Control system and method for vehicle

Abstract

Aspects of the invention relate to a speed control system (15) for a vehicle (10), a method and a vehicle (10). One aspect relates to an off-road speed control system (15). The system (15) causes the vehicle (10) to travel at the target speed value. The system (15) receives travel height information indicative of a travel height setting of a suspension of the vehicle (10) and sets a maximum vehicle speed limit based at least in part on the travel height information.

Description

Technical Field

[0001] The present disclosure relates to a control system and method for a vehicle. Aspects of the invention relate to a speed control system for a vehicle, a system for controlling a vehicle speed, a vehicle, a method for controlling a vehicle speed, and a non-transitory computer-readable storage medium.

[0002] The contents of WO2013 / 124321 are incorporated herein by reference. Background Art

[0003] It is known to provide a speed control system for a vehicle, in particular a speed control system for causing the vehicle to operate according to a target speed value. It is desirable to provide an improved speed control system for assisting a driver in negotiating terrain having obstacles such as rocks, boulders or other obstacles with abrupt changes in height of the driving surface that must be negotiated.

[0004] It is an object of the present invention to address one or more disadvantages associated with the prior art. Summary of the invention

[0005] Aspects and embodiments of the present invention provide a speed control system, a system for controlling the speed of a vehicle, a vehicle and a method for controlling the speed of a vehicle as claimed in the accompanying claims.

[0006] According to one aspect of the present invention, there is provided an off-road speed control system for a vehicle, the speed control system being configured to cause the vehicle to operate according to a target speed value, the speed control system comprising one or more controllers, the speed control system being configured to:

[0007] receiving ride height information indicative of a ride height setting of a suspension of the vehicle; and

[0008] A maximum vehicle speed limit is set based at least in part on the ride height information.

[0009] Embodiments of the present invention have the advantage that vehicle composure and driver comfort may be enhanced. This is because the amount of available travel of the vehicle's suspension is dependent on the vehicle ride height setting. By limiting vehicle speed based on ride height information, a reduction in vehicle noise, vibration and harshness may be enjoyed. This is at least in part due to a reduced probability of the suspension reaching the limit of travel when travelling over terrain. It will be appreciated that for lower values ​​of vehicle ride height, the maximum vehicle speed limit may be lower.

[0010] In some embodiments, reduced wear may be enjoyed while preventing the amount of travel of the vehicle's suspension from reaching travel limits.

[0011] The ride height information may include: i) a signal indicative of a predetermined ride height setting for an electronically adjustable suspension system of the vehicle; or ii) a signal indicative of a ride height difference between a measured ride height and a reference ride height provided by a passive suspension system of the vehicle.

[0012] Optionally, the speed control system is configured to receive coupling information indicative of an amount of coupling of the front wheels and the rear wheels of the vehicle; and

[0013] A maximum vehicle speed limit CA_set-speed is further set based at least in part on the coupling information.

[0014] It should be understood that references to front and rear wheels refer to the front and rear wheels that support the vehicle on the terrain.

[0015] For higher amounts of articulation at the front and rear wheels of the vehicle, the value of CA_set-speed may be lower.

[0016] For lower values ​​of vehicle ride height, the value of CA_set_speed may be lower.

[0017] Optionally, the speed control system is configured to:

[0018] determining a cross-articulation value indicating an amount of cross-articulation of wheels of the vehicle based on the articulation information; and

[0019] A maximum vehicle speed limit CA_set-speed is set based at least in part on the cross-link value.

[0020] Optionally, for higher values ​​of the cross-join value CrossArtc_L, the value of CA_set-speed is lower.

[0021] Alternatively, for lower values ​​of vehicle ride height, the value of CA_set_speed is lower.

[0022] Optionally, the cross join value depends on:

[0023] a first coupling value indicating the degree to which the wheels of the first diagonal wheelset are coupled in a positive or negative direction relative to a baseline value and the degree to which the wheels of the pair are coupled in phase with each other;

[0024] a second coupling value indicating the degree to which the wheels of a second diagonal wheelset, different from the first diagonal wheelset, are coupled in a positive or negative direction relative to the baseline value and the degree to which the wheels of the pair are coupled in phase with each other; and

[0025] The first and second coupling values ​​correspond to the extent to which the respective pairs move in anti-phase with respect to each other.

[0026] It will be appreciated that the cross-coupling value is a measure of the degree of cross-coupling of a first wheelset and a second wheelset, wherein the second wheelset is spaced apart from the first wheelset along the longitudinal axis of the vehicle. The cross-coupling value is dependent on:

[0027] a first coupling value indicating the degree to which the wheels of the first diagonal wheelset are coupled in a positive or negative direction relative to a baseline value and the degree to which the wheels are coupled in phase with each other;

[0028] a second coupling value indicating the degree to which the wheels of a second diagonal wheelset, different from the first diagonal wheelset, are coupled in a positive or negative direction relative to the baseline value and the degree to which the wheels are coupled in phase with each other; and

[0029] The first coupling value and the second coupling value correspond to the extent to which the respective pairs move in anti-phase with respect to each other.

[0030] Optionally, the cross-join value CrossArtc_L is calculated according to the following formula:

[0031] CrossArtc_L=abs(FL-FR)+abs(RL-RR)+abs(FL-RL)+abs(FR-RR)-abs(FL-RR)-abs(FR-RL)

[0032] Among them, FL is the left front suspension height, FR is the right front suspension height, RL is the left rear suspension height, and RR is the right rear suspension height.

[0033] Optionally, the speed control system is configured to receive a signal indicative of a vehicle speed VREF, the speed control system being configured to further limit the vehicle speed dependent on the value of VREF.

