Vehicle control system and method

Abstract

Aspects of the present invention relate to a speed control system (15), method, and vehicle (10). The system causes the vehicle (10) to travel at a target speed value. The speed control system receives articulation information indicating an amount of articulation of the front and rear wheels of the vehicle, and determines a cross-articulation value, CrossArtc_L, indicating an amount of cross-articulation of the wheels of the vehicle in response to the articulation information. The system limits the vehicle speed at least partially depending on the cross-articulation value.

Description

Technical Field

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

[0002] The content of WO2013 / 124321 is incorporated herein by reference.

Background Art

[0003] It is known to provide a speed control system for a vehicle, particularly a speed control system for operating a vehicle according to a target speed value. It is desirable to provide an improved speed control system to assist a driver in driving on terrain with obstacles such as rocks, boulders, or other obstacles with a rapidly changing driving surface height.

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to solve one or more drawbacks associated with the prior art.

Means for Solving the Problems

[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 described in the appended claims.

[0006] According to one aspect of the present invention, there is provided a speed control system for a vehicle, the speed control system being configured to operate the vehicle according to a target speed value, the speed control system including one or more controllers, receiving articulation information indicating an amount of articulation between the front and rear wheels of the vehicle; Determine a cross-articulation value CrossArtc_L indicating the amount of cross-articulation of the vehicle's wheels according to the articulation information; and Limit the vehicle speed at least partially depending on the cross-articulation value It is configured as follows.

[0007] Embodiments of the present invention have the advantage that they can improve the stability of the vehicle and / or the comfort of the driver. This is because the speed control system is configured to limit the vehicle speed according to the amount of articulation of the front and rear wheels of the vehicle. Information indicating the amount of articulation of the vehicle's wheels can provide an indication of the terrain on which the vehicle is traveling. Furthermore, by limiting the vehicle speed when certain conditions regarding wheel articulation are met, it is possible to reduce the noise, vibration, and discomfort of the vehicle. This is at least partially due to the low likelihood of the movement amount of the vehicle's suspension reaching the movement limit. In some embodiments, wear reduction may be achieved when preventing the movement amount of the vehicle's suspension from reaching the movement limit.

[0008] Wheel articulation means the position of the wheel relative to the range of movement of the suspension system associated with that wheel, and the position should be understood to be defined relative to a reference position. The reference position may be the position of the wheel midway between the upper and lower limits of the movement of the wheel by the suspension system.

[0009] The articulation of a particular axle means the difference in the articulation of the left and right wheels of the axle, regardless of whether the wheels are connected by a single physical axle or have left and right axles respectively.

[0010] The cross-articulation value is a measure of the degree of cross-articulation between a first wheel pair and a second wheel pair, and the second wheel pair should be understood to be spaced apart from the first wheel pair along the longitudinal axis of the vehicle.

[0011] Optionally, the speed control system may be an "off-road" or "off-highway" speed control system.

[0012] Optionally, the speed control system may be configured to determine a maximum allowable vehicle speed CA_set_speed at least partially depending on a cross-articulation value CrossArtc_L and limit the vehicle speed so that the vehicle speed does not exceed the value of CA_set_speed.

[0013] Optionally, the higher the value of the cross-articulation value CrossArtc_L, the lower the value of CA_set_speed.

[0014] Optionally, the cross-articulation value depends on the following: A first articulation value indicating how much the wheels of the first diagonal wheel pair are articulated in the positive or negative direction with respect to a reference value and how much the wheels are in phase with each other; A second articulation value indicating how much the wheels of a second diagonal wheel pair different from the first diagonal wheel pair are articulated in the positive or negative direction with respect to a reference value and how much the wheels are in phase with each other; and The degree to which the first and second articulation values correspond to the out-of-phase movement of the respective pairs with respect to each other.

[0015] Optionally, the speed control system can be configured to receive wheel articulation signals S_FL, S_FR, S_RL, S_RR, where S_FL is a signal indicating the height FL of the front left suspension, S_FR is a signal indicating the height FR of the front right suspension, S_RL is a signal indicating the height RL of the rear left suspension, and S_RR is a signal indicating the height RR of the rear right suspension.

[0016] Optionally, the cross-articulation 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) In the formula, FL is the height of the front left suspension, FR is the height of the front right suspension, RL is the height of the rear left suspension, and RR is the height of the rear right suspension.

[0017] Optionally, the speed control system is configured to receive a signal indicating the vehicle speed VREF, and the speed control system is further configured to limit the vehicle speed according to the value of VREF.

[0018] Optionally, when VREF exceeds a predetermined upper limit value, the speed control system does not limit the vehicle speed according to the cross-articulation value.

[0019] Optionally, the speed control system becomes inoperative when it exceeds a predetermined speed control system inoperative value, and when it exceeds a predetermined upper limit value, depending on the cross-articulation value being smaller than the predetermined speed control system inoperative value, the speed control system does not limit the vehicle speed.

[0020] The advantage of this function is that it can reduce the number of false trigger events that cause an undesirable decrease in vehicle speed according to the cross-articulation value. The predetermined upper limit value at which the speed control system does not limit the vehicle speed according to the cross-articulation value can be set to a value at which a decrease in vehicle speed is considered undesirable, for example, a speed at which it is unlikely that the vehicle is traveling on a rocky terrain that requires a relatively low speed.

