Control apparatus and method for controlling vehicle speed

Abstract

A control apparatus (100) for controlling a speed of a vehicle and a method for controlling a speed of a vehicle are provided. The method includes determining (S102) a maximum allowable vehicle speed profile (30) for an upcoming road segment (22) including an event (24) expected to require a reduction in vehicle speed. The method further comprises determining (S103) a desired vehicle speed profile (32) to reach a lowest point (31) of the determined maximum allowable speed profile (30) while avoiding the vehicle speed being higher than the determined maximum allowable vehicle speed profile (30). The method further comprises simulating (S104) a vehicle speed profile (34) of the first braking mode and braking (S108) the vehicle (1) according to the first braking mode when the simulated vehicle speed profile (34) of the first braking mode meets at least a first predefined criterion.

Description

Technical Field

[0001] The present disclosure generally relates to a method for controlling a vehicle speed of a vehicle. The present disclosure also generally relates to a control device configured to control a vehicle speed of a vehicle. Furthermore, the present disclosure generally relates to a computer program and a computer readable medium. Furthermore, the present disclosure generally relates to a cruise control system configured to control a vehicle speed of a vehicle. The present disclosure also generally relates to a vehicle. Background Art

[0002] Today, heavy vehicles, such as buses and trucks, are often equipped with various control systems configured to control the operation of the vehicle to achieve various objectives, such as improving safety, reducing the vehicle's energy consumption and / or improving the driver's comfort. Some of these control systems are configured to predict the future behavior of the vehicle if the vehicle is controlled according to different control strategies, taking into account, for example, data about the characteristics of an upcoming road section. Thereafter, these predictions determined by simulation can be used in order to determine the most appropriate strategy for controlling the vehicle for the upcoming road section.

[0003] Some control systems configured to control the operation of a vehicle may be activated and deactivated by, for example, the driver of the vehicle. In certain circumstances, such control systems may cause the vehicle to behave differently than the driver might expect and / or in a manner that is irritating to the driver. This, in turn, may cause the driver to deactivate the control system and thereby fail to take advantage of the benefits that may be achieved by the control system. It is therefore important to develop control systems that cause the vehicle to behave as the driver expects and that do not carry the risk of causing annoyance to the driver.

[0004] A specific example of a control system that can be activated / deactivated by the driver of the vehicle and thus depends on the driver's willingness to use the control system is a cruise control system. When activated, the cruise control system, for example, avoids the need for the driver to operate the accelerator pedal in order to maintain the vehicle speed, and thus improves the driver's comfort. There are various types of cruise control. They are configured to operate according to different control functions and therefore may have different effects on, for example, the operation of the vehicle.

[0005] For example, constant speed cruise control is intended to maintain a substantially constant vehicle speed, such as a set speed selected by the driver of the vehicle, and is therefore typically configured to maintain the vehicle speed within a relatively narrow permissible speed range about the set speed. Thus, constant speed cruise control controls the vehicle with the purpose of maintaining the set speed regardless of whether the vehicle is traveling uphill, downhill, or on a level running surface. This means that the vehicle may accelerate over the top of a hill, only to brake immediately on the subsequent downhill slope to avoid exceeding the set speed. Although such cruise control will cause the vehicle to behave as the driver intended, it is an uneconomical way of running a vehicle, particularly in the case of heavy vehicles, as it may typically excessively increase the energy consumption of the vehicle, and therefore increase operating costs (such as fuel costs).

[0006] Another type of cruise control is a look-ahead cruise control (sometimes also called predictive cruise control). Look-ahead cruise control is a cruise control that uses information about an upcoming road section (i.e., a road section ahead of the vehicle) and can plan a vehicle speed profile for the upcoming road section based on said information. Said information about the upcoming road section can usually be derived from map data in combination with information about the geographic location of the vehicle, but in some cases can also be derived from sensors arranged in or on the vehicle and / or supplemented with, for example, historical data related to the upcoming road section. Thereafter, when the vehicle travels along the road section in question, the look-ahead cruise control can control the vehicle speed according to the planned vehicle speed profile. Compared with a conventional constant speed cruise control, a look-ahead cruise control has the advantage of being able to save a lot of energy (such as fuel). For example, in the case where the upcoming road section includes an uphill slope followed by a downhill slope, if the vehicle speed will increase during the downhill slope in order to reach a set speed, the vehicle can be accelerated to a speed that is lower than the set speed at the top of the hill. In order to take advantage of the positive effects that can be obtained by look-ahead cruise control, the permissible speed range of a vehicle for such cruise control is usually much larger than the permissible speed range of a constant speed cruise control. However, when using look-ahead cruise control, changes in vehicle speed may sometimes be perceived as a nuisance by the driver, in which case the driver may choose to deactivate the look-ahead cruise control. This in turn may result in increased energy consumption of the vehicle and therefore increased operating costs.

[0007] Yet another example of a cruise control is an adaptive cruise control, which is configured to automatically adjust the vehicle speed in order to maintain a safe distance from one or more vehicles in front of the vehicle including the adaptive cruise control. The adaptive cruise control typically uses information from sensors arranged in or on the vehicle (e.g., radar, laser, or camera) in order to obtain information about the vehicle's surroundings. It should be noted here that both constant speed cruise control and look-ahead cruise control can be supplemented with an adaptive cruise control function if desired.

[0008] Cruise control systems have generally been developed primarily for highway driving. However, it would be desirable to be able to take advantage of, for example, look-ahead cruise control when driving on country roads as well. Compared to highways, however, such roads may include various additional circumstances that need to be considered. For example, country roads may include tighter bends, intersections, roundabouts, stop signs, etc., which may require considerable adjustments to the vehicle's speed. Summary of the invention

[0009] The object of the present invention is to achieve an improved method for reducing the speed of a vehicle which allows the vehicle to maintain a safe vehicle speed through an anticipated road event requiring a reduction in the vehicle speed and which is independent of actions taken by a possible driver of the vehicle.

[0010] This object is achieved by the subject matter of the enclosed independent claims.

[0011] The present disclosure provides a method for controlling a vehicle speed of a vehicle, performed by a control device. The method comprises the following steps: determining a maximum allowable vehicle speed curve for an upcoming road section including an event expected to require a reduction in vehicle speed. The method further comprises the following steps: determining a desired vehicle speed curve based on the determined maximum allowable vehicle speed curve to reach a minimum point of the determined maximum allowable speed curve while avoiding a vehicle speed higher than the determined maximum allowable vehicle speed curve. The desired vehicle speed curve is designed to achieve a desired characteristic. The method further comprises the following steps: simulating a vehicle speed for at least an initial portion of the upcoming road section in a case where the vehicle is to be braked according to a first braking mode, thereby obtaining a simulated vehicle speed curve for the first braking mode. The method further comprises the following steps: braking the vehicle according to the first braking mode when the obtained simulated vehicle speed curve for the first braking mode at least meets a first predefined criterion depending on the determined desired vehicle speed curve.

[0012] The method described herein enables a controlled reduction in vehicle speed when the vehicle is travelling along a road section that includes an event that requires a reduction in vehicle speed compared to, for example, the current vehicle speed or the current target vehicle speed, without compromising the safety of vehicle operation or the desired characteristics of vehicle operation, while avoiding excessively low average travel speeds for the road section. This in turn has the advantage that the vehicle behaves as, for example, the driver of the vehicle or other traffic can expect.

[0013] The method may further comprise the step of simulating the vehicle speed for at least the initial portion of the upcoming road section if the vehicle is to be braked according to a second braking mode, thereby obtaining a simulated vehicle speed profile for the second braking mode. The step may be followed by the step of braking the vehicle according to the second braking mode when the obtained simulated vehicle speed profile for the first braking mode does not meet the first predefined criterion and the obtained simulated vehicle speed profile for the second braking mode at least meets the first predefined criterion. Thus, a suitable braking mode may be identified and utilized even if the simulated vehicle speed profile for the first braking mode does not meet the first predefined criterion.

[0014] A first predefined criterion may suitably be that, for a defined distance interval, the difference between the integral of the desired vehicle speed profile and the integral of the simulated vehicle speed profile is less than a predefined threshold, optionally in combination with the difference being equal to or above zero. The distance interval is defined by the distance points corresponding to the initial vehicle position for which the simulated vehicle speed profile has been made and the distance points at which the simulated vehicle speed profile coincides with the desired vehicle speed profile. By means of this first predefined criterion, the distance loss of the vehicle when travelling along the road section is reduced.