[0034] In another aspect of the present invention, there is provided a system for controlling vehicle speed, the system comprising:

[0035] An off-road speed control system according to the preceding aspect; and

[0036] One or more sensors configured to output information indicative of an amount of articulation of the front and rear wheels of the vehicle.

[0037] In some embodiments, one or more sensors may include an accelerometer or a gyroscope. Other suitable sensors are known to those skilled in the art and may be used in further embodiments.

[0038] In yet another aspect of the present invention, there is provided a vehicle comprising the off-road speed control system of the preceding aspect or the system of the preceding aspect.

[0039] In another aspect of the present invention, a method for controlling vehicle speed implemented by an off-road speed control system is provided, the method comprising:

[0040] causing the vehicle to operate according to the target speed value;

[0041] receiving ride height information indicative of a ride height setting of a suspension of the vehicle; and

[0042] A maximum vehicle speed limit is set based at least in part on the ride height information.

[0043] The ride height information may include: i) a signal indicative of a predetermined ride height setting for an electronically adjustable suspension system of the vehicle; or ii) a signal indicative of a ride height difference between a measured ride height and a reference ride height provided by a passive suspension system of the vehicle.

[0044] Optionally, the method comprises:

[0045] receiving coupling information indicating an amount of coupling of front wheels and rear wheels of the vehicle; and

[0046] A maximum vehicle speed limit is further set based at least in part on the connection information.

[0047] Optionally, the method comprises:

[0048] determining a cross-coupling value indicating an amount of cross-coupling of wheels of the vehicle based on the coupling information; and

[0049] A maximum vehicle speed limit CA_set-speed is set based at least in part on the cross-link value.

[0050] Optionally, the method comprises:

[0051] According to the higher value of the cross-join value CrossArtc_L, the value of CA_set-speed is set to a lower value; and

[0052] Based on the lower value of the vehicle's ride height, the value of CA_set_speed is set to a lower value.

[0053] In yet another aspect of the present invention, a non-transitory computer-readable storage medium storing instructions is provided, which, when executed by one or more electronic processors, causes the one or more electronic processors to perform the method of the aforementioned aspect.

[0054] Within the scope of the present application, it is expressly intended that the various aspects, embodiments, examples and alternatives set forth in the preceding paragraphs, claims and / or the following description and drawings, in particular their individual features, may be employed independently or in any combination. That is, all embodiments and / or features of any embodiment may be combined in any manner and / or combination unless these features are incompatible. The applicant reserves the right to change any originally filed claim or to file any new claim accordingly, including the right to amend any originally filed claim to be subordinate to and / or incorporate any features of any other claim, even though protection was not originally claimed in this manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0056] Figure 1 A schematic diagram showing a vehicle having a speed control system according to an embodiment of the present invention is shown;

[0057] Figure 2 A schematic diagram showing a steering wheel of a vehicle having a speed control system according to an embodiment of the present invention;

[0058] Figure 3 A schematic diagram of a vehicle control unit or system (VCU) according to an embodiment of the present invention is shown;

[0059] Figure 4 Is has Figure 3 Schematic diagram of the change of the CA_set_speed value of the VCU of the vehicle according to VREF and S_comfort;

[0060] Figure 5 A schematic diagram of a VCU according to an embodiment of the present invention is shown;

[0061] Figure 6 It is shown that Figure 5 A diagram of an expected change in vehicle speed VREF as a function of time after a reduction in the value of CA_set_speed is triggered after a vehicle of a VCU encounters a bump in a driving surface sufficient to trigger a reduction in vehicle speed, the diagram illustrating the reduction in speed of a vehicle having ride height settings of (a) off-road height, (b) normal road height, and (c) approach height;

[0062] Figure 7 Shows Figure 5 The operation mode of the VCU of the implementation mode; and

[0063] Figure 8 (a) by Figure 3The VCU of an embodiment includes and is configured to implement according to Figure 3 The electronic controller 15' of the speed control system of the embodiment of the present invention and (b) the electronic controller 15' of the speed control system of the present invention are Figure 5 The VCU of an embodiment includes and is configured to implement according to Figure 5 A schematic diagram of an electronic controller of an embodiment of a speed control system. DETAILED DESCRIPTION

[0064] The contents of WO2013 / 124321 are incorporated herein by reference.

[0065] Figure 1 1 is a schematic diagram of a vehicle 10 according to an embodiment of the present invention. The vehicle 10 has a prime mover or motor 11 in the form of an internal combustion engine. The engine 11 is coupled to a transmission 12 by means of a coupling 13. The coupling 13 is arranged so that the transmission 12 can gradually reach a speed compatible with the motor speed when the vehicle 10 accelerates from rest. The coupling 13 is typically a friction clutch, a torque converter, etc. The transmission 12 is arranged to drive a pair of rear wheels 10RW and, in addition, optionally a pair of steerable front wheels 10FW. An accelerator pedal 1 enables the driver to control the amount of torque generated by the motor 11 under the control of a powertrain controller 17, while a brake pedal 2 enables the driver to apply a braking system under the control of a brake controller 16. A driving mode selector 19 is provided, by means of which the driver can select a road driving mode or one of a plurality of off-road driving modes, the plurality of off-road driving modes including a grass / gravel / snow (GGS) driving mode, a sand (S) driving mode, and a mud and rut (MR) driving mode. In some embodiments, the selector also enables selection of an "auto response mode" in which the vehicle 10 automatically determines the best driving mode at any given moment. The driving mode may be referred to as a "terrain response" (or "TR") mode or TR mode or TR mode.

