Driver assistance system in a motor vehicle

Abstract

Driver assistance system in a motor vehicle with a detection system (E1, E2) for detecting upcoming events (vE) that require a reduction of the current speed to a reduced target speed, a functional unit (FE) for determining a deceleration strategy for reducing the speed from the current speed (v) to the target speed at the location of the upcoming event (vE), wherein the functional unit (FE) initially determines a first single- or multi-stage deceleration strategy upon detecting an upcoming event (vE) that requires a speed reduction, wherein the deceleration stages of the first deceleration strategy are determined depending on the position (s) of a driving experience switch, by means of which the driver can select a driving mode,and with an indication system (ABE) for issuing a request (Ah) to the driver at a defined time before reaching the upcoming event (vE) requiring a speed reduction to allow automatic implementation of the deceleration strategy, wherein the functional unit (FE) initiates automatic implementation of the deceleration strategy upon confirmation (z) of the request (Ah) by the driver.

Description

[0001] The invention relates to a driver assistance system in a motor vehicle for determining a deceleration strategy and for automatically implementing the deceleration strategy.

[0002] In principle, many driver assistance systems designed as cruise control systems are already known, which regulate the speed of the motor vehicle to a predetermined desired or target speed. In addition to these longitudinal control systems, some manufacturers now also offer longitudinal control systems enhanced with distance control, so-called distance-related longitudinal control systems or cruise control systems. Such systems - for example, those offered by the applicant of the present patent application under the name "Active Cruise Control" - make it possible to automatically control the motor vehicle at a desired or correspondingly lower speed while maintaining a desired distance from a vehicle in front. If a distance sensor system attached to the motor vehicle, which can operate in particular on a radar basis, detects a target object or a vehicle in front.(Motor) vehicle in its own lane, the vehicle's own speed is adapted - e.g. by initiating a suitable braking torque - to the speed of the vehicle in front or the target object in such a way that a distance control contained in the "active cruise control" or in the corresponding longitudinal control system automatically regulates and maintains a distance to the vehicle in front or the target object in accordance with the situation.

[0003] Furthermore, so-called speed limitation systems are known, which prevent the speed set by the driver from being exceeded.

[0004] DE 10 2012 211 967 A1 describes a combination of a speed limitation system and a cruise control system, whereby the maximum speed of the speed limitation system can be adopted as the (new) target speed for the cruise control instead of the set speed.

[0005] Finally, newer vehicles also have driver assistance systems that can predict speed limits using either map data from a navigation system and / or image processing and continuously display them to the driver so that they can independently adjust their speed to the speed limit if necessary (e.g. BMW Speed ​​Limit Info).

[0006] DE 10 2008 018 421 A1 discloses a driver assistance system for transmitting and receiving speed data and / or traffic density data to control a cruise control system. This system uses the received data to determine a maximum permissible speed and communicates this to the driver by issuing a corresponding message. The driver can adopt this maximum permissible speed for their cruise control system by simply activating the button.

[0007] Finally, DE 10 2011 119 007 A1 discloses a method for operating a vehicle and a correspondingly designed control unit, wherein a coasting distance of the vehicle is determined as a function of the current speed and a target speed reduced due to a speed reduction, wherein the coasting distance of the vehicle is determined either for a freewheeling operating state or an overrun cut-off operating state. Depending on the coasting distance determined, either an output can be generated for the driver which is intended to prompt the driver to adopt a certain driving style, or a corresponding control signal can be transmitted to an automatic cruise control function, i.e. either the driving style is left to the driver and merely a hint is issued, or automatic cruise control takes place independently of the driver.

[0008] If only a hint is given, the level of support from the system is relatively low, but if automatic control is carried out straight away, the driver's control task is restricted too much.

[0009] Furthermore, a deceleration control of a vehicle is known from DE 10 2012 213 229 A1, wherein the deceleration maneuver is divided into two phases.

[0010] Finally, DE 10 2012 213 321 A1 discloses a method for operating a vehicle, wherein during a coasting of the vehicle in order to reach a route position at a desired speed, different actions are carried out depending on the comparison of the actual vehicle speed with the desired vehicle speed.