[0015] The method may further comprise the step of determining, based on the obtained simulated vehicle speed profile of the first braking mode, a braking duration until the simulated vehicle speed profile coincides with the expected vehicle speed profile. If so, a step of braking the vehicle according to the first braking mode may be performed when the determined duration is equal to or higher than a predefined minimum acceptable duration for the first braking mode. Thereby, it may be avoided that the braking mode for braking the vehicle needs to be changed shortly after having been activated, which change shortly after having been activated may, for example, increase wear on the component parts of the vehicle. This is particularly the case when the change of the braking mode may involve connecting / disconnecting a clutch and / or performing a gear shift, or even mechanically connecting / disconnecting a braking system.

[0016] The method may further comprise the step of simulating the vehicle speed for at least an adjacent portion of the upcoming road section in the event that the vehicle is to be braked according to a third braking mode when the vehicle is braked according to the first braking mode and before the vehicle reaches the lowest point of the determined maximum permissible speed profile. Thereby, a simulated vehicle speed profile for the third braking mode is obtained. The method may then comprise braking the vehicle according to the third braking mode when the obtained simulated vehicle speed profile for the third braking mode at least meets the first predefined criterion. Thereby, the braking of the vehicle may be changed to a more appropriate braking mode for a portion of the (initially upcoming) road section before the vehicle reaches the lowest point of the determined maximum permissible speed profile and at an appropriate distance.

[0017] The method according to the present disclosure may optionally further include the following steps: when the vehicle (i) reaches a distance point equal to or less than a predetermined distance from the lowest point of the determined maximum allowable speed curve, (ii) is estimated to reach a distance point corresponding to the lowest point of the determined maximum allowable speed curve within a predefined duration, and / or (iii) reaches a vehicle speed within a predetermined acceptable speed range of the lowest point of the determined maximum allowable speed curve, determining whether the vehicle can reach a vehicle speed equal to or lower than the vehicle speed of the lowest point of the determined maximum allowable speed curve at the lowest point of the determined maximum allowable speed by braking the vehicle by coasting. In the case where it is determined that the vehicle can reach a vehicle speed equal to or lower than the vehicle speed of the lowest point of the determined maximum allowable speed curve at the lowest point of the determined maximum allowable speed curve by braking the vehicle by coasting, the method may include initiating braking the vehicle by coasting. Thereby, it is possible to achieve a safe and energy-saving reduction in vehicle speed to the lowest point of the determined maximum allowable speed curve.

[0018] The method as described herein may be suitably incorporated into a cruise control of a vehicle. Thus, the method described herein may be configured, for example, to temporarily override a control function configured to substantially maintain a set speed selected by a driver of the vehicle or another control system in the event that an upcoming road section includes an event that is expected to require a reduction in the vehicle's speed. Thus, the cruise control may be used in a wider range of driving situations, such as also when driving on country roads that include more events that may require a change in the vehicle's speed than highway driving. Furthermore, when the cruise control includes the method described herein, the vehicle may be operated safely and efficiently without compromising the driver's comfort or behaving in a manner that is not expected by, for example, the driver of the vehicle or the surrounding traffic.

[0019] The aforementioned events expected to require a reduction in vehicle speed may include, for example, a bend in the road, an intersection, a roundabout and / or a speed limit sign, or may consist of them.

[0020] The method may further comprise the step of determining, based on data selected from data relating to the geographic location of the vehicle in combination with map data or historical data, data obtained from another vehicle and / or from infrastructure and / or data obtained from one or more sensors on board the vehicle, that an upcoming segment of road for the vehicle includes an event expected to require a reduction in the vehicle speed.

[0021] The present disclosure also provides a computer program comprising instructions, which, when executed by a control device, cause the control device to perform the method as described above.

[0022] The present disclosure also provides a computer-readable medium comprising instructions, which, when executed by a control device, causes the control device to perform the method as described above.

[0023] In addition, the present disclosure provides a control device configured to control a vehicle speed of a vehicle. The control device is configured to determine a maximum allowable vehicle speed curve for an upcoming road section including an event expected to require a reduction in vehicle speed. The control device is further configured to determine a desired vehicle speed curve based on the determined maximum allowable vehicle speed curve to reach the lowest point of the determined maximum allowable speed curve while avoiding a vehicle speed higher than the maximum allowable vehicle speed curve, the desired vehicle speed curve being designed to achieve a desired characteristic. The control device is further configured to simulate a vehicle speed for at least an initial portion of the upcoming road section in a case where the vehicle is to be braked according to a first braking mode, thereby obtaining a simulated vehicle speed curve for the first braking mode. In addition, the control device is configured to brake the vehicle according to the first braking mode when the obtained simulated vehicle speed curve for the first braking mode at least meets a first predefined criterion depending on the determined desired vehicle speed curve.

[0024] The control arrangement provides the same advantages as described above with respect to the corresponding method for controlling the vehicle speed of a vehicle.

[0025] The present disclosure also provides a cruise control system configured to control the vehicle speed of a vehicle. The cruise control system includes the control device configured to control the vehicle speed of the vehicle as described above.

[0026] The present disclosure also provides a vehicle, the vehicle comprising a control device configured to control the vehicle speed of the vehicle as described above. The vehicle may be a heavy vehicle, such as a bus or a truck, but is not limited thereto. In addition, the vehicle may be a vehicle partially or fully operated by a driver, or a fully autonomous vehicle. In addition, the vehicle may be driven by an internal combustion engine, may be a hybrid vehicle, or may be a fully electric vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 schematically shows a side view of an example of a vehicle,

[0028] Figure 2 schematically illustrates an exemplary situation in which a vehicle is travelling on a road and in which an upcoming road segment includes an event that may require a reduction in the vehicle's speed,

[0029] Figure 3 A flow chart schematically illustrating an exemplary embodiment of a method described herein for controlling a vehicle speed of a vehicle is presented,

[0030] Figure 4 presents a graph of vehicle speed versus distance for an instance of an upcoming road segment including an event requiring a reduction in vehicle speed,

[0031] Figure 5 An exemplary embodiment of an apparatus is schematically shown which may comprise, consist of or be comprised in a control device as described herein which is configured to control a vehicle speed of a vehicle. DETAILED DESCRIPTION

[0032] The invention will be described in more detail below with reference to exemplary embodiments and the accompanying drawings. However, the invention is not limited to the exemplary embodiments discussed and / or shown in the accompanying drawings, but may be varied within the scope of the appended claims. Furthermore, the drawings should not be considered to be drawn to scale, as some features may be enlarged in order to more clearly illustrate the invention or its features.

[0033] The method for controlling the speed of a vehicle described herein was developed primarily for the purpose of increasing the driver's willingness to utilize the control functions available in the vehicle and thus utilizing such control functions for the intended purpose, such as reducing the vehicle's energy consumption, improving safety and / or improving comfort. However, it should be noted that the method described herein can also be advantageously used in vehicles that are not operated by a driver, i.e., autonomous vehicles.

[0034] Unless explicitly disclosed otherwise, the term “driver” is deemed in the present disclosure to include a person who is present on board the vehicle and drives the vehicle as well as a person who controls the vehicle from a location remote from the vehicle, such as at a remote control center.

[0035] In the present disclosure, the term "braking mode" is intended to mean a control mode by which a reduction in vehicle speed can be achieved. The braking mode can be achieved by using one or more braking systems of the vehicle. In the case where the braking mode includes using more than one braking system of the vehicle, these braking systems are operated simultaneously to provide braking force (e.g., in the form of braking torque). Examples of the braking system of the vehicle include various auxiliary braking systems, including various engine braking systems (such as exhaust brake systems, compression release brake systems, or variable vane brake systems), regenerative braking systems, and retarder, but are not limited thereto. Another example of the braking system of the vehicle is the service brake. It is well known that for some auxiliary braking systems, the deliverable braking torque depends on the speed of the propulsion unit of the vehicle. In this case, the braking mode can be associated with the current gear ratio of the gearbox of the vehicle. The braking mode performed can alternatively include causing the vehicle to coast or slide. Alternatively, the braking mode can be achieved by controlled reduction of the propulsion force provided by the propulsion unit of the vehicle in order to reduce the vehicle speed (without using the braking system of the vehicle or putting the gearbox in neutral).