[0066] The vehicle 10 has a vehicle control unit (VCU) 15 which is operable to implement a low speed vehicle speed control function or system. The low speed vehicle speed control function may also be referred to as an "off-road" or "off-highway" cruise control function or system. The low speed vehicle speed control function is operable if the vehicle speed VREF does not exceed a predetermined maximum speed. In this embodiment, the predetermined maximum speed is 30 km / h. Above 30 km / h, the VCU 15 is operable to implement a higher speed speed control function or system. The VCU 15 may be described as implementing a low speed control system or a high speed control system. Both the low speed control system and the high speed control system functions are controlled by a user via input controls mounted to a steering wheel 171 of the vehicle 10. In Figure 2171 is shown in more detail in . It should be understood that a low speed vehicle speed control function or system may be useful when driving in off-highway driving conditions, while a high speed control function or system may be useful in highway driving conditions, such as when driving on a relatively smooth, dry asphalt or concrete driving surface.

[0067] The input controls include a "set speed" control 173, actuation of which sets the value of the parameter driver_set_speed to be substantially equal to the current vehicle speed. Pressing a "+" (or "plus") button 174 enables the set speed to be increased, while pressing a "-" (or "minus") button 175 enables the set speed to be decreased. In some embodiments, if the speed control function is inactive when the "+" button 174 is pressed, the speed control function is activated.

[0068] In the present embodiment, the VCU 15 is configured to implement an active speed control system (or "active cruise control") when a higher speed speed control system is operating. The active speed control system is configured to keep the vehicle 10 at a predetermined distance behind the leading vehicle in certain circumstances, as will be explained. The steering wheel 171 also has a pair of following distance control buttons 178, 179, which are used to set the value of the parameter distance_following, which is the distance that the driver expects the vehicle 10 to remain behind the leading vehicle. The VCU 15 is operable to control the distance at which the vehicle 10 remains behind the leading vehicle, which is substantially equal to the distance represented by the parameter distance_following. The first of the buttons 178 is operable to increase the value of the parameter distance_following, and thus increase the distance between the vehicle 10 and the leading vehicle, while the second of the buttons 179 is operable to reduce the value of the parameter distance_following. The vehicle 10 has a radar module 5 mounted to the front thereof and arranged to project a radar beam in a direction in front of the vehicle 10. The module 5 is arranged to detect radiation reflected by the leading vehicle and determine the distance of the leading vehicle from the vehicle 10 (as the "host" vehicle). The module 5 is provided with a signal indicating the current speed of the host vehicle 10. From this signal and data about the variation of the distance of the leading vehicle from the host vehicle 10 as a function of time, the module 5 is able to calculate the speed of the leading vehicle. Other arrangements for determining the distance to the leading vehicle and the speed of the leading vehicle are also useful. In some embodiments, no active speed control functionality is provided and the following distance control buttons 178, 179 are omitted. In some embodiments, the radar module 5 is omitted.

[0069] The higher speed speed control system is not the subject of the present application. Unless otherwise stated, the remainder of this specification relates to the low speed speed control system.

[0070] When the low speed control system is activated, the VCU 15 controls the speed of the vehicle 10 according to a target speed value, which is set to be substantially equal to the set speed driver_set_speed selected by the driver or a lower value (if this is desired), as described in more detail below. The VCU 15 achieves this by calculating the maximum allowed speed max_set_speed of the vehicle 10 at a given moment. The VCU 15 sets the value of max_set_speed to the value of the driver set speed driver_set_speed unless a lower value is desired, as described in more detail below. The VCU 15 controls the speed of the vehicle 10 according to max_set_speed as the target speed value of the vehicle by making the vehicle speed VREF equal to the value of max_set_speed.

[0071] The VCU 15 then outputs the acceleration target value acc_tgt at a given time to the powertrain controller 17 and the brake controller 16 so as to maintain the vehicle speed as determined by reference to the vehicle reference speed VREF at a desired value. If the driver overrides the speed control system and VREF exceeds 30 km / h, the speed control system suspends operation until VREF drops to 30 km / h or less.

[0072] The driver can set the value of driver_set_speed of the low-speed speed control system to the current vehicle speed VREF (assuming VREF does not exceed 30km / h) by pressing the "set speed" control 173 while the vehicle 10 is moving. When the VCU 15 detects that the "set speed" control 173 has been pressed, the VCU 15 takes a snapshot of the current speed VREF of the vehicle 10 and sets the value of driver_set_speed to correspond to the current speed. (It should be understood that if VREF exceeds 30km / h and the set speed control 173 is pressed, a higher speed speed control system is activated. In this embodiment, if the higher speed speed control system has been activated because the value of driver_set_speed has been set to a value exceeding 30km / h, the low-speed speed control system will not automatically reactivate once the speed drops below 30km / h.)

[0073] As described above, when the vehicle 10 is traveling along a road and a higher speed control system is active, i.e. VREF and driver_set_speed exceed the minimum allowed set speed set_speed_min (30 km / h in this embodiment), the VCU 15 is operable to enable the user to command the VCU 15 to maintain the current vehicle speed by pressing the set speed control 173. In the absence of traffic ahead of the vehicle 10 or other factors requiring a lower speed (see below), the VCU 15 controls the speed VREF of the vehicle 10 to maintain VREF substantially equal to the set speed value driver_set_speed.

[0074] In this embodiment, if the VCU 15 (by means of the radar module 5) detects the presence of a leading vehicle in front of the vehicle 10, the VCU 15 is operable to reduce the speed of the host vehicle 10 according to the speed of the leading vehicle so as to maintain a distance of no less than a prescribed distance behind the leading vehicle. The driver can set the prescribed distance by means of the "following distance" control buttons 178, 179 as described above. This function is only available when the higher speed speed control system is active.

