METHOD FOR ACTIVATING AT LEAST ONE FUNCTION OF A MOTOR VEHICLE, DRIVER ASSISTANCE SYSTEM AND MOTOR VEHICLE

Description

[0001] The invention relates to a method for activating at least one function of a motor vehicle. Furthermore, the invention also relates to a driver assistance system for a motor vehicle and a motor vehicle with a driver assistance system.

[0002] It is known from the prior art that distances to objects or obstacles in the vicinity of a motor vehicle can be detected. Depending on such a distance, for example, if this distance differs from a threshold value, a motor vehicle function, such as issuing a warning message, is activated. Such a method is described, for example, in DE 198 43 564 A1 and US Pat. No. 6,433,679 B1. DE 10 2009 058 528 A1 also describes a similar method in which, if a specific criterion is met, a warning signal is issued by the output device of a motor vehicle.This criterion may consist in the distance between the object and the motor vehicle decreasing within a given time interval, the instantaneous value of the distance between the object and the motor vehicle falling below a given threshold, or the reduction in the distance per unit of time exceeding a given threshold.

[0003] Naturally, hardware-related latency always occurs in motor vehicles when functions are activated. In the context of the collision avoidance systems described above, this means that if a warning signal is to be issued as soon as a detected object falls below a certain distance from the vehicle, this warning signal will only be issued when the actual distance to the object is significantly less than this predetermined distance or limit due to latency. Especially in the context of collision warning systems, this can have devastating consequences, as the driver is then alerted to an object or obstacle far too late to react in time.

[0004] To reduce such latency times, US 2009 / 0 254 260 A1 describes a system that uses ultrasonic sensors to detect the surroundings. To reduce the latency times of the ultrasonic sensors, they are operated in different modes, which are selected depending on the vehicle speed.

[0005] DE 10 2014 111 951 A1 shows a method for warning a driver of a motor vehicle of the presence of an object in the surroundings of the motor vehicle by means of a driver assistance system, in which a position of the object is determined by means of a sensor device, an anticipated travel path of the motor vehicle is determined, a collision distance, which describes a distance between the motor vehicle and the object when the motor vehicle is moving within the determined travel path, is determined on the basis of the determined position of the object and the determined travel path, a value for a minimum distance between the motor vehicle and the object is determined and a warning signal is issued if the value for the minimum distance falls below a predetermined limit, wherein the determined value for the minimum distance is adapted depending on the determined collision distance.

[0006] The object of the present invention is to provide a method for activating at least one function of a motor vehicle, a driver assistance system and a motor vehicle, which enable a reduction of the influence of latency times on the activation of functions in the simplest possible way.

[0007] This object is achieved by a method, a driver assistance system, and a motor vehicle having the features according to the respective independent claims. Advantageous embodiments of the invention are the subject of the dependent patent claims, the description, and the figures.

[0008] In a method according to the invention for activating at least one function of a motor vehicle, a first distance of the motor vehicle to at least one object in the surroundings of the motor vehicle is determined. The first distance represents a minimum distance between the motor vehicle and the at least one object. Furthermore, a second distance is predicted, representing a path length from the current position of the motor vehicle to a collision with the at least one object.Furthermore, it is checked whether the second distance decreases within a predetermined period of time, and if the check shows that the second distance decreases, the determined first distance is reduced, thereby providing a reduced third distance, and wherein, furthermore, to compensate for a latency time between initiating the activation of the at least one function and executing the at least one function, the at least one function of the motor vehicle is activated as a function of the reduced third distance.

