Vehicle speed 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 (15) uses a pitch rate signal indicating the rate of change of the pitch of the vehicle (10) and a road surface gradient signal indicating the gradient of the road surface on which the vehicle (10) is traveling to determine whether the vehicle has reached the summit. The determination of reaching the summit depends on the rate of change of the pitch exceeding a predetermined value and the gradient value of the road surface being less than a predetermined value. The speed control system (15) outputs a speed reduction signal for reducing the speed of the vehicle when the vehicle reaches the summit.

Description

【Technical Field】 【0001】 The present disclosure 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 in traversing terrain having obstacles such as slopes that a driver must overcome. 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 When traveling on terrain that includes the crest of a slope that causes the vehicle's nose to dip in front of the vehicle, the driver may want to reduce the speed of the vehicle as it passes over the crest. Reducing the speed helps the driver survey the terrain in front of the vehicle and plan the vehicle's path as it passes through the terrain. 【0005】 An object of the present invention is to solve one or more drawbacks associated with the prior art. 【Means for Solving the Problems】 【0006】 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. 【0007】 According to one aspect of the present invention, a speed control system for a vehicle is provided, which is configured to operate the vehicle according to a target speed value, and includes one or more controllers, the speed control system is Receive a pitch rate signal indicating the rate of change of the vehicle's pitch; Receive a running surface gradient signal indicating the gradient of the running surface on which the vehicle is traveling; and This includes determining whether the vehicle has reached the top based on the following: The rate of change of pitch exceeds a predetermined value; and The gradient of the running surface must be less than a specified value; The speed control system is configured to output a speed reduction signal to decrease the vehicle's speed when it determines that the vehicle has reached the top of the hill. 【0008】 Embodiments of the present invention have the advantage of reducing the driver's workload because the speed control system reduces the vehicle's speed when it determines that the vehicle has reached the top of the terrain, eliminating the need for the driver to slow down the vehicle to survey the terrain ahead before crossing the terrain. Rather, the speed control system determines when it is appropriate to slow down the vehicle and takes appropriate action. Furthermore, the speed control system improves vehicle stability because the speed is reduced at the appropriate time during the process of crossing the terrain. 【0009】 Some embodiments of the present invention also have the advantage of reducing driver discomfort. It should be understood that if the speed control system does not intervene to reduce the vehicle speed when it reaches a peak, the driver may perceive the speed as too high for the type of terrain, become uneasy about the vehicle's speed, and lose confidence in the speed control system. 【0010】 The applicant recognized that user satisfaction could be improved by reducing the possibility of the speed control system mistakenly detecting the top of a track and unnecessarily slowing down, thereby inconveniencing the user, if a speed reduction is triggered in response to certain conditions being met with respect to the rate of change of pitch and the gradient of the running surface. Therefore, embodiments of the present invention aim to mitigate the problem of the vehicle being mistakenly determined to have reached the top of a track. 【0011】 It should be understood that "pitch" refers to the pitch orientation of a vehicle. 【0012】 Reaching the peak should be understood as corresponding to a decrease in the vehicle's pitch, that is, the front of the vehicle moving downward relative to the rear of the vehicle. 【0013】 In this specification, it should be understood that a positive gradient corresponds to an uphill slope, and a negative gradient corresponds to a downhill slope. 【0014】 The speed control system is an "off-road" or "off-highway" speed control system. Optionally, the system may be configured to reduce speed when it determines that the vehicle has reached its peak by at least one of the following: Application of brake torque by the vehicle's braking system; and A reduction in the amount of positive drive torque applied to one or more wheels of a vehicle. 【0015】 Optionally, the system may be configured to select the amount of speed reduction based on the gradient of the running surface. For example, on low-grip surfaces such as grass, gravel, or snow, the speed may be reduced even more than on high-grip surfaces such as asphalt or concrete. 【0016】 The advantage of this feature is that the speed control system can reduce the vehicle's speed depending on whether it has climbed to a suitable gradient on the road surface. 【0017】 The amount of speed reduction is optional and is selected based on the instantaneous gradient of the running surface. 【0018】 Therefore, the amount of deceleration is selected according to the gradient of the running surface corresponding to the vehicle's current position, but it should be understood that there may be delays associated with acquiring and processing sensor data to obtain such data. Thus, if the gradient changes while the speed is decreasing, the amount of brake torque and / or the reduction in applied propulsion torque may be changed accordingly. The speed may decrease, for example, to less than 30 km / h, 30 km / h, 25 km / h, 20 km / h, 15 km / h, 12 km / h, 10 km / h, 5 km / h, 3 km / h, or 1 km / h. 【0019】 Optionally, the system may be configured to calculate an estimated surface gradient value based on the surface gradient signal, and the speed control system may be configured to reduce the vehicle speed if it determines that the vehicle has reached the top of the surface gradient, in accordance with the estimated surface gradient value. 【0020】 Optionally, the system may be configured to reduce the vehicle's speed if it determines that the vehicle has reached its peak by at least one of the following: A predetermined speed reduction period after it is determined that the vehicle has reached the top, and The predetermined speed reduction distance after it is determined that the vehicle has reached the summit. 【0021】 The predetermined deceleration period can be any appropriate time period, such as 1 second, 2 seconds, 5 seconds, 10 seconds, or any other appropriate value. The predetermined deceleration distance can be any appropriate distance, such as 1x the wheelbase, 2x the wheelbase, 3x the wheelbase, or any other appropriate distance. It should be understood that the wheelbase refers to the distance between the centers of the front wheels and rear wheels of the vehicle in a direction parallel to the vehicle's longitudinal axis. 【0022】 Optionally, if the system decelerates the vehicle's speed in response to the first determination that the vehicle has reached the summit, the control system may be configured not to further decelerate the vehicle's speed in response to the second determination that the vehicle has reached the summit, unless the second determination occurs under at least one of the following conditions: after at least a predetermined summit detection period has elapsed since the first determination that the vehicle has reached the summit, and after at least a predetermined summit detection distance has elapsed since the first determination that the vehicle has reached the summit. 