[0075] The vehicle 10 has a human machine interface (HMI) in the form of a touch screen 18, by means of which the VCU 15 can communicate with the user. As described above, when the low speed control system is active, the VCU 15 is operable to calculate the maximum permissible value max_set_speed of the set speed according to the terrain on which the vehicle is traveling. The VCU 15 is operable to calculate the maximum permissible value max_set_speed of the set speed by means of a "maximum set speed calculation" part (or "engine") 15a. Therefore, the VCU 15 is operable to limit the maximum speed at which it will control the operation of the vehicle 10 according to the terrain. When operating under off-road conditions, embodiments of the present invention enable improved vehicle composure with reduced driver intervention. That is, because the VCU 15 determines the maximum permissible value max_set_speed of the set speed and limits the set speed accordingly, the driver does not need to intervene to reduce the value of the vehicle set speed when the main terrain allows, and increase the set speed when the main terrain allows.

[0076] Figure 3 15a. The manner in which the VCU 15 determines the value of max_set_speed is shown. As described above, the VCU 15 includes a "maximum set speed calculation" portion (or "engine") 15a. The VCU 15 also includes a "maximum cross-link (CA) set speed calculation" module (or "engine") 15b (also referred to as a "cross-link module" 15b). Additionally, the input to the "maximum set speed calculation" portion (or "engine") includes a "lateral acceleration limit calculation" portion 15d.

[0077] The "maximum set speed calculation" portion 15a of the VCU 15 is configured to receive inputs corresponding to a plurality of vehicle parameters in addition to the current value of driver_set_speed. As described above, the "maximum set speed calculation" portion 15a outputs a value of max_set_speed that is no greater than the value of driver_set_speed, but may be lower if the "maximum set speed calculation" portion 15a determines that driving conditions require, as described in further detail below. These parameters are: (a) a current vehicle reference value μmeas of the coefficient of surface friction, which is a value calculated by the VCU 15 based on one or more parameters such as the value of the amount of torque applied to the wheel causing excessive wheel slip; (b) a value μTRmode of the expected coefficient of surface friction corresponding to the currently selected vehicle driving mode, which is a prescribed value for each driving mode; (c) a current value of the steering angle “STEERING ANGLEδ” corresponding to the steerable road wheel angle or steering wheel position; (d) the vehicle's current yaw rate (determined by the output of a reference accelerometer) “YAW RATE”; (e) a current measured value of the lateral acceleration “MEASURED LAT.ACC.” (also determined by the output of a reference accelerometer); and (f) a current measured value of the surface roughness “SURFACEROUGHNESS” (determined by a reference suspension connection). In some embodiments, the VCU 15 may also receive: (g) a signal "GPS LOCATION" indicating the current location of the vehicle (which is determined by reference to a global satellite positioning system (GPS) output or other global navigation satellite system or other positioning system); and (h) information "CAMERA" obtained with the aid of a camera system. The information obtained with the aid of a camera system or an imaging system may include, for example, an alarm in the event that it is determined that the vehicle 10 may be about to leave an off-road lane or track.

[0078] The "lateral acceleration limit calculation" section 15d of the VCU 15 is configured to determine the maximum permissible rate max_lat_acc of the lateral acceleration of the vehicle 10 during the traveling process based on the reference value μmeas of the surface friction coefficient and the expected value μTRmode of the surface friction coefficient. When the vehicle turns, the VCU 15 uses this value max_lat_acc to limit the value of max_set_speed in order to prevent understeering.

[0079] In the present embodiment, the "maximum set speed calculation" portion 15a of the VCU 15 is also operable to calculate the radius of curvature of the path of the vehicle 10 on the terrain based on the steering angle. The VCU 15 compares the radius of curvature with the vehicle yaw rate and the measured lateral acceleration. If the VCU 15 detects the presence of understeer, the VCU 15 is operable to reduce the value of max_set_speed accordingly with the aid of the "maximum set speed calculation" portion 15a. In some embodiments where a signal indicating the current position of the vehicle is received, the VCU 15 may also take into account the vehicle's travel path determined by the reference position signal in order to increase the reliability of determining the amount of understeer (if any) present.

[0080] In some embodiments, yaw rate and measured lateral acceleration are not employed in determining the amount of understeer present. Other arrangements are also useful.

[0081] The VCU 15 also determines the value of max_set_speed based on the value of the surface roughness of the terrain that the vehicle 10 is traveling on. The value of max_set_speed may decrease as the surface roughness increases.

[0082] The "maximum cross-articulation (CA) setting speed calculation" module 15b is configured to calculate the maximum value of the allowed vehicle speed based on the amount of cross-articulation of the vehicle suspension at a given moment.

[0083] In the embodiment shown, module 15b receives the following signal:

[0084] - a vehicle reference speed signal VREF, which indicates the speed of the vehicle on the ground;

[0085] - Connection information in the form of wheel connection signals S_FL, S_FR, S_RL, S_RR, wherein S_FL is a signal indicating the left front suspension height FL, S_FR is a signal indicating the right front suspension height FR, S_RL is a signal indicating the left rear suspension height RL, and S_RR is a signal indicating the right rear suspension height RR.

[0086] The wheel coupling signals are received from respective wheel coupling sensors associated with respective wheels of the vehicle. Each wheel coupling sensor is arranged to output a respective wheel coupling signal indicating the height of the suspension associated with the wheel corresponding to the sensor. In some embodiments, more than one wheel coupling sensor may be associated with each wheel or at least one of the wheels. Additionally, in some embodiments, the module 15b may receive one or both of the following signals:

[0087] - a signal TRmode indicating the driving mode in which the vehicle is currently operating (TRmode); and

[0088] A comfort signal S_comfort, which is indicative of the comfort level desired by the occupants of the vehicle (see below).