[0009] The first distance therefore represents the shortest distance between the motor vehicle and the detected object, while the second distance is the distance to collision, also known as the distance to collision (DTC). The invention is based on the finding that the latency can be effectively compensated for by reducing the detected minimum distance. If, for example, a minimum distance of 35 centimeters to the object is measured, this is treated during further processing as if it were only 30 centimeters, for example. This means that functions that primarily serve to avoid collisions can be triggered earlier, effectively compensating for the latency between the triggering and the actual execution of such a function. The latency times are therefore still present, but are compensated for by the earlier initiation of the function trigger.However, in order to avoid unnecessary and premature triggering of such functions, it is particularly advantageous that the reduction of the first distance is only carried out if a reduction of the second distance, i.e. the distance to the collision, is detected. This is because this second distance also contains a statement about the probability of a collision. For this purpose, the predicted distance to the collision, i.e. the second distance, is first considered, in particular over a predetermined period of time, which is, for example, between 100 milliseconds and 150 milliseconds. If a reduction or decrease in the distance to the collision is detected during this period, the determined minimum distance, i.e. the first distance, is reduced, for example, by a factor to a new minimum distance, which provides the third distance.This advantageously ensures that the first distance is only reduced if the risk of collision can be considered increased by reducing the second distance. If, for example, the motor vehicle is moving parallel to an object, such as a peripheral structure or curb, the distance to the collision would also be considered infinite. In such a case, it would also be unnecessary to reduce the first distance. This would then result in a greater distance having to be maintained from peripheral structures in order to avoid constant and unnecessary function activation. The invention therefore effectively compensates for latency times and thus significantly increases road safety, while still avoiding unnecessary and premature function activations.

[0010] The determination of the first distance can be based, for example, on environmental detection by the motor vehicle's environmental sensors, which are designed to detect the surroundings of the motor vehicle and by means of which objects or obstacles in the vicinity of the motor vehicle can be detected. For example, such a minimum distance can then be determined using cameras, e.g., stereo cameras, ultrasonic sensors, radar, laser scanners, and so on. Furthermore, the second distance, i.e. the distance to the collision, can be calculated based on determined movement parameters that can be provided by the motor vehicle's detection means. Based on these movement parameters, such as speed, acceleration, steering angle, and so on, a driving area ahead in which the motor vehicle will move can be predicted.If a detected object lies within this pre-calculated driving range, the shortest possible driving trajectory up to the collision can be determined, which accordingly represents the distance up to the collision, i.e. the second distance.

[0011] In an advantageous embodiment of the invention, the at least one function is activated as a function of the third distance such that the activation of the at least one function is initiated when the third distance is smaller than a predetermined limit. Thus, if, for example, a reduction in the distance to the collision is detected, it is not the actual distance to the object that is compared with this limit, but rather this reduced third distance, so that the function is initiated significantly earlier and executed accordingly when the actual minimum distance, i.e., the first distance, has approximately reached this limit.

[0012] Especially in this context, when using a limit value, it is particularly advantageous to reduce the first distance to the third reduced distance to compensate for the latency, rather than, for example, changing the limit value itself. This has the advantage that, for numerous subsystems of the motor vehicle that provide distance-dependent function triggers based on various different limit values, these different limit values ​​do not have to be changed accordingly for all of these functions. This reduced third distance can now advantageously be provided to all of these subsystems, which treat them accordingly as if it were the actually determined minimum distance, i.e., the first distance.This allows a one-time reduction of the first distance to the third distance to provide latency compensation for all subsystems of the motor vehicle that use the minimum distance to an object to trigger a function.

[0013] In an advantageous embodiment of the invention, the at least one function represents the output of a warning signal to the driver. This advantageously allows the driver to be alerted to an object at an early stage. This warning signal can be output visually, acoustically, and / or haptically, for example, by a corresponding output device of the motor vehicle. The resulting compensation of the latency advantageously prevents the driver from being alerted to objects too late.

[0014] In a further advantageous embodiment of the invention, the at least one function represents an emergency braking assistance function, in particular according to which the motor vehicle is automatically decelerated upon activation. The execution of the function thus consists in automatically initiating a braking operation. The possibility of compensating for the latency according to the invention advantageously prevents such an emergency braking operation from being initiated too late due to the latency.

[0015] The threshold against which the third distance is compared can also be set differently for different functions. This means that a different threshold can be selected for issuing a warning signal than for the emergency braking assistance function. Numerous other functions are also conceivable that can be triggered depending on the reduced third distance.

[0016] In a further advantageous embodiment of the invention, the second distance is predicted as a function of at least one detected movement parameter of the motor vehicle. Based on movement parameters of the motor vehicle, which describe, for example, a current movement of the motor vehicle or the movement of the motor vehicle over its previous time course, the movement course can advantageously be extrapolated or a future travel trajectory can be predicted, based on which the distance until the collision with the object can be easily calculated.