[0021] The inoperative value of the predetermined speed control system can be any appropriate value, such as 30 km / h, 25 km / h, 35 km / h, or other appropriate values.

[0022] The predetermined upper limit value at which the speed control system does not limit the vehicle speed according to the cross-articulation value can be any appropriate value, such as 10 km / h, 8 km / h, 15 km / h, or other appropriate values.

[0023] Optionally, the speed control system receives the following signals: a signal TRmode indicating the driving mode (TR mode) in which the vehicle is currently operating; and a comfort signal S_comfort indicating the level of comfort required by the vehicle occupants and can be configured to receive either or both of them, wherein the speed control system is configured to limit the vehicle speed further depending at least in part on the signal TRmode and / or the signal S_comfort.

[0024] In a further aspect of the present invention, a speed control system according to the foregoing aspect; and one or more sensors configured to output information indicating the articulation amount of the front and rear wheels of the vehicle are provided for a system for controlling the speed of a vehicle.

[0025] In some embodiments, the one or more sensors can include an accelerometer or a gyroscope. Other suitable sensors are known to those skilled in the art and may be utilized in further embodiments.

[0026] In another aspect of the present invention, there is provided a vehicle including the speed control system of the foregoing aspect or the system of the foregoing aspect.

[0027] In yet another aspect, there is provided a method for controlling the speed of a vehicle executed by a speed control system, the method comprising: operating the vehicle according to a target speed value; receiving articulation information indicating the articulation amount of the front and rear wheels of the vehicle; and Limiting the vehicle speed at least partially depending on the articulation information comprises.

[0028] In a further aspect, a method of controlling the speed of a vehicle executed by a speed control system is provided, the method comprising operating the vehicle according to a target speed value; receiving articulation information indicating the amount of articulation of the front and rear wheels of the vehicle; determining a cross-articulation value, CrossArtc_L, indicating the amount of cross-articulation of the vehicle's wheels in response to the articulation information; and limiting the vehicle speed at least partially depending on the cross-articulation value comprises.

[0029] Optionally, the method comprises determining a maximum allowable vehicle speed CA_set_speed at least partially depending on the cross-articulation value CrossArtc_L, and limiting the vehicle speed so that the vehicle speed does not exceed the value of CA_set_speed comprises.

[0030] In a further aspect of the present invention, there is provided a non-transitory computer-readable storage medium storing instructions that, when executed by one or more electronic processors, cause the one or more electronic processors to execute the method of the foregoing aspect.

[0031] In one aspect of the present invention, there is provided a system for controlling the speed of a vehicle, the speed control system being configured to operate the vehicle according to a target speed value and including one or more controllers, receiving articulation information indicating the amount of articulation of the front and rear wheels of the vehicle; and limiting the vehicle speed at least partially depending on the articulation information is configured to.

[0032] In a further aspect of the present invention, a speed control system for a vehicle is provided, the speed control system being configured to operate the vehicle in accordance with a target speed value and including one or more controllers, receiving cross-articulation information indicative of an amount of cross-articulation of wheels of the vehicle; and limiting the vehicle speed at least partially depending on the cross-articulation information is configured to.

[0033] Within the scope of the present application, it is expressly intended that the various aspects, embodiments, examples, and alternatives described in the preceding paragraph, claims, and / or the following description and drawings, particularly their individual features, can be employed independently or in any combination. That is, all embodiments and / or features of embodiments can be combined in any manner and / or combination as long as such features are not incompatible. The applicant reserves the right to amend the originally filed claims and / or to file new claims accordingly. This includes the right to amend the originally filed claims to be dependent on the features of other claims and / or to incorporate the features of other claims, even if not originally so claimed.

[0034] One or more embodiments of the present invention will be described by way of example only with reference to the accompanying drawings.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

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Figure 8

[0036] The content of WO2013 / 124321 is incorporated herein by reference.

[0037] FIG. 1 is a schematic view of a vehicle 10 according to an embodiment of the present invention. The vehicle 10 has a prime mover or a motor 11 in the form of an internal combustion engine. The engine 11 is coupled to a transmission 12 by a coupling 13. The coupling 13 is arranged such that when the vehicle 10 is accelerated from a stopped state, the transmission 12 can gradually reach a speed that matches the motor speed. The coupling 13 is typically a friction clutch, a torque converter, or the like. The transmission 12 is configured to drive a pair of rear wheels 10RW and, optionally, also a pair of steerable front wheels 10FW. By means of an accelerator pedal 1, the driver can control the amount of torque generated by the motor 11 under the control of a powertrain controller 17, and by means of a brake pedal 2, the driver can apply a braking system under the control of a brake controller 16. A driving mode selector 19 is provided, and using this, the driver can select one of a plurality of off-road driving modes including an on-road driving mode, or 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 "automatic response mode" in which the vehicle 10 automatically determines the optimal driving mode at any given time. The driving mode may be called the "terrain response" (or "TR") mode, or the TR mode, or the TR mode.