【0023】 The predetermined summit detection period can be any suitable time period, such as 2 seconds, 5 seconds, 10 seconds, or other suitable values. The predetermined summit detection distance can be any suitable distance, such as 1 times the wheelbase, 2 times the wheelbase, 3 times the wheelbase, or other suitable distances. 【0024】 In some embodiments, the predetermined summit detection period is substantially 2 times the predetermined speed reduction period. 【0025】 In one embodiment, the predetermined speed reduction period is 2 seconds and the predetermined summit detection period is 4 seconds. 【0026】 In one embodiment, the predetermined speed reduction distance corresponds to approximately 2 times the vehicle's wheelbase, and the predetermined summit detection distance corresponds to approximately 4 times the wheelbase. 【0027】 Optionally, a speed control system configured to output a speed reduction signal to reduce the vehicle's speed in response to a determination that the vehicle has reached the summit includes a speed control system configured to output a vehicle deceleration requirement corresponding to the required deceleration rate of the vehicle. 【0028】 The deceleration requirement can also be said to be an acceleration requirement when the acceleration rate is negative. It should be understood that when speed reduction is required, the deceleration requirement usually corresponds to a negative acceleration rate, that is, the deceleration of the vehicle. 【0029】 Optionally, the system can also be configured so that the vehicle deceleration request depends at least partially on the gradient of the running surface. 【0030】 Optionally, the system may be configured so that the magnitude of the deceleration request increases in proportion to the increase in the gradient of the running surface. 【0031】 Optionally, the vehicle's deceleration request depends at least in part on a user-selectable input indicating a desired level of occupant comfort. 【0032】 Optionally, the system may be configured so that the magnitude of the deceleration request increases in proportion to an increase in the desired level of comfort for the occupants. 【0033】 According to another aspect of the present invention, a system for controlling the speed of a vehicle is provided, which includes: Speed ​​control system according to the above-described embodiment; and One or more sensors configured to output signals indicating the following: The pitch of the vehicle and / or the rate of change of the vehicle's pitch; and The gradient of the running surface. 【0034】 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. 【0035】 According to yet another aspect of the present invention, a vehicle is provided which includes the speed control system of the aforementioned aspect or the system of the aforementioned aspect. 【0036】 A further aspect of the present invention provides a method for controlling the speed of a vehicle performed by a speed control system, the method comprising operating the vehicle according to a target speed value, and further, Receiving a pitch rate signal indicating the rate of change in the vehicle's pitch attitude; Receiving a track gradient signal indicating the gradient of the track surface on which the vehicle is traveling; and This includes determining whether the vehicle has reached the top based on the following: The rate of change in pitch attitude exceeds a predetermined value; and The gradient of the running surface must be less than a specified value; This method includes outputting a speed reduction signal to decrease the vehicle's speed in response to the determination that the vehicle has reached the top. 【0037】 In one aspect of the present invention, a vehicle speed control system is provided, which includes the following: A means of automatically operating a vehicle according to a target speed value; Means for receiving pitch rate information indicating the rate of change in the pitch attitude of a vehicle; Means for receiving running surface gradient information indicating the gradient of the running surface on which the vehicle is traveling; and A means for determining that a vehicle has reached the top, wherein the means for determining that a vehicle has reached the top is configured such that, as pitch rate information, the change in vehicle pitch attitude exceeds a predetermined rate in the direction corresponding to the decrease in pitch attitude, and the gradient value of the running surface is below a limit value, and the means for determining that a vehicle has reached the top corresponds to a gradient value greater than zero for uphill gradients and a gradient value less than zero for downhill gradients. Includes, A speed control system configured to reduce the vehicle's speed when it is determined that the vehicle has reached the top of a slope. 【0038】 According to yet another aspect of the present invention, a non-temporary computer-readable storage medium is provided which, when executed by one or more electronic processors, stores instructions causing one or more electronic processors to perform the method of the above-described aspect. 【0039】 Within the scope of this application, the various aspects, embodiments, examples, and alternatives described in the preceding paragraph, claims, and / or the following description and drawings, in particular their individual features, are expressly intended to be adopted independently or in any combination. That is, all embodiments and / or features of embodiments can be combined in any way and / or combination, provided that such features are incompatible. The applicant reserves the right to modify the initially filed claims and to file new claims accordingly. This includes the right to modify the initially filed claims to depend on or incorporate features of other claims, even if not originally claimed so. 【0040】 One or more embodiments of the present invention will be described only by reference to the accompanying drawings. [Brief explanation of the drawing] 【0041】 [Figure 1] Figure 1 is a schematic diagram of a vehicle having a speed control system according to an embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram of the steering wheel of a vehicle having a speed control system according to an embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram of a speed control system according to an embodiment of the present invention. [Figure 4] Figure 4 shows a vehicle according to an embodiment of the present invention climbing a slope towards the top. [Figure 5] Figure 5 shows a vehicle according to an embodiment of the present invention climbing a slope towards another peak. [Figure 6] Figure 6 shows a vehicle according to an embodiment of the present invention moving along a horizontal running surface toward another peak. [Figure 7] Figure 7 shows a vehicle according to an embodiment of the present invention climbing a slope towards the top, with another peak ahead. [Figure 8]Figure 8 is a graph of the target peak acceleration determined by the speed control system as a function of the gradient of the running surface and the comfort parameter settings. [Figure 9] Figure 9 is a flow diagram showing the operation of the velocity control system for detecting the peak and mitigating jerk. [Figure 10] Figure 10 is a flow diagram further illustrating the operation of the velocity control system to mitigate jerk after the peak event has ended. [Figure 11] Figure 11 is a schematic diagram of an electronic controller included in a vehicle control unit (VCU) and configured to implement the VCU's speed control system. [Modes for carrying out the invention] 【0042】 The contents of WO2013 / 124321 are incorporated herein by reference. 