[0036] In the present disclosure, coasting is taken to mean that in the case of a vehicle comprising an internal combustion engine as a propulsion unit, the internal combustion engine is disconnected from the gearbox, usually by opening the clutch or putting the gearbox in neutral. Depending on the circumstances, the internal combustion engine can sometimes be turned off during coasting in order to reduce energy consumption (i.e. fuel consumption), but usually the internal combustion engine remains idling. Coasting with the internal combustion engine turned off is sometimes also referred to as "slipping". For electric vehicles, in the present disclosure, coasting is taken to mean that the gearbox is in neutral and the motor constituting the propulsion unit of the vehicle is turned off. In some cases, the inverter controlling the motor can also be turned off in order to further reduce energy consumption during coasting.

[0037] In the present disclosure, coasting is taken to mean, in the case where the vehicle comprises an internal combustion engine as a propulsion unit, switching off the internal combustion engine while keeping the internal combustion engine connected to the gearbox. The gears are engaged during coasting (i.e. the gearbox is not in neutral). During coasting, the kinetic energy of the vehicle is used to drag the internal combustion engine, which in turn provides a braking force to the vehicle. Coasting can also be achieved when the vehicle comprises a propulsion unit in the form of an electric motor. Also in this case, the kinetic energy of the vehicle is used to drag the electric motor, which provides a braking force to the vehicle.

[0038] Furthermore, in this disclosure, the term "distance point" is used to describe a geographical location located somewhere along an upcoming road segment.

[0039] In this disclosure, the term "vehicle speed" is used to describe the speed at which a vehicle is traveling. However, there is a distinction between actual or current vehicle speed and predicted or simulated vehicle speed. The predicted or simulated vehicle speed is not the actual current vehicle speed, but rather a calculated or estimated future vehicle speed.

[0040] According to the present disclosure, a method for controlling vehicle speed is provided. The method is performed by a control device configured thereby. The method described herein comprises the following steps: determining a maximum permissible vehicle speed curve for an upcoming road section including an event expected to require a reduction in vehicle speed. The upcoming road section is used herein to describe a road section in front of a vehicle and on which the vehicle is about to travel. According to an alternative, the upcoming road section may be immediately in front of the vehicle. In other words, the upcoming road section may start from the current position of the vehicle. Alternatively, the upcoming road section for which the maximum permissible vehicle speed curve is determined may be a preselected distance in front of the current vehicle position, for example, starting from 10 meters, 50 meters or 100 meters in front of the vehicle. Examples of events expected to require a reduction in vehicle speed may include one or more bends, intersections, roundabouts and / or speed limit signs of a road, but are not limited thereto. The event expected to require a reduction in vehicle speed is not necessarily a permanent event, but may also be a temporary event, such as roadwork, queuing or traffic accidents.

[0041] The presence and characteristics of an event expected to require a reduction in the vehicle speed and the characteristics of the event may be determined based on geolocation data of the vehicle in combination with map data, based on information from sensors onboard the vehicle, based on stored historical data relating to the upcoming road section in combination with the geolocation data of the vehicle and / or based on information received from other vehicles and / or infrastructure (e.g., information received via a conventional V2X communication system). The presence and characteristics of an event expected to require a reduction in the vehicle speed may be determined by the control device, or information relating to such a determination may be received by the control device from another control system of the vehicle. Thus, the method may comprise the following steps: comprising determining that the upcoming road section includes an event expected to require a reduction in the vehicle speed compared to the current vehicle speed or a current target vehicle speed. In the present disclosure, the term "target vehicle speed" is to be interpreted broadly and may, for example, be the set speed of the cruise control of the vehicle or a legally set speed limit, but is not limited thereto.

[0042] The maximum allowable vehicle speed profile described above may depend on factors such as the maximum allowable lateral acceleration and / or the maximum allowable wheel slip of the vehicle. For example, the maximum allowable lateral acceleration may be a maximum allowable lateral acceleration defined or otherwise selected by a control system of the vehicle, or a maximum allowable lateral acceleration set by a driver of the vehicle. Similarly, the maximum allowable wheel slip may be defined or selected by a control system of the vehicle, or set by a driver of the vehicle. The maximum allowable vehicle speed profile provides the maximum allowable vehicle speed at each distance point of the upcoming road segment, thereby ensuring that the vehicle can be safely driven throughout the upcoming road segment. Methods for determining a maximum allowable vehicle speed profile for an upcoming road segment are previously known in the art, and therefore will not be discussed further in this disclosure.

[0043] The method for controlling the speed of a vehicle described herein further comprises the following steps: determining a desired vehicle speed curve based on the determined maximum permissible vehicle speed curve. The desired vehicle speed curve is designed to achieve at least one desired characteristic, such as comfort for the vehicle driver, and / or to achieve the desired drivability of the vehicle. The drivability may, for example, depend on a driving mode (also referred to as a performance mode) selected by, for example, the driver of the vehicle. Examples of such driving modes include, but are not limited to, an economic driving mode, a standard driving mode, and a power driving mode. The desired vehicle speed curve is determined so as to reach the lowest point of the determined maximum permissible speed curve. This means that the desired vehicle speed curve is determined so that if the vehicle follows the desired vehicle speed curve, it will reach a vehicle speed corresponding to the lowest maximum permissible speed as defined by the determined maximum permissible speed curve at a distance point corresponding to the distance point at which the lowest maximum vehicle speed must be reached according to the determined maximum permissible vehicle speed curve, or appropriately at a preselected distance offset in front of it. Therefore, the latter alternative results in the desired vehicle speed curve reaching the lowest maximum permissible speed at a distance point in front of the lowest point of the determined maximum permissible speed curve. It should be noted here that the above-mentioned preselected distance offset may depend on the lowest maximum permissible vehicle speed defined by the determined maximum vehicle speed curve. For example, the preselected distance offset may be smaller in the case of a lower lowest maximum permissible vehicle speed of, for example, 20 km / h, than in the case of a higher lowest maximum permissible vehicle speed of, for example, 60 km / h. In addition, the desired vehicle speed curve is determined so as to avoid that the vehicle speed is higher than the determined maximum permissible vehicle speed curve at any distance point of the upcoming road section. In other words, for each distance point, the desired vehicle speed curve defines a vehicle speed that is equal to or lower than the vehicle speed defined by the determined maximum permissible vehicle speed curve at the distance point. In addition, the desired vehicle speed curve should be appropriately as close as possible to the determined maximum permissible speed curve while achieving the desired characteristics. Therefore, the reason is that if the desired vehicle speed curve will deviate too much from the determined maximum permissible speed curve, the subsequent braking step according to the present method (as will be described below) will result in an excessive reduction in the average vehicle speed. This in turn results in a longer duration that the vehicle will travel on the upcoming road section, and may also cause irritation to the possible driver of the vehicle and the drivers of other vehicles traveling on the same road section.

[0044] The method for controlling the speed of a vehicle described herein further comprises the following steps: simulating the vehicle speed for at least an initial portion of an upcoming road section in the event that the vehicle will be braked according to a first braking mode, thereby obtaining a simulated vehicle speed curve for the first braking mode. The initial portion of the upcoming road section is intended herein to mean the first portion of the upcoming road section as seen from the current position of the vehicle, i.e., the portion of the upcoming road section closest to the vehicle. Preferably, the vehicle speed is simulated at least to a distance point corresponding to the lowest point of a determined maximum allowable vehicle speed curve. In other words, the initial portion of the upcoming road section may constitute the distance between the current position of the vehicle (assuming that the upcoming road section discussed above is immediately in front of the vehicle) and the distance point corresponding to the lowest point of the determined maximum allowable vehicle speed curve. If desired, it is naturally possible to simulate the vehicle speed for the entire upcoming road section, but this is not necessary for the purposes of the method described herein.