[0011] The object of the invention is to provide a driver assistance system which supports the driver in a necessary speed reduction without restricting the driver's control task too much.

[0012] This problem is solved by a driver assistance system according to patent claim 1. Advantageous further developments arise from the dependent claims.

[0013] The basic idea of ​​the invention is to provide a deceleration strategy with targeted control of a section of the route in sailing, towing, and / or braking. At least the length of the sailing and towing sections should be adjustable by application. The remaining section should be decelerated, as this is the only way to achieve a certain speed at a defined location.

[0014] The driver assistance system essentially comprises a detection system for detecting upcoming events that require a reduction of the current speed to a reduced target speed, a functional unit for determining a suitable deceleration strategy for reducing the speed from the current speed to the target speed at the location of the upcoming event, and an indication system for issuing a request indication to the driver at a defined time before reaching the upcoming event requiring a speed reduction to allow automatic implementation of the deceleration strategy.Only when the driver allows the automatic implementation of the deceleration strategy by confirming the request does the functional unit initiate the automatic implementation of the deceleration strategy by sending corresponding control signals to the drive and / or braking unit.

[0015] The relevant upcoming events requiring a reduction in speed can be detected either from map data of a navigation system and / or through image processing of forward-looking sensors and / or by a Car-to-X communication unit by receiving relevant data from other vehicles or from traffic signs or traffic control systems. The upcoming events can thus be, for example, temporary or permanent speed limits, which are either indicated directly on a traffic sign or can be derived from general traffic regulations (e.g., in Germany, the speed limit for driving through a town is 50 km / h).The target speed at the location of the upcoming event, which is decisive for the deceleration strategy, can be either the actually specified speed limit or a speed that deviates from the specified speed limit by a specified amount, either upwards or downwards, whereby the amount and direction of the deviation can be set, for example, by the driver in a central vehicle menu.

[0016] Alternatively or additionally, the driver can also set location-based speed limits on a familiar route using an on-board or off-board interface. When driving along the route with an active longitudinal guidance system, these speed limits can be taken into account accordingly. The driver can also choose in advance, for example, whether they want to generally observe all self-defined speed limits or select speed limits based on a rule (e.g., only on a specific route, for certain road classes, at a specific time of day, depending on weather conditions, etc.).For a specific route section, several speed profiles can also be created, which are then active according to predefined rules (speed profile for good road conditions, speed profile for wet roads and / or speed profile for snow-covered roads).

[0017] The driver assistance system according to the invention is further characterized in that, upon detecting an upcoming event that requires a reduction in speed, the functional unit first determines a first deceleration strategy, wherein the deceleration level to be used for the first deceleration strategy is determined depending on predetermined parameters. Within the meaning of the predetermined parameters, the current operating conditions of the vehicle and / or current system settings and / or driver inputs and / or relevant environmental conditions can be evaluated. The first deceleration strategy can be single-stage or multi-stage. All operating modes of the motor vehicle that cause a deceleration of the vehicle can be defined as deceleration levels, such as coasting mode (interruption of traction, e.g., by opening the connection unit between the transmission and engine), overrun mode, and braking mode.A single-stage deceleration strategy means that only a single deceleration stage (e.g., coasting) is used to decelerate the vehicle throughout the entire deceleration strategy. A multi-stage deceleration strategy consists of more than one stage in succession (e.g., coasting followed by braking).

[0018] In principle, when determining the deceleration strategy, in addition to the relevant framework conditions such as the difference between the current and target speeds and the distance to the location of the relevant event ahead, other criteria that influence the vehicle's deceleration effect can also be taken into account. These influencing factors can be current factors in particular, but they can also include known, future factors that will affect the deceleration up to the location of the event ahead. For example, these could include the road gradient, wind and other weather conditions, the current vehicle load, or similar factors.Likewise, the choice of the delay stages to be taken into account in the first delay strategy (and, in the case of several delay stages, the respective share of the delay stage in the total delay) can be determined depending on the parameters mentioned above.