[0017] It is particularly advantageous if the movement parameter represents the speed of the motor vehicle and / or the steering angle of the motor vehicle. Both variables are preferably taken into account when determining the second distance. Other movement parameters, such as the acceleration or deceleration of the motor vehicle at a current time, can also be used to predict the expected path and thus also predict the second distance, i.e., the distance to the collision.

[0018] According to the invention, the third distance is reduced by a predetermined factor compared to the first distance. In other words, the third distance is determined by multiplying the first distance by this predetermined factor. This factor is correspondingly less than 1 and is dimensioned such that it can provide compensation for the latency. The factor can advantageously be determined depending on certain variables or parameters to enable better adaptation to the situation.

[0019] According to the invention, the factor is predetermined as a function of a speed, in particular a current speed, of the motor vehicle. It is particularly advantageous that this dependency is designed such that the greater the motor vehicle speed, the greater the reduction in the third distance compared to the first distance. For a given latency period, a motor vehicle traveling at a higher speed also covers a greater distance during this latency period than at a lower speed. The corresponding adjustment of the factor can compensate for these distance differences at different speeds and thus the corresponding latency periods through the corresponding speed-dependent reductions in a particularly adapted manner.

[0020] The factor can also be adjusted depending on further parameters, such as the second distance or the change in the second distance within the predetermined time interval. If, for example, the distance to the collision decreases very rapidly within this predetermined time interval, a correspondingly lower factor can be selected to provide a greater reduction in the third distance compared to the first distance. If the distance to the collision is large, for example, only a slight reduction in the third distance can be selected, whereas if the distance to the collision is small, a greater reduction in the third distance compared to the first distance can be selected.

[0021] The reduction in the third distance compared to the first distance is thus preferably proportional to the vehicle speed and / or proportional to the temporal change in the second distance and / or indirectly proportional to the second distance. This makes it possible to provide latency compensation adapted to different situations. The factor itself can also be determined as a function of the latency. This, in turn, can be measured, for example, result from an average of several latency measurements, be provided by test drives, or similar. This makes it possible to avoid both excessive latency compensation and insufficient compensation.

[0022] As already described at the beginning, in order to avoid unnecessary or premature activation of a function, it is advantageous to reduce the first distance to the third distance only if the second distance, i.e., the distance to the collision, decreases within the predetermined time interval. Accordingly, an advantageous embodiment of the invention provides that, if the check reveals that the second distance has not decreased during the predetermined time interval, the at least one function of the motor vehicle is activated as a function of the first distance.

[0023] This function can then be triggered in a similar way to the function triggered as a function of the third distance. Preferably, the at least one function of the motor vehicle is activated as a function of the first distance in such a way that the activation of the at least one function is initiated when the first distance is less than the predetermined limit value. In this case, if no reduction in the distance to the collision has been detected, the actually measured minimum distance to the object is compared with the predetermined limit value in order to decide whether or not the function should now be triggered. Since the risk of collision can be assessed as correspondingly low because the distance to the collision is not reduced, unnecessary precautionary measures that would lead to premature or unnecessary function triggering can advantageously be dispensed with.

[0024] In a further advantageous embodiment of the invention, the predetermined limit value is between 0.1 and 0.5 m, preferably between 0.2 and 0.4 m, such as 0.3 m. Such a dimensioning of the limit value is particularly advantageous when the function involves issuing the warning signal, as well as in situations such as parking maneuvers or when exiting a parking space. In other situations or for other functions, the limit value can also be dimensioned differently.

[0025] A driver assistance system according to the invention for a motor vehicle is designed to carry out a method according to the invention or one of its embodiments.

[0026] A motor vehicle according to the invention has a driver assistance system according to the invention. The motor vehicle is preferably designed as a passenger car.

[0027] The features, combinations of features and their advantages mentioned with reference to the method according to the invention and its embodiments apply equally to the driver assistance system according to the invention and the motor vehicle according to the invention.

[0028] Furthermore, it is preferred that the motor vehicle has at least one environmental sensor, such as a radar sensor, for detecting the at least one object in the surroundings of the motor vehicle. The motor vehicle can also have multiple and / or other sensors, such as cameras, laser scanners, radars, or the like, for environmental detection.