[0038] Vehicle 10 is equipped with a vehicle control unit (VCU) 15 that is operable to execute a low-speed vehicle speed control function or system. The low-speed vehicle speed control function is also referred to as an "off-road" or "off-highway" cruise control function or system. The low-speed vehicle speed control function is operable when the vehicle speed VREF does not exceed a predetermined maximum speed. In this embodiment, the predetermined maximum speed is 30 km / h. When the speed exceeds 30 km / h, the VCU 15 is operable to execute a higher-speed control function or system. The VCU 15 can be described as implementing a low-speed control system or a high-speed control system. The functions of both the low-speed control system and the high-speed control system are controlled by the user via an input control attached to the steering wheel 171 of the vehicle 10. The steering wheel 171 is shown in more detail in FIG. 2. The low-speed vehicle speed control function or system is useful during off-highway driving conditions, and it should be understood that the high-speed control function or system is useful during on-highway driving conditions such as on a relatively smooth and dry paved road surface or a concrete driving surface.

[0039] The input control includes a "set speed" control 173, and when this is actuated, the value of the parameter driver_set_speed is set to be approximately equal to the current vehicle speed. Pressing the "+" (or "plus") button 174 can increase the set speed, and pressing the "-" (or "minus") button 175 can decrease the set speed. In some embodiments, when the speed control function is not active when the "+" button 174 is pressed, the speed control function becomes active.

[0040] In this embodiment, when the high-speed speed control system is operating, the VCU 15 is configured to execute an active speed control system (or "active cruise control"). As will be described later, the active speed control system is configured to maintain a predetermined distance behind a preceding vehicle for the vehicle 10 in certain situations. The wheel 171 also has a pair of following distance control buttons 178, 179 for setting the value of the parameter distance_following. This parameter is the distance that the driver desires to maintain the vehicle 10 behind the preceding vehicle. The VCU 15 is operable to control the vehicle 10 to maintain a distance substantially equal to the distance represented by the parameter distance_following behind the preceding vehicle. The first button 178 is operable to increase the value of the parameter distance_following and thus increase the distance between the vehicle 10 and the preceding vehicle, while the second button 179 is operable to decrease the value of the parameter distance_following. The vehicle 10 has a radar module 5 attached to its front surface and configured to project a radar beam in the forward direction of the vehicle 10. The module 5 is configured to detect the radiation reflected by the preceding vehicle and determine the distance between the preceding vehicle and the vehicle 10 ("host" vehicle). A signal indicating the current speed of the host vehicle 10 is provided to the module 5. From this signal and data regarding the change in the distance from the host vehicle 10 to the preceding vehicle as a function of time, the module 5 can calculate the speed of the preceding vehicle. Other configurations for determining the distance from the preceding vehicle and the speed of the preceding vehicle are also useful. In some embodiments, the active speed control function is not provided and the following distance control buttons 178, 179 are omitted. In some embodiments, the radar module 5 is omitted.

[0041] The high-speed speed control system is not the subject of this application. Unless otherwise specified, the remainder of this specification relates to the low-speed speed control system.

[0042] When the low-speed speed control system is activated, the VCU 15 controls the speed of the vehicle 10 in accordance with a set speed selected by the driver, a target speed value set to a value approximately equal to the driver_set_speed, or, as will be described in more detail below, a lower value if desired. The VCU 15 accomplishes this by calculating a maximum allowable speed, max_set_speed, of the vehicle 10 at a particular point in time. The VCU 15 sets the value of max_set_speed to the value of the driver set speed driver_set_speed, except when a lower value is desired, as will be described in more detail below. The VCU 15 controls the speed of the vehicle 10 in accordance with the max_set_speed, which is the target speed value of the vehicle, by making the vehicle speed VREF equal to the value of max_set_speed.

[0043] The low-speed control system or low-speed control system may be referred to herein as an off-road speed control system.

[0044] Next, the VCU 15 outputs a target value of acceleration, acc_tgt, at a particular point in time to the power train controller 17 and the brake controller 16 so that the vehicle speed determined with reference to the vehicle reference speed VREF maintains a desired value. When the driver overrides the speed control system and VREF exceeds 30 km / h, the speed control system stops operating until VREF is 30 km / h or less.

[0045] The driver can set the value of driver_set_speed of the low-speed speed control system to the current vehicle speed VREF (on the condition that VREF does not exceed 30 km / h) by pressing the "Set Speed" control 173 during the running of the vehicle 10. When the VCU 15 detects that the "Set Speed" control 173 has been pressed, it acquires 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 when VREF exceeds 30 km / h and the Set Speed control 173 is pressed, the high-speed speed control system is activated. In this embodiment, since the value of driver_set_speed is set to a value exceeding 30 km / h, when the high-speed speed control system is activated, the low-speed speed control system does not automatically restart even if the speed drops below 30 km / h).

[0046] As described above, when the vehicle 10 is running along the road and the high-speed speed control system is active, that is, when VREF and driver_set_speed exceed the minimum allowable set speed set_speed_min (30 km / h in this embodiment), the VCU 15 operates so that the user can instruct the VCU 15 to maintain the current vehicle speed by pressing the Set Speed control 173. When there is no traffic in front of the vehicle 10 or there are no other factors (see below) requiring a low speed, the VCU 15 controls the speed VREF of the vehicle 10 to maintain VREF approximately equal to the set speed value driver_set_speed.