[0019] In particular, to determine the deceleration type(s) or level(s) for the initial deceleration strategy, it is first possible to determine, based on the specified parameters, which deceleration levels are generally permitted at the current time. Advantageously, the deceleration level to be used for the initial deceleration strategy is then at least the deceleration level that results in the least deceleration of all permitted deceleration levels. For example, coasting mode may be generally prohibited due to a driving mode selected by the driver (e.g., "sporty"), meaning that it cannot be permitted as a deceleration type for the initial deceleration strategy.In this case, coasting mode can be specified as the sole deceleration stage or as the first deceleration stage of the multi-stage deceleration strategy for the first deceleration strategy, as this has a lower deceleration effect than braking. However, if coasting mode is permitted, coasting mode would be specified as the sole deceleration stage or as the first deceleration stage of the multi-stage deceleration strategy for the initial deceleration strategy, as this, in turn, results in a lower deceleration effect than coasting mode. However, coasting mode may also not be permitted as a deceleration stage due to existing transmission parameters, e.g., an excessively low transmission oil temperature.However, the mere fact that the transmission is not currently in neutral, i.e. there is no interruption in the power transmission between the transmission and the drive, does not affect the admissibility of sailing mode as a deceleration type for the initial single-stage deceleration strategy.

[0020] For improved drivability, a multi-stage deceleration strategy can advantageously be determined as the first deceleration strategy. In the multi-stage first deceleration strategy, the strategy is constructed in such a way that the further deceleration stages follow a first long deceleration stage with a low deceleration effect, with the intended duration of the deceleration stages being further shortened as the deceleration effect of the deceleration stage increases. In a particularly advantageous embodiment, a combination of a long sailing phase followed by a short overrun phase, which in turn is followed by a very short braking phase, can be selected for the first deceleration strategy as a multi-stage deceleration strategy. The number of stages and their lengths can depend on various influencing factors, such as:the position of the driving experience switch, the current speed, the speed difference between the current speed and the target speed, the topology and existing target objects and, if applicable, their position.

[0021] Advantageously, depending on the first deceleration strategy, the functional unit initiates the request via the hint system at least approximately at the time at which the first deceleration strategy would have to be implemented, so that the target speed is (approximately) reached at the location of the upcoming event. If the functional unit determines, for example based on the speed difference to be overcome and possibly other criteria (such as road gradient, wind, load), that the first deceleration strategy would have to be implemented no later than 500 m before the event occurs, the functional unit initiates the hint system, when the 500 m distance to the relevant event is reached, issuing a corresponding request to the driver to allow the automatic implementation of the deceleration strategy. The request can be issued as an acoustic, visual and / or haptic signal.A premature issuing of the request would therefore not be advantageous, since if the driver immediately confirmed the request and the deceleration strategy was therefore immediately implemented (which the driver also expects when activated), the target speed at the location of the upcoming event would not be reached, but might even be undercut, even with the slightest deceleration effect.

[0022] In order to address the problem that the driver does not immediately confirm the request and thus the deceleration strategy is not implemented immediately at the time the request is issued, the deceleration strategy is adapted or recalculated, preferably continuously, but at the latest from the time the driver confirms the request, and is then implemented accordingly after the automatic implementation is permitted, in order to ensure that the target speed is reached at the location of the upcoming event even if the automatic implementation of the deceleration strategy is permitted later.

[0023] Since, after the time at which the request is issued, the target speed at the location of the occurring event can no longer be achieved with the previously determined first deceleration strategy (with the lowest deceleration effect), the functional unit will advantageously determine a new deceleration strategy depending on the permitted deceleration levels, at the earliest from the time at which the request was issued, but at the latest from the time at which the driver has permitted the automatic implementation of the deceleration strategy, which can also consist of other or several levels or types of deceleration, whereby the deceleration strategy can be based on the normal deceleration behavior of a driver.

[0024] Specifically, the functional unit can determine an adapted one-, two-, or three-stage deceleration strategy taking into account the permitted deceleration types and at least depending on the difference between the current speed and the target speed and / or depending on the distance to the event ahead, wherein, preferably with increasing deceleration requirements, at least those deceleration stages with which a greater deceleration can be achieved are incorporated into the one-, two-, or three-stage deceleration strategy. In other words, if only a small deceleration requirement is required, the target speed at the location of the event occurring (e.g.due to a small difference in speed to be overcome and / or an even greater distance to the event ahead) preferentially includes those permitted deceleration stages in the adapted deceleration strategy which result in a lower deceleration, whereby in the case of a high deceleration requirement, braking operation is primarily (or only) taken into account as the sole deceleration stage when determining the deceleration strategy.