[0089] In an embodiment, the cross-coupling value depends on a first coupling value, which indicates the degree to which the wheels of the first diagonal wheel pair are coupled in a positive or negative direction relative to a baseline value. For example, the left front wheel and the right rear wheel can be considered to form a first diagonal wheel pair. In some embodiments, a baseline value, which can be zero, is set by the speed control system, and a value is assigned to the coupling of the first diagonal wheel pair relative to the baseline value. When the left front wheel of the first diagonal wheel pair is higher than the right rear wheel, the coupling value of the diagonal wheel pair can be considered to be positive. When the left front wheel of the diagonal wheel pair is lower than the right rear wheel, the coupling value of the first diagonal wheel pair can be considered to be negative. It should be understood that in other embodiments, the positive and negative directions can be opposite, and / or the baseline can be set differently.

[0090] In an embodiment, the cross-coupling value depends on the degree to which the wheels are coupled in phase with each other. For example, if both the left front wheel and the right rear wheel are in a maximum compression scenario, i.e., the left front suspension height signal indicates that the left front suspension is in the highest position and the right rear suspension height signal indicates that the right rear suspension is also in the highest position, then the first diagonal wheel pair including the left front wheel and the right rear wheel can be considered to be in phase. Alternatively, if both the left front wheel and the right rear wheel are in a maximum extension scenario, i.e., the left front suspension height signal indicates that the left front suspension is in the lowest position and the right rear suspension height signal indicates that the right rear suspension is also in the lowest position, then the first diagonal wheel pair including the left front wheel and the right rear wheel can be considered to be in phase.

[0091] In an embodiment, the cross-coupling value depends on a second coupling value indicating the degree to which the wheels of a second diagonal wheelset, different from the first diagonal wheelset, are coupled in a positive or negative direction relative to the baseline value. For example, if the first coupling value relates to a first diagonal wheelset comprising a left front wheel and a right rear wheel, the second coupling value depends on a second diagonal wheelset comprising a right front wheel and a left rear wheel. The coupling value of the second diagonal wheelset may be calculated in the same manner as the coupling value of the first diagonal wheelset.

[0092] In embodiments, the degree to which the wheels of the second diagonal wheelset are coupled in-phase should be understood to be calculated in the same manner as the degree to which the wheels of the first diagonal wheelset are coupled in-phase, as previously described.

[0093] In an embodiment, the cross-link value depends on the degree to which the first and second link values ​​correspond to anti-phase motion of the respective pairs relative to each other. The maximum anti-phase position of the first and second diagonal wheel pairs will occur when the first diagonal wheel pair is in a maximum compression scenario (as previously discussed) and the second diagonal wheel pair is in a maximum extension scenario (as previously discussed). It should be understood that anti-phase does not necessarily mean this maximum position, but rather any position of the diagonal wheel pairs relative to each other.

[0094] The cross-connection amount CrossArtc_L of the vehicle suspension is calculated by module 15b according to the connection information according to the following formula:

[0095] CrossArtc_L=abs(FL-FR)+abs(RL-RR)+abs(FL-RL)+abs(FR-RR)-abs(FL-RR)-abs(FR-RL)

[0096] Where FL is the left front suspension height, FR is the right front suspension height, RL is the left rear suspension height, and RR is the right rear suspension height, and these suspension heights are relative to a reference height. In this embodiment, the reference height (or "reference" position) is the mid-position between the extremes of the up and down motion of each wheel. It should be understood that other reference positions may be used without affecting the value of CrossArtc_L.

[0097] As described above, in some embodiments of the present invention, the cross-connect module 15b of the VCU 15 is configured to receive a comfort signal S_comfort indicating a desired comfort setting, which is an indication of a desired occupant comfort level. The comfort setting can be adjusted by the user via the touch screen 18, but other input devices such as a rotary dial are also useful. In some embodiments, the comfort signal S_comfort indicates whether the comfort setting has a value of 0 (zero), 1, 2, 3 or 4. A value of zero is considered to correspond to an "off" condition of the comfort setting, indicating that passenger comfort is not considered when setting the value of CA_set_speed.

[0098] In the present embodiment, the cross-coupling module 15b determines the value of CA_set_speed based on the vehicle reference speed VREF, the wheel cross-coupling value CrossArtc_L and the value of TRmode. Figure 4 The change of the value of CA_set_speed according to VREF and CrossArtc_L is schematically shown.

[0099] If the value of VREF is within the range of 8km / h≤VREF≤10km / h and the cross-coupling amount CrossArtc_L of the vehicle suspension exceeds the minimum value CrossArtc_L_min, the value of CA_set_speed is set to decrease from the upper limit allowable value CA_set_speed_upper to the minimum allowable value CA_set_speed_min in a substantially linear manner according to the increase in the value of CrossArtc_L. In the present embodiment, the value of CrossArtc_L_min is set to a value of 0.03, but other values ​​are also useful.

[0100] If the value of VREF is less than 8 km / h, i.e., VREF<8 km / h, and the amount of cross-coupling CrossArtc_L of the vehicle suspension exceeds the minimum value CrossArt_L_min, the value of CA_set_speed is set to decrease from the upper limit permissible value CA_set_speed_upper to the minimum permissible value CA_set_speed_min in a more aggressive or abrupt manner according to the increase in the value of CrossArtc_L than when the value of VREF is in the range of 8≤VREF≤10 km / h. In the present embodiment, the cross-coupling module 15b is configured so that the value of CA_set_speed decreases in a substantially exponential manner, the rate at which CA_set_speed itself decreases decreasing according to the increase in the amount of cross-coupling of the vehicle suspension.

