Method for operating an automatic distance control system in a motor vehicle

Abstract

The invention relates to a method for operating an automatic distance control system in a motor vehicle (1). In a normal mode (25), the automatic distance control system controls longitudinal guidance (14) of the motor vehicle (1) according to a sensed control object (7). The method comprises: sensing (S1) the control object (7), which is located in front of the motor vehicle (1) in a direction of travel (6), for the automatic distance control system by evaluating an item of sensor information (21) captured by means of a sensor device (11) of the motor vehicle (1); for the sensed control object (7), determining (S2) an item of duration information (22) which describes a duration for which the control object (7) is sensed as an object in the surroundings of the motor vehicle (1); checking (S3) whether the determined item of duration information (22) is less than a predefined duration limit value (24); if this is the case, changing (S4) an operating mode of the automatic distance control system from the normal mode (25) to a transition mode (26) in which the longitudinal guidance (14) of the motor vehicle (1) is controlled with a smaller rate of change than in the normal mode (25).

Description

[0001] Method for operating an automatic distance control system in a motor vehicle

[0002] The invention relates to a method for operating an automatic distance control system in a motor vehicle. Furthermore, the invention relates to a distance control system for a motor vehicle, a motor vehicle, and a computer program product for implementing such a method.

[0003] A motor vehicle may have an automatic distance control system as a vehicle function, which is designed to control the longitudinal guidance of the motor vehicle depending on a control object detected in front of the motor vehicle in a direction of travel. The automatic distance control system can, for example, accelerate the motor vehicle by controlling a drive device of the motor vehicle or decelerate the motor vehicle by controlling a braking system of the motor vehicle.

[0004] When operating the automatic distance control, a situation can arise in which the previously detected control object leaves a road on which the motor vehicle is traveling and / or changes lanes. The motor vehicle then detects a new control object, which the automatic distance control is subsequently based on. A sensor device of the motor vehicle, by means of which the control object is detected when the automatic distance control is operated, can temporarily detect sensor information for the new control object during this change of control object. This information is erroneous and / or inaccurate and can be used to overestimate or underestimate, for example, the speed of the new control object and / or its distance from the motor vehicle. After a short period of time, for example 1 or 2 seconds, reliable and accurate sensor information is typically detected again by the sensor device.However, during the phase of erroneous and / or inaccurate sensor information, this may cause an abrupt change in the speed of the motor vehicle and / or cause a user of the motor vehicle to feel bumpy driving.

[0005] US 2022 / 0234583 A1 describes a driver assistance system that can quickly determine a swerving maneuver by a vehicle ahead based on lane information received from a camera. US 2012 / 0209492 A1 describes a method for regulating the acceleration control of a vehicle. A type of change in the driving situation for the vehicle is detected, and the acceleration control is regulated based on the detected type.

[0006] The KR 2018 0126160 shows an automatic distance control that can reduce the risk of a sudden reduction in speed before a collision due to a vehicle driving in front of the motor vehicle.

[0007] It is the object of the invention to provide a solution by means of which automatic distance control in a motor vehicle can be reliably carried out when a control object changes.

[0008] The problem is solved by the subject matter of the independent patent claims.

[0009] A first aspect of the invention relates to a method for operating an automatic distance control system in a motor vehicle. The automatic distance control system can alternatively be referred to as adaptive cruise control, adaptive cruise control, or adaptive cruise control (ACC). Adaptive distance control is based, for example, on the fact that a position and speed of a vehicle traveling ahead, which can be referred to as the control object, are determined by a sensor device of the motor vehicle and then the speed of the vehicle and its distance from the vehicle traveling ahead are controlled by controlling the longitudinal guidance of the vehicle, i.e., for example, by acceleration and braking interventions. In a normal mode of the automatic distance control system, the longitudinal guidance of the vehicle is controlled or triggered depending on the detected control object.

[0010] The method comprises detecting the control object that is located in front of the motor vehicle in a direction of travel of the motor vehicle. Between the motor vehicle and the detected control object there is no other object that could be assumed to be a control object. The control object is, for example, a vehicle, in particular another motor vehicle and / or a bicycle. The control object is detected by evaluating sensor information that is detected by a sensor device of the motor vehicle. The sensor device comprises, for example, at least one radar device and / or at least one other sensor that can measure or at least estimate a distance to an object in an environment of the motor vehicle. To detect the control object, a control object recognition criterion can, for example, be applied to the sensor information.The control object recognition criterion comprises at least one algorithm and / or a rule, the implementation of which can determine from the sensor information whether a control object is located in front of the motor vehicle in the direction of travel and is, for example, moving or stationary there.