[0045] The simulation of the vehicle speed profile of the upcoming road section itself is well known today to those skilled in the art and will therefore not be described in detail herein. In addition to geographical data (including topography) related to the upcoming road section, examples of factors that are typically taken into account in such simulations include, for example, current vehicle speed, vehicle configuration, vehicle load, etc. Advanced simulations of vehicle speed profiles may also take into account additional factors, such as weather conditions and / or traffic conditions.

[0046] The above-mentioned simulation of the vehicle speed can be appropriately performed under the condition of braking according to the braking mode requested at the current time point, or when the upcoming road section starts at a certain distance ahead of the current vehicle position, at the time point when the vehicle is estimated to reach the upcoming road section. The current time point is intended to mean the time point at which the simulation of the vehicle speed is performed and is therefore associated with the current position of the vehicle. It should be noted here that the activation of the actual braking power by using the braking mode when the request has been generated occurs with a certain delay, which depends on, for example, the activation time of the device through which the braking force is applied (such as the activation time of one or more braking systems). In addition, such simulation may also cause a certain delay. However, such factors can be easily taken into account when performing the simulation. Therefore, when discussing in this article, the expression "if braking will be requested at present..." or similar expressions should be interpreted as taking into account such delay factors when the braking power / braking force is actually applied according to the braking mode. However, the present method generally does not include any prediction of the time point when the braking mode should be activated. Instead, each simulation of the vehicle speed profile for any portion of the upcoming road section is performed under the condition that a request to reduce the vehicle speed by using a braking mode is generated at a time point substantially corresponding to the time point at which the simulation is performed (appropriately taking into account the delay factors mentioned above). As an alternative to performing the simulation of the vehicle speed under the condition that braking is performed according to the braking mode requested at the current time point, the simulation of the vehicle speed may be performed under the condition that braking is performed according to the braking mode requested after a preselected time (e.g., after 5 seconds, 8 seconds, or 10 seconds) has passed from the time point at which the simulation of the vehicle speed is performed.

[0047] The method for controlling the speed of a vehicle described herein further comprises the following steps: braking the vehicle according to the first braking mode when the obtained simulated vehicle speed profile of the first braking mode satisfies at least a first predefined criterion, which first predefined criterion depends on the determined desired vehicle speed profile. In other words, a request to brake the vehicle according to the first braking mode is generated when it is determined that the obtained simulated vehicle speed profile of the first braking mode satisfies at least the first predefined criterion. In the case where the vehicle speed profile has been simulated for an upcoming road section starting from the current vehicle position, the braking is suitably initiated as soon as possible after it has been determined that the obtained simulated vehicle speed profile of the first braking mode satisfies at least the first predefined criterion. However, in the case where the vehicle speed profile has been simulated for a road section starting at a certain distance ahead of the vehicle, the braking is suitably initiated when the vehicle reaches or is estimated to reach the starting point of the road section.

[0048] Nowadays, the various braking modes available for braking a particular vehicle can usually be pre-ranked by, for example, the vehicle manufacturer based on various parameters, such as the energy efficiency and / or wear of the component parts of the vehicle, in combination with the braking power available for the different braking modes. When pre-ranking the braking modes, the driving mode (performance mode) can also be taken into account. Therefore, this pre-ranking of the braking modes results in one braking mode taking precedence over another braking mode. The first braking mode described above can suitably be the braking mode with the highest ranking among the braking modes available for the vehicle, that is, the most preferred braking mode that meets the parameters for pre-ranking. Data related to the pre-ranking can be stored in the control device described in this article, or retrieved by the control device from other sources, such as another control system onboard the vehicle or a remote control center. In other words, the control device described in this article can be configured to determine the first braking mode based on stored data related to the priority ranking of the available braking modes that can brake the vehicle.

[0049] According to one exemplary embodiment of the pre-sequencing of the braking modes described above, freewheeling may be the braking mode with the highest priority, followed by coasting, and thereafter by various braking modes using one or more auxiliary braking systems of the vehicle, optionally in combination with the service brakes.

[0050] The method described herein may further comprise the step of simulating the vehicle speed for (at least) the initial part of the upcoming road section in the case where the vehicle is to be braked according to the second braking mode, thereby obtaining a simulated vehicle speed curve for the second braking mode. For example, the step may be performed substantially simultaneously with the simulation of the vehicle speed in the case where the vehicle is to be braked according to the first braking mode. Alternatively, the step of simulating the vehicle speed under the condition of braking the vehicle according to the second braking mode may be performed only when the obtained simulated vehicle speed curve for the first braking mode does not meet the first predefined criterion. It should be noted here that, if desired, the simulation of the vehicle speed for one or more additional braking modes (i.e., braking modes other than the first braking mode and the second braking mode) for the initial part of the upcoming road section may also be performed naturally. Thereafter, the obtained simulated vehicle speed curve for the second braking mode may be compared with the expected vehicle speed curve in order to determine whether it meets the first predefined criterion. As previously mentioned, the first predefined criterion depends on the determined expected vehicle speed curve. The purpose of this comparison is to determine whether the second braking mode is an appropriate braking mode under the current conditions. According to the above-mentioned pre-ranking of the available braking modes of the vehicle, the second braking mode may be a braking mode with a lower ranking than the first braking mode.

[0051] In case the obtained simulated vehicle speed profile for the first braking mode does not meet the first predefined criterion but the obtained simulated vehicle speed profile for the second braking mode meets the first predefined criterion, the method may comprise the step of braking the vehicle according to the second braking mode.

[0052] In the event that both the simulated vehicle speed profile of the first braking mode and the simulated vehicle speed profile of the second braking mode meet the first predefined criterion, the method may include evaluating which of the first braking mode and the second mode constitutes the most appropriate braking mode. This may be done, for example, by a pre-ranking of the braking modes as discussed above, or based on an evaluation of the energy consumption of the vehicle, etc. Thereafter, the method includes braking the vehicle in accordance with the braking mode found to constitute the most appropriate braking mode of the first braking mode and the second braking mode.

[0053] According to the method described herein, braking the vehicle according to a braking mode (e.g., a first braking mode or a second braking mode) is performed when the obtained simulated vehicle speed profile satisfies at least a first predefined criterion. Suitably, the first predefined criterion may be that, for a defined distance interval, the difference between the integral of the desired vehicle speed profile (i.e., the area under the curve representing the profile in a graph showing vehicle speed versus distance) and the integral of the simulated vehicle speed profile is less than a predefined threshold. The distance interval is defined by a distance point corresponding to an initial vehicle position for which a simulated vehicle speed profile has been made (e.g., which may be the current vehicle position) and a distance point at which the simulated vehicle speed profile coincides with the desired vehicle speed profile. Alternatively, the first predefined criterion may be that, for a defined distance interval, the difference between the integral of the desired vehicle speed profile and the integral of the simulated vehicle speed profile is less than a predefined threshold and is equal to or above zero. It should be noted here that the above-mentioned predefined threshold may depend on one or more parameters related to the vehicle speed, such as the difference in vehicle speed between the set speed of the cruise control (if applicable) and the vehicle speed of the lowest point of the determined maximum permissible vehicle speed profile. The two above-exemplified alternatives to the first predefined criterion ensure that the vehicle does not experience too high a "distance loss" when travelling the upcoming road section due to too much reduction in vehicle speed during braking. Such a "distance loss" may, for example, be felt by the driver as an unexpected increase in the distance to another vehicle in front of the driver's vehicle. However, the latter alternative to the first predefined criterion also ensures that the actual vehicle speed when braking the vehicle will not exceed the vehicle speed defined by the desired vehicle speed profile at any distance point.

[0054] According to another alternative, the first predefined criterion may be that the simulated vehicle speed curve should not deviate from the expected vehicle speed curve by more than a predefined speed threshold (i.e. a certain value, such as 5 km / h) at any distance point before the distance point at which the simulated vehicle speed curve coincides with the expected vehicle speed curve. Although this alternative may result in the vehicle having a vehicle speed close to the expected vehicle speed curve when being braked, it will not have the same advantages as the alternative that takes into account the difference between the integral of the expected vehicle speed curve and the simulated vehicle speed curve, and may therefore result in the above-mentioned "distance loss" caused by the vehicle (when being braked) being likely to obtain a lower average speed experienced over the distance.

