect of the invention, there is provided a vehicle comprising the system or the control system described above. According to another aspect of the invention, there is provided a method for controlling a vehicle suspension system of a vehicle, the method comprising: receiving an angle of steer; determining whether to adjust one or more suspension parameters of a wheel of the vehicle in dependence on the received angle of steer; and outputting a control signal to adjust the one or more parameters in dependence on the determination. According to another aspect of the invention, there is provided computer readable instructions which, when executed by one or more processors, cause the one or more processors to perform the method according to the above. In some example implementations, when the vehicle is travelling at a low speed (for example less than 5kph, for example as measured by a wheel speed sensor) and while manoeuvring the vehicle experiences full steering lock (for example with the use of a steering angle sensor), then an air spring for that corner of the vehicle (corresponding to that wheel) is raised, for example by 10mm, to reduce the risk of interference between the wheel and the vehicle body (inside of wheel well). This system could be further enhanced by dynamic damping if fitted, as the damper could also be stiffened simultaneously with the air spring. 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 anyway 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 vehicle having a control system according to an embodiment of the invention; Figure 2 shows a schematic illustration of the control system within Figure 1; Figure 3 shows a schematic block diagram of the inputs to and outputs from the control method, according to an embodiment; Figure 4 schematically illustrates wheel deflection resulting from encountering a kerb, for each of an unadjusted suspension (Figure 4A), a raised suspension (Figure 4B) and a stiffened suspension (Figure 4C); Figure 5 shows a schematic illustration of a vehicle, and its wheels, encountering a kerb; Figure 6 shows a schematic flow diagram of an example suspension control process; and Figure 7 shows a schematic flow diagram illustrating an example scenario utilising the present technique. DETAILED DESCRIPTION A system in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 1. As shown in Figure 1, a vehicle 1 is provided, which comprises a set of road wheels 10a, 10b, 10c, 10d, each mounted to a respective active suspension assembly 12a, 12b, 12c, 12d. The active suspension assemblies are individually controllable by a controller 200, in a manner which will be described below. The active suspension assemblies 12a, 12b, 12c, 12d may each report back a current suspension state, including suspension height and stiffness. The front road wheels 10a, 10b are steerable (and are shown in Figure 1 as being angled so that the vehicle 1 will steer right when moving forwards), and the rear road wheels 10c, 10d may in some implementations also be steerable. Although not shown in the interests of clarity, the vehicle 1 is also provided with a propulsion system which may include one or both of an internal combustion engine and a set of electric motors, a steering assembly, and other vehicle systems. A sensor package 14 is shown, and is able to provide sensor inputs to the controller 200. In practice, the sensor package 14 may include various sensors and systems provided on (or even offboard) the vehicle 1. The sensor package 14 may for example include a GPS system (for determining and outputting vehicle position and / or speed / velocity), a telematics system (which may include accelerometers able to determine vehicle roll and pitch), a camera system or other environmental imaging system, amongst others. One sensor system shown separately in Figure 1 is a wade detection system 16 mounted to or at the wing-mirrors of the vehicle 1. Conventionally used to measure water depth (by measuring the distance to a water surface beneath the wingmirrors), this can be used with the present technique to determine whether the vehicle 1 is proximate a kerb (which will register as a reduced distance from the sensor compared with a road surface on which the vehicle 1 is travelling). The present technique can be used with any suspension system which is capable of adjusting a suspension height (ride height) and / or is capable of adjusting a stiffness and / or damping coefficient of the suspension. Suspension systems commonly comprise two interrelated parts, these being a spring, and a damper. The spring permits displacement / deflection of the wheel in response to a force, but returns the position of the wheel (via a series of oscillations) to its original state. The amount of permitted deflection and the oscillation behaviour is a function of the spring rate of the springs, with a higher spring rate providing a firmer feel and a lower spring rate providing a softer feel. The springs may be air springs, in which case the spring rate is a function of the material and structure encapsulating the air, and the volume of air in the structure. By injecting additional air into the air spring, the ride height is increased (and similarly