[0101] In the present embodiment, the coupling module 15b is configured such that the value of CA_set_speed_upper is 10 km / h and the value of CA_set_speed_min is 1.8 km / h. In some embodiments, other values ​​of CA_set_speed_upper and CA_set_speed_min may be useful.

[0102] In the present embodiment, if the value of VREF exceeds a predetermined upper limit value (10 km / h in the present embodiment), the value of CA_set_speed is set to a value corresponding to the maximum allowed value of max_set_speed, so that the value of max_set_speed is not affected by the value of CA_set_speed. This is at least in part because it is considered unlikely that the vehicle 10 will traverse rocky terrain if the vehicle is travelling at a speed exceeding 10 km / h. Therefore, any deviation of the value of CrossArtc_L above the minimum value CrossArtc_L_min (above which the VCU 15 intervenes to limit the vehicle speed) is likely to be transient and may be due to wheel bounce rather than to the presence of rocky terrain. In some embodiments, other values ​​of the predetermined upper limit value, such as 12 km / h, 9 km / h or any other suitable value, may be useful.

[0103] In some embodiments, the speed control system is inoperable above a predetermined speed control system inoperable value. The predetermined upper limit value is less than the predetermined speed control system inoperable value. The system inoperable value refers to the case where the maximum allowed value of max_set_speed is 30km / h, but other values ​​may be useful in some embodiments.

[0104] In some embodiments, when the condition that the value of VREF is within the range of 8 km / h ≤ VREF ≤ 10 km / h is met, the value of CA_set_speed may be more sharply decreased according to CrossArtc_L with increasing comfort parameter values. In some embodiments, for values ​​of the comfort parameter of 2 or more, the value of CA_set_speed may be decreased according to the comfort parameter. Thus, in some embodiments, as the comfort setting increases from a value of 2 to a value of 4, the value of CA_set_speed may be more sharply increased according to CrossArtc_L.

[0105] It will be appreciated that as long as the car is travelling on a properly articulated surface, the VCU 15 maintains a low value of CA_set_speed in response to the increase in the value of CrossArtc_L. Once the car leaves the articulated surface and the value of CrossArtc_L decreases, the VCU 15 increases the value of CA_set_speed back to the maximum allowed value of the vehicle set speed (i.e., 30 km / h in this embodiment). It will be appreciated that the VCU 15 limits the rate at which the value of CA_set_speed increases to avoid excessive haste.

[0106] As described above, in some embodiments, when calculating the value of CA_set_speed, the cross-link module 15b may also take into account the driving mode in which the vehicle 10 is operating, as determined by reference to the TRmode signal.For higher desired values ​​of occupant comfort, the value of CA_set_speed may be lower.

[0107] In the present embodiment, the cross-connect module 15b is implemented in software run by the VCU 15. In some embodiments, the module 15b may be a separate dedicated electronic module having a processor associated therewith and arranged to output a signal indicative of the value of CA_set_speed.

[0108] Ride Height

[0109] Figure 5 The configuration of the VCU 215 according to another embodiment of the present invention is shown. Figure 5 The implementation method and Figure 3 Similar features of the embodiment of the present invention are shown with the same reference numerals increased by 200. In the embodiment shown, the cross-link module 215b is configured to receive a further signal S_ride_height providing ride height information indicative of a ride height setting for the vehicle 10. It will be appreciated that in this embodiment, the driver is able to set a ride height for the vehicle corresponding to the distance the underside of the vehicle is above the ground when the vehicle is stationary on a flat, level surface.

[0110] In this embodiment, the VCU 215 is configured to allow the vehicle ride height to be set to one of three predetermined settings, each corresponding to a different distance between the ground and a given location on the underside of the vehicle:

[0111] (a) Off-road driving height;

[0112] (b) normal road riding height; and

[0113] (c) Approaching ride height.

[0114] It will be appreciated that the off-road ride height corresponds to a ride height that is higher than the road ride height, thereby providing greater ground clearance, which in turn is a ride height that is higher than the access ride height. The access ride height is intended to facilitate more convenient access to the vehicle, such as for passenger boarding and alighting or cargo loading and unloading.

[0115] exist Figure 5 In an embodiment of the present invention, the cross-connect module 215b is configured to connect the vehicle to the vehicle when the driving height is set to the normal road driving height. Figure 3That is, when the ride height is set to the normal road ride height, the cross-connect module 215b is configured to output the Figure 4 The graph shows the calculated value of CA_set_speed.

[0116] However, when the ride height is set to a ride height different from the normal road ride height, the cross-connect module 215b is configured to calculate the corresponding Figure 4 , but with the x-axis scaled by a predetermined scaling factor so that the value of CA_set_speed is changed for a given value of CrossArtc_L_Max relative to operation at a normal road ride height.

[0117] In this embodiment, when the ride height is set to be close to the ride height, the cross-connect module 215b is configured to scale by a scaling factor of 3. Figure 4 The x-axis of the graph of CA_set_speed is such that the value of CA_set_speed is reduced for a given value of CrossArtc_L_Max relative to operation at Normal Road Ride Height. This is because, when Access Height is selected, there is an increased risk that the vehicle may come to ground when passing over rocky terrain. Therefore, a CrossArtc_L_Max value of 0.2 in Normal Road Ride Height will be equivalent to a value of 0.6 in Access Height.

[0118] It will be appreciated that other values ​​of the scaling factor, such as 0.2, 0.4, 0.6, 0.8, or any other suitable value, may be useful in some implementations.