【0043】 Figure 1 is a schematic diagram of a vehicle 10 according to one 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 a coupling 13. The coupling 13 is positioned so that when the vehicle 10 is accelerating from a standstill, the transmission 12 gradually reaches a speed compatible with the motor speed. The coupling 13 is typically a friction clutch, a torque converter, etc. The transmission 12 is configured to drive a pair of rear wheels 10RW and, optionally, a pair of steerable front wheels 10FW. An accelerator pedal 1 allows 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 allows the driver to apply the braking system under the control of a brake controller 16. A driving mode selector 19 is provided, which allows the driver to select an on-road driving mode or one of several off-road driving modes, including a grass / gravel / snow (GGS) driving mode, a sand (S) driving mode, and a mud and rutted (MR) driving mode. In some embodiments, the selector also allows the vehicle 10 to select an "auto-response mode" in which it automatically determines the optimal driving mode at any given time. The driving mode may be called a "terrain response" (or "TR") mode. 【0044】 Vehicle 10 is equipped with a vehicle control unit (VCU) 15 capable of operating to perform a low-speed vehicle speed control function or system. The low-speed vehicle speed control function is also called an “off-road” or “off-highway” cruise control function or system. The low-speed vehicle speed control function is activatable when 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 can operate to perform a high-speed speed control function or system. The VCU 15 can be described as performing either a low-speed speed control system or a high-speed speed control system. Both the low-speed speed control system and the high-speed speed control system functions are controlled by the user via input controls mounted on the steering wheel 171 of vehicle 10. The steering wheel 171 is shown in more detail in Figure 2. It is important to understand that the low-speed vehicle speed control function or system is useful when driving under off-highway driving conditions, while the high-speed speed control function or system is useful when driving under on-highway driving conditions, such as on relatively smooth and dry paved or concrete surfaces. 【0045】 The input controls include a "speed setting" control 173, which, when activated, sets the value of the parameter driver_set_speed to approximately equal the current vehicle speed. Pressing the "+" (or "plus") button 174 increases the set speed, and pressing the "-" (or "minus") button 175 decreases the set speed. In some embodiments, if the speed control function is not active when the "+" button 174 is pressed, the speed control function is activated. 【0046】 In this embodiment, the VCU 15 is configured to perform an active speed control system (or "active cruise control") when the high-speed control system is operating. The active speed control system is configured to maintain a predetermined distance behind a preceding vehicle in certain situations, as will be described later. The wheel 171 also has a pair of follow distance control buttons 178, 179 for setting the value of the parameter distance_following. This parameter is the distance at which the driver wishes to maintain the vehicle 10 behind the preceding vehicle. The VCU 15 is operable to control the vehicle 10 to maintain a distance behind the preceding vehicle that is substantially equal to the distance represented by the parameter distance_following. 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, and the second button 179 is operable to decrease the value of the parameter distance_following. The vehicle 10 has a radar module 5 mounted on its front and configured to project a radar beam in the forward direction of the vehicle 10. Module 5 is configured to detect radiation reflected by a preceding vehicle and determine the distance between the preceding vehicle and vehicle 10 ("host" vehicle). Module 5 is provided with a signal indicating the current speed of the host vehicle 10. From this signal and data on the change in distance from the host vehicle 10 to the preceding vehicle as a function of time, 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, an active speed control function is not provided, and the subsequent distance control buttons 178, 179 are omitted. In some embodiments, radar module 5 is omitted. 【0047】 High-speed control systems are not the subject of this application. The remainder of this specification relates to low-speed control systems unless otherwise specified. 【0048】 When the low-speed control system is activated, the VCU 15 controls the speed of the vehicle 10 according to a target speed value that is substantially equal to the driver-selected set speed, driver_set_speed, or a lower value if desired, as will be explained in more detail below. The VCU 15 does this by calculating the maximum allowable speed of the vehicle 10 at a given time, max_set_speed. 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 will be explained in more detail below. The VCU 15 controls the speed of the vehicle 10 according to the target speed value of the vehicle, max_set_speed, by ensuring that the vehicle speed VREF is equal to the value of max_set_speed. 【0049】 Next, the VCU 15 outputs a target acceleration value acc_tgt at a specific point in time to the powertrain controller 17 and the brake controller 16 so that the vehicle speed, determined by referring to the vehicle reference speed VREF, maintains a desired value. If 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. 【0050】 The driver can set the value of driver_set_speed in the low-speed control system to the current vehicle speed VREF (provided that VREF does not exceed 30 km / h) by pressing the "speed setting" control 173 while the vehicle 10 is in motion. When the VCU 15 detects that the "speed setting" control 173 has been pressed, it 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 30 km / h and the set speed control 173 is pressed, the high-speed control system is activated. In this embodiment, since the value of driver_set_speed is set to a value exceeding 30 km / h, the low-speed control system will not automatically restart even if the speed falls below 30 km / h if the high-speed control system is activated.) 【0051】 As described above, when the vehicle 10 is traveling along the road and the high-speed control system is active, i.e., 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 in such a way that the user can be instructed to maintain the current vehicle speed by pressing the set speed control 173. If there is no traffic ahead of the vehicle 10, or no other factors (described later) that require 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. 【0052】 In this embodiment, if the VCU 15 (by the radar module 5) detects the presence of a preceding vehicle in front of the vehicle 10, the VCU 15 can operate to reduce the speed of the host vehicle 10 in accordance with the speed of the preceding vehicle in order to maintain a distance of a specified distance or more 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 is only available when the high-speed control system is active. 【0053】 The vehicle 10 has a human-machine interface (HMI) in the form of a touchscreen 18, through which the VCU 15 can communicate with the user. As described above, when the low-speed control system is active, the VCU 15 can be operated to calculate the maximum allowable set speed max_set_speed depending on the terrain the vehicle is traveling on. Thus, the VCU 15 can be operated to limit the maximum speed at which the vehicle 10 is controlled depending on the terrain. Embodiments of the present invention can reduce driver intervention and improve vehicle stability when operating in off-highway conditions. That is, since the VCU 15 determines the maximum allowable set speed max_set_speed and limits the set speed accordingly, the driver does not need to intervene to lower the vehicle set speed value when the terrain allows, or to increase the set speed when the terrain allows. 