[0047] In this embodiment, when the VCU 15 detects (by the radar module 5) that there is a preceding vehicle in front of the vehicle 10, the VCU 15 can operate to reduce the speed of the host vehicle 10 according to the speed of the preceding vehicle in order to maintain a distance greater than or equal to a specified distance behind the preceding vehicle. The specified distance can be set by the driver using the "Following Distance" control buttons 178, 179 as described above. This function can only be used when the high-speed speed control system is active.

[0048] Vehicle 10 is equipped with a human machine interface (HMI) in the form of a touch screen 18, through which the VCU 15 can communicate with the user. As described above, when the low-speed speed control system is active, the VCU 15 is operable to calculate the maximum allowable 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 allowable value max_set_speed of the set speed by the "maximum set speed calculation" part (or "engine") 15a. Therefore, the VCU 15 is operable to limit the maximum speed for controlling the vehicle 10 according to the terrain. Embodiments of the present invention can reduce driver intervention and improve the stability of the vehicle when operating under off-highway conditions. That is, since the VCU 15 determines the maximum allowable value max_set_speed of the set speed and limits the set speed accordingly, the driver does not need to intervene to lower the value of the vehicle set speed when the terrain requires it, nor does the driver need to intervene to increase the set speed when the terrain permits it.

[0049] Figure 3 shows how the VCU 15 determines the value of max_set_speed. As described above, the VCU 15 includes a "maximum set speed calculation" part (or "engine") 15a. It also includes a "maximum cross-articulation (CA) set speed calculation" module (or "engine") 15b (also referred to as the "cross-articulation module" 15b). Further, the input to the "maximum set speed calculation" part (or "engine") includes a "lateral acceleration limit calculation" part 15d.

[0050] The "maximum set speed calculation" part 15a of the VCU15 is configured to receive inputs corresponding to several vehicle parameters in addition to the current value of driver_set_speed. As described above, the "maximum set speed calculation" part 15a outputs a value of max_set_speed that is less than or equal to the value of driver_set_speed, but it may be lower if the "maximum set speed calculation" part 15a determines that the operating conditions so require. Details will be described below. The parameters are as follows: (a) The reference value of the current vehicle's surface friction coefficient, "μmeas", is a value calculated by the VCU15 based on the value of one or more parameters such as the amount of torque applied to a wheel that has induced excessive wheel slip; (b) The value of the predicted surface friction coefficient corresponding to the currently selected vehicle driving mode, "μTRmode", is a value defined for each driving mode; (c) The current value of the steering angle corresponds to the steerable road wheel angle or to the position of the steering wheel, "steering angle, δ"; (d) The current yaw rate of the vehicle (determined with reference to the output of the accelerometer), "yaw rate"; (e) The current measured value of the lateral acceleration, "MEASURED LAT.ACC." (determined with reference to the output of the accelerometer); (f) The current measured value of the surface roughness, "SURFACE ROUGHNESS" (determined with reference to the articulation of the suspension). In some embodiments, the VCU15 may also receive (g) a signal indicating the current position of the vehicle, "GPS position" (determined with reference to the output of the Global Positioning System (GPS) or other global navigation satellite systems or other positioning systems), and (h) information obtained by a camera system, "camera". The information obtained by the camera system or image system may include, for example, warnings in the case where it is determined that the vehicle 10 may deviate from the off-road lane or the track.

[0051] The "Lateral Acceleration Limit Calculation" part 15d of the VCU15 is configured to determine the maximum allowable lateral acceleration max_lat_acc of the vehicle 10 during travel from the reference value μmeas of the surface friction coefficient and the predicted value μTRmode of the surface friction coefficient. The VCU15 uses this value of max_lat_acc to limit the value of max_set_speed when the vehicle is cornering and prevent understeer.

[0052] In this embodiment, the "Maximum Set Speed Calculation" part 15a of the VCU15 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 VCU15 compares this radius of curvature with the yaw rate of the vehicle and the measured lateral acceleration. When the VCU15 detects the presence of understeer, the VCU15 is operable to reduce the value of max_set_speed accordingly by the "Maximum Set Speed Calculation" part 15a. In some embodiments where a signal indicating the current position of the vehicle is received, the VCU15 can also consider the travel path of the vehicle determined with reference to the position signal and enhance the reliability of the determination of the amount of understeer present (if any).

[0053] In some embodiments, the yaw rate and the measured lateral acceleration are not used for determining the amount of understeer present. Other configurations are also useful.

[0054] The VCU15 also determines the value of max_set_speed according to the value of the surface roughness of the terrain on which the vehicle 10 is traveling. When the surface roughness increases, the value of max_set_speed may decrease.

[0055] The "Maximum Cross Articulation (CA) Set Speed Calculation" module 15b is configured to calculate the maximum value of the allowable vehicle speed based on the amount of cross articulation of the vehicle suspension at a specific instant.