[0119] In the present embodiment, the minimum allowed value CA_set_speed_min of CA_set_speed is maintained at 1.8 km / h for each ride height setting. However, it will be appreciated that in some embodiments, when a close ride height has been selected, a different value of CA_set_speed_min may be employed, such as a value of 1 km / h or any other suitable value.

[0120] In some embodiments, if the cross-link module 215b causes a decrease in CA_set_speed when the vehicle is traveling at a near ride height setting, the cross-link module 215b causes the driver to be alerted to the fact that intervention has occurred via the HMI touchscreen 18. For example, the cross-link module 215b may be configured to cause the HMI touchscreen 18 to advise the driver to "raise the vehicle's ride height if it is appropriate to do so."

[0121] When the ride height is set to off-road ride height, the cross-join module 215b is set to scale the Figure 4 The x-axis of the graph of is such that the value of CA_set_speed is increased for a given value of CrossArtc_L_Max relative to operation at normal road ride height. This is because, when an off-road ride height is selected, there is a reduced risk that the vehicle may ground contact when traversing rocky terrain.

[0122] Thus, a CrossArtc_L_Max value of 0.2 in normal road ride height will be equivalent to a value of 0.15 in off-road height. It will be appreciated that in some embodiments, other values ​​of the scaling factor, such as 0.5, 0.25 or any other suitable value, may be useful.

[0123] As described above, in this embodiment, the minimum allowed value CA_set_speed_min of CA_set_speed is maintained at 1.8 km / h for each ride height setting. However, it will be appreciated that in some embodiments, when an off-road ride height has been selected, a different value of CA_set_speed_min may be employed, such as a value of 4 km / h or any other suitable value.

[0124] Figure 6 It is shown that Figure 5 Schematic diagram of expected change in vehicle speed VREF as a function of time after a vehicle encounters a bump in the driving surface, triggering a decrease in the value of CA_set_speed. The figure shows the vehicle speed VREF as a function of time before and after encountering a bump in the driving surface, which triggers a decrease in the vehicle speed due to the bump at time t1. The change in VREF for a vehicle with three different ride height settings is shown, namely (a) off-road height, (b) normal road height, and (c) approach height. Time t2 represents the approximate time to reach a new vehicle speed VREF in each of the three ride height settings (a), (b), and (c).

[0125] from Figure 6 It can be seen that the value of CA_set_speed corresponding to the off-road ride height setting is higher than the value of CA_set_speed for the normal road ride height setting, which in turn is higher than the value of CA_set_speed for the near ride height setting. Figure 6As shown, the difference between the values ​​of CA_set_speed in the off-road ride height setting and the normal road ride height setting is much smaller than the difference between the values ​​of CA_set_speed in the normal road ride height and the approach ride height setting. However, it can be seen that the reduction in vehicle speed from the prevailing speed at time t1 to the corresponding value of CA_set_speed is similar for each ride height setting. This may be at least in part to reduce the inconvenience to the driver caused by the suspension reaching the limit of travel in an abrupt manner when driving in each setting, especially in the approach ride height setting with the minimum available travel.

[0126] Figure 7 Shows Figure 5 The operation mode of the VCU 215 of the embodiment.

[0127] At step S101 , the VCU 15 determines the value of CrossArt_L based on the wheel articulation signal received as described above.

[0128] At step S103 , the VCU calculates the value of CA_set-speed based on VREF, CrossArt_L and the ride height setting.

[0129] At step S105 , the VCU 15 calculates the value max_set-speed′ of max_set-speed without considering CA_set-speed.

[0130] At step S107, the VCU 15 determines whether max_set-speed' is less than CA_set-speed. If max_set-speed' is less than CA_set-speed, the method continues at step S109, otherwise the method continues at step S111.

[0131] At step S109, the VCU 15 sets the value of max_set-speed to the value of max_set-speed'. The method then continues at step S101.

[0132] At step S111 , the VCU sets the value of max_set-speed to the value of CA_set-speed. Then, the method continues at step S101 .

[0133] Figure 8 are schematic diagrams of (a) an electronic controller 15 ′ included by VCU 15 and configured to implement a speed control system of VCU 15 , and (b) an electronic controller 215 ′ included by VCU 215 and configured to implement a speed control system of VCU 215 .

[0134] Refer to above Figure 5 In the described embodiment of the invention, the driver is able to set the ride height of the vehicle to one of a plurality of predetermined ride heights, namely an off-road ride height, a normal road ride height and an approach ride height. In such an embodiment, the signal S_ride_height providing ride height information may indicate a setting of an adjustable suspension system (e.g. an adjustable air suspension system) of the vehicle, wherein the air pressure of an adjustable air spring associated with each respective wheel of the vehicle is adjusted to vary the vehicle ride height, i.e. the distance between a given position on the underside of the vehicle and a point on the ground.

[0135] A further embodiment of the invention will now be described which is suitable for use with a vehicle having a so-called passive suspension system. In a vehicle having a passive suspension system, the suspension may be provided by a coil spring and damper arrangement associated with each wheel of the vehicle. The height of the vehicle body relative to the ground is therefore determined by the weight of the vehicle body supported via the coil springs (i.e. the sprung mass of the vehicle) and the weight of any passengers and / or cargo carried by the vehicle. For a given vehicle, the greater the load carried, the lower the ride height of the vehicle body relative to the ground. This is because as the mass of the load carried by the vehicle increases, the springs of the passive suspension system are compressed by a greater amount, which in turn causes the ride height of the vehicle to be reduced.