【0054】 Figure 3 shows how the VCU15 determines the value of max_set_speed. The VCU15 includes a "maximum set speed calculation" section (or "engine") 15a, a "top acceleration request calculation" section (or "engine") 15b, and a "vehicle acceleration calculation" section (or "engine") 15c. Furthermore, the input to the "maximum set speed calculation" section (or "engine") 15a includes a "lateral acceleration limit calculation" section 15d. 【0055】 The "vehicle acceleration calculation" section 15c is configured to calculate a target value acc_tgt for the acceleration of the vehicle 10 at a specific point in time, based on received inputs including inputs from the "maximum set speed calculation" section 15a and the "peak acceleration request calculation" section 15b. As described above, the "vehicle acceleration calculation" section 15c optionally outputs the desired acceleration value at a predetermined point in time acc_tgt as a speed reduction signal to the powertrain controller 17 and the brake controller 16, and the powertrain controller 17 and the brake controller 16 attempt to make the actual vehicle acceleration equal to acc_tgt as quickly as possible within a predetermined comfort limit. The brake controller or powertrain controller can change the speed by applying brakes or brake torque to the wheels of the vehicle by the vehicle braking system. Alternatively, or in addition to that, acceleration or deceleration of the vehicle can also be achieved by reducing the amount of positive drive torque applied to one or more wheels of the vehicle. The VCU 15 controls the acceleration (positive or negative) at a specific point in time by changing the value of acc_tgt output by the "vehicle acceleration calculation" unit 15c at a desired speed. In some embodiments, including the embodiment shown in Figure 3, the "vehicle acceleration calculation" unit 15c receives a value of the comfort parameter COMFORT, which indicates the level of comfort required by the vehicle occupants, as will be explained in more detail below. The "vehicle acceleration calculation" unit 15c then adjusts the maximum allowable rate of change of acceleration (or "jerk") at a specific point in time according to the value of the comfort parameter, thereby controlling occupant comfort. Therefore, if the level of occupant comfort requirements is high, the "vehicle acceleration calculation" unit 15c reduces the maximum allowable jerk to enhance occupant comfort. Thus, if a change in vehicle acceleration is necessary, the "vehicle acceleration calculation" unit 15c limits the rate of change of acceleration to enhance occupant comfort. The maximum allowable jerk is sometimes called the "jerk limit." 【0056】 The "Maximum Set Speed ​​Calculation" section 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 mentioned above, the "Maximum Set Speed ​​Calculation" section 15a outputs a max_set_speed value that is not greater than the value of driver_set_speed, but may be less if the "Maximum Set Speed ​​Calculation" section 15a determines that this is required by the driving conditions, as will be explained in more detail below. The parameters are as follows: (a) The reference value of the current vehicle surface friction coefficient "μmeas" is a value calculated by VCU15 based on the value of one or more parameters, such as the amount of torque applied to the wheel that induced excessive wheel slip; (b) The expected surface friction coefficient value corresponding to the currently selected vehicle driving mode "μTRmode" is a value specified for each driving mode; (c) The current value of the steering angle corresponds to the steerable load wheel angle, or, in some embodiments, to the steering wheel position "steering angle, δ"; (d) The current yaw rate of the vehicle (determined by referring to the output of the accelerometer), "yaw rate"; (e) The current measured value of lateral acceleration "MEASURED LAT.ACC." (determined by referring to the output of the accelerometer); (f) The current measured value of surface roughness "SURFACE ROUGHNESS" (determined by referring to the articulation of the suspension). In some embodiments, the VCU 15 may also receive (g) a signal indicating the vehicle's current position, “GPS position” (determined by referring to a Global Positioning System (GPS) output or other Global Navigation Satellite System or other positioning system), and / or (h) information “camera” acquired by a camera system. Information acquired by a camera system or imaging system may include, for example, a warning if it is determined that the vehicle 10 may deviate from an off-road lane or track. 【0057】 The "lateral acceleration limit calculation" section 15d of the VCU15 is configured to determine the maximum allowable lateral acceleration max_lat_acc of the moving vehicle 10 from the reference value μmeas and the expected value μTRmode of the road friction coefficient. The VCU15 uses this max_lat_acc value to limit the value of max_set_speed when the vehicle is cornering, thereby preventing understeer. 【0058】 In this embodiment, the "maximum set speed calculation" portion 15a of the VCU 15 can also be operated to calculate the radius of curvature of the vehicle 10's path on the terrain based on the steering angle. The VCU 15 compares this radius of curvature with the vehicle's yaw rate and the measured lateral acceleration. If the VCU 15 detects the presence of understeer, it can be operated to reduce the value of max_set_speed accordingly. In some embodiments where a signal indicating the vehicle's current position is received, the VCU 15 can also consider the vehicle's path of travel, which is determined by referring to the position signal, to increase the reliability of the determination of the amount of understeer present (if any). 【0059】 In some embodiments, the yaw rate and measured lateral acceleration are not used to determine the amount of understeer. Other configurations are also useful. 【0060】 The "Maximum Set Speed ​​Calculation" section 15a of VCU15 also determines the value of max_set_speed according to the surface roughness value of the terrain on which the vehicle 10 is traveling. If the surface roughness increases, the value of max_set_speed may decrease. 【0061】 In this embodiment, the crest acceleration request calculation unit 15b of the VCU 15 also receives a running surface gradient signal indicating the gradient of the running surface on which the vehicle 10 travels, and a pitch rate signal indicating the rate of change of the pitch of the vehicle 10. The crest acceleration request calculation unit 15b of the VCU 15 is configured to generate a value tgt_crest_acc, which is the desired acceleration rate of the vehicle 10 at a predetermined time. The crest acceleration request calculation unit 15b outputs an acceleration request signal acc_demand to the vehicle acceleration calculation unit 15c in order to accelerate the vehicle 10 to the desired speed tgt_crest_acc. 【0062】 If the peak acceleration request calculation unit 15b determines that the vehicle has not reached the peak, the value of the parameter acc_demand is set to correspond to the maximum allowable value Amax of the vehicle acceleration. This is to ensure that the vehicle acceleration calculation unit 15c does not reduce the vehicle speed in response to the acc_demand signal, but only in response to the max_set_speed signal received from the maximum set speed calculation unit 15a. 【0063】 The crest acceleration request calculation unit 15b determines that the vehicle has reached the crest, and sets the value of the parameter acc_demand to correspond to the desired acceleration rate tgt_crest_acc. The crest acceleration request calculation unit 15b of the VCU 15 is configured to determine whether the vehicle has reached the crest based on the gradient signal ("GRADIENT") and the pitch rate signal ("PITCHRATE"). It should be understood that the value of the acceleration rate acc_demand corresponds to a negative acceleration rate in order to reduce the vehicle speed when it is determined that the vehicle has reached the crest. 