[0055] The step of braking the vehicle according to a braking mode (e.g., the first braking mode or the second braking mode) according to the method described herein may be performed only when a first predefined criterion depending on a determined desired vehicle speed profile is met. Alternatively, the step of braking the vehicle according to a braking mode according to the method described herein may be performed when both the first predefined criterion and the second predefined criterion (and optionally, if desired, further predefined criteria) are met. In contrast to the first predefined criterion, the second predefined criterion does not necessarily depend on a determined desired vehicle speed profile, but this is preferred.

[0056] An example of such a second predefined criterion may be that the possible duration of braking according to the relevant braking mode before a change to another braking mode may be required is equal to or higher than a predefined minimum acceptable duration of the relevant braking mode. The reason for such a second predefined criterion may, for example, be to avoid inappropriate temporary changes in vehicle operation, which may excessively increase wear of the component parts of the vehicle and / or may cause interference (for example, which may lead to reduced driver comfort). As an illustrative example, such a second predefined criterion related to the possible duration of braking according to the braking mode may, for example, be used for the purpose of avoiding multiple gear changes in too short a period of time. In the case where the first predefined criterion is related to the difference between the integral of the expected vehicle speed curve and the simulated vehicle speed curve as discussed above, the second predefined criterion may alternatively be that at any distance point, the simulated vehicle speed curve should not deviate from the expected vehicle speed curve by more than a predefined speed threshold (i.e., a specific value, such as 5 km / h), or should be within a speed range (such as ±10%) about the expected vehicle speed curve.

[0057] The method described herein may comprise the step of determining, based on the obtained simulated vehicle speed profile of the first braking mode, a braking duration until the simulated vehicle speed profile coincides with the desired vehicle speed profile. In this case, the step of braking the vehicle according to the first braking mode may be performed not only when it is determined that the first predefined criterion is met, but also when the determined duration is equal to or higher than a predefined minimum acceptable duration for the first braking mode. This constitutes an example of performing the step of braking the vehicle according to the first braking mode when the obtained simulated vehicle speed profile of the first braking mode satisfies both the first predefined criterion and the second predefined criterion, where the second predefined criterion constitutes a braking duration until the simulated vehicle speed profile of the first braking mode coincides with the determined desired vehicle speed profile being equal to or higher than the predefined minimum acceptable duration for the first braking mode.

[0058] In many cases, it may be necessary or at least appropriate to change the braking mode for braking the vehicle before the vehicle actually reaches the determined maximum allowable minimum point. Therefore, the method described herein may also include the following steps: when the vehicle is braked according to the first braking mode and the second braking mode and before the vehicle reaches the minimum point of the determined maximum allowable speed curve, simulate the vehicle speed for at least an adjacent portion of the upcoming road section under the condition that the vehicle will be braked according to the third braking mode. Thereby, a simulated vehicle speed curve for the third braking mode is obtained. When the vehicle is braked according to the first braking mode or the second braking mode, the vehicle has already started to travel on the upcoming road section for which the maximum allowable speed curve has been determined. For the reasons stated, the term "adjacent portion of the upcoming road section" is used herein to describe a portion of the road section for which the maximum allowable speed curve has been determined and which is immediately in front of the vehicle at the time point when the above-mentioned simulation is performed under the condition of braking the vehicle according to the third braking mode. Essentially, this corresponds to a step of simulating the vehicle speed for at least an initial portion of an upcoming section if the vehicle were to be braked according to the first braking mode or the second braking mode, with the difference that the vehicle is currently located at a different distance point of the section for which the maximum permissible speed profile has been determined and therefore the adjacent portion may only partially overlap or differ from the initial portion of the section.

[0059] The obtained simulated vehicle speed profile for the third braking mode may then be compared to the determined expected vehicle speed profile in order to determine whether it meets the first predefined criterion (and optionally, where applicable, the second predefined criterion). The method may then further comprise braking the vehicle according to the third braking mode when the obtained simulated vehicle speed profile for the third braking mode meets at least the first predefined criterion. In other words, this means that if it is found that the vehicle can be braked according to the third braking mode in view of the simulated vehicle speed profile for the braking mode meeting the first predefined criterion, the method may comprise changing the braking mode for braking the vehicle from the first braking mode or the second braking mode to the third braking mode.

[0060] When the vehicle approaches a distance point and / or vehicle speed that is within a predetermined acceptable range of the lowest point of the determined maximum allowable vehicle speed profile, or when it is estimated that the vehicle will reach a distance point corresponding to the lowest point within a predefined duration, it may sometimes be appropriate to substantially ignore the determined expected vehicle speed profile. For example, this may be the case when the vehicle can be braked in a more energy-efficient manner at the last part of the section of road for which the maximum vehicle speed profile has been determined than if the vehicle were braked according to a braking mode that satisfies the first predefined criterion based on the simulated vehicle speed profile. More specifically, for example, in the case where the vehicle can safely reach the lowest point of the determined maximum allowable vehicle speed profile (at any distance point, the vehicle speed will not exceed the determined maximum allowable vehicle speed profile), it may be appropriate to change the braking mode to coasting unless the vehicle has already been braked by coasting.

[0061] Thus, if desired, the method described herein may include the step of determining whether the vehicle can reach a vehicle speed at the lowest point of the determined maximum allowable speed curve that is equal to or lower than the vehicle speed at the lowest point of the determined maximum allowable speed curve by braking the vehicle by coasting when the vehicle (i) reaches a distance point that is equal to or lower than a predetermined distance from the lowest point of the determined maximum allowable speed curve, (ii) is estimated to reach a distance point corresponding to the lowest point of the determined maximum allowable speed curve within a predefined duration, and / or (iii) reaches a vehicle speed within a predetermined acceptable speed range for the lowest point of the determined maximum allowable speed curve. This may be done independently of the determined desired vehicle speed curve. The method may then include the step of initiating braking the vehicle by coasting when it is determined that the vehicle can reach a vehicle speed at the lowest point of the determined maximum allowable speed curve that is equal to or lower than the vehicle speed at the lowest point of the determined maximum allowable speed curve by braking the vehicle by coasting.

[0062] The method for controlling the speed of a vehicle described herein can be appropriately incorporated into the cruise control of a vehicle. Such a cruise control can be appropriately a look-ahead cruise control, but an external cruise control is also reasonable. When the method described herein is incorporated into the cruise control, it can be appropriately configured to temporarily override the control function configured to control the speed of the vehicle according to the current set speed of the cruise control (e.g., such set speed selected by the driver of the vehicle) in the case of determining that the upcoming road section includes an event that is expected to require a reduction in the speed of the vehicle compared to the predefined speed range of the set speed. Thus, the cruise control can be used in a wider range of driving situations, such as, also when driving on rural roads that include more events that may require a change in the speed of the vehicle compared to highway driving. The extended range of driving situations during which the cruise control can be used also inherently allows the extended use of other energy-saving functions that can be incorporated into the cruise control. In addition, when the cruise control includes the method described herein, the vehicle can be safely and efficiently operated without compromising the comfort of the driver or behaving in a manner that is not expected by the driver of the vehicle or the surrounding traffic, for example.

[0063] The execution of the method for controlling the vehicle speed of a vehicle described herein may be controlled by programming instructions. These programming instructions are typically in the form of a computer program that, when executed in or by a control device, causes the control device to implement a desired form of control action. Such instructions may typically be stored on a computer readable medium.

[0064] The present disclosure also relates to a control device configured to control the vehicle speed of a vehicle according to the above method.The control device may be configured to perform any of the steps of the method for controlling the vehicle speed of a vehicle as described herein.

[0065] More specifically, the present disclosure provides a control device configured to control a vehicle speed of a vehicle, wherein the control device is configured to determine a maximum allowable vehicle speed profile for an upcoming road section including an event expected to require a reduction in vehicle speed. The control device is further configured to determine a desired vehicle speed profile based on the determined maximum allowable vehicle speed profile to reach a minimum point of the determined maximum allowable speed profile while avoiding a vehicle speed higher than the maximum allowable vehicle speed profile, the desired vehicle speed profile being designed to achieve a desired characteristic. Furthermore, the control device is configured to simulate a vehicle speed for at least an initial portion of the upcoming road section in a case where the vehicle is to be braked according to a first braking mode, thereby obtaining a simulated vehicle speed profile for the first braking mode. The control device is further configured to brake the vehicle according to the first braking mode when the obtained simulated vehicle speed profile for the first braking mode at least meets a first predefined criterion depending on the determined desired vehicle speed profile.