[0011] For the detected control object, the method includes determining duration information. The duration information describes a period of time since the control object has been detected as an object in the environment of the motor vehicle. The duration information can be determined by evaluating the sensor information, for example, by applying a duration determination criterion to the sensor information. To determine the duration information, for example, sensor information that was recorded in a predetermined time interval and stored in the motor vehicle is evaluated in order to trace back, for example, when the control object was first detected as an object in the environment. The time period from this first detection can then be determined and provided as the duration information.The object does not have to have been recognized as the control object in the specified time interval, but can simply have been detected as any object in the surroundings of the motor vehicle. The specified time interval comprises, for example, 5 minutes, 3 minutes, 2 minutes, 1 minute, 30 seconds, 10 seconds or, in particular, 5 seconds. Larger or smaller time intervals or time intervals between the ones mentioned are possible. Ultimately, it is therefore determined since when the motor vehicle has been able to locate the object, which has now been detected as the control object, in the surroundings of the motor vehicle. The duration determination criterion comprises at least one algorithm and / or a rule, the implementation of which can determine the duration information. The surroundings here are limited, for example, to a detection range of the sensor device that detects the sensor information.

[0012] In a situation in which a detected control object has not yet been detected, for example because the previous control object has turned or left a lane that the motor vehicle is traveling in, a vehicle driving ahead that is no longer obscured by the control object can be detected as a new control object. If the new control object is a truck, for example, it may be the case that this truck was already detected as an object when the previous control object was still driving ahead of the motor vehicle and was the control object for automatic distance control. In this case, the time duration information is relatively large because the control object has already been detected as an object in the environment for a time period greater than 0.However, if the previous control object is a truck which, for example, obscures a passenger car driving ahead of it for the sensor device of the motor vehicle, then after, for example, the truck and thus the previous control object have driven off and / or changed lanes with the new control object, there may be an object previously unknown to the motor vehicle and therefore not detected in the environment, for which, for example, the time duration information during detection is 0. In other words, the age of the control object is determined based on the time since it has been detected as an object in the environment.

[0013] The method comprises checking whether the determined duration information is less than a predefined duration limit value. The predefined duration limit value can be fixed and be, for example, 1 second or 2 seconds. Shorter or longer duration limits or duration limits between 1 second and 2 seconds are possible. If the determined duration information is less than the predefined duration limit value, an operating mode of the automatic distance control changes from normal mode to a transition mode. In transition mode, the longitudinal guidance of the motor vehicle is controlled at a lower rate of change than in normal mode. Apart from the lower rate of change, the transition mode can correspond to the normal mode. The lower rate of change causes, for example, that a desired speed change, such as an increase in speed or a

[0014] Speed ​​reduction occurs in a longer time interval and thus more slowly than would be the case in normal mode. If, for example, the motor vehicle is to be accelerated in transition mode because the speed determined for the detected control object is high compared to the current speed of the vehicle, this acceleration is limited compared to normal mode because it occurs more slowly due to the smaller or reduced rate of change compared to normal mode. A similar procedure can be followed if the motor vehicle is to brake due to the detected control object. In other words, the rate of a desired change with regard to the longitudinal guidance of the motor vehicle, such as acceleration or braking, is limited and kept lower than in normal mode.This ensures that even in phases with only limited sensor information or even erroneous and / or inaccurate sensor information, such as in the first few seconds after detecting a new control object, automatic distance control continues to operate reliably, since the effects on longitudinal guidance are mitigated by reducing the rate of change. For example, if the detected sensor information regarding the new control object initially fluctuates significantly, this fluctuation can be at least somewhat cushioned by reducing the rate of change. According to the invention, automatic distance control in the motor vehicle can therefore be reliably implemented when changing the control object.

[0015] The method according to the invention is preferably carried out by a control device of the motor vehicle. It can therefore be understood as a computer-implemented method. The control device receives, for example, the sensor information from the sensor device in order to be able to carry out the method. Furthermore, the control device can be designed to control the longitudinal guidance of the motor vehicle, i.e., the braking system and / or the drive system of the motor vehicle. It can control the longitudinal guidance of the motor vehicle.