【0064】 In particular, the peak acceleration request calculation unit 15b of the VCU 15 is configured to determine that the vehicle has reached its peak when the following conditions are met: (a) The rate of change of the vehicle's pitch, determined by referring to the pitch rate signal, exceeds a predetermined value over a predetermined period of time, and (b) The gradient value of the running surface, determined by referring to the gradient signal of the running surface, is below a predetermined value. 【0065】 In this specification, the gradient value of the running surface may be referred to as the running surface gradient value. 【0066】 In this embodiment, the predetermined value for the rate of change of the vehicle's pitch is 5 degrees per second, the predetermined period is 1 second, and the predetermined value for the gradient of the running surface is +5%. Therefore, it is understood that for the peak acceleration request calculation unit 15b of the VCU 15 to determine that the vehicle has reached the peak, the gradient of the running surface must be less than +5% (uphill gradient), that is, the gradient of the running surface must be an uphill gradient of less than 5%. The running surface gradient condition should be understood to be satisfied, for example, when the gradient of the running surface is +4%, substantially zero (corresponding to a horizontal plane), or negative (corresponding to a downhill slope). Other predetermined values ​​for the rate of change of pitch, predetermined period, and predetermined gradient may be useful in some embodiments. 【0067】 As described above, the peak acceleration request calculation unit 15b of the VCU 15 should be understood to output an acc_demand value corresponding to the maximum allowable value Amax of the vehicle's acceleration if it determines that the vehicle has not reached its peak. This is so that the vehicle acceleration calculation unit 15c ignores the acc_demand signal and prioritizes the max_set_speed signal received from the maximum set speed calculation unit 15a of the VCU 15. 【0068】 In some embodiments, when the VCU 15 determines that the conditions for determining that the vehicle has reached the top are met, it sets the value of acc_demand to a fixed predetermined value corresponding to a negative acceleration, i.e., a deceleration rate, instructing the vehicle acceleration calculation unit 15c to impose a deceleration rate on the vehicle 10. In response to receiving a request from the "top acceleration request calculation" unit 15b for a negative acceleration rate for the vehicle 10, the vehicle acceleration calculation unit 15c of the VCU 15 decreases the value of the vehicle speed VREF by a rate corresponding to the requested deceleration rate acc_demand. 【0069】 In some embodiments, acc_demand is output as a deceleration signal that can be operated to reduce or replace max_set_speed or driver_set_speed. The deceleration signal may be output to a powertrain controller or control system, or to another vehicle system such as a brake or braking controller or control system, so that the vehicle speed is reduced while the peak is identified. 【0070】 In this embodiment, the value of acc_demand itself depends on at least one parameter. In this embodiment, when the VCU 15 determines that the conditions for determining that the vehicle has reached its peak are met, the "peak acceleration request" calculation unit 15b of the VCU 15 calculates a value of tgt_crest_acc that depends on the following parameter: (1) The current value of the running surface gradient. The value of tgt_crest_acc becomes negatively larger as the running surface gradient becomes larger (corresponding to a gradually increasing deceleration rate); (2) The driving mode the vehicle is currently operating in ("TR mode"); (3) The value of the comfort parameter "COMFORT" (which indicates the level of comfort required by the vehicle's occupants). The value of tgt_crest_acc increases in the negative direction as the required level of comfort increases (corresponding to a gradually increasing deceleration rate). Therefore, the decrease in the speed of vehicle 10 during the period in which deceleration is imposed increases as the required level of comfort increases. 【0071】 It is understood that the value of tgt_crest_acc can be set according to the driving mode according to an empirically determined lookup table (LUT). In this embodiment, when the selected driving mode (TR mode) is the sand mode, no reduction in vehicle speed occurs in response to the determination that the vehicle has reached the top, but a reduction occurs in all other driving modes such as the GGS driving mode and the highway driving mode. In this embodiment, the value of tgt_crest_acc calculated in driving modes other than the sand mode is substantially the same for a predetermined set of conditions including the VREF value, gradient, and rate of change of pitch. In some alternative embodiments, the value of tgt_crest_acc calculated by the top acceleration request calculation unit 15b in at least two driving modes other than the sand mode may differ for a predetermined set of conditions. 【0072】 In this embodiment, the VCU 15 is configured to receive an input indicating a desired level of occupant comfort via the touchscreen 18, although other input devices such as a rotary dial may also be useful. In this embodiment, the comfort signal indicates whether the comfort setting value is 0 (zero), 1, 2, 3, or 4. A value of zero is considered to correspond to the "off" state of the comfort setting, indicating that passenger comfort is not considered when setting the value of tgt_crest_acc. In this embodiment, the VCU determines the value of tgt_crest_acc according to the gradient of the running surface and increases the value of tgt_crest_acc by a coefficient such that the vehicle speed value decreases progressively larger as the comfort setting value increases. The input indicating a desired level of occupant comfort described in this embodiment is user-selectable and can therefore be called a user-selectable input indicating a desired level of occupant comfort, a desired value of an occupant comfort parameter, a comfort parameter, a desired level of occupant comfort, a value of a comfort parameter, or a level of comfort required by the occupants of the vehicle. 【0073】 In some embodiments, it should be understood that the vehicle 10 does not have a function that allows the driver to input desired values ​​for occupant comfort parameters. 【0074】 In this embodiment, to avoid inconveniencing the user, the VCU 15 is configured so that the value of max_set_speed does not fall below a predetermined minimum value. Therefore, when the vehicle speed VREF reaches a predetermined minimum allowable value, the vehicle acceleration calculation unit 15c does not attempt to reduce the vehicle speed in response to a negative acceleration request from the top acceleration request calculation unit 15b. In this embodiment, the predetermined minimum value is 2 km / h, but other values ​​can be used depending on the embodiment. 【0075】 As described above, in this embodiment, the VCU15 is configured to determine that the vehicle has reached the top when the top conditions (a) and (b) above are met, and to calculate the value of tgt_crest_acc according to the parameters (1) to (3) above. 【0076】 As described above, in this embodiment, the VCU 15 calculates the value of the parameter tgt_crest_acc and instructs the "vehicle acceleration calculation" unit 15c to apply an acceleration to the vehicle 10 according to the value of tgt_crest_acc. In this embodiment, after it is determined that the vehicle has reached the top, this acceleration rate is applied for a predetermined period, i.e., a predetermined speed reduction period. In this embodiment, the predetermined speed reduction period is 2 seconds, but depending on the embodiment, it may be 1 second, 5 seconds, 10 seconds, or other appropriate periods. 