[0029] Further features of the invention emerge from the claims, the figures and the description of the figures. The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination, but also in other combinations without departing from the scope of the invention. Thus, embodiments are to be regarded as encompassed and disclosed by the invention that are not explicitly shown and explained in the figures, but which emerge and can be produced by separate combinations of features from the explained embodiments. Embodiments and combinations of features are also to be regarded as disclosed that therefore do not have all the features of an originally formulated independent claim.Furthermore, embodiments and combinations of features are to be regarded as disclosed, in particular by the embodiments set out above, which go beyond or deviate from the combinations of features set out in the references to the claims.

[0030] Showing: Fig. 1 shows a schematic representation of a motor vehicle with a driver assistance system for activating a distance-dependent function according to a first exemplary embodiment of the invention; Fig. 2 shows a schematic representation of the motor vehicle according to a second exemplary embodiment of the invention; Fig. 3 shows a schematic representation of the motor vehicle according to a third exemplary embodiment of the invention; and Fig. 4 shows a flowchart illustrating a method for activating a function of the motor vehicle according to an exemplary embodiment of the invention.

[0031] Fig. 1 shows a schematic representation of a motor vehicle 1 with a driver assistance system 2 for distance-dependent triggering of a function according to an embodiment of the invention. In this example, the motor vehicle 1 has, by way of example, an environmental sensor 3, which can be a radar sensor and / or a camera and / or an ultrasonic sensor. In particular, the motor vehicle 1 can also have any number of such sensors, for example, distributed around the motor vehicle 1, in order to enable 360° environmental detection. The environmental sensor 3 shown is to be regarded as representative of any designed environmental sensor system with any number of environmental sensors. Fig. 1 The areas shown in the plan view around the motor vehicle 1 are intended to illustrate the detection areas of the environment sensor 3, whereby only one of these areas is provided with the reference symbol 3a by way of example. The driver assistance system 2 also has an evaluation device 4, which is designed to evaluate the sensor data detected by the environment sensor 3 and, depending on the evaluation, to activate a function of the motor vehicle 1. Such a function can, for example, represent the output of a warning signal to the driver, for which purpose the driver assistance system 2 can have a corresponding output device 5, such as a display, a loudspeaker or the like. The output device 5 can also have vibration elements for outputting a haptic signal, for example via the steering wheel of the motor vehicle.The driver assistance system 2 can also be coupled to further detection means 6 of the motor vehicle 1, for example for detecting certain movement parameters of the motor vehicle 1, such as the vehicle speed, the steering angle, an acceleration, and so on.

[0032] The data of the surroundings of the motor vehicle 1 recorded by the at least one surroundings sensor 3 of the motor vehicle 1 are evaluated by the evaluation device 4. Based on the recorded data, objects or obstacles, such as the object designated here as an example with 8, can be detected in the surroundings of the motor vehicle. Furthermore, based on this recorded data, a first distance, which represents a minimum distance d1, can be determined. This minimum distance d1 therefore represents the shortest distance between the motor vehicle 1 and the object 8. Furthermore, a second distance, which represents a distance D until the collision, is also predicted. This distance D thus indicates the distance that the motor vehicle must travel from its current position until it collides with the object 8. This distance D is calculated based on the determined movement parameters provided by the detection means 6 of the motor vehicle 1.Based on these movement parameters, the evaluation device 4 can calculate an upcoming driving range 7 or a driving curve. If the detected object 8 lies within this precalculated driving range 7, the shortest possible driving trajectory up to the collision can be determined, which accordingly represents the distance D to the collision.

[0033] Typically, collision warning systems have a predefined limit value. If the detected distance to the object falls below this limit, a function is triggered, such as issuing a warning signal. If this limit value is 30 centimeters, for example, a function is triggered as soon as the detected distance falls below 30 centimeters. However, before the function is actually executed, such as the warning signal being issued, there is a certain latency period during which the vehicle continues to move. So that when the warning signal is issued, the distance to the object is no longer 30 centimeters, but only 27 or 25 centimeters, for example. This can, under certain circumstances, lead to a driver no longer being able to react in time, and a collision becomes unavoidable.