[0016] One embodiment provides for the determination of collision information that describes a predicted time until a collision of the motor vehicle with the detected control object. Switching to transition mode only occurs if the determined collision information lies within a predefined collision information value range that is assigned to a non-critical situation. The collision information can, for example, be a value that is compared with the predefined value range. This value is, for example, fixed and stored in the motor vehicle, i.e., for example, in a memory device of the motor vehicle.In a situation defined as critical, the collision information typically lies outside the specified collision information value range. Therefore, if collision information is detected within the specified collision information value range, it can be assumed that the situation is non-critical and therefore non-critical. A non-critical situation is characterized by the fact that, for example, no emergency stop, no braking, and / or no other action is required. This ensures that, in situations where the duration information is less than the specified duration limit, the system only actually switches to transition mode if there is no risk of collision, since only a non-critical situation is detected. This provides additional safeguards for switching to transition mode.It can be provided that, for example, if the determined duration information is less than the specified duration limit, the switch to transition mode is prevented if the collision information lies outside the specified collision information value range. If the switch has already occurred and it is only then determined that the collision information lies outside the collision information value range, the system can immediately switch back to normal mode.

[0017] Another exemplary embodiment provides that the collision information is determined by applying a collision determination criterion to a control object speed information item, a distance information item, and / or an airspeed information item. The collision determination criterion comprises at least one algorithm and / or a rule, the implementation of which, based on one or more of the three aforementioned pieces of information, i.e., the control object speed information item, the distance information item, and / or the control object speed information item, can determine or calculate the collision information item, i.e., the time until the potential collision of the motor vehicle with the detected control object. The control object speed information item describes a speed of the control object. The distance information item describes a distance between the motor vehicle and the control object.The airspeed information describes the current speed of the motor vehicle and thus its airspeed. The controlled object speed information, the distance information, and / or the airspeed information can each be determined from the sensor information by applying appropriate criteria and / or recorded using appropriate sensors of the motor vehicle. Preferably, only the sensor information is required in order to be able to determine the information required for the method, such as the controlled object speed information, the distance information, and / or the airspeed information, based on various evaluation steps and, if applicable, criteria. This makes it clear how the collision information can be reliably determined.

[0018] Another exemplary embodiment provides for the determination of airspeed information that describes the current speed of the motor vehicle. The airspeed information is, in particular, identical to the airspeed information mentioned in connection with the collision information. Switching to transition mode only occurs if the determined airspeed information is greater than a predefined minimum speed. A check is therefore carried out to determine whether the motor vehicle is traveling fast enough to permit switching to transition mode. For example, the minimum speed may be 70 kilometers per hour, so that the operating mode only switches to transition mode if the motor vehicle is traveling at more than 70 kilometers per hour and the determined duration information is less than the predefined duration limit.In particular, a third requirement can be specified that the collision information must be within the specified collision information value range in order to switch from normal mode to transition mode. If, for example, the requirement for the vehicle's own speed information is not met, it can be specified that the automatic cruise control remains in normal mode or immediately switches from transition mode to normal mode. Ultimately, a limit value can be specified regarding a speed limit for the vehicle, for example, to exclude certain situations in which the procedure, i.e., switching to transition mode, is not intended.By specifying the minimum speed, for example, automatic distance control intended for highways can be included in the method according to the invention, but automatic distance control in a residential area with a maximum speed below the minimum speed can be excluded. This allows for a situation-dependent switching to transition mode.

[0019] Another exemplary embodiment provides for a check to determine whether the detected control object is different from a previously detected control object. Only if this is the case is the duration information determined and checked. It can be provided that the duration information is not continually determined and checked while a specific control object is being detected, but rather it can be provided that the method is actually only designed for a change of control object, so that, for example, only when an object that has not previously been detected as a control object is detected as a control object. The duration information can only then be determined and checked for this newly detected rule object. The determination of the duration information can therefore not, for example, take place continuously for the previous control object, but only specifically for the newly detected rule object.This makes it clear that the method according to the invention is intended for exit and / or lane-change situations in which the control object changes, since only then are potential deteriorations in the sensor information expected. This is particularly resource-efficient, as unnecessary determination and verification of the duration information is prevented.

[0020] In another exemplary embodiment, after switching to transition mode, the duration information is still determined and checked to see whether it is less than the predefined duration limit. As soon as the determined duration information is greater than or equal to the duration limit, the system switches from transition mode to normal mode. The transition mode is therefore intended for a maximum time limited by the duration limit. If the duration limit is 1 second, the system switches back to normal mode no later than 1 second after switching to transition mode. This procedure is based on the knowledge that, for example, after the duration limit has been reached, it can be assumed with a high probability that sensor information on the new control object is now available that is sufficiently accurate and reliable to operate the automatic distance control in normal mode.For this reason, after the specified duration limit has elapsed, the system can switch back to a rate of change intended for normal mode, which is large compared to the rate of change in transition mode. This makes it clear that the switch to transition mode is intended only for a limited time.