【0077】 In another embodiment, the VCU 15 may calculate the value of the parameter tgt_crest_acc and, after determining that the vehicle has reached its peak, instruct the "vehicle acceleration calculation" section 15c to impose an acceleration rate corresponding to the value of tgt_crest_acc on the vehicle 10 over a predetermined distance called a predetermined deceleration distance. The predetermined deceleration distance can be any appropriate distance, such as 1x the wheelbase, 2x the wheelbase, 3x the wheelbase, or any appropriate distance. It should be understood that for a distance to be considered appropriate, the distance does not need to be an integer or a number of integers of the wheelbase. The wheelbase refers to the distance between the centers of the front wheels and rear wheels of the vehicle in a direction parallel to the longitudinal axis of the vehicle. 【0078】 Figure 4 shows vehicle 10 climbing a slope towards the summit C, and once it passes the summit C, the running surface becomes almost horizontal. When vehicle 10 passes the summit C, VCU 15 detects a decrease in the gradient of the running surface and a decrease in vehicle pitch (i.e., vehicle pitch attitude). If the rate of change of pitch exceeds a predetermined value of 5 degrees per second, and the gradient of the running surface is less than a 5% (uphill) gradient, i.e., the gradient is less than 5%, horizontal, or downhill, VCU 15 determines that vehicle 10 has reached the summit and begins calculating the value of tgt_crest_acc according to the above parameters (1) to (3). 【0079】 Figure 5 shows vehicle 10 climbing a slope towards the summit C, and beyond the summit C the running surface becomes a negative (downhill) gradient. When vehicle 10 passes the summit C, VCU 15 detects the decrease in the gradient of the running surface and the decrease in vehicle pitch (i.e., vehicle pitch attitude). If the rate of change of pitch exceeds a predetermined value of 5 degrees per second, and the gradient of the running surface is less than a 5% (uphill) gradient, i.e., the gradient is less than 5%, horizontal, or downhill, VCU 15 determines that vehicle 10 has reached the summit and begins calculating the value of tgt_crest_acc according to the above parameters (1) to (3). 【0080】 Figure 6 shows vehicle 10 moving towards the summit C across a nearly horizontal running surface (i.e., a gradient of nearly 0%). Beyond the summit C, the running surface becomes a negative gradient (downhill). Therefore, the summit condition (b), which is that the running surface gradient value determined by referring to the running surface gradient signal is 5% or less, is met. When vehicle 10 passes the summit C, VCU 15 detects a decrease in vehicle pitch (i.e., vehicle pitch attitude). When the rate of change of pitch exceeds a predetermined value of 5 degrees per second, VCU 15 determines that the summit condition (a) is met and vehicle 10 has reached the summit. Next, VCU 15 begins calculating the value of tgt_crest_accin according to the parameters (1) to (3) above. 【0081】 In this embodiment, when the VCU 15 calculates the value of tgt_crest_acc in response to the first determination that the vehicle has reached the top, the VCU 15 will not impose further deceleration in response to the second determination that the vehicle has reached the top, unless a second determination is made after a predetermined top detection period has elapsed since the first determination that the vehicle has reached the top. 【0082】 In some embodiments, a predetermined peak detection period corresponds to substantially twice the predetermined deceleration period. Other multiples may also be useful in some embodiments. 【0083】 In this embodiment, the predetermined peak detection period is 4 seconds, which is twice the predetermined speed reduction period of 2 seconds. However, depending on the embodiment, it may be 5 seconds, 10 seconds, or any other appropriate period. 【0084】 In another embodiment, when the VCU 15 calculates the value of acc_demand in response to the first determination that the vehicle has reached its peak, the VCU 15 will not impose further deceleration in response to the second determination that the vehicle has reached its peak unless a second determination is made after a predetermined peak detection distance has elapsed since the first determination that the vehicle has reached its peak. The predetermined peak detection distance can be any appropriate distance, such as 1x the wheelbase, 2x the wheelbase, 3x the wheelbase, 4x the wheelbase, or any appropriate distance. 【0085】 In some embodiments, a predetermined peak detection distance corresponds substantially to twice a predetermined velocity reduction distance. Other multiples may also be useful in some embodiments. 【0086】 In one embodiment, the predetermined speed reduction distance corresponds to approximately twice the vehicle's wheelbase, and the predetermined peak detection distance corresponds to approximately four times the wheelbase. 【0087】 Figure 7 shows the path of vehicle 10 over two peaks separated by a relatively short distance. Vehicle 10 is shown climbing the hill towards the first peak C1. When the vehicle passes peak C1, the conditions are met at position X1 for VCU 15 to determine that vehicle 10 has reached the top of the mountain. Therefore, VCU 15 calculates the acceleration value tgt_crest_acc that is imposed on the vehicle when it passes the peak. 【0088】 After passing position X1, the VCU 15 starts a timer. The VCU 15 continues to calculate the value of tgt_crest_acc according to the values ​​of the aforementioned parameters (a) to (c). After a predetermined deceleration period (2 seconds in this embodiment) has elapsed, the vehicle 10 stops calculating the value of tgt_crest_acc according to the values ​​of the aforementioned parameters (a) to (c) and sets the value of acc_demand to the maximum allowable value Amax of the vehicle acceleration as described above. Therefore, the vehicle acceleration calculation unit 15c ignores the value of acc_demand received when determining the vehicle speed and returns the vehicle speed to the lower of the current value of the driver-set speed and the current value of max_set_speed. 【0089】 Referring further to Figure 7, position X2 is the position of vehicle 10, where conditions (a) to (c) are met again, and VCU 15 makes a second determination that the vehicle has reached the top. However, if the time required to move from position X1 to position X2 is less than the predetermined top detection period (4 seconds in this embodiment) after the first determination that the vehicle has reached the top at position X1, VCU 15 ignores the fact that the top has been detected. However, if the predetermined top detection period has elapsed by the time the vehicle reaches position X2, VCU 15 responds to the arrival at position X1 in the manner described above. That is, VCU 15 starts a timer, calculates the value of tgt_crest_acc according to the values ​​of parameters (a)-(c), and imposes deceleration on the vehicle. 【0090】 Figure 8 shows the determination of the tgt_crest_acc and acc_demand values ​​by VCU15. In Figure 8, the horizontal axis represents the road surface gradient, with 0% representing a zero gradient state ("0% flat road"). On the horizontal axis, moving to the left of the 0% flat road state increases the road surface gradient in the uphill direction, and moving to the right of the 0% flat road state increases the road surface gradient in the downhill direction. 