by extracting air from the air spring, the ride height is decreased). Additionally, adding air into the air spring stiffens the air spring, and thus the suspension. The damper resists (slows) the movement permitted by the springs, and dampens the oscillations to bring the wheel back to a steady (original) state more quickly. The amount of damping provided by the dampers is governed by a coefficient of damping. The damper is typically an oil-filled cylinder containing a piston, which moves within the cylinder as the wheel moves, but which resists such movement due to the oil needing to flow around or through (a valve in) the piston, and the frictional losses of this process leading to kinetic energy being dissipated as heat. Various techniques are known for adapting the coefficient of damping of a damper, for example a in the cylinder which is able to open (to reduce damping by permitting a greater flow rate of oil) and close (to increase damping by restricting the flow rate of oil), and the use of magnetorheological fluid with a controllable viscosity. The present technique adjusts the suspension of a wheel in anticipation of, or upon, ascending ordescending a kerb. Preferably, when climbing ordescending a kerb, the suspension (height) should be raised, and both the spring stiffness (of the air spring) and the damping coefficient (of the corresponding damper) should be increased. However, some of the benefits of the present technique are obtained by adjusting only one or two of these parameters. In some cases a suspension assembly may not include both adaptive spring suspension and adaptive damping, in which case it will only be possible to adjust certain parameters which reduce the likelihood of the wheel coming into contact with the inside of the wheel arches I wells. The present technique influences the existing suspension control system to increase the stiffness and / or damping (increased spring rate and / or increased damping rate) and / or ride height (raised suspension) provided by the suspension system for individual or groups (e.g. left or right) of wheels of the vehicle, to permit the vehicle to ascend or descend a kerb without a wheel interfering with (contacting) an inside surface of its respective wheel arch. To achieve this, control currents for the dampers and the air spring volumes of the suspension assemblies 12a, 12b, 12c, 12d may be individually and dynamically controlled by the controller 200. The various controllable parameters of the suspension system may comprise a spring rate and / or a damping rate of one or more elements of the suspension system (such as a damper or an air spring). Increasing the spring rate will have the effect of making the suspension stiffer, while increasing the damping rate will have the effect of increased dampening of vibration / oscillation of the suspension system. The active suspension may be configured for active damping. The active damping may be controlled using a pump-controlled hydraulic circuit or equivalent. Bump force and / or rebound force may be individually controllable. The active suspension may be configured for active spring control. The active spring control may be controlled using a pump-controlled pneumatic system, or equivalent. Spring force (spring rate) may be controllable. Ride height of the vehicle body (ora portion of the vehicle body where only a subset of the vehicle wheels are subject to ride height adjustment) above a prevailing driving surface may be controllable, for example by altering an amount of air in air springs - with an increased volume of air increasing the ride height and a reduced volume of air reducing the ride height. The vehicle 1 as illustrated in Figure 1 comprises one controller 200, although it will be appreciated that this is merely illustrative. The controller 200 is configured to implement any one or more of the methods described herein. Figure 2A illustrates how a control system 208 (which may be provided in part by the controller 200) may be implemented. The control system 208 of Figure 2A illustrates the controller 200. In other examples, the control system 208 may comprise a plurality of controllers 200. In examples any suitable control system 208 can be used. The controller 200 of Figure 2A includes at least one processor 202; and at least one memory device 204 electrically coupled to the electronic processor 202 and having instructions 206 (for example a computer program) stored therein, the at least one memory device 204 and the instructions 206 configured to, with the at least one processor 202, cause any one or more of the methods described herein to be performed. Also illustrated in the example of Figure 2A are one or more vehicle systems 226. In examples, the vehicle system(s) 226 can comprise any suitable vehicle system(s). For example, the vehicle system(s) 226 can comprise any suitable vehicle system(s) 226 from which the control system 208 can receive and / or to which the control system 208 can transmit, directly or indirectly, one or more signals 20, for example to control the suspension system 12a, 12b, 12c, 12d of the vehicle 1. Such vehicle systems 226 may include the various systems providing the sensor functionality 