[0021] In addition, one embodiment provides for inaccuracy information to be determined in the transition mode. This information describes an inaccuracy in distance information describing a distance between the motor vehicle and the control object, and / or an inaccuracy in control object speed information describing a speed of the control object. The distance information is, in particular, identical to the distance information mentioned in connection with the collision information, and the control object speed information is, in particular, identical to the control object speed information mentioned in connection with the collision information.

[0022] A check is carried out to determine whether the determined inaccuracy information lies within a predefined inaccuracy value range that is associated with reliable detection of the control object. A value range is defined for the inaccuracy information that is associated with reliable detection of the control object. This means that it is defined in such a way that, if the inaccuracy lies within this value range, reliable detection of the control object can be assumed. If the inaccuracy information lies outside the inaccuracy value range, it is assumed that the detection of the control object is too inaccurate to allow, for example, the operation of automatic distance control depending on the distance information and / or the control object speed information.As soon as the determined inaccuracy information lies within the specified inaccuracy value range and thus reliable information on the distance and / or the controlled object speed is available, the system switches from transition mode to normal mode. For example, the process can switch back to normal mode before the time period limited by the duration limit has elapsed if sufficiently accurate data is available, i.e., the distance to the controlled object and / or the speed of the controlled object can be determined sufficiently reliably and accurately, so that transition mode is no longer required. The longitudinal guidance is then controlled at the rate of change specified in normal mode. Therefore, various ways of switching back to normal mode are possible.

[0023] In a further exemplary embodiment, it is provided that the rate of change in the transition mode is predetermined as a function of the motor vehicle's own speed information. It is therefore predetermined as a function of the own speed information. The own speed information is, for example, in particular equal to the own speed information mentioned in connection with the collision information. It can thus be provided that a fast-moving motor vehicle, for example, is predetermined a smaller rate of change compared to a slower-moving motor vehicle. This assignment can be predetermined in reverse, so that, for example, the rate of change is reduced less for a faster-moving motor vehicle than for a slower-moving motor vehicle, in order to be able to take longer braking distances at higher speeds into account, for example.It can therefore be provided that the rate of change is specified dynamically, in particular depending on the speed.

[0024] In addition, one embodiment provides that the control of the longitudinal guidance comprises accelerating or decelerating the motor vehicle. Acceleration occurs by controlling the drive device and deceleration by controlling the braking system of the motor vehicle. In transition mode, the rate of change for acceleration is specified differently than the rate of change for deceleration. For example, it can be provided that acceleration, which is typically perceived less strongly by an occupant of the motor vehicle, is always less affected by the reduction in the rate of change than deceleration, in order to prevent, for example, obstructing another road user following behind due to abrupt, in particular unexpected, deceleration of the motor vehicle. How precisely the rate of change for acceleration and / or the rate of change for deceleration is specified can be situation-dependent and / or arbitrarily specified.Furthermore, the vehicle's own speed information can be taken into account. Ultimately, this also allows for different longitudinal control or longitudinal guidance commands to vary the rate of change, allowing for a particularly differentiated reduction in the rate of change.

[0025] According to a further exemplary embodiment, the respective rate of change for acceleration or deceleration is specified depending on whether the motor vehicle was accelerating or decelerating at the time of switching to the transition mode. Therefore, not only is the type of longitudinal guidance currently desired considered, for example based on the currently acquired sensor information, but also the type of longitudinal guidance that has been provided so far, i.e. up to a point in time at which, for example, a request to control the longitudinal guidance was made based on the new control object. It is therefore possible to distinguish whether, for example, a motor vehicle that is currently supposed to accelerate has already been accelerated or whether it has previously been decelerated. Alternatively or additionally, it can be taken into account whether the motor vehicle is currently supposed to be decelerated but has previously been accelerating or has also been decelerated.In this context, it may be desirable, for example, that if the motor vehicle has previously accelerated and a further acceleration is desired at the current time, this is permitted less quickly and thus with a smaller rate of change than a now desired deceleration during previous accelerations, in order to, for example, reduce a potential risk of collision. Alternatively or additionally, if the motor vehicle has previously decelerated and an acceleration is now desired, this may be permitted sooner than further deceleration, in order, for example, to prevent the motor vehicle from decelerating even further on a highway. These statements are purely exemplary. Other relationships are therefore possible between the current control request for the longitudinal guidance and the previously performed control of the longitudinal guidance.The method can therefore be specifically adapted to the current situation. It is therefore versatile. In another exemplary embodiment, the rate of change in transition mode is set at a predetermined value. It can thus be provided that the rate of change is always reduced by a predetermined factor or a predetermined value, regardless of whether, for example, acceleration or deceleration of the motor vehicle is desired and / or regardless of how the longitudinal control or longitudinal guidance of the motor vehicle has been carried out to date. The predetermined value can, for example, be specified by a manufacturer of the automatic distance control system and / or the motor vehicle. This makes the method particularly quick and easy to implement, since the reduction in the rate of change can be specified across the board.