【0091】 As described above, if the VCU 15 determines that the vehicle has not reached the top of the slope, it sets the value of the parameter acc_demand output from the top-of-slope acceleration request calculation unit 15b to the maximum allowable value Amax. Therefore, the vehicle acceleration calculation unit 15c does not decrease the value of acc_tgt in response to the reception of the acc_demand signal; rather, the speed is controlled according to the value of max_set_speed received from the maximum set speed calculation unit 15a. 【0092】 As described above, the speed control system performed by the VCU 15 should be understood as being configured such that the vehicle acceleration calculation unit 15c cannot reduce the vehicle speed to a value below a predetermined minimum value. In this embodiment, the predetermined minimum value is 2 km / h, but other values ​​may be useful depending on the embodiment. 【0093】 If the conditions for the peak are met, VCU15 calculates the value of tgt_crest_acc, as described above and shown in Figure 8. 【0094】 As can be seen in Figure 8, the value of tgt_crest_acc is set to a negative value depending on the value of the comfort parameter (corresponding to the vehicle's increasingly rapid deceleration). In this embodiment, as shown in trace "A" in Figure 8, when the value of the comfort parameter is zero (corresponding to the "off" state) or value "1", when the gradient reaches 2% in the downhill direction (i.e., the gradient is minus 2% or "-2%)", the value of tgt_crest_acc changes from Amax to a negative value. These states are shown by the lines labeled "Comfort = 0, 1" in Figure 8. 【0095】 When the comfort parameter value is "2", the value of acc_demand changes from Amax to the value of tgt_crest_acc. This means that when the gradient reaches 0%, the negative value of acceleration increases. This state is shown in Figure 8 by the trace "B" and the line labeled "Comfort=2". 【0096】 When the comfort parameter value is "3" or "4", the value of tgt_crest_acc increases to a negative value when the gradient falls below +5%. When the comfort parameter value is "4", the rate of increase of tgt_crest_acc in the negative direction is steeper. That is, the gradient of the plot of tgt_crest_acc as a function of the gradient becomes steeper, and the decrease in speed is greater than when the comfort parameter value is "3" or less. This condition is shown in Figure 8 by the trace "C" and the lines labeled "Comfort=3" or "Comfort=4". 【0097】 In this embodiment, when the comfort parameter is set to the highest required value for occupant comfort, the VCU 15 is configured to determine that the vehicle has reached its peak when the downward pitch rate is lower than when the comfort parameter is lower. This state is shown by the line labeled "Comfort = 4" in Figure 8. In this embodiment, when the comfort parameter is set to the value "4", the VCU 15 is configured to require that the gradient be less than 5% and that the pitch rate be greater than 3 degrees / second. Other values ​​for the pitch rate, such as 2 degrees / second, 2.5 degrees / second, 4 degrees / second, or other appropriate values, may be useful in some embodiments. Other values ​​for the gradient may also be useful in some embodiments. 【0098】 If the comfort parameter value is 1, 2, or 3, or any other value, it should be understood that a different pitch rate value may be required before reaching the peak. 【0099】 As described above, the "Climb Acceleration Request Calculation" section 15b receives a value for a comfort parameter and determines the value of tgt_crest_acc in part depending on the comfort parameter. In some embodiments, the "Climb Acceleration Request Calculation" section 15b also adjusts the speed at which the vehicle takes the desired acceleration rate tgt_crest_acc, depending on the value of the comfort parameter, in order to limit the maximum value of jerk experienced at a particular moment. The maximum allowable value of jerk (i.e., the jerk limit) is lower as the required level of occupant comfort increases. 【0100】 Figure 9 shows how the jerk value limit changes when the acceleration request changes after peak detection. In other words, Figure 9 shows the operation of the jerk mitigation function of the "peak acceleration request calculation" unit 15b when peak detection occurs. 【0101】 In step S101, the "peak acceleration request calculation" unit 15b determines whether a peak has been detected. If no peak has been detected, step S101 is repeated. If a peak has been detected, the process proceeds to step S103. 【0102】 In step S103, the "Climb Acceleration Request Calculation" unit 15b calculates the target acceleration value tgt_crest_acc in response to the determination that the vehicle has reached the crest. The value of tgt_crest_acc is calculated according to the gradient of the driving surface, the driving mode, and the values ​​of the comfort parameters. The value of tgt_crest_acc is used to calculate the desired acceleration rate value acc_demand for the vehicle 10 at a particular point in time. The value of acc_demand is calculated from the value of tgt_crest_acc and is limited so that the maximum jerk does not exceed the jerk limit value. 【0103】 In step S105, the "maximum acceleration requirement calculation" section 15b determines whether the current value of acc_tgt output by the "vehicle acceleration calculation" section 15c is less than 0 meters / second. If the value of acc_tgt is less than 0, the method proceeds to step S107; otherwise, the method continues to step S109. 【0104】 In step S107, the "peak acceleration request calculation" unit 15b sets the value of the signal acc_demand to the current value of acc_tgt output by the "vehicle acceleration calculation" unit 15c, and proceeds to step S111. 【0105】 In step S109, the "peak acceleration request calculation" unit 15b sets the value of the signal acc_demand to zero, that is, a value corresponding to zero acceleration rate. 【0106】 In step S111, the "peak acceleration request calculation" unit 15b determines whether the value of acc_demand is equal to the value of tgt_crest_acc determined in step S103. 【0107】 If the value of acc_demand is tgt_crest_acc, the method proceeds to step S113; otherwise, it continues to step S115. 【0108】 In step S113, the "peak acceleration request calculation" section 15b terminates the jerk relaxation function and continues to output an acc_demand value equal to the tgt_crest_acc value calculated in step S103. 【0109】 In step S115, the "peak acceleration request calculation" section 15b reduces the value of acc_demand by a calibrated amount, and then proceeds to step S111 after a predetermined time has elapsed. Step S111 is repeated until the target value of acceleration acc_demand output by the "peak acceleration request calculation" section 15b matches the target value tgt_crest_acc. The amount by which the "peak acceleration request calculation" section 15b reduces the value of acc_demand and the predetermined time are set so that the amount of jerk the vehicle receives does not exceed a predetermined jerk amount (jerk limit value). In this embodiment, the predetermined jerk amount depends on the value of the comfort parameter, and it should be understood that the higher the required level of comfort, the lower the predetermined jerk amount. As mentioned above, in this embodiment, the higher the value of the comfort parameter, the higher the required level of comfort. 【0110】 It should be understood that the amount by which the "peak acceleration request calculation" unit 15b reduces the value of acc_demand and the value of the predetermined time are adjusted so that the amount of jerk experienced by the vehicle does not exceed the predetermined jerk amount. As described above with respect to Figure 9, in this embodiment, it is understood that the predetermined jerk amount depends on the value of the comfort parameter, and the predetermined jerk amount decreases as the required level of comfort increases. Also, as described above, in this embodiment, the higher the value of the comfort parameter, the higher the required level of comfort. 