14, the wade sensors 16, the suspension systems 12a, 12b, 12c, 12d, a steering system and so on. Figure 2B illustrates a non-transitory computer readable storage medium 218 comprising the instructions 206 (computer software). Accordingly, Figure 2B illustrates a non-transitory computer readable medium 218 comprising computer readable instructions 206 that, when executed by a processor 202, cause performance of at least one or more of the methods described herein. Figure 3 schematically illustrates a control block diagram for the present technique, showing the main signals received at and output by the controller 200. In particular, the input signals include a speed signal S1, which may be received from a GPS system, or from a wheel speed sensor (from an ABS system) for example, a steering angle S2, which may include a steering direction, and which may be provided by a steering system of the vehicle, a roll angle S3, which may be provided by a vehicle telematics system, a kerb presence signal S4, indicative of the presence and position (for example proximate the left side or the right side of the vehicle 1) of a kerb, and a torque signal S5, indicative of an amount of torque being applied in moving the vehicle. The kerb presence signal S4 may be generated in response to imaging of the terrain in the vicinity of the vehicle using a camera system, and processing the images to detect a kerb, or may be generated in response to a raised area proximate the vehicle as identified by the wade detection system 16. The torque signal S5 may be significant in determining that a particular wheel 10a, 10b, 10c, 10d of the vehicle is currently climbing or descending a kerb. In particular, when a wheel is climbing a kerb, an increased torque is required (compared with when the vehicle is traversing a flat road surface), while when a wheel is descending a kerb, an opposite torque is experienced as the wheel descends the kerb underthe weight of the vehicle 1 (ratherthan due to the application of propulsion torque). Depending on the inputs S1 to S5, a first output S6 is made to an air suspension system for one or more of the vehicle wheels 10a, 10b, 10c, 10d, to raise or lower the suspension, and / or a second output S7 is made to dynamic dampers for the vehicle wheels 10a, 10b, 10c, 10d, to modify a damping coefficient of the suspension. In some implementations, the signals S1 to S4 may trigger the suspension system to be adjusted in preparation for a road wheel to climb or descend a kerb, while the torque signal S5 may be used to confirm that the ascent or descent is taking place, and be used to ensure that the adjusted suspensions settings persist until the kerb ascent or descent has completed. Figures 4A to 4D show the effect of applying the output signals S6 and S7 to a wheel of the vehicle 1. Figure 4A (left) shows a position of the wheel 10 within a wheel arch 15 of the vehicle 1 while the vehicle 1 is stationary and on a level surface. In this state there is substantial clearance I gap (distance di) between the upper surface of the wheel 10 and the underside of a top portion of the wheel arch 15, and also a substantial clearance I gap (distance d2) between a rear surface of the wheel 10 and a rear inner surface of the wheel arch 15. Figure 4A (right) shows how the wheel 10 moves upwardly into the wheel arch 15 while the vehicle 1 is climbing ordescending a kerb. It can be seen that in this state the upper surface of the wheel 10 is very close to the underside and rear of the wheel arch 15, with distances di and d2 becoming small or even zero. In practice, during a turn the wheel 10 is angled within the wheel arch, and due to having a particular width (thickness) has an increased likelihood of coming into contact with the inside of the wheel arch 15. This is particularly the case if the wheel of the vehicle is larger than originally specified for the arch 15 at the design stage. Figure 4B (left) shows a position of the wheel 10 within the wheel arch 15 while the vehicle 1 is stationary, but with the suspension being raised (based on the signal S6). It can be seen that the gap di between the top of the wheel 10 and the bottom of the wheel arch 15 is larger than the gap di with Figure 4A (left), similarly the gap d2 between the rear surface of the wheel 15 and the rear inner surface of the wheel arch 15 is larger than the gap d2 with Figure 4A (left). As a result, when the wheel 10 ascends or descends the kerb, while the wheel 10 is still deflected (as with Figure 4A), giving rise to the position shown in Figure 4B (right), since the amount of deflection is substantially the same as with Figure 4A but the starting point provided for a larger gap, the wheel 10 remains an appropriate distance from the inside of the wheel arch 15 even when ascending or descending the kerb. Figure 4C (left) shows a position of the wheel 10 within the wheel arch 15 while the vehicle 1 is stationary, but with the suspension being stiffened I damping coefficient modified (based on the signal S7). It can be seen that the position of the wheel within the gap between the top of the wheel 10 and the bottom of the wheel arch 15 is approximately the same as with Figure 4A (left). However, in