[0026] In a further exemplary embodiment, it is provided that the sensor information is acquired by means of a radar device and / or a lidar device. Alternatively or additionally, the sensor information can be acquired by means of an ultrasonic sensor and / or a camera of the motor vehicle and evaluated accordingly in order to be able to determine at least the controlled object speed information, the distance information and / or the vehicle's own speed information. At least the vehicle's own speed information can alternatively or additionally be acquired and / or calculated by sensors in the motor vehicle, which are assigned, for example, to the drive device. Other or additional sensor information than that mentioned is possible. The sensor information is transmitted, for example, to the control device so that it can carry out the method described above.

[0027] A further aspect of the invention relates to a distance control system for a motor vehicle. This system is designed to carry out the method described above. It carries out the method described above. The control device, the sensor device, and the systems for longitudinal guidance or longitudinal control of the motor vehicle, such as the braking system and / or the drive device, can be included in the distance control system.

[0028] The control device comprises, for example, a processor device. This can comprise at least one microprocessor, microcontroller, FPGA (Field Programmable Gate Array), and / or DSP (Digital Signal Processor). Furthermore, it can comprise program code, which can alternatively be referred to as a computer program product. The program code can be stored in a data memory of the processor device.

[0029] Another aspect of the invention relates to a motor vehicle with a distance control system. The motor vehicle is designed to carry out the method described above. The motor vehicle is, for example, a passenger car, a truck, a bus, a motorcycle, and / or a moped.

[0030] A further aspect of the invention relates to a computer program product. The computer program product is a computer program. The computer program product comprises instructions that, when the program is executed by a computer, such as by the control devices, cause the computer to perform the steps of the method according to the invention provided for the control device.

[0031] The exemplary embodiments described in connection with the method according to the invention, both individually and in combination with one another, apply accordingly, to the motor vehicle according to the invention, the distance control system according to the invention, and the computer program product according to the invention, as applicable. The invention encompasses combinations of the described exemplary embodiments.

[0032] Showing:

[0033] Fig. 1 is a schematic representation of a motor vehicle with an automatic distance control system; and

[0034] Fig. 2 shows a schematic representation of a method for operating an automatic distance control in a motor vehicle.

[0035] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0036] Fig. 1 shows a motor vehicle 1 which is located on a road 2. It is traveling in a first lane 3 of the road 2. Adjacent to the first lane 3 there is a second lane 4 and a third lane 5. The road 2 is, for example, a highway. The motor vehicle 1 is traveling in one direction of travel 6 in the first lane 3. In front of the motor vehicle 1 there is a control object 7 which in this case is another motor vehicle 1. The control object 7 can alternatively be another vehicle, such as a bicycle. In addition, until recently there was another control object 8 in front of the motor vehicle 1, which in this case is also another motor vehicle 1. However, this previous control object 8 has changed to the second lane 4 and is therefore no longer the control object 8 for automatic distance control of the motor vehicle 1.This is a situation in which a previous rule object 8 is no longer suitable as rule object 7, 8 and therefore a new rule object 7 is recorded and used.

[0037] The motor vehicle 1 has a distance control system 9. This comprises, for example, a control device 10 of the motor vehicle 1. The distance control system 9 can also have a sensor device 11. The sensor device 11 comprises, for example, at least one radar device 12 and / or at least one lidar device 13. Alternatively or additionally, the distance control system 9 can comprise at least one ultrasonic sensor and / or at least one camera as the sensor device 11. Ultimately, the controlled object 7 should be able to be detected by means of the sensor device 11, wherein in particular its speed and a distance between the motor vehicle 1 and the controlled object 7 should be determined from sensor information 21 (see reference numeral 21 in Fig. 2) of the sensor device 11. Other arrangements of the sensor device 11 as well as more or fewer sensors of the sensor device 11 than outlined here are possible.

[0038] The distance control system 9 here comprises components for a longitudinal guide 14 of the motor vehicle 1. The control device 10 can, for example, generate or determine at least one control command for the longitudinal guide 14 and control the longitudinal guide 14 according to this command. The longitudinal guide 14 comprises, for example, a drive device and a braking system of the motor vehicle 1. The automatic distance control is therefore ultimately designed to control the longitudinal guide 14 of the motor vehicle 1 depending on the detected control object 7.