[0056] In the illustrated embodiment, the module 15b receives the following signals: - A vehicle reference speed signal VREF indicating the speed of the vehicle on the ground; - Articulation information in the form of wheel articulation signals S_FL, S_FR, S_RL, S_RR, where S_FL is a signal indicating the height FL of the front left suspension, S_FR is a signal indicating the height FR of the front right suspension, S_RL is a signal indicating the height RL of the rear left suspension, and S_RR is a signal indicating the height RR of the rear right suspension.

[0057] The wheel articulation signals are received from respective wheel articulation sensors associated with each wheel of the vehicle. Each wheel articulation sensor is arranged to output a respective wheel articulation signal indicating the height of the suspension associated with the wheel corresponding to that sensor. In some embodiments, a plurality of wheel articulation sensors may be associated with each wheel, or at least one wheel. In some embodiments, module 15b may further receive one or both of the following signals: - A signal TRmode indicating the driving mode (TR mode) in which the vehicle is currently operating, and - A comfort signal S_comfort indicating the level of comfort required by the vehicle occupants (see below).

[0058] In one embodiment, the cross-articulation value depends on a first articulation value indicating the degree to which the wheels of the first diagonal wheel pair are articulated in a positive or negative direction with respect to a reference value. For example, the front left wheel and the rear right wheel are considered to form the first diagonal wheel pair. The reference value (which may be zero depending on the embodiment) is set by the speed control system, and a value is given to the articulation of the first diagonal wheel pair with respect to the reference value. The value of the articulation of the diagonal wheel pair can be regarded as positive when the front left wheel is higher than the rear right wheel of the first diagonal wheel pair. The value of the articulation of the first diagonal wheel pair can be regarded as negative when the front left wheel is lower than the rear right wheel of the diagonal wheel pair. In other embodiments, it is understood that the positive and negative directions may be reversed and / or the baseline may be set differently.

[0059] In one embodiment, the cross-articulation value depends on the degree to which the wheels are articulated in phase with each other. For example, the first diagonal wheel pair composed of the front left wheel and the rear right wheel is in phase when both the front left wheel and the rear right wheel are in the maximum compression scenario, that is, when the height signal of the front left suspension indicates that the front left suspension is in the highest position and the height signal of the rear right suspension indicates that the rear right suspension is also in the highest position. Alternatively, the first diagonal wheel pair composed of the front left wheel and the rear right wheel can be regarded as in phase when both the front left wheel and the rear right wheel are in the maximum extension scenario, that is, when the front left suspension height signal indicates that the front left suspension is in the lowest position and the rear right suspension height signal indicates that the rear right suspension is also in the lowest position.

[0060] In one embodiment, the cross-articulation value depends on a second articulation value indicating the degree to which the wheels of a second diagonal wheel pair, different from the first diagonal wheel pair, are articulated in a positive or negative direction with respect to the baseline value. For example, when the first articulation value relates to a first diagonal wheel consisting of a front left wheel and a rear right wheel, the second articulation value depends on a second diagonal wheel pair consisting of a front right wheel and a rear left wheel. The articulation value of the second diagonal wheel pair can be calculated in the same way as the articulation value of the first diagonal wheel pair.

[0061] In one embodiment, it is understood that the degree to which the wheels of the second diagonal wheel pair are connected in the same phase is calculated in the same way as the degree to which the first diagonal wheel pair is connected in the same phase, as described above.

[0062] In one embodiment, the cross-articulation value depends on the degree to which the first articulation value and the second articulation value correspond to the out-of-phase movement of each pair with respect to each other. The maximum out-of-phase position of the first diagonal wheel pair and the second diagonal wheel pair occurs when the first diagonal wheel pair is in the maximum compression scenario and the second diagonal wheel pair is in the maximum extension scenario, as described above. It is understood that the out-of-phase does not necessarily mean this maximum position, but any position where the diagonal wheel pairs are in opposite positions.

[0063] The cross-articulation amount CrossArtc_L of the vehicle suspension is calculated from the articulation information by module 15b according to the following formula.

[0064] CrossArtc_L = abs(FL - FR) + abs(RL - RR) + abs(FL - RL) + abs(FR - RR) - abs(FL - RR) - abs(FR - RL)

[0065] Here, FL is the height of the front left suspension, FR is the height of the front right suspension, RL is the height of the rear left suspension, and RR is the height of the rear right suspension. The height of the suspension is based on the reference height. In this embodiment, the reference height (or "reference" position) is the position midway between the upper and lower limits of the movement of each wheel. It should be understood that other reference positions can be used without affecting the value of CrossArtc_L.

[0066] As described above, in some embodiments of the present invention, the cross-articulation module 15b of the VCU 15 is configured to receive a comfort signal S_comfort indicating a desired comfort setting that represents a desired level of passenger comfort. The comfort setting can be adjusted by the user via the touch screen 18, although other input devices such as a rotary dial can also be useful. In some embodiments, the comfort signal S_comfort indicates whether the value of the comfort setting is 0 (zero), 1, 2, 3, or 4. The value 0 is considered to correspond to the "off" state of the comfort setting and indicates that the passenger comfort is not considered when setting the value of CA_set_speed.