this case, when the wheel 10 ascends or descends the kerb, the wheel 10 is deflected less due to the stiffer suspension, giving rise to the position shown in Figure 4C (right), again with the wheel 10 remaining an appropriate distance (di and d2) from the inside of the wheel arch even when ascending ordescending the kerb. It will be appreciated that the suspension stiffness, damping and height may be simultaneously adjusted by the present technique (using the signals S6 and S7 in parallel), resulting in a combinatorial beneficial effect on the space between the wheel and the arches while the vehicle is ascending or descending a kerb. Referring to Figures 5A and 5B, the vehicle 1 is shown prior to a kerb ascent (Figure 5A) and prior to a kerb descent (Figure 5B). For each of Figures 5A and 5B the top portion shows a plan view of the vehicle and kerb, while the bottom portion shows a view of the wheel of the vehicle and its relationship to the kerb, when viewed from behind. In Figure 5A, the right-hand side of the vehicle 1 is adjacent to a kerb 500, which is to the right of the vehicle (that is, the wheels of the vehicle are all on the road). The right front wheel 10b of the vehicle is angled towards the kerb 500. As such, if the vehicle 1 is travelling in a forward direction the right front wheel 10b will climb the kerb 500. Since this can be expected to happen only at low speeds, and with relatively large steering angles, a condition for adjusting the vehicle suspension may be set in dependence on speed and steering angle criteria (such as that the speed is less than a speed threshold, and the steering angle is greater than an angle threshold). In Figure 5B, the right-hand side of the vehicle 1 is adjacent to a kerb 500, but on the pavement or other surface and off the road (that is, the left-side wheels of the vehicle are on the road, whereas the right-side wheels of the vehicle are on the pavement, with the kerb being beneath the vehicle). The right front wheel 10b of the vehicle is angled towards the kerb 500. As such, if the vehicle 1 is travelling in a forward direction the right front wheel 10b will descend the kerb 500. Again, since this can be expected to happen only at low speeds, and with relatively large steering angles, a condition for adjusting the vehicle suspension may be set in dependence on speed and steering angle criteria (such as that the speed is less than a speed threshold, and the steering angle is greater than an angle threshold). In Figure 6, an example process for the suspension control is shown. At a step A1, the speed of the vehicle 1 is determined. This may be a wheel speed measured at the vehicle wheels or a vehicle speed measured by a GPS system of the vehicle, for example. At a step A2 the vehicle speed is compared with a speed threshold. If the vehicle speed is greater than the speed threshold, the kerb encounter function is not activated and the process returns to the step A1, where the vehicle speed continues to be monitored. If the vehicle speed is determined at the step A2 to be less than the speed threshold, then at a step A3 a steering angle is obtained. At a step A4 the steering angle is compared with an angle threshold. If the steering angle is less than the angle threshold, the kerb encounter function is not activated and the process returns to the step A1. If the steering angle is determined at the step A4 to be greater than the angle threshold, the system attempts to identify a likelihood of one or more wheels of the vehicle encountering a kerb at a step A5, and identifying which (if any) of the wheel suspensions to raise and / or stiffen. The step A5 includes identifying the presence (or absence) of a kerb in the vicinity of the vehicle, and if a kerb is identified, determining whether the left front or right front wheel of the vehicle is likely to encounter it, depending on the identified location of the kerb with respect to the vehicle, a current steering direction, and driving direction - forward or reverse. Table 1 below sets out the suspension adjustment actions which may take place in response to particular inputs. If no kerb is detected at the step A5, the process returns to the step A1. If it is determined at the step A5 that the front-right suspension should be raised and / or stiffened / dampened, then at a step A6 signals are sent to the suspension system to trigger that adjustment. If it is determined at the step A5 that the front-left suspension should be raised and / or stiffened / dampened, then at a step A7 signals are sent to the suspension system to trigger that adjustment. Following this, at a step A8 the system monitors for a stop condition to discontinue the kerb encounter function. Stop conditions may include the vehicle coming to a stop, the vehicle speed increasing to above a threshold value (which may be the same or different to the threshold speed value used at the step A2), the steering angle dropping below a threshold value (which may be the same or different to the threshold angle used at the step A4), the position of the vehicle with respect to the kerb satisfying one or more criteria (for example one or more of the wheels being at least a predetermined