[0034] To avoid this, according to this exemplary embodiment of the invention, such latency times can advantageously be compensated, thereby enabling timely activation of a function and simultaneously preventing unnecessary or premature activations. This is accomplished as follows. For this purpose, the predicted distance D to the collision is first considered, in particular over a predetermined period of time, which is preferably between 100 milliseconds and 150 milliseconds. If a reduction or decrease in the distance D to the collision is detected during this period, the determined minimum distance d1 is reduced by a factor to a new minimum distance d2, which provides a third distance.During further processing, in particular when the function is triggered, this new reduced minimum distance d2 is treated as if it were the actually measured or determined minimum distance d1. Instead of comparing the actually determined minimum distance d1 with a predetermined limit value G, the new reduced minimum distance d2 is compared with this limit value G. If this new minimum distance d2 falls below the predetermined limit value G, the corresponding function is triggered, which can be provided, for example, by issuing a warning signal to the driver or by triggering an emergency brake or something similar. This means that the function can be triggered earlier than if the time of function triggering was based on the actually determined minimum distance d1. This is also shown in . Fig.1 illustrated. As can be seen, the actually determined minimum distance d1 in this example is still greater than the predetermined limit value G. With conventional methods, a function would therefore not yet be triggered. The reduced minimum distance d2, on the other hand, is already smaller than the limit value G, so that in this example a function is triggered. By reducing the minimum distance d1 to the reduced minimum distance d2, it is effectively ensured that function triggers are initiated earlier in situations in which the risk of collision is classified as increased, which can be determined based on the detected reduction in the distance D to the collision.

[0035] If, on the other hand, it is determined that the distance D until the collision does not decrease during the predetermined period of time, for example, it remains the same or even increases, the minimum distance d1 is not reduced and, in order to check whether a function triggering is necessary or not, this actually determined minimum distance d1 is compared with the limit value G.

[0036] Fig. 2 also shows a schematic representation of the motor vehicle 1 from Fig. 1 in a slightly different situation according to a further embodiment of the invention. The motor vehicle 1 can again be Fig. 1 described. The Fig. 1 The procedure for triggering the function described is the same. In this example in Fig. 2 However, a different distance D was predicted until the collision with the object 8. In this example, based on the movement parameters of the motor vehicle 1 provided by the detection means 6, it was calculated that there was no risk of collision with the front of the vehicle 1 as in Fig. 1 shown, but instead with the rear of the motor vehicle 1.

[0037] Fig. 3 also shows a schematic representation of the motor vehicle 1 from Fig. 1 , again in a different situation, according to a further exemplary embodiment of the invention. In this example, the detected object 8 is not arranged laterally in relation to the motor vehicle, but is located directly ahead in the direction of travel. In this example, the minimum distance d1 between motor vehicle 1 and object 8, detected by the at least one environment sensor 3, and the distance D up to the collision correspond. If, in this example, the motor vehicle moves further, the distance D up to the collision is reduced. Accordingly, the determined minimum distance d1 is again reduced by a factor to the reduced minimum distance d2 and compared with the limit value G. If this reduced distance d2 is smaller than the limit value G, a corresponding function is activated.

[0038] Fig. 4shows a flowchart to illustrate a method for activating a function of a motor vehicle according to an embodiment of the invention. The method begins in step S1, in which a predetermined limit value G is initially defined. Furthermore, in step S2, it is checked whether an object 8 has been detected in the surroundings of the motor vehicle 1. If this is not the case, this check is carried out in step S2 until this is the case. Accordingly, the process then proceeds to step S3, in which, on the one hand, the minimum distance d1 of the motor vehicle 1 to the object 8 is calculated, and the distance D until the collision of the motor vehicle 1 with the object 8 is predicted. Subsequently, in step S4, it is checked whether the distance D has decreased within a predetermined observation period.If this is not the case, a check is performed in step S5 to determine whether the determined minimum distance d1 is smaller than the previously defined limit value G. If this is the case, a function, such as the output of a warning signal, is initiated in step S6. Subsequently, the minimum distance d1 is recalculated in step S7, and a check is performed again in step S5 to determine whether the current minimum distance d1 is smaller than the limit value G.