[0067] In this embodiment, the cross-articulation module 15b determines the value of CA_set_speed based on the vehicle reference speed VREF, the wheel cross-articulation value CrossArtc_L, and the value of TRmode. Figure 4 schematically shows the change in the value of CA_set_speed as a function of VREF and CrossArtc_L.

[0068] When the value of VREF is within the range of 8 ≤ VREF ≤ 10 km / h and the cross-articulation amount CrossArtc_L of the vehicle suspension exceeds the minimum value CrossArtc_L_min, the value of CA_set_speed is set to a value that decreases substantially linearly from the upper limit allowable value CA_set_speed_upper to the minimum allowable value CA_set_speed_min as a function of the increase in the value of CrossArtc_L. In this embodiment, the value of CrossArtc_L_min is set to 0.03, but other values can also be used.

[0069] When the value of VREF is less than 8 km / h, that is, VREF < 8 km / h, and the cross-articulation amount CrossArtc_L of the vehicle suspension exceeds the minimum value CrossArt_L_min, the value of CA_set_speed is set to a value that decreases more aggressively or rapidly from the upper limit allowable value CA_set_speed_upper to the minimum allowable value CA_set_speed_min as a function of the increase in the value of CrossArtc_L than when the value of VREF is within the range of 8 ≤ VREF ≤ 10 km / h. In this embodiment, the cross-articulation module 15b is configured such that the value of CA_set_speed decreases substantially exponentially, and the rate of decrease of CA_set_speed itself decreases as a function of the increase in the cross-articulation amount of the vehicle suspension.

[0070] In this embodiment, the articulation module 15b is configured such that the value of CA_set_speed_upper is 10 km / h, while 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.

[0071] In this embodiment, when the value of VREF exceeds a predetermined upper limit value (10 km / h in this embodiment), the value of CA_set_speed is set to a value corresponding to the maximum allowable 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 because, at least partially, when the vehicle is traveling at a speed exceeding 10 km / h, it is considered that the possibility of vehicle 10 traveling on a rocky terrain is low. Therefore, when the value of CrossArtc_L exceeds the minimum value CrossArtc_L_min at which the VCU15 intervenes to limit the vehicle speed, it is temporary and may be due to wheel bounce rather than the presence of a rocky terrain. In some embodiments, other values of the predetermined upper limit value, such as 12 km / h, 9 km / h, or other suitable values, may be useful.

[0072] In some embodiments, the speed control system becomes inoperable when it exceeds a predetermined speed control system inoperable value. The predetermined upper limit value is smaller than the predetermined speed control system inoperable value. The system inoperable value refers to the case where the maximum allowable value of max_set_speed is 30 km / h, but in some embodiments, other values may be useful.

[0073] In some embodiments, when the condition that the value of VREF is within the range of 8 ≤ VREF ≤ 10 km / h is satisfied, as the value of the comfort parameter increases, the value of CA_set_speed may decrease more rapidly as a function of CrossArtc_L. In some embodiments, when the value of the comfort parameter is 2 or more, the value of CA_set_speed may decrease as a function of the comfort parameter. Therefore, in some embodiments, as the comfort setting increases from value 2 to value 4, the value of CA_set_speed may increase more rapidly as a function of CrossArtc_L.

[0074] It should be understood that while the vehicle is traveling on an appropriate articulation surface, VCU15 maintains the value of CA_set_speed low in response to an increase in the value of CrossArtc_L. When the vehicle leaves the articulation surface and the value of CrossArtc_L decreases, VCU15 increases the value of CA_set_speed to the maximum allowable value of the vehicle set speed, i.e., 30 km / h in this embodiment. It should be understood that VCU15 limits the rate of increase of the value of CA_set_speed in order to avoid excessive jerk.

[0075] As described above, in some embodiments, the cross-articulation module 15b can also consider the driving mode in which the vehicle 10 is operating, which is determined with reference to the TRmode signal, when calculating the value of CA_set_speed. The higher the desired value of passenger comfort, the lower the value of CA_set_speed may be.

[0076] In this embodiment, the cross-articulation module 15b is implemented by software executed by VCU15. In some embodiments, the module 15b may be a separate dedicated electronic module having an associated processor and configured to output a signal indicating the value of CA_set_speed.

[0077] Vehicle height FIG. 5 shows the configuration of VCU215 according to a further embodiment of the present invention. Similar features of the embodiment of FIG. 5 and the embodiment of FIG. 3 are indicated by adding 200 to the same reference numerals. In the illustrated embodiment, the cross-articulation module 215b is configured to receive a further signal S_ride_height that provides ride height information indicating the ride height setting of the vehicle 10. In this embodiment, it is understood that when the vehicle is stationary on a flat horizontal surface, the driver can set the ride height of the vehicle corresponding to the distance from the underside of the vehicle to the ground.

[0078] In this embodiment, the VCU215 is configured to be able to set the vehicle height to any one of three predetermined settings corresponding to different distances between the ground and a specific position on the lower side of the vehicle. (a) Vehicle height during off-road, (b) Vehicle height during normal on-road driving, and (c) Vehicle height during access.