distance from the kerb, or a particular number or ones of the wheels, such as both wheels to one side of the vehicle, having ascended, or descended, the kerb), a time period elapsing, or various other conditions. At a step A9 it is determined whether such a stop condition has occurred. If not, then the process returns to the step A8 where monitoring for a stop condition continues. If a stop condition does occur, then at a step A10 the suspension settings are reverted, for example by lowering the suspension, and softening the suspension, and the process then returns to the step A1. Kerb detected Kerb to left of vehicle Kerb to right of vehicle Front wheels pointed left Front wheels pointed right Drive or Reverse Action No No No N / A N / A N / A No action Yes Yes No Yes No Drive Adjust front left Yes Yes No No Yes Drive No action Yes No Yes Yes No Drive No action Yes No Yes No Yes Drive Adjust front right Yes Yes No Yes No Reverse No action Yes Yes No No Yes Reverse Adjust front left Yes No Yes Yes No Reverse Adjust front right Yes No Yes No Yes Reverse No action Table 1 considers only the likely interactions of the front vehicle wheels with a kerb. The front wheels are important because large steering angles are achieved only by the front wheels, and these determine both the likelihood of encountering the kerb, and the likelihood of the wheel conflicting with the arches. Accordingly, Table 1 relates to an implementation in which adjustments are made only to the front suspension. However, if it is desirable to control also the rear wheel suspension, then it may simply be enough to simultaneously adjust the front and rear wheel suspension (of the same side) under the control conditions of Figure 5 and Table 1 (that is, where Table 1 indicates that the front left suspension should be adjusted, then the rear left suspension will be adjusted too, and where Table 1 indicates that the front right suspension should be adjusted, then the rear right suspension will be adjusted too). Alternatively, rather than only adjusting the suspension for the wheel(s) likely to encounter the kerb, the suspension for both front wheels could be adjusted. In this case, where Table 1 indicates that the front left suspension should be adjusted, then the front right suspension will be adjusted too, and where Table 1 indicates that the front right suspension should be adjusted, then the front left suspension will be adjusted too. Finally, rather than adjusting the suspension for only some wheels of the vehicle, similar benefits can be achieved by simultaneously adjusting all wheels of the vehicle under the control conditions of Figure 5 and Table 1 (which will involve adjusting the suspension in relation to all wheels of the vehicle underthe control conditions of Figure 6 and Table 1), such that where Table 1 indicates that the front left suspension should be adjusted, then the front right suspension, and the suspension for both rear wheels will be adjusted too, and where Table 1 indicates that the front right suspension should be adjusted, then the front left suspension, and the suspension for both rear wheels will be adjusted too. In an alternative implementation, the step A5 could be carried out entirely based on torque. In particular, it can be assumed that when ascending a kerb, increased motor torque will be required (compared with progressing on a flat driving surface), whereas when descending a kerb, reduced motor torque will be required (compared with progressing on a flat driving surface). Accordingly, in such an implementation, if no raised or reduced torque requirement is identified, the process may simply return from the step A5 to the step A1 (with no suspension adjustment), whereas if a raised torque requirement is identified then the process may progress to the step A6 or A7 (or both A6 and A7 for the suspension for both front wheels to be adjusted), and from there onto the steps A8 to A10, as per the above. In this implementation the step A8 (end condition) may be reached when the torque requirement reverts to an expected level fordriving on a flat surface (no kerb). Various use cases may be considered for triggering the raising I stiffening of the suspension. For example: (A) The vehicle is being driven on the left side of the road, adjacent to a kerb. The vehicle is slowed, and the steering angle adjusted to angle the wheels towards the kerb. The relatively slow speed and the relatively high steering angle are indicative of a likelihood of mounting (ordescending) a kerb, and so the suspension is raised and / or stiffened for at least the front left wheel of the vehicle. The front left wheel encounters and climbs the kerb, and due to the raised I stiffened suspension has a reduced likelihood of the wheel coming into contact with the inside of the wheel arch. The steering angle of the front wheels is then adjusted in the opposite direction to bring the longitudinal axis of the vehicle generally parallel with the kerb. During this time the rear left wheel of the vehicle also mounts the kerb. Optionally the suspension on this rear wheel may also be raised and / or stiffened, although this is less important since the risk of contact of the wheel with the