[0025] In order to best replicate the deceleration behavior of an average, forward-looking driver, the functional unit is advantageously designed such that, when continuously adjusting the deceleration strategy—where possible and appropriate—a multi-stage, i.e., two- or three-stage, deceleration strategy is determined. Initially, deceleration is controlled by initiating coasting and / or coasting, and only then is deceleration controlled by braking to achieve the target speed. In other words, a controllable deceleration stage with a low deceleration effect is selected as the first deceleration stage, and a deceleration stage with a large, advantageously controllable, deceleration is selected as the last deceleration stage.Ideally, the adapted deceleration strategy is determined in such a way that each deceleration level is used for approximately the same distance or the ratio of the deceleration levels used is approximately identical for all route sections.

[0026] As already mentioned at the beginning, there are basically three relevant deceleration stages that can be taken into account when determining the deceleration strategy: coasting, overrun, and braking. Advantageously, provided that all deceleration stages are generally permitted, all three deceleration stages can be taken into account in the one-, two-, or three-stage deceleration strategy. When determining and implementing the deceleration strategy, the deceleration can be controlled to a target thrust torque dependent on the deceleration strategy during overrun and / or the target braking torque dependent on the deceleration strategy during braking. In other words, during overrun and / or braking, the extent of the deceleration to be achieved can be controlled by appropriate target specifications within the selected deceleration stage.Such control is not possible in sailing mode, as no corresponding influence on the drive unit is possible due to the interruption of traction.

[0027] The invention will now be explained in more detail using the following exemplary embodiment. Fig. 1 an exemplary structure of a driver assistance system in a motor vehicle for determining a deceleration strategy and automatically implementing the deceleration strategy, Fig. 2 a first example of a determined and automatically implemented delay strategy, and Fig. 3 a second example of a determined and automatically implemented delay strategy.

[0028] In detail, the Fig. 1 as a central element of the driver assistance system, a functional unit FE which receives input signals e1 of a first detection unit E1, input signals e2 of a second detection unit E2, a speed signal v, a status signal s of a driving experience switch and an authorization signal z for allowing automatic implementation of a determined deceleration strategy.

[0029] The first detection unit E1 can, for example, be a forward-facing (e.g., video) sensor mounted on the vehicle, which detects upcoming speed-limiting events that may require a reduction of the current speed to a reduced target speed. The second detection unit E2 can, for example, be an in-vehicle navigation system, which, depending on the known position of the vehicle and a road section ahead, also detects upcoming speed-limiting events. Both the first detection unit E1 and the second detection unit E2 are designed in such a way that they can detect the location of the upcoming speed-limiting event, thus also the actual speed limit, and transmit this information to the functional unit FE.

[0030] Furthermore, the functional unit FE receives a signal + / - Δv from a central menu unit zME located in the vehicle, which indicates the upward or downward deviation specified by the driver to be used to determine the target speed from the actual speed limit. This setting can be changed by the driver at any time.

[0031] Finally, the FE functional unit receives additional relevant data s from which it can determine which deceleration types are currently permitted. As an example, the FE functional unit is connected to a so-called driving experience switch (FES), which the driver can use to select a vehicle operating mode. For example, if the driver has selected Sport mode, coasting is generally not permitted, which the FE functional unit must take into account when determining the deceleration strategy.

[0032] As soon as the FE functional unit has relevant data e1 and / or e2 about an upcoming speed-limiting event and the level of the speed limit, the FE functional unit can first determine the target speed at the location of the upcoming event, taking into account the driver's input from the central menu unit zME, and then plan a first deceleration strategy based on the permitted deceleration levels. In this example, the deceleration level with the least deceleration effect is used as the sole deceleration level. Alternatively, the first deceleration strategy can also be structured such that a combination of a long coasting phase followed by a short overrun phase, which in turn is followed by a very short braking phase, is selected for the first deceleration strategy.