[0136] In the presently described embodiment in which the ride height of the vehicle is set according to the mass of the load carried by the vehicle, the signal S_ride_height provides ride height information indicative of the ride height setting of the vehicle. In particular, when the vehicle is stationary on level ground, the signal may indicate the ride height of the fully loaded vehicle relative to the unloaded vehicle ride height (i.e., the nominal or reference ride height). In one example, the ride height of the vehicle may be measured using one or more sensors disposed on the vehicle body. The sensors may be positioned near each corner of the vehicle so as to measure the distance between each corner of the vehicle and the ground below each corner, respectively. In this way, the value of the measured ride height may be calculated based on the average of the measurements taken at each vehicle corner. In one example, the ride height measurement is performed only when it is determined that the vehicle is on substantially level ground (e.g., as determined by an inclinometer disposed on the vehicle). In this way, the fully loaded vehicle ride height may be determined more accurately. Additionally, the ride height measurement may be performed only when the vehicle is stationary or traveling at a speed below a threshold, such as at "key on" before starting a journey. In other embodiments, sensors arranged at different positions on the vehicle body may be used, for example the sensors may be mounted on the side mirrors of the vehicle for measurement. Additionally or alternatively, the sensors may be arranged to measure the degree of compression of an element of the passive suspension system (e.g. the degree of compression of a coil spring) so that the ride height of the vehicle above the ground can be determined based on the degree of compression, i.e. based on the difference from the degree of compression in the spring when the vehicle is unloaded. The ride height measurement may be measured by a sensor, for example an optical sensor such as a camera, an ultrasonic sensor, a laser sensor, a radar sensor or other suitable type of sensor.

[0137] 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 speed control system for a vehicle, the speed control system being configured to cause the vehicle to operate according to a target speed value, the speed control system comprising one or more controllers, the speed control system being configured to: receiving ride height information indicative of a ride height setting of a suspension of the vehicle; and A maximum vehicle speed limit CA_set-speed is set based at least in part on the ride height information.

2. The speed control system according to claim 1, wherein: The ride height information comprises: i) a signal indicative of a predetermined ride height setting of an electronically adjustable suspension system of the vehicle; or ii) a signal indicative of a ride height difference between a measured ride height and a reference ride height provided by a passive suspension system of the vehicle.

3. The speed control system according to claim 1 or claim 2, further configured to receive coupling information indicating the coupling amount of the front wheels and the rear wheels of the vehicle; and A maximum vehicle speed limit CA_set-speed is further set at least partially based on the coupling information.

4. The speed control system according to claim 3, wherein: For higher amounts of articulation of the front and rear wheels of the vehicle, the value of CA_set-speed is lower.

5. The speed control system according to claim 3 or claim 4, wherein: For lower values ​​of vehicle ride height, the value of CA_set_speed is lower.

6. The speed control system according to claim 3, wherein the speed control system is configured to: determining a cross-coupling value indicating an amount of cross-coupling of wheels of the vehicle based on the coupling information; and A maximum vehicle speed limit CA_set-speed is set based at least in part on the cross-link value.

7. The speed control system according to claim 6, wherein: For higher values ​​of the cross-join value CrossArtc_L, the value of CA_set_speed is lower, and / or wherein, For lower values ​​of vehicle ride height, the value of CA_set_speed is lower.

8. The speed control system according to claim 6 or claim 7, wherein: The cross join value depends on: a first coupling value indicating the degree to which the wheels of the first diagonal wheelset are coupled in a positive or negative direction relative to a baseline value and the degree to which the wheels of the pair are coupled in phase with each other; a second coupling value indicating the degree to which the wheels of a second diagonal wheelset, different from the first diagonal wheelset, are coupled in a positive or negative direction relative to a baseline value and the degree to which the wheels of the pair are coupled in phase with each other; and The first link value and the second link value correspond to the degree of anti-phase movement of the respective pairs relative to each other, optionally wherein the cross link value CrossArtc_L is calculated according to the following formula: CrossArtc_L=abs(FL-FR)+abs(RL-RR)+abs(FL-RL)+abs(FR-RR)-abs(FL-RR)-abs(FR-RL) Among them, FL is the left front suspension height, FR is the right front suspension height, RL is the left rear suspension height, and RR is the right rear suspension height.

9. A speed control system according to any preceding claim, the speed control system being arranged to receive a signal indicative of a vehicle speed VREF, the speed control system being arranged to limit the vehicle speed further dependent on the value of VREF.

10. A system for controlling the speed of a vehicle, comprising: A speed control system according to any preceding claim; as well as One or more sensors configured to output information indicative of an amount of articulation of the front and rear wheels of the vehicle.

11. A vehicle comprising a speed control system according to any one of claims 1 to 9 or a system according to claim 10.

12. A method for controlling vehicle speed implemented by a speed control system, comprising: causing the vehicle to operate according to a target speed value; receiving ride height information indicative of a ride height setting of a suspension of the vehicle; as well as A maximum vehicle speed limit is set based at least in part on the ride height information.

13. The method according to claim 12, wherein: The ride height information comprises: i) a signal indicative of a predetermined ride height setting of an electronically adjustable suspension system of the vehicle; or ii) a signal indicative of a ride height difference between a measured ride height and a reference ride height provided by a passive suspension system of the vehicle.

14. The method according to claim 12 or claim 13, further comprising: receiving coupling information indicating an amount of coupling of front wheels and rear wheels of the vehicle; as well as The maximum vehicle speed limit is further set based at least in part on the connection information.

15. A non-transitory computer-readable storage medium storing instructions which, when executed by one or more electronic processors, cause the one or more electronic processors to perform the method of any one of claims 12 to 14.

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