arches is less in the absence of the wheel being turned (steered) within the arch. The suspension settings are returned to normal after an end condition, as discussed above. (E3) The vehicle is being driven on the left side of the road, adjacent to a kerb. The vehicle is slowed, and the steering angle adjusted to angle the wheels towards the kerb. The relatively slow speed and the relatively high steering angle are indicative of a likelihood of mounting (ordescending) a kerb, and so the suspension is raised and / or stiffened for at least the front left wheel of the vehicle. The front left wheel encounters and climbs the kerb, and due to the raised I stiffened suspension has a reduced likelihood of the wheel coming into contact with the inside of the wheel arch. Unlike scenario A, with scenario B the vehicle is not steered immediately to be parallel. Instead, the front right wheel of the vehicle encounters and climbs the kerb (either before or after the rear left wheel, depending on the angle of the vehicle with the kerb), and finally the rear right wheel of the vehicle climbs the kerb. It is desirable in this use case that at least the front right wheel suspension be adjusted. This could be achieved by either raising I stiffening both the left and right front wheels of the vehicle at the same time before the left front wheel climbs the kerb), or by raising I stiffening the right front wheel suspension later (but before the front right wheel climbs the kerb). The timing for the raising / stiffening of the suspension of the right front wheel of the vehicle could be based on the steering angle and speed of the vehicle, to define an offset for the triggering of the raising I stiffening of the suspension of the front right wheel. (C) As per scenarios A or B, but the right-hand side of the vehicle climbs a kerb to the right of the vehicle. (D) The vehicle is being manoeuvred (preferably at a low speed), and the steering angle exceeds a threshold value for which mounting a kerb may result in interference between a front wheel and the respective wheel arch of the vehicle. The suspension for one or both of the front wheels of the vehicle is therefore raised and / or stiffened in case one or both wheels encounters a kerb. In a simple case this may happen when the steering angle exceeds an angle threshold, and preferably (although not essentially in some implementations) when the vehicle or wheel speed is below a speed threshold. In some cases, a further condition may apply forthe suspension to be raised and / orstiffened, forexample a torque requirement to progress the vehicle exceeding a kerb climbing threshold (indicative that a wheel of the vehicle has encountered and started to climb a kerb) or dropping below a kerb descending threshold (indicative that a wheel of the vehicle has encountered and started to descend a kerb). Other conditions could be used instead or as well - such as the kerb being detected by one or more vehicle sensors, as described above. It will be appreciated that the above use cases are exemplary, and other cases may be envisaged. Where the vehicle is manoeuvring in reverse, the rear or front wheels may encounter the kerb first, depending on the relative positioning of the vehicle and the kerb, and the steering angle. Again, in some implementations the suspension may only be adjusted forthe front wheels. As will be understood from the above, in some cases the vehicle may entirely ascend the kerb (that is, both left and right-side wheels of the vehicle may climb the kerb), or entirely descend the kerb (that is, both left and right side wheels of the vehicle may drop down from the kerb). Provided that the system is able to track the relative positions of the kerb with the wheels of the vehicle or otherwise identify that the wheels encounter the kerb (for example based on torque requirements), it is possible to raise or stiffen the suspension for each wheel at or just before that wheel encounters the kerb, and retain that state until the kerb has been completely ascended or descended (either by that wheel, or by the vehicle as a whole). For example, if a vehicle is to entirely mount a kerb to the left of the vehicle, the front-left wheel 10a may first climb the kerb, followed by the rear-left wheel 10d, followed by the front-right wheel 10b, followed by the rear-right wheel 10c. Rather than adjusting the suspension of different wheels of the vehicle at different times in a sequence, the suspension of all wheels of the vehicle (or at least all of those which will be subject to adjustment at all) may be simultaneously adjusted (raised and stiffened) in advance of the first of the wheels mounting the kerb, until a stop condition has been reached (which may be for example that the steering angle changes to satisfy a predetermined criteria, or that all wheels have ascended the kerb, or that the vehicle has come to a rest, or until the speed has exceeded a threshold, optionally for longer than a predetermined duration). The vehicle may be configurable to operate in a kneel mode. With the kneel mode the suspension height (of all wheels) is automatically lowered under certain conditions, to facilitate entry to or exit from the vehicle. The