[0066] The control device may include one or more control units. Where the control device includes a plurality of control units, each control unit may be configured to control a particular function / action, or a particular function / action may be divided between more than one control unit. The control device may be a control device of a vehicle. Alternatively, one or more control units of the control device may be arranged remotely from the vehicle, for example at a remote control centre or the like.

[0067] The present disclosure also relates to a vehicle including the above-mentioned control device. The vehicle can be, for example, a land-based heavy vehicle, such as a truck or a bus, but is not limited thereto. The vehicle can be configured to be operated (completely or partially) by a driver or to be an autonomous driving vehicle. The vehicle can also include one or more braking systems, which are configured to brake the vehicle and can be configured to operate according to different braking modes. The vehicle can be a vehicle driven only by an internal combustion engine. Alternatively, the vehicle can be a hybrid vehicle, in which case the vehicle includes an electric motor in addition to the internal combustion engine. The vehicle can also be a fully electric vehicle, in which case the vehicle does not include an internal combustion engine, but includes one or more electric motors used as (one or more) propulsion units.

[0068] Figure 1 Schematically shown is a side view of an example of a vehicle 1, here shown as a truck. The vehicle 1 comprises a powertrain 2, which comprises an internal combustion engine 3 used as a propulsion unit, and a gearbox 4. The internal combustion engine 3 may be connected to the gearbox via a clutch (not shown). The gearbox 4 may be connected to drive wheels 7 of the vehicle 1 via an output shaft 6 of the gearbox 4. The vehicle further comprises front wheels 8 and optionally also trailing axle wheels 9. It should be noted that although Figure 1 A vehicle 1 is shown comprising a drive wheel 7 arranged in front of a tag axle wheel 9 and thus a driven axle arranged in front of the tag axle, but in case the vehicle comprises such a tag axle, possible tag axles may alternatively or additionally be arranged in front of the drive axle. The vehicle 1 may alternatively or additionally comprise a plurality of driven axles with associated drive wheels 7.

[0069] As shown, the vehicle 1 may include service brakes 10 arranged at the respective drive wheels 7, and preferably also at any other wheel of the vehicle. The vehicle 1 may also include at least one auxiliary braking system 5, the braking power of which can be delivered depends on the speed of the internal combustion engine 3; for example a compression release braking system, an exhaust braking system or a variable vane braking system. The vehicle 1 may additionally or alternatively include an auxiliary braking system, such as a retarder 11, the braking power of which can be delivered is substantially independent of the speed of the internal combustion engine. As shown, such a retarder 11 may, for example, be connected to the output shaft of the gearbox 4. Alternatively, the retarder may be connected to a shaft of the internal combustion engine.

[0070] As previously mentioned, the present disclosure is not limited to vehicles driven by an internal combustion engine. The vehicle 1 may additionally or alternatively include one or more electric motors (not shown). In the case where the vehicle includes at least one electric motor, the vehicle may also include an auxiliary braking system (not shown) in the form of a regenerative braking system. In the regenerative braking system, the electric motor can be operated as a generator to convert the kinetic energy of the vehicle into electrical energy, which can be used to charge an energy storage device (not shown) of the vehicle. Thereafter, when the electric motor is operated as a propulsion unit of the vehicle, the energy stored in the energy storage device can be used for the purpose of driving the electric motor.

[0071] The vehicle 1 may further comprise a control device 100 as described herein configured to control a vehicle speed of the vehicle. The control device 100 may for example be configured to control any of the above-mentioned braking systems of the vehicle 1 in order to control the vehicle speed 1 .

[0072] The vehicle 1 may further include a cruise control system 200. The control device 100 may be a part of the cruise control system 200, or separate from the cruise control system 200 but configured to communicate therewith.

[0073] Figure 2 The schematic diagram shows a vehicle 1 (such as Figure 1 1) is an exemplary situation in which a vehicle 1 is traveling on a road 20 in a direction as indicated by arrow 15. For ease of explanation, the upcoming section of the road 20 shown by bracket 22 may include an event 24, which may require a reduction in the travel speed of the vehicle 1 compared to the current vehicle speed so that the vehicle safely passes through the event 24. The event 24 that may require a reduction in the travel speed of the vehicle 1 is shown in the figure as consisting of a first slight curve 24a to the right as experienced in the direction of travel of the vehicle, followed by a substantially U-shaped curve 24b. However, it should be noted that the event 24 that may require a reduction in the vehicle speed may be any type of event as described herein, and therefore may alternatively be, for example, a speed limit sign or a roundabout. The maximum allowable vehicle speed along the upcoming section 22 that ensures that the vehicle 1 can safely pass the event 24 will generally vary between different distance points 25a, 25b, 25c of the upcoming section 22. For the event 24 shown in the figure, the maximum allowable vehicle speed is generally lower at the distance point 25c than the distance point 25a due to the curvature of the road 20. This means that for the upcoming road segment 22 comprising the event 24 , a maximum permissible speed profile may need to be determined.

[0074] Figure 3 A flow chart schematically illustrating one exemplary embodiment of the method described herein for controlling the vehicle speed of a vehicle is presented. In the flow chart, optional steps are shown with dashed boxes / lines.

[0075] The method may include step 101: determining whether the upcoming road segment includes an event that may require a reduction in vehicle speed compared to the current vehicle speed or the current target vehicle speed. The current target vehicle speed may be, for example, a set speed for a cruise control (if present and activated). In the event that the upcoming road segment does not include such an event, the method may revert to the start. However, in the event that the upcoming road segment includes an event that may require a reduction in vehicle speed, the method proceeds to a subsequent step.

[0076] The method comprises a step S102 of determining a maximum allowable vehicle speed profile for an upcoming road section including an event anticipated to require a reduction in vehicle speed.

[0077] The method further comprises a step S103 of determining a desired vehicle speed profile based on the determined maximum permissible vehicle speed profile obtained in step S102 to reach the lowest point of the determined maximum permissible speed profile while avoiding a vehicle speed higher than the determined maximum permissible vehicle speed profile. The desired vehicle speed profile is designed to achieve desired characteristics, such as driver comfort and / or to meet the conditions of a currently activated performance mode.

[0078] The method further comprises step S104: simulating the vehicle speed for at least an initial portion of the upcoming road section if the vehicle is to be braked according to the first braking mode, thereby obtaining a simulated vehicle speed profile for the first braking mode. It should be noted here that although step S104 is shown as being performed after step S103, steps S103 and S104 may be performed in any order, including simultaneously. If desired, step S104 may also be performed, for example, simultaneously with step S102.

[0079] After steps S103 and S104, the method proceeds to step S105: determining whether the simulated vehicle speed profile of the first braking mode (obtained in step S104) meets a first predefined criterion, the first predefined criterion being dependent on the determined expected vehicle speed profile (obtained in step S103). The first predefined criterion may for example be that, for a distance interval, the difference between the integral of the expected vehicle speed profile and the integral of the simulated vehicle speed profile is less than a predefined threshold, optionally in combination with the difference being equal to or above zero. The distance interval is defined by the distance points corresponding to the initial vehicle position for which the simulated vehicle speed profile has been made and the distance points at which the simulated vehicle speed profile coincides with the expected vehicle speed profile. In case the upcoming road section for which the simulation of the vehicle speed profile is performed is immediately ahead of the vehicle, the initial vehicle position may for example correspond to the current vehicle position.

[0080] As will be described below, in the event that it is determined in step S105 that the first predefined criterion is met, the method may proceed to step S106 or step S108. In the event that it is determined in step S105 that the first predefined criterion is not met, the method may alternatively proceed to step S109 which will be described below.

[0081] The method may optionally include step S106: determining, based on the obtained simulated vehicle speed curve of the first braking mode, a braking duration until the simulated vehicle speed curve coincides with the expected vehicle speed curve. Thereafter, the method may proceed to step S107 of determining whether the simulated vehicle speed curve satisfies a second predefined criterion, wherein the second predefined criterion is that the duration obtained in step S106 is equal to or longer than a predefined minimum acceptable duration of the first braking mode. In the event that the second predefined criterion is met, the method proceeds to step S108. However, in the event that the second predefined criterion is not met, the method may proceed to step S109. It should be noted here that although steps S106 and S107 are shown as being performed when it is determined in step S105 that the first predefined criterion is met, steps S106 and S107 may alternatively be integrated in step S105.