[0039] Fig. 2 outlines a method for operating the automatic distance control, i.e. for operating the distance control system 9. In a method step S1, the control object 7 is detected by evaluating sensor information 21 detected by the sensor device 11. For example, a control object recognition criterion 20 can be applied to the sensor information 21. The method step S1 and the further method steps S2 to S11 are preferably carried out by means of the control device 10 of the motor vehicle 1. The control object 7 is located in front of the motor vehicle 1 in the direction of travel 6. Thus, there is no other object between the motor vehicle 1 and the control object 7 that could be a potential control object 7, 8.If, for example, the previous control object 8 were still located between the motor vehicle 1 and the control object 7, this previous control object 8 would be the control object 7, 8, which is recorded in method step S1.

[0040] In a method step S2, a piece of duration information 22 is determined for the detected control object 7. This describes a period of time since the control object 7 has been detected as an object in the environment of the motor vehicle 1. It does not have to have been detected as a control object 7, 8, but merely as any object located in the environment of the motor vehicle 1. The duration information 22 can be determined, for example, by applying a duration determination criterion 23 to the sensor information 21. It is assumed here that sensor information 21 for at least one predetermined past time window is stored in the motor vehicle 1, for example in a memory device of the motor vehicle 1. This stored sensor information 21 can be accessed to determine when the control object 7 was first detected as an object, so that the duration information 22 can be calculated.

[0041] In a method step S3, a check is performed to determine whether the determined duration information 22 is less than a predefined duration limit 24. The duration limit 24 is, for example, 1 second or 2 seconds. Larger or smaller duration limit 24, as well as duration limit 24 values ​​between the specified duration limit 24, are possible.

[0042] If it is determined in method step S3 that the determined duration information 22 is less than the predefined duration limit value 24, a change in the operating mode of the automatic distance control from a normal mode 25 to a transition mode 26 occurs in method step S4. In transition mode 26, the longitudinal guidance 14 of the motor vehicle 1 is controlled at a lower rate of change than in normal mode 25. The rate of change describes, for example, a changed speed or changed acceleration of the motor vehicle 1 in a predefined time interval and thus per time. Ultimately, it describes how quickly this change is implemented when the longitudinal guidance 14 changes, i.e., for example, how hard the braking is applied to achieve a certain braking target and / or how hard the acceleration is applied to achieve a desired increase in speed.Ultimately, by reducing the rate of change, a braking or acceleration command takes longer than would be the case in normal mode 25.

[0043] If it is determined in method step S3 that the time duration information 22 is less than the time duration limit value 24 or equal to the time duration limit value 24, in a method step S5 the system can switch from the transition mode 26 back to the normal mode 25 and / or remain in the normal mode 25 if no switch to the transition mode 26 has yet taken place.

[0044] It can be provided that, after method step S4, the duration information 22 is continuously determined and checked to determine whether it is less than the specified duration limit value 24. As soon as this is no longer the case, a change can be made from transition mode 26 to normal mode 25 in method step S5.

[0045] In a method step S6, it can be provided that collision information 27 is determined. This describes a predicted time until a collision of the motor vehicle 1 with the detected control object 7. The change to the transition mode 26 preferably only takes place if the determined collision information

[0046] 27 lies within a predefined collision information value range 32, which can be determined in a method step S7. The predefined collision information value range 32 is assigned to a non-critical situation and is a fixed value here. If this check is successful, i.e., if the determined collision information 27 lies within the predefined collision information value range 32, method step S4 is performed. However, if the determined collision information 27 does not lie within the predefined collision information value range 32, method step S5 can be performed, or switching to transition mode 26 can be prevented altogether.

[0047] It can be provided that in method step S6 a collision determination criterion

[0048] 28 is applied to a control object speed information item 29, a distance information item 30, and / or an own speed information item 31. The control object speed information item 29 describes a speed of the control object 7. The distance information item 30 describes a distance between the motor vehicle 1 and the control object 7. The own speed information item 31 describes a current speed of the motor vehicle 1. These three pieces of information, i.e., the control object speed information item 29, the distance information item 30, and / or the own speed information item 31, can each be determined, for example, from the sensor information item 21 of the sensor device 11 and / or taking into account driving information provided by at least one sensor that monitors a journey of the motor vehicle 1 and calculated by evaluating it, in particular by means of the control device 10.