condition may be for the vehicle speed dropping below a second speed threshold for at least a predetermined period of time. There is an interaction between the kneel mode and the presently described kerb bump mitigation function in that they both have low speed activation requirements, but they each require a generally opposite adjustment of the suspension - with the kerb bump mitigation function requiring ride height to be raised rather than lowered. One way of adjudicating between the two modes is to rely on the steering angle, with the kerb mitigation function taking precedence over the kneel mode when the steering angle exceeds the angle threshold. Referring to Figure 7, an example scenario using the present technique and switching between the kneel mode and the kerb bump mitigation function is illustrated. At a step B1, the vehicle slows to less than 5kph. At a step B2, the vehicle has remained at a speed of less than 5kph for at least X seconds (X may be any number of seconds, for example 2 seconds). As a result, at a step B3 the vehicle begins to kneel (suspension lowers). This functionality is intended to lower the vehicle to aid in entry to or exit from the vehicle when it comes to a stop. However, this functionality provides a conflict with a need to mount a kerb without the wheel contacting the inside of the wheel arches. At a step B4, the vehicle achieves a steering angle greater than 25 degrees and a speed of less than 2kph for 1.5 seconds, at which point at a step B5 the suspension of the front kerbside wheel (and optionally others) is raised for a period of time. During this time, at a step B6 the kerb is mounted with the suspension in raised condition. Subsequently, at a step B7, if the vehicle speed is still less than 5kph when vehicle descends kerb, the suspension is raised, or remains raised. At a step B8, the suspension returns to previous or standard settings after the vehicle stops for more than 5 seconds, or the kneel condition is manually selected by a user. In some cases the suspension may be raised to a maximum (permissible) value to prepare for climbing or descending a kerb. In other cases the suspension may be raised, but to a value less than the maximum possible value. The suspension assemblies may comprise a height sensor which is able to report back, to the controller, a current suspension height value. The controller may use the reported height to confirm that the suspension has been adequately raised (and if not to (for example) inject more air to raise it further), and I or to identify by how much the suspension is required to be raised. Where the vehicle is currently in a kneel mode (suspension lowered to facilitate entry into or exit from the vehicle), the height sensor will also be able to indicate this, should this information not be available directly. In cases in which the vehicle includes (automatically or manually) selectable driving modes, the steering-angle dependent suspension adjustment function described herein may only apply in a subset of these modes. For example, this function may not be applied in an off road mode or a sports mode, but may apply in a general mode or city driving mode. Since the present technique may be applied to both climbing a kerb and dropping down from a kerb, in some implementations the controller 200 may, following the kerb being climbed and prior to the vehicle being powered off, store state information including the fact that the vehicle has already ascended a kerb, and optionally including information regarding the position of the kerb relative to the vehicle. Then, when the vehicle is powered on, the controller 200 is able to recall that the vehicle is currently partly on the kerb (and preferably its position relative to the kerb), and thus prepare the suspension for one or more wheels of the vehicle to be raised and / or stiffened in preparation for (or when) descending the kerb. Alternatively, the vehicle may be able to self-determine that it is partly parked over a kerb based on (for example) a roll sensor (accelerometer) or similar, which can return whether the vehicle is level (and thus not parked over a kerb) or in a partially rolled position (which may indicate that it is parked over a kerb, with some of the wheels up on the pavement and the others down on the road). The steering angle threshold used to trigger or feed into the suspension adjustment may be any value. Preferably though a value in the range of 15 to 40 degrees, or more preferably between 20 and 30 degrees, and still more preferably approximately 25 degrees, is used. The ride height adjustment may be any value, but is preferably between 5mm and 25mm, and more preferably approximately 10mm. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. A control system for controlling a suspension system of a vehicle, the control systemcomprising one or more processors collectively configured to:receive an angle of steer;determine whether to adjust one or more suspension parameters of a wheel of the vehicle in dependence on the received angle of steer being greater than an angle threshold; andoutput a control signal to adjust the one or more suspension parameters in dependence on the determination.