[0039] In other words, the warning signal is issued as long as the minimum distance d1 falls below the limit value G. If, however, it is determined in step S5 that the minimum distance d1 does not fall below the limit value G, the process starts again from the beginning and checks again in step S2 whether the object 8 is still detected.

[0040] If, on the other hand, it is determined in step S4 that the distance D has decreased during the predetermined observation period, such as a period between 100 milliseconds and 150 milliseconds, the determined minimum distance d1 is reduced by a factor to a new reduced minimum distance d2 in step S8. Subsequently, in step S9, it is checked whether this reduced minimum distance d2 falls below the limit value G. If this is the case, the corresponding function is activated in step S10 and, for example, a warning signal is again issued. Here, too, it is preferably provided that this warning signal is issued, or in general the function remains activated, as long as the reduced minimum distance d2 falls below the limit value G. The calculation of the limit value G for this time period is based on measurement data currently acquired in each time step, as illustrated by step S11.If, however, it is determined in step S9 that the reduced distance d2 does not fall below the limit value G, the process starts again from the beginning and checks whether object 8 or other objects are detected.

[0041] The determination of the limit value G does not necessarily have to occur in the first step S1, but can be provided at any point, as long as it occurs before the comparisons in step S9 or S5. It is also advantageous to determine the limit value G as a function of the current vehicle speed, and optionally also as a function of the distance D to the collision determined in step S3. This allows for optimal situational adaptation to compensate for latency times.

Claims

1. Method for activating at least one function of a motor vehicle (1), having the steps of: - determining a first distance (d1) between the motor vehicle (1) and at least one object (8) in an environment of the motor vehicle (1), wherein the first distance (d1) represents a minimum spacing between the motor vehicle (1) and the at least one object (8); - predicting a second distance (D) representing a travel distance from a current position of the motor vehicle (1) to a collision with the at least one object (8); - checking whether the second distance (D) decreases within a predetermined period of time; - if the check reveals that the second distance (D) decreases, decreasing the determined first distance (d1) by multiplying the determined first distance (d1) by a predetermined factor, thereby providing a decreased third distance (d2), wherein the factor is predetermined on the basis of a speed of the motor vehicle (1); and - activating the at least one function of the motor vehicle (1) on the basis of the decreased third distance (d2) in order to compensate for a latency between initiating the activation of the at least one function and performing the at least one function.

2. Method according to Claim 1, characterized in that the at least one function is activated on the basis of the third distance (d2) in such a way that the activation of the at least one function is initiated when the third distance (d2) is less than a predetermined limit value (G).

3. Method according to one of the preceding claims, characterized in that the at least one function involves outputting a warning signal to the driver.

4. Method according to one of the preceding claims, characterized in that the at least one function is an emergency braking assistance function, in particular according to which the motor vehicle (1) is automatically decelerated when activated.

5. Method according to one of the preceding claims, characterized in that the second distance (D) is predicted on the basis of at least one captured motion parameter of the motor vehicle (1).

6. Method according to Claim 5, characterized in that the motion parameter is a speed of the motor vehicle (1) and / or a steering angle of the motor vehicle (1).

7. Method according to one of the preceding claims, characterized in that if the check reveals that the second distance (D) has not decreased during the predetermined time interval, the at least one function of the motor vehicle (1) is activated on the basis of the first distance (d1).

8. Method according to Claim 7, characterized in that the at least one function of the motor vehicle (1) is activated on the basis of the first distance (d1) in such a way that the activation of the at least one function is initiated when the first distance (d1) is less than the predetermined limit value (G).

9. Method according to one of the preceding claims, characterized in that the predetermined limit value (G) is between 0.1 and 0.5 metres, preferably between 0.2 and 0.4 metres.

10. Driver assistance system (2) for a motor vehicle (1), having an evaluation device (4) which is designed to evaluate sensor data captured by an environmental sensor (3) and to activate a function of the motor vehicle (1) on the basis of the evaluation, wherein the driver assistance system (2) is further designed to carry out a method according to one of the preceding claims.

11. Motor vehicle (1) having a driver assistance system (2) according to Claim 10.

12. Motor vehicle (1) according to Claim 11, characterized in that the motor vehicle (1) has at least one environmental sensor (3) for detecting the at least one object (8) in the environment of the motor vehicle (1).