[0082] The method further comprises a step S108 of braking the vehicle according to the first braking mode when the obtained simulated vehicle speed profile of the first braking mode satisfies at least the first predefined criterion (determined in step S105 ).

[0083] As described above, in the event that it is determined in step S105 that the obtained vehicle speed profile for the first braking mode does not satisfy the first predefined criterion (or as determined in step S107 that the second predefined criterion is not satisfied), the method may proceed to optional step S109. In the accompanying drawings, step S109 is shown as being performed after step S105. However, it should be noted that, if desired, step S109 may alternatively be performed in parallel with step S104.

[0084] Optional step S109 comprises simulating the vehicle speed for at least the initial portion of the upcoming road section if the vehicle is to be braked according to the second braking mode, thereby obtaining a simulated vehicle speed profile for the second braking mode. After step S109, the method may proceed to step S110: determining whether the simulated vehicle speed profile for the second braking mode (obtained in step S109) satisfies the first predefined criterion discussed above. If so, the method may proceed to step S111 of braking the vehicle according to the second braking mode. Although not shown in the figure, the method may also include a step integrated in step S110 or performed after step S109: determining whether the obtained simulated vehicle speed profile for the second braking mode satisfies the second predefined criterion. In this case, step S111 is performed in response to determining that both the first predefined criterion and the second predefined criterion are satisfied.

[0085] In case it is determined in step S111 that the obtained simulated vehicle speed profile of the second braking mode does not meet the first predefined criterion, the method may end or alternatively proceed to a step of simulating a vehicle speed profile of a further braking mode (in addition to the first braking mode and the second braking mode). In the latter case, the obtained simulated vehicle speed profile of the further braking mode may be compared with the determined expected vehicle speed profile to determine whether the first predefined criterion is met, and if so, a step of braking the vehicle according to the further braking mode.

[0086] After step S108 (or S111, if present), the method may optionally include step S114: simulating the vehicle speed for at least an adjacent portion of the upcoming road segment if the vehicle is to be braked according to the third braking mode, thereby obtaining a simulated vehicle speed profile for the third braking mode. Step 114 is performed when braking of the vehicle according to the first braking mode (or alternatively, the second braking mode) has been initiated. This will generally also mean that the vehicle has started to travel along the initial upcoming road segment and has therefore passed the distance point at which step S104 is performed.

[0087] The method may further include step S115: determining whether the simulated vehicle speed curve of the third braking mode obtained in step S114 satisfies the first predefined criterion. In the case where it is determined that the simulated vehicle speed curve obtained for the third braking mode satisfies the first predefined criterion, the method may proceed to step S116 of braking the vehicle according to the third braking mode. In the case where it is determined that the simulated vehicle speed curve obtained for the third braking mode does not satisfy the predefined criterion, the method may, for example, revert to step S114. Alternatively, the method may end or proceed to a step of simulating a vehicle speed curve of yet another braking mode (in addition to the first braking mode and the third braking mode, and in the case of executing step S111, also in addition to the second braking mode).

[0088] For the purpose of further illustrating the method described herein for controlling the vehicle speed of a vehicle, Figure 4 A graph of vehicle speed V versus distance D is presented for an example of an upcoming road segment 22 including an event requiring a reduction in vehicle speed. At the start of the method described herein, vehicle 1 is present at distance point DO and has a vehicle speed VO. Figure 4 Further shown is a determined maximum permissible vehicle speed curve 30. The determined maximum permissible speed curve 30 defines the highest possible speed of the vehicle 1 at any distance point along the upcoming road section 22 to allow the vehicle to travel safely along the upcoming road section 22, and includes a minimum point 31. The minimum point 31 defines the lowest maximum permissible speed V31 of the vehicle and the distance point D31 at which the vehicle speed must be reached.

[0089] It is often inappropriate, or even impossible, to control the vehicle speed so as to precisely follow the determined maximum permissible speed curve 30. As previously mentioned, the method described herein comprises the step of determining a desired vehicle speed curve 32 designed to achieve the desired characteristics. The desired vehicle speed is determined so as to reach the lowest point 31 of the determined maximum permissible vehicle speed curve while also avoiding that the vehicle speed is above the determined maximum permissible vehicle speed curve at any distance point. The desired vehicle speed curve 32 may be suitably designed so as to ensure that the vehicle speed is reduced to the lowest maximum permissible speed V31 at a suitable distance point D32 before the lowest point 31 of the determined maximum permissible speed curve. The distance between the distance points D32 and D31 may be described as a preselected distance offset.

[0090] Figure 4Further shown is a simulated vehicle speed curve 34 obtained for a first braking mode of the vehicle. According to the method described herein, the vehicle may be braked according to the first braking mode when it is determined that the simulated vehicle speed curve 34 for the first braking mode satisfies at least a first predefined criterion, wherein the first predefined criterion depends on the determined desired vehicle speed curve 32. As described above, the first predefined criterion may be that for a defined distance interval, the difference between the integral of the desired vehicle speed curve 32 and the integral of the simulated vehicle speed curve 34 is less than a predefined threshold, optionally in combination with the difference being equal to or above zero, wherein the distance interval is defined by the distance points corresponding to the initial vehicle position for which the simulated vehicle speed curve has been made and the distance points at which the simulated vehicle speed curve coincides with the desired vehicle speed curve 32. In the figure, the distance interval is defined by the distance point DO corresponding to the distance point of the current vehicle position, and the distance point D33. The above-mentioned difference between the integral of the desired vehicle speed curve 32 and the integral of the simulated vehicle speed curve 34 represents the area 33 between the desired vehicle speed curve 32 and the obtained simulated vehicle speed curve 34 of the first braking mode. This area 33 represents the “distance lost” by the vehicle 1 when travelling along the road section 22 compared to what would have been the case if the desired vehicle speed profile 32 were to be followed, and should therefore preferably be small.

[0091] When the vehicle is traveling along the road section 22 while being braked according to, for example, the first braking mode, the method may include simulating one or more additional vehicle speed profiles under conditions where the vehicle will be braked according to other braking modes. The simulated vehicle speed profiles obtained therefrom may be compared with the expected vehicle speed profiles to determine whether they meet the first predefined criteria. Figure 4 An example of an acquired simulated vehicle speed curve 36 for a third braking mode (typically achieving a higher braking power than the first braking mode) obtained when the vehicle has reached a distance point D36 is shown. The distance point D36 here corresponds to the initial vehicle position for which the simulated vehicle speed curve 36 has been produced. In the case where the acquired simulated vehicle speed curve 36 for the third braking mode meets a first predefined criterion, the method described herein may include changing the braking of the vehicle from the first braking mode to the third braking mode. In other words, in the case where, for a distance interval defined by the distance point D36 and the distance point D37 where the simulated vehicle speed curve coincides with the expected vehicle speed curve, the difference between the integral of the expected vehicle speed curve 32 and the integral of the simulated vehicle speed curve 36 is less than a predefined threshold, optionally in combination with the case where the difference is equal to or above zero, the vehicle may be braked according to the third braking mode according to the method described herein.

[0092] Figure 5 Schematically, an exemplary embodiment of the device 500 is shown. The control device 100 described above may, for example, comprise the device 500, consist of the device 500, or be comprised in the device 500.

[0093] The device 500 includes a non-volatile memory 520, a data processing unit 510 and a read / write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program such as an operating system is stored for controlling the functions of the device 500. The device 500 also includes a bus controller, a serial communication port, an I / O device, an A / D converter, a time and date input and transmission unit, an event counter and an interrupt controller (not depicted). The non-volatile memory 520 also has a second memory element 540.