[0033] Based on the determined first deceleration strategy, the functional unit FE initiates the output of a request signal by sending a corresponding signal af to a display and control unit ABE, which comprises a warning system HS and a control element BE, at approximately the time at which the determined single-stage deceleration strategy would have to be implemented, so that the determined target speed is reached at the location of the upcoming event. At the same time, the functional unit FE continuously adapts the deceleration strategy from the time the request is issued, so that the target speed at the location of the upcoming event can be reached even if the distance continuously decreases or the current speed v changes.

[0034] As soon as the driver confirms the request signal by operating the control element BE, the display and control unit ABE sends a corresponding "permission" signal z back to the functional unit FE. The functional unit FE then begins to automatically implement the (most recently determined) deceleration strategy by sending the corresponding "sail," "coast," or "MBr" control signals to the drive unit AE and / or brake unit BrE. During the control process, the deceleration strategy continues to be adapted to the current situation and implemented accordingly, ensuring that the target speed is reached at the location of the upcoming event.

[0035] Based on the two following descriptions of Fig. 2 and Fig. 3, two different examples of different implemented delay strategies are presented. Both Fig. 2 and Fig. 3 show a distance d, where a speed limit of 50 km / h applies at location vE, which is also assumed to be the target speed below. It is further assumed that the vehicle approaching the speed limit is moving at a constant speed of 80 km / h. For the sake of completeness, it is pointed out that at this point in time the vehicle is moving at this speed either due to active speed control (e.g. cruise control) with the corresponding initial speed of 80 km / h or due to a corresponding "manual" driver input by pressing the accelerator pedal. Furthermore, in both examples it is assumed that coasting mode is generally permitted as a deceleration stage and that this coasting mode has the lowest deceleration effect of all permitted deceleration stages.Due to the difference in speed between the current speed and the target speed to be achieved, it follows that coasting mode would have to be initiated at location Ah, so that the target speed would be reached at location vE solely through coasting mode and its deceleration effect a1 (dashed line). Based on this knowledge, a corresponding prompt is issued to the driver at location Ah. Upon confirmation, a (most recently) determined deceleration strategy is automatically implemented. If a multi-stage deceleration strategy were selected as the first deceleration strategy, the prompt would only be issued at a later time.

[0036] In the Fig. 2, the automatic implementation of the deceleration strategy is now authorized at location Z1 by actuating a corresponding control element. Since a certain amount of time has already passed since the request was issued at location Ah and the automatic implementation of the deceleration strategy was authorized at location Z1, and thus the distance to the location vE of the speed-limiting event has decreased, the target speed can no longer be achieved by coasting alone.The deceleration strategy, which has since been adapted, is now structured as a three-stage deceleration strategy. The system initially switches to coasting mode, in which the vehicle is decelerated with a first deceleration a1. At location dü1, the system switches from coasting mode to coasting mode, in which the vehicle is decelerated with a second deceleration a2. Only at location dü2 does the system switch from coasting mode to braking mode, in which the vehicle is braked by controlling the deceleration a3. To make the deceleration strategy as pleasant as possible for the driver, the three consecutive deceleration stages are each implemented for an equal distance d.

[0037] In the Fig.3, the automatic implementation of the deceleration strategy is only permitted at a later time Z2, so that the distance to the speed-limiting event is very short. Since a three-stage deceleration strategy no longer appears appropriate due to the short distance, a correspondingly adapted single-stage deceleration strategy is implemented here, with the braking mode that can achieve the greatest deceleration being selected as the deceleration stage. The braking torque Mbr, which causes a corresponding deceleration a4, is regulated so that the target speed can still be reached at the location vE of the upcoming event.

[0038] The two examples show that even if the basic conditions are initially identical, a constant adjustment of the deceleration level is necessary so that after allowing the automatic implementation of the deceleration strategy, the target speed is reached at the location of the speed-reducing event.