[0079] It should be understood that the off-road vehicle height corresponds to a higher vehicle height than the on-road vehicle height and provides a greater ground clearance. The on-road vehicle height is higher than the access vehicle height. The access vehicle height is aimed at facilitating easier access to the vehicle, such as for passengers to board and alight or for loading and unloading cargo.

[0080] In the embodiment of FIG. 5, the cross-articulation module 215b is configured to operate in the same manner as the embodiment of FIG. 3 when the vehicle height is set to the normal on-road vehicle height. That is, when the vehicle height is set to the normal on-road vehicle height, the cross-articulation module 215b is configured to output the value of CA_set_speed calculated according to the plot of FIG. 4.

[0081] However, when the vehicle height is set to a vehicle height other than the normal on-road vehicle height, the cross-articulation module 215b is configured to calculate the value of CA_set_speed corresponding to the plot of FIG. 4, but the x-axis is scaled by a predetermined scale factor, and for the operation at the normal on-road vehicle height, the value of CA_set_speed is changed for a specific value of CrossArtc_L_Max.

[0082] In this embodiment, when the vehicle height is set to the access vehicle height, the cross-articulation module 215b is configured to scale the x-axis of the plot in FIG. 4 by a scale factor of 3. As a result, the value of CA_set_speed decreases for a specific value of CrossArtc_L_Max compared to the operation at the normal on-road vehicle height. This is because when the access vehicle height is selected, the risk of the vehicle grounding increases when driving on rocky terrain. Therefore, if the value of CrossArtc_L_Max at the normal on-road vehicle height is 0.2, it corresponds to 0.6 at the access vehicle height.

[0083] In some embodiments, it should be understood that other values of the scale factor, such as 0.2, 0.4, 0.6, 0.8, or other suitable values, may be useful.

[0084] In this embodiment, the minimum allowable value CA_set_speed_min of CA_set_speed remains 1.8 km / h for each vehicle height setting. However, when the access vehicle height is selected, it should be understood that in some embodiments, different values of CA_set_speed_min, such as other suitable values like 1 km / h, may be used.

[0085] In some embodiments, when the cross-articulation module 215b decreases CA_set_speed while the vehicle is driving at the access vehicle height setting, the cross-articulation module 215b warns the driver that an intervention has been made by the HMI touch screen 18. For example, the cross-articulation module 215b may be configured such that the HMI touch screen 18 advises the driver to "raise the vehicle height if appropriate".

[0086] When the vehicle height is set to the off-road vehicle height, the cross-articulation module 215b is set to scale the x-axis of the plot in FIG. 4 by a scale factor of 0.75, and the value of CA_set_speed increases for a specific value of CrossArtc_L_Max compared to the operation at the normal on-road vehicle height. This is because when the off-road vehicle height is selected, the risk of grounding when the vehicle passes through rocky terrain is reduced.

[0087] Therefore, if the value of CrossArtc_L_Max at the normal on-road vehicle height is 0.2, it corresponds to a value of 0.15 at the off-road height. It should be understood that in some embodiments, other values of the scale factor (such as 0.5, 0.25, or other suitable values) may be useful.

[0088] As described above, in this embodiment, the minimum allowable value CA_set_speed_min of CA_set_speed remains 1.8 km / h for each vehicle height setting. However, it should be understood that in some embodiments, different values of CA_set_speed_min (such as other suitable values like 4 km / h) may be used when the off-road vehicle height is selected.

[0089] FIG. 6 is a schematic diagram showing the change in the vehicle speed VREF expected as a function of time after the value of CA_set_speed is triggered to decrease after the vehicle equipped with the VCU 215 in FIG. 5 encounters a bump. The graph shows the vehicle speed VREF as a function of time before and after encountering a bump on the driving surface that triggers a decrease in the vehicle speed due to the bump at time t1. The change in VREF is shown for vehicles with three different ride height settings: (a) off-road height, (b) normal on-road height, and (c) access height. Time t2 represents approximately the time at which a new vehicle speed VREF is achieved for each of the three ride height settings (a), (b), and (c).

[0090] From FIG. 6, it can be seen that the value of CA_set_speed corresponding to the off-road vehicle height setting is higher than that of the normal on-road vehicle height setting and even higher than that of the access vehicle height setting. As shown in FIG. 6, the difference in the value of CA_set_speed between the off-road and normal on-road vehicle height settings is much smaller than the difference in the value of CA_set_speed between the normal on-road vehicle height setting and the access vehicle height setting. However, it can be seen that the decrease in vehicle speed from the current speed at time t1 to the value of the corresponding CA_set_speed is the same for each vehicle height setting. This may be to at least partially reduce the inconvenience to the driver caused by the suspension suddenly reaching the limit of the travel distance when driving in each setting, especially in the access vehicle height setting where the available travel distance is the shortest.

[0091] FIG. 7 shows the operation method of the VCU215 of the embodiment in FIG. 5.

[0092] In step S101, the VCU15 determines the value of CrossArt_L based on the wheel articulation signal received as described above.

[0093] In step S103, the VCU calculates the value of CA_set-speed according to VREF, CrossArt_L, and the vehicle height setting.