【0111】 Figure 10 shows how the VCU 15 controls the vehicle's speed after the summit event has finished. 【0112】 In step S201, the "summit acceleration request calculation" section 15b determines whether the summit event has finished. If the event has finished, the method proceeds to step S203; otherwise, step S201 is repeated. 【0113】 In step S203, the "Climbing Acceleration Requirement Calculation" section 15b sets the value of tgt_crest_acc to the maximum allowable value of acceleration Amax, and the method proceeds to step S205. 【0114】 In step S205, the "peak acceleration request calculation" unit 15b determines whether the value of acc_demand currently output by the "peak acceleration request calculation" unit 15b is equal to the value of tgt_crest_acc. If acc_demand = tgt_crest_acc, the method proceeds to step S207; otherwise, the method continues to step S209. 【0115】 In step S207, the "peak acceleration request calculation" unit 15b terminates the jerk mitigation function and maintains the value of acc_demand until the next peak is detected. 【0116】 In step S209, the "acceleration request calculation" section 15b increases the value of acc_demand by a calibrated amount. After a predetermined time has elapsed, the process proceeds to step S205. 【0117】 It should be understood that the amount by which the "peak acceleration request calculation" unit 15b reduces the value of acc_demand and the value of the predetermined time are adjusted so that the amount of jerk experienced by the vehicle does not exceed the predetermined jerk amount. As described above with respect to Figure 9, in this embodiment, it is understood that the predetermined jerk amount depends on the value of the comfort parameter, and the predetermined jerk amount decreases as the required level of comfort increases. Also, as described above, in this embodiment, the higher the value of the comfort parameter, the higher the required level of comfort. 【0118】 Figure 11 is a schematic diagram of an electronic control unit 15' included in the VCU 15 and configured to implement the speed control system of the VCU 15. 【0119】 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

[Claim 1] A vehicle speed control system, configured to operate a vehicle according to a target speed value, comprising one or more controllers, wherein the speed control system is The vehicle receives a pitch rate signal indicating the rate of change of pitch per second; Receiving a running surface gradient signal indicating the gradient of the running surface on which the vehicle is traveling; and This includes determining whether the vehicle has reached the top based on the following: The rate of change of pitch per second exceeds a predetermined value; and The gradient value of the aforementioned running surface is less than a predetermined value; A speed control system configured to output a speed reduction signal to reduce the speed of the vehicle in response to a determination that the vehicle has reached the top. [Claim 2] The speed control system according to claim 1, configured to reduce the speed of the vehicle when it is determined that the vehicle has reached the top by at least one of the following: Application of brake torque by the vehicle's braking system; and A reduction in the amount of positive driving torque applied to one or more wheels of the vehicle. [Claim 3] The speed control system according to claim 1, configured such that the amount of speed reduction is selected according to the gradient of the running surface. [Claim 4] The speed control system according to claim 3, wherein the amount of speed reduction is selected substantially according to the instantaneous gradient of the running surface. [Claim 5] A speed control system according to any one of claims 1 to 3, configured to calculate an estimated running surface gradient value based on the running surface gradient signal, and further configured to reduce the vehicle speed when it is determined that the vehicle has reached the top according to the estimated running surface gradient value. [Claim 6] A speed control system according to any one of claims 1 to 3, configured to reduce the speed of a vehicle in response to the determination that the vehicle has reached the top by at least one of the following: A predetermined speed reduction period after it is determined that the vehicle has reached the summit; and A predetermined speed reduction distance after it is determined that the vehicle has reached the summit. [Claim 7] A speed control system according to any one of claims 1 to 3, wherein when the speed of the vehicle is reduced in response to a first determination that the vehicle has reached its destination, the speed of the vehicle is not further reduced in response to a second determination that the vehicle has reached its peak, unless the second determination occurs under at least one of the following conditions: After the predetermined summit detection period has elapsed following the first determination that the vehicle has reached the summit; and / or After a predetermined summit detection distance has elapsed following the first determination that the vehicle has reached the summit. [Claim 8] The speed control system according to any one of claims 1 to 3, wherein the speed control system configured to output a speed reduction signal for reducing the speed of the vehicle in response to a determination that the vehicle has reached the top, includes a speed control system configured to output a vehicle deceleration request corresponding to the required deceleration rate of the vehicle. [Claim 9] The speed control system according to claim 8, wherein the vehicle deceleration request is configured to depend at least partially on the gradient of the running surface. [Claim 10] The speed control system according to claim 9, wherein the magnitude of the deceleration request is configured to increase in accordance with the increase in the gradient of the running surface. [Claim 11] The speed control system according to claim 8, wherein the vehicle deceleration request depends at least in part on a user-selectable input indicating a desired level of occupant comfort. [Claim 12] A vehicle speed control system, A speed control system according to any one of claims 1 to 3; and A speed control system including one or more sensors configured to output signals indicating the following: The pitch of the vehicle and / or the rate of change of the pitch of the vehicle; and The gradient of the running surface. [Claim 13] A vehicle comprising the speed control system according to any one of claims 1 to 3. [Claim 14] A method for controlling the speed of a vehicle performed by a speed control system, comprising operating the vehicle according to a target speed value, the method further includes: Receiving a pitch rate signal that indicates the rate of change of the vehicle's pitch attitude per second; Receiving a running surface gradient signal indicating the gradient of the running surface on which the vehicle is traveling; and This includes determining whether the vehicle has reached the top based on the following: The rate of change of pitch attitude per second exceeds a predetermined value; and The gradient value of the aforementioned running surface is less than a predetermined value; A method comprising outputting a speed reduction signal to reduce the speed of the vehicle in response to a determination that the vehicle has reached the top. [Claim 15] A non-temporary, computer-readable storage medium that, when executed by one or more electronic processors, stores instructions causing the one or more electronic processors to perform the method according to claim 14.

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