[0094] A computer program P is provided, comprising instructions for controlling a vehicle speed of a vehicle. The computer program comprises instructions for determining a maximum allowable vehicle speed profile for an upcoming road section including an event expected to require a reduction in the vehicle speed. The computer program further comprises instructions for determining a desired vehicle speed profile based on the determined maximum allowable vehicle speed profile to reach a minimum point of the determined maximum allowable speed profile while avoiding vehicle speeds above the determined maximum allowable vehicle speed profile, the desired vehicle speed profile being designed to achieve desired characteristics. The computer program further comprises instructions for simulating a vehicle speed for at least an initial portion of the upcoming road section in a case where the vehicle is to be braked according to a first braking mode, thereby obtaining a simulated vehicle speed profile for the first braking mode. The computer program further comprises instructions for braking the vehicle according to the first braking mode when the obtained simulated vehicle speed profile for the first braking mode at least meets a first predefined criterion depending on the determined desired vehicle speed profile.

[0095] The program P may be stored in the storage 560 and / or the read / write memory 550 in an executable form or a compressed form.

[0096] The data processing unit 510 may perform one or more functions, ie, the data processing unit 510 may implement a portion of the program P stored in the memory 560 or a portion of the program P stored in the read / write memory 550 .

[0097] The data processing device 510 can communicate with the data port 599 via a data bus 515. The non-volatile memory 520 is intended to communicate with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit 510 via a data bus 511. The read / write memory 550 is suitable for communicating with the data processing unit 510 via a data bus 514. Communication between the components can be achieved through a communication link. The communication link can be a physical connection (such as an optical communication line), or a non-physical connection (such as a wireless connection, for example a radio link or a microwave link).

[0098] As data are received on the data port 599, they may be temporarily stored in the second memory element 540. When the received input data has been temporarily stored, the data processing unit 510 is ready to implement code execution as described above.

[0099] Parts of the methods described herein may be implemented by the apparatus 500 by means of the data processing unit 510 running a program stored in the memory 560 or the read / write memory 550. When the apparatus 500 runs the program, the methods described herein are performed.

Claims

1. A method for controlling a vehicle speed of a vehicle (1) performed by a control device (100), the method comprising the following steps: determining (S102) a maximum permissible vehicle speed profile (30) for an upcoming road segment (22) including an event (24) anticipated to require a reduction in vehicle speed, Based on the determined maximum permissible vehicle speed profile (30), determining (S103) a desired vehicle speed profile (32) to reach a minimum point (32) of the determined maximum permissible speed profile (30) while avoiding vehicle speeds above the determined maximum permissible vehicle speed profile (30), the desired vehicle speed profile (32) being designed to achieve desired characteristics, simulating (S104) a vehicle speed for at least an initial portion of the upcoming road section if the vehicle is to be braked according to a first braking mode, thereby obtaining a simulated vehicle speed curve (34) for the first braking mode, and The vehicle (1) is braked (S108) according to the first braking mode when the obtained simulated vehicle speed profile (34) of the first braking mode meets at least a first predefined criterion depending on the determined desired vehicle speed profile (32).

2. The method according to claim 1, further comprising: simulating (S109) a vehicle speed for at least the initial portion of the upcoming road section (22) if the vehicle (1) is to be braked according to a second braking mode, thereby obtaining a simulated vehicle speed profile for the second braking mode, and When the simulated vehicle speed curve (34) obtained for the first braking mode does not satisfy the first predefined criterion and the simulated vehicle speed curve obtained for the second braking mode at least satisfies the first predefined criterion, the vehicle (1) is braked (S111) according to the second braking mode.

3. A method according to any one of claims 1 and 2, wherein the first predefined criterion is that, for a distance interval defined by a distance point (D0, D36) corresponding to an initial vehicle position for which the simulated vehicle speed curve has been produced and a distance point (D33, D37) at which the simulated vehicle speed curve (34, 36) coincides with the expected vehicle speed curve (32), the difference between the integral of the expected vehicle speed curve (32) and the integral of the simulated vehicle speed curve (34, 36) is less than a predefined threshold, optionally in combination with the difference being equal to or above zero.

4. The method according to any one of the preceding claims, further comprising: determining a braking duration until the simulated vehicle speed profile (34) coincides with the desired vehicle speed profile (32) based on the obtained simulated vehicle speed profile (34) of the first braking mode, and When the determined duration is equal to or higher than a predefined minimum acceptable duration of the first braking mode, a step of braking (S108) the vehicle (1) according to the first braking mode is performed.

5. The method according to any one of the preceding claims, further comprising: When the vehicle (1) is braked according to the first braking mode and before the vehicle reaches the lowest point (31) of the determined maximum permissible speed curve (30), simulating (S114) the vehicle speed for at least an adjacent portion of the upcoming road section in the event that the vehicle (1) is braked according to a third braking mode, thereby obtaining a simulated vehicle speed curve (36) for the third braking mode, and When the obtained simulated vehicle speed curve (36) of the third braking mode satisfies at least the first predefined criterion, the vehicle (1) is braked (S116) according to the third braking mode.

6. The method according to any one of the preceding claims, further comprising: When the vehicle (1) (i) reaching a point at which the distance from the lowest point (31) of the determined maximum permissible speed curve (30) is equal to or less than a predetermined distance, (ii) a distance point that is estimated to be reached within a predefined duration corresponding to the lowest point of the determined maximum permissible speed profile, and / or (iii) upon reaching a vehicle speed within a predetermined acceptable speed range of the lowest point (31) of the determined maximum permissible speed curve (30), determining whether the vehicle (1) can reach a vehicle speed (V31) at the lowest point (31) of the determined maximum permissible speed curve (30) equal to or lower than the vehicle speed (V31) at the lowest point (31) of the determined maximum permissible speed curve (30) by braking the vehicle (1) by coasting, and When it is determined that the vehicle (1) can reach a vehicle speed (V31) equal to or lower than the vehicle speed (V31) at the lowest point (31) of the determined maximum allowable speed curve (30) by braking the vehicle by coasting, braking the vehicle (1) by coasting is initiated.

7. Method according to any of the preceding claims, wherein the method is incorporated into a cruise control (200) of the vehicle (1).

8. A method according to any one of the preceding claims, wherein the event (24) expected to require a reduction in the vehicle's speed comprises a bend in the road, a junction, a roundabout or a speed limit sign.

9. The method according to any one of the preceding claims, further comprising the steps of: Based on data selected from data relating to the geographic location of the vehicle in combination with map data or historical data, data obtained from another vehicle and / or from infrastructure and / or data obtained from one or more sensors on board the vehicle (1), it is determined (S101) that an upcoming road section (22) for the vehicle (1) includes an event (24) expected to require a reduction in the vehicle's speed.

10. A computer program comprising instructions which, when executed by a control device (100), cause the control device (100) to carry out the method according to any one of the preceding claims.

11. A computer readable medium comprising instructions which, when executed by a control device (100), cause the control device (100) to perform the method according to any one of claims 1 to 9.

12. A control device (100) configured to control a vehicle speed of a vehicle (1), wherein the control device (100) is configured to: determining a maximum permissible vehicle speed profile (30) for an upcoming road segment (22) including an event (24) anticipated to require a reduction in vehicle speed, Based on the determined maximum permissible vehicle speed profile (30), determining a desired vehicle speed profile (32) to reach a minimum point (31) of the determined maximum permissible speed profile (30) while avoiding vehicle speeds above the maximum permissible vehicle speed profile (30), the desired vehicle speed profile (32) being designed to achieve desired characteristics, simulating a vehicle speed for at least an initial portion of the upcoming road section (22) if the vehicle (1) were to be braked according to a first braking mode, thereby obtaining a simulated vehicle speed profile (34) for the first braking mode, and The vehicle (1) is braked according to the first braking mode when the obtained simulated vehicle speed profile (34) of the first braking mode meets at least a first predefined criterion dependent on the determined desired vehicle speed profile (32).

13. A control device (100) according to claim 12, wherein the first predefined criterion is that, for a distance interval defined by a distance point (DO, D36) corresponding to an initial vehicle position for which the simulated vehicle speed curve has been produced and a distance point at which the simulated vehicle speed curve (34, 36) coincides with the expected vehicle speed curve (32), the difference between the integral of the expected vehicle speed curve (32) and the integral of the simulated vehicle speed curve (34, 36) is less than a predefined threshold, optionally in combination with the difference being equal to or above zero.

14. A cruise control system (200) configured to control the vehicle speed of a vehicle (1), the cruise control system (200) comprising a control device (100) according to any one of claims 12 or 13.

15. A vehicle (1) comprising a control device (100) according to any one of claims 12 or 13.

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