[0039] The targeted initial activation of coasting and / or coasting mode during automatic deceleration results in customer-like behavior, which can significantly increase the acceptance of such systems. However, this alone cannot ensure that the desired speed is reached at the desired location, as it is a control system and external disturbances (e.g., gradients, wind resistance) cannot be compensated for. The remaining distance in braking mode, through appropriate control of the deceleration or braking torque, ensures that the target speed can be reached at the specified location.

Claims

[1] Driver assistance system in a motor vehicle with a detection system (E1, E2) for detecting upcoming events (vE) that require a reduction of the current speed to a reduced target speed, a functional unit (FE) for determining a deceleration strategy for reducing the speed from the current speed (v) to the target speed at the location of the upcoming event (vE), wherein the functional unit (FE) upon detecting an upcoming event (vE) that requires a speed reduction, first determines a first single- or multi-stage deceleration strategy, wherein the deceleration stages of the first deceleration strategy are determined depending on the position (s) of a driving experience switch, by means of which the driver can select a driving mode,and with an indication system (ABE) for issuing a request (Ah) to the driver at a defined time before reaching the upcoming event (vE) requiring a speed reduction to allow automatic implementation of the deceleration strategy, wherein the functional unit (FE) initiates automatic implementation of the deceleration strategy upon confirmation (z) of the request (Ah) by the driver. [2] Driver assistance system according to claim 1, characterized bythat the deceleration stage which causes the least deceleration (a1) of the vehicle out of all permitted deceleration stages is defined as the first or sole deceleration stage of the first deceleration strategy, and wherein, in the case of a multi-stage first deceleration strategy, the strategy is advantageously constructed in such a way that the further deceleration stages follow a first long deceleration stage with a low deceleration effect (a1), wherein the intended duration of the deceleration stages is further shortened with increasing deceleration effect (a2, a3) of the deceleration stage. [3] Driver assistance system according to one of the preceding claims, characterized by that the first deceleration stage of the first deceleration strategy is sailing mode (sailing) if sailing is permitted, otherwise it is pushing mode (pushing). [4] Driver assistance system according to one of the preceding claims, characterized bythat the functional unit (FE), depending on the first deceleration strategy, initiates the request indication (Ah) via the indication system (HS) at the time at which the first deceleration strategy would have to be implemented, so that the target speed is approximately reached at the location of the upcoming event (vE). [5] Driver assistance system according to one of the preceding claims, characterized by that the functional unit (FE) continuously determines an adapted single-stage or multi-stage deceleration strategy depending on the permitted deceleration types, but in particular at the earliest from the time at which the request (Ah) was initiated or at the latest from the time at which the driver has permitted the automatic implementation of the deceleration strategy. [6] Driver assistance system according to claim 5, characterized bythat the functional unit (FE) determines an adapted one-, two- or three-stage deceleration strategy taking into account the permitted deceleration stages and depending on the difference in speed between the current speed (v) and the target speed and / or depending on the distance to the event ahead (vE), wherein advantageously the deceleration is to be controlled first and only then is the deceleration regulated so that the target speed is reached. [7] Driver assistance system according to claim 5 or 6, characterized bythat the adapted two- or three-stage deceleration strategy is constructed in such a way that a deceleration stage with a low deceleration is selected as the first deceleration stage and / or a deceleration stage with the greater deceleration is selected as the last deceleration stage, wherein the deceleration is advantageously controlled at the last deceleration stage. [8] Driver assistance system according to one of claims 5 to 6, characterized by that when determining an adapted two- or three-stage deceleration strategy, the deceleration strategy is determined in such a way that each deceleration stage is used for approximately the same distance (d). [9] Driver assistance system according to one of claims 5 to 8, characterized bythat a sailing operation (sailing) and / or a coasting operation (coasting) and / or a braking operation (MBr) of the vehicle is defined as the deceleration stages of the adapted one-, two- or three-stage deceleration strategy, wherein advantageously, when implementing the deceleration strategy, during coasting operation (coasting), the deceleration is regulated to a target thrust torque dependent on the deceleration strategy and / or during braking operation (MBr), the deceleration is regulated to a target braking torque dependent on the deceleration strategy. [10] Driver assistance system according to one of the preceding claims, characterized by that the functional unit (FE) takes into account currently available and / or future environmental information when determining the deceleration strategy.

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