[0049] In a method step S8, it can be provided that the airspeed information 31 is determined, and in a method step S9, it is checked whether the determined airspeed information 31 is greater than a predetermined minimum speed 33. The predetermined minimum speed 33 can be, for example, 70 kilometers per hour. Higher or lower minimum speeds 33 are possible.

[0050] If it is determined in method step S9 that the determined airspeed information 31 is greater than the minimum speed 33, method step S6 can take place, i.e., switching to transition mode 26. However, it is assumed here that the check in method step S3 has also shown that the duration information 22 is less than the duration limit value 24. For method step S4 to take place after method steps S9 and S7, this requires that method step S3 has taken place and that it has been determined that the duration information 22 is less than the duration limit value 24. Method steps S1 to S4 must therefore take place before method steps S6 or S8 can even be carried out.

[0051] If it is determined in method step S9 that the airspeed information 31 is less than or equal to the minimum speed 33, method step S5 can be carried out or it can be provided that the operating mode remains in normal mode 25 and does not change to transition mode 26.

[0052] It can further be provided that a check is carried out to determine whether the detected control object 7 is different from the previously detected control object 8. Only if this is the case can it be provided that method steps S2 and following take place, i.e., that the time duration information 22 is determined and checked. In a method step S10, after method step S4, inaccuracy information 34 can be determined that describes an inaccuracy in the distance information 30 and / or an inaccuracy in the controlled object speed information 29. For this purpose, for example, an inaccuracy determination criterion 35 can be applied to the controlled object speed information 29 and / or the distance information 30. It can also be applied, for example, to information about the sensor device 11 and its measurement accuracy and / or measurement speed.

[0053] In a method step S11, it can be checked whether the determined inaccuracy information 34 lies within a predefined inaccuracy value range 36. This range is assigned to a reliable detection of the control object 7. As soon as the determined inaccuracy information 34 lies within the predefined inaccuracy value range 36, a switch can be made from transition mode 26 back to normal mode 25, i.e., method step S5 can be performed.

[0054] It can be provided that the rate of change in transition mode 26 is predetermined depending on the vehicle's own speed information 31. The control of the longitudinal guidance 14 can generally comprise accelerating or decelerating the motor vehicle 1. For the transition mode 26, the rate of change for acceleration can be predetermined differently than the rate of change for decelerating, so that these two different influences on the longitudinal guidance 14 are treated differently. In addition, or alternatively, the respective rate of change for acceleration or deceleration can be predetermined depending on whether the motor vehicle 1 was just accelerating or decelerating at the time of switching to the transition mode 26. Alternatively, the rate of change in the transition mode 26 can be set at a predetermined value.

[0055] Overall, the examples show a gentle acceleration request from the automatic distance control when a primary target, i.e., the control object 7, has a low object age, i.e., when the duration information 22 is less than the duration limit 24. Thus, an automatic distance control is shown in which acceleration request changes are limited, primarily based on the fact that the control object 7 exists for less than a predefined time threshold (duration limit 24). Other factors may also have an influence, such as the collision information 27 and / or the airspeed information 31.

[0056] For example, if the front camera, acting as sensor device 11, detects a new object, the distance and speed information output may be inaccurate and may fluctuate significantly in the first few seconds. If such an object is then selected as the control object 7, the acceleration request will vary in a similar way to the inaccurate data of the object. These fluctuations lead to a jerky feeling while driving.

[0057] If control object 7 meets the following conditions, the speed at which the acceleration request is implemented should be limited:

[0058] - The control object 7 is in front of the motor vehicle 1 ;

[0059] - The object age (duration information 22) of the control object 7 is less than a (configurable) time threshold (duration limit value 24);

[0060] - The value for the time to collision (Collision Information 27) is not critical; and

[0061] - The ego speed (own speed information 31 ) is greater than a (configurable) speed threshold (minimum speed 33).

[0062] For example, the speed limit of the acceleration request (rate of change) can be configured for four different cases:

[0063] - Acceleration request > 0 and acceleration request

[0064] - Acceleration request > 0 and deceleration request

[0065] - Acceleration request < 0 and acceleration request

[0066] - Acceleration request < 0 and deceleration request.

[0067] The main advantage is that for control objects 7 with a low object age, the acceleration applied by the control device 10 varies much less and changes only slowly. This significantly reduces the jerky feeling when driving.

[0068] The vehicle in front of motor vehicle 1 changes to the adjacent lane (cut-out scenario). After the cut-out, a new control object 7 is detected in front of motor vehicle 1. Since this has not yet been detected, for example, by the camera as sensor device 11, it takes a few seconds until the target speed and distance can be correctly output. With automatic distance control without the above-described adjustments to the rate of change, motor vehicle 1 may brake sharply after the cut-out because the camera detects the target speed (control object speed information 29) as significantly too low. With automatic distance control with the settings described above, motor vehicle 1 brakes smoothly and without jerking after the cut-out because the rate of change of the acceleration request is changed due to the limitation, compared to normal mode 25.