2. The control system of claim 1, wherein the one or more suspension parameters compriseone or more of a suspension height, a suspension stiffness, and a damping coefficient.

3. The control system of claim 1 or claim 2, configured to:receive a speed of the vehicle, andadjust the one or more suspension parameters in dependence on the angle of steer being greater than the angle threshold and the vehicle speed being less than a speed threshold.

4. The control system of any preceding claim, configured to:determine if the wheel is being steered towards, or is proximate, a kerb based on one or more sensor signals, andadjust the one or more suspension parameters in dependence on the wheel being steered towards the kerb or being proximate the kerb, and the angle of steer being greater than the angle threshold.

5. The control system of claim 4, wherein one of the one or more sensor signals measures adistance to ground from a fixed point on the vehicle.

6. The control system of claim 4 or claim 5, wherein one of the one or more sensor signals isan image signal having a field of view which includes an area proximate the wheel.

7. The control system of any preceding claim, configured to:determine an applied torque, andadjust the one or more suspension parameters in dependence on the determined torque, and the angle of steer being greater than the angle threshold.

8. The control system of any preceding claim, configured to adjust the one or more suspensionparameters only for one wheel of the vehicle in response to the angle of steer being greater than the angle threshold.

9. The control system of any of claims 1 to 7, configured to adjust the one or more suspensionparameters for both wheels on one side of the vehicle and not adjust the one or more suspension parameters for wheels on the other side of the vehicle in response to the angle of steer being greater than the angle threshold.

10. The control system of any preceding claim, configured to raise the suspension of the wheelto a maximum height of the suspension system in response to the angle of steer being greater than the angle threshold.

11. The control system of any preceding claim, wherein the vehicle is operable in a plurality ofterrain modes, and wherein the control system is configured to raise and / or stiffen the suspension of the wheel in dependence on the angle of steer being above the angle threshold in only one or more of a subset of the plurality of terrain modes.

12. A system comprising the control system of any preceding claim and a vehicle suspensionsystem.

13. A vehicle comprising the system of claim 12 or the control system of claims 1 to 11.

14. A method for controlling a vehicle suspension system of a vehicle, the method comprising:receiving an angle of steerdetermining whether to adjust one or more suspension parameters of a wheel of the vehicle in dependence on the received angle of steer; andoutputting a control signal to adjust the one or more suspension parameters in dependence on the determination.

15. Computer readable instructions which, when executed by one or more processors, cause theone or more processors to perform the method according to claim 14.s

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