[0094] In step S105, the VCU15 calculates the value of max_set-speed, max_set-speed’, without considering CA_set-speed.

[0095] In step S107, the VCU15 determines whether max_set-speed’ is smaller than CA_set-speed. If max_set-speed’ is smaller than CA_set-speed, the method proceeds to step S109; otherwise, the method proceeds to step S111.

[0096] In step S109, the VCU 15 sets the value of max_set-speed to the value of max_set-speed’. Then, the method proceeds to step S101.

[0097] In step S111, the VCU sets the value of max_set-speed to the value of CA_set-speed. Then, this method proceeds to step S101.

[0098] FIG. 8 is a schematic diagram of (a) an electronic controller 15’ included in the VCU 15 and configured to implement the speed control system of the VCU 15, and (b) an electronic controller 215’ included in the VCU 215 and configured to implement the speed control system of the VCU 215.

[0099] It is understood that various changes and modifications can be made to the present invention without departing from the scope of the present invention.

Claims

1. A speed control system for a vehicle, configured to operate the vehicle according to a target speed value and including one or more controllers, receiving articulation information indicating an amount of articulation of the front and rear wheels of the vehicle; determining a cross-articulation value CrossArtc_L indicating an amount of cross-articulation of the wheels of the vehicle according to the articulation information; and limiting the vehicle speed at least partially depending on the cross-articulation value A speed control system configured as described above.

2. The speed control system according to claim 1, wherein a maximum allowable vehicle speed CA_set-speed is determined at least partially depending on the cross-articulation value CrossArtc_L, and the vehicle speed is limited so that the vehicle speed does not exceed the value of CA_set-speed.

3. The speed control system according to claim 2, wherein the higher the value of the cross-articulation value CrossArtc_L, the lower the value of CA_set-speed.

4. The speed control system according to any one of claims 1 to 3, wherein the cross-articulation value depends on the following: A first articulation value indicating how much the wheels of the first diagonal wheel pair are articulated in the positive or negative direction with respect to a reference value and how much the phases of the wheels are articulated with respect to each other; A second articulation value indicating how much the wheels of a second diagonal wheel pair different from the first diagonal wheel pair are articulated in the positive or negative direction with respect to a reference value and how much the phases of the wheels are articulated with respect to each other; and The degree to which the first and second articulation values correspond to the opposite-phase movements of the respective pairs with respect to each other.

5. The speed control system according to any one of claims 1 to 4, configured to receive wheel articulation signals S_FL, S_FR, S_RL, S_RR, where S_FL is a signal indicating the height FL of the front left suspension, S_FR is a signal indicating the height FR of the front right suspension, S_RL is a signal indicating the height RL of the rear left suspension, and S_RR is a signal indicating the height RR of the rear right suspension.

6. The speed control system according to any one of claims 1 to 5, wherein the cross-articulation 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) wherein FL is the height of the front left suspension, FR is the height of the front right suspension, RL is the height of the rear left suspension, and RR is the height of the rear right suspension. **Claim 7** The speed control system according to any one of claims 1 to 6, configured to receive a signal indicating the vehicle speed VREF and further configured to limit the vehicle speed according to the value of VREF. **Claim 8** The speed control system according to claim 7, wherein when VREF exceeds a predetermined upper limit value, the vehicle speed is not limited according to the cross-articulation value. **Claim 9** The speed control system according to claim 8, wherein the speed control system becomes inoperative when it exceeds a predetermined speed control system inoperative value, and the predetermined upper limit value is smaller than the predetermined speed control system inoperative value. **Claim 10** The speed control system according to any one of claims 1 to 9, configured to receive one or both of the following signals: - A signal TRmode indicating the driving mode (TR mode) in which the vehicle is currently operating, and - A comfort signal S_comfort indicating the level of comfort required by the vehicle occupants (see below), wherein the speed control system is configured to limit the vehicle speed further depending at least in part on the signal TRmode and / or the signal S_comfort. **Claim 11** The speed control system according to any one of claims 1 to 10; and One or more sensors configured to output information indicating the articulation amount of the front and rear wheels of the vehicle A system for controlling the speed of a vehicle. **Claim 12** A vehicle including the speed control system according to any one of claims 1 to 10 or the system according to claim 11. **Claim 13** A method for controlling the speed of a vehicle executed by a speed control system, comprising: Operating the vehicle according to a target speed value; Receiving articulation information indicating the articulation amount of the front and rear wheels of the vehicle; Determining a cross-articulation value, CrossArtc_L, indicative of a cross-articulation amount of a wheel of a vehicle in accordance with the articulation information; and Limiting a vehicle speed at least partially depending on the cross-articulation value A method comprising the above steps. **Claim 14** Determining a maximum allowable vehicle speed, CA_set-speed, at least partially depending on the cross-articulation value CrossArtc_L, and Limiting the vehicle speed such that the vehicle speed does not exceed the value of CA_set-speed The method according to claim 13, comprising the above steps. **Claim 15** A non-transitory computer-readable storage medium storing instructions that, when executed by one or more electronic processors, cause the one or more electronic processors to execute the method according to claim 13 or claim 14.

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