Claims

Patent claims 1. A method for operating an automatic distance control in a motor vehicle (1) which, in a normal mode (25), controls a longitudinal guide (14) of the motor vehicle (1) depending on a detected control object (7), the method comprising: - detecting (S1) the control object (7) which is located in front of the motor vehicle (1) in a direction of travel (6) of the motor vehicle (1) for the automatic distance control by evaluating sensor information (21) detected by means of a sensor device (11) of the motor vehicle (1); - for the detected control object (7), determining (S2) a time duration information item (22) which describes a time duration since which the control object (7) has been detected as an object in an environment of the motor vehicle (1); - checking (S3) whether the determined duration information (22) is less than a predetermined duration limit value (24); and - if this is the case, changing (S4) an operating mode of the automatic distance control from the normal mode (25) to a transition mode (26) in which the control of the longitudinal guidance (14) of the motor vehicle (1) takes place at a smaller rate of change than in the normal mode (25).

2. Method according to claim 1, wherein collision information (27) is determined (S6) which describes a predicted time until a collision of the motor vehicle (1) with the detected control object (7), and the change to the transition mode (26) only takes place if the determined collision information (27) lies in a predetermined collision information value range (32) (S7) which is assigned to a non-critical situation.

3. Method according to claim 2, wherein the collision information (27) is determined by applying a collision determination criterion (28) to a control object speed information (29) describing a speed of the control object (7), a distance information (30) describing a distance between the motor vehicle (1) and the control object (7), and / or a Own speed information (31) which describes a current speed of the motor vehicle (1) is determined.

4. Method according to one of the preceding claims, wherein an item of own speed information (31) is determined (S8) which describes a current speed of the motor vehicle (1), and the change to the transition mode (26) only takes place if the determined item of own speed information (31) is greater than a predetermined minimum speed (33) (S9).

5. Method according to one of the preceding claims, wherein it is checked whether the detected control object (7) is different from a previously detected control object (8), and only if this is the case the time duration information (22) is determined and checked.

6. Method according to one of the preceding claims, wherein after changing to the transition mode (26), the time duration information (22) is further determined and checked to see whether it is less than the predetermined time duration limit value (24), wherein as soon as the determined time duration information (22) is greater than or equal to the time duration limit value (24), a change is made from the transition mode (26) to the normal mode (25) (S5).

7. Method according to one of the preceding claims, wherein in the transition mode (26) an inaccuracy information item (34) is determined (S10) which describes an inaccuracy in a distance information item (30) describing a distance between the motor vehicle (1) and the control object (7), and / or an inaccuracy in a control object speed information item (29) describing a speed of the control object (7), and it is checked (S11) whether the determined inaccuracy information item (34) lies within a predetermined inaccuracy value range (36) which is assigned to a reliable detection of the control object (7), wherein as soon as the determined inaccuracy information item (34) lies within the predetermined inaccuracy value range (36), a change is made from the transition mode (26) to the normal mode (25) (S5).

8. Method according to one of the preceding claims, wherein the rate of change in the transition mode (26) is predetermined as a function of an own speed information (31) of the motor vehicle (1), which describes a current speed of the motor vehicle (1).

9. Method according to one of the preceding claims, wherein the control of the longitudinal guide (14) comprises an acceleration or braking of the motor vehicle (1) and in the transition mode (26) the rate of change for the acceleration is specified differently than the rate of change for the braking.

10. The method according to claim 9, wherein the respective rate of change for the acceleration and the braking is predetermined depending on whether the motor vehicle (1) was accelerated or braked at a time of changing to the transition mode (26).

11. Method according to one of claims 1 to 7, wherein the rate of change in the transition mode (26) is set to a predetermined value.

12. Method according to one of the preceding claims, wherein the sensor information (21) is detected by means of a radar device (12), a lidar device (13), an ultrasonic sensor and / or a camera of the motor vehicle (1).

13. Distance control system (9) for a motor vehicle (1), wherein the distance control system (9) is designed to carry out a method according to one of the preceding claims.

14. Motor vehicle (1) with a distance control system (9) according to claim 13, wherein the motor vehicle (1) is designed to carry out a method according to one of claims 1 to 12.

15. A computer program product comprising instructions which, when executed by a computer, cause the computer to perform a method according to any one of claims 1 to 11.

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