METHOD AND DEVICE FOR OPERATING A VEHICLE IN AN AUTOMATED DRIVING OPERATION

Description

[0001] The invention relates to a method for operating a vehicle in an automated driving mode according to the features of the preamble of claim 1 and a device for carrying out the method.

[0002] From the prior art, as described in DE 10 2017 011 808 A1, a method for controlling the movement of a vehicle in an automated driving mode and a device for carrying out the method are known. The automated driving mode can be switched from a regular operating mode, in which the vehicle is automatically guided to a predetermined target position, to an emergency operating mode, in which the vehicle is automatically guided to an emergency stop position. The control is carried out in the regular operating mode by means of a main control unit and in the emergency operating mode by means of a secondary control unit. The automated driving mode is switched from the regular operating mode to the emergency operating mode if a functional impairment of the main control unit is detected in the regular operating mode.In regular operating mode, control is carried out based on a regular target trajectory leading to the target position, which is continuously determined by the main control unit in regular operating mode. In emergency operating mode, control is carried out based on an emergency operating target trajectory stored in the secondary control unit and leading to the emergency stop position, which was determined by the main control unit in regular operating mode before the operating mode was switched to emergency operating mode and was fed to the secondary control unit for storage. In regular operating mode, in addition to the emergency operating target trajectory, a lane profile of a lane traveled by the vehicle that belongs to the emergency operating target trajectory is also determined and fed to the secondary control unit for storage. The emergency operating target trajectory and the associated lane profile are determined in a vehicle-fixed coordinate system of the main control unit.In emergency mode, the lane path of the vehicle is determined in a vehicle-specific coordinate system of the secondary control unit. In emergency mode, a deviation between the coordinate systems of the main control unit and the secondary control unit is compensated based on the lane path stored in the secondary control unit and the lane path determined by the secondary control unit.

[0003] DE 10 2015 003 124 A1 describes a method and a device for operating a vehicle in automated driving mode. During normal operation of automated driving mode, an emergency target trajectory is continuously determined and stored, which is to form the basis for automated trajectory control of the vehicle after the occurrence of at least one predetermined error event. Upon detection of the occurrence of at least one predetermined error event, an emergency operating mode is activated, in which automated trajectory control of the vehicle is initiated and carried out according to the emergency target trajectory stored before the occurrence of at least one predetermined error event for a predetermined period of time and / or until the vehicle comes to a standstill, if and as long as no driver of the vehicle takes over control of the vehicle.

[0004] In "Manipulating a 10-bit signal down to 8 bits", October 6, 2015 (2015-10-06), XP002807336, found on the Internet at https: / / www.mikrocontroller.net / topic / 378404, it is described how a 10-bit signal can be scaled down to 8 bits.

[0005] A method for adaptive bit-width reduction in a neural network is known from the publication K. Choi et al: "Bit-width reduction and customized register for low cost convolutional neural network accelerator, 2017 IEEE / ACM International Symposium on Low Power Electronics and Design (ISLPED), Taipei, Taiwan, 2017, pp. 1-6, doi: 10.1109 / ISLPED.2017.8009164.

[0006] From the publication Qing er al: "AdaBits: Neural Network Quantization With Adaptive Bit-Widths," ARXIV. ORG, CORNELL UNIVERSITY LIBRARY, 201 OLIN LIBRARY CORNELL UNIVERSITY ITHACA, NY 14853, December 20, 2019, XP081621157, a method for adaptively determining bit widths of weights and activations of a neural network is known.

[0007] From DE 10 2016 006 137 A1 a method for locating a vehicle is known in which a current position of the vehicle is determined by means of a satellite-based navigation system and, based on the determined position, a future position of the vehicle is predicted in a dead reckoning using data from an inertial sensor system of the vehicle.

[0008] The invention is based on the object of specifying a method for operating a vehicle in an automated driving mode that is improved compared to the prior art and a device for carrying out the method that is improved compared to the prior art.

[0009] The object is achieved according to the invention by a method for operating a vehicle in an automated driving mode having the features of claim 1 and a device for carrying out the method having the features of claim 6.

[0010] Advantageous embodiments of the invention are the subject of the subclaims.

[0011] In a method for operating a vehicle in automated driving mode, in particular in highly automated or autonomous driving mode, a target trajectory is regularly, in particular continuously, determined in a regular operating mode by means of a main control unit, along which the vehicle is automatically guided, in particular by means of the main control unit, to a predetermined target position. This target position is, in particular, a desired target position desired by at least one person, in particular by a user of the vehicle. It is specified, for example, by this person or in another way.

[0012] In addition, in this regular operating mode, the main control unit regularly, in particular continuously, determines a driving specification for an emergency operating mode, in particular in parallel with the determination of the target trajectory, and transmits this driving specification to a secondary control unit and stores it there. This driving specification is also referred to as the fallback path. In the event of a failure of the main control unit, the vehicle is automatically guided into a, in particular safe, stopping position by means of the secondary control unit in emergency operating mode in accordance with the driving specification. The stopping position is therefore in particular an emergency stopping position. The driving specification is thus determined in such a way that this, i.e. guiding the vehicle in emergency operating mode into the, in particular safe, stopping position, is achieved.

[0013] According to the invention, the driving specification comprises information about a course of a path along which the vehicle is to be guided to the, in particular safe, stopping position, about a course of a speed at which the vehicle is to be guided along the path, and about a position of at least one lane marking or multiple lane markings relative to the path. The course of the path is determined by a series of path points. Each path point is assigned at least one distance value or exactly one distance value that corresponds to a distance of the respective path point from the left or right lane marking. In particular, this results in the position of the at least one lane marking or multiple lane markings relative to the path.For example, it can also be provided that each path point is assigned two distance values, with one distance value corresponding to the distance of the respective path point from the left lane marking and the other distance value corresponding to the distance of the respective path point from the right lane marking. The distance values ​​are provided as digital data with a limited bit width for transmission to the secondary control unit. Thus, a maximum bit width for the digital data of the distance values ​​is specified, which cannot be exceeded. This limits the representable value range of the distance values.It is therefore provided that if a track width is greater than the representable value range of the distance values, the distance values ​​are reduced by scaling before transmission to the secondary control unit, in particular are reduced to the value range representable using the limited bit width, and are recalculated in the secondary control unit after transmission. The scaling of the distance values ​​takes place in particular in the main control unit. The track width relates in particular to a lane which the vehicle is to use, i.e. on which the path runs. The track width is specified in particular by the left and right lane markings, i.e. by a marking distance between the left and right lane markings, in particular between the inner edge of the respective lane marking.

[0014] A device according to the invention is designed and configured to carry out this method. It comprises the main control unit and the secondary control unit. The main control unit is configured to regularly determine the target trajectory in regular operating mode and to automatically guide the vehicle along the determined target trajectory to the specified target position.The main control unit is also configured to regularly determine the driving specification for the emergency operating mode and transmit it to the secondary control unit, wherein the driving specification comprises information about the course of the path along which the vehicle is to be guided to the, in particular, safe, stopping position, about the course of the speed at which the vehicle is to be guided along the path, and about the position of at least one lane marking relative to the path, wherein the course of the path is determined by a series of path points, wherein each path point is assigned at least one distance value that corresponds to the distance of the respective path point to the left or right lane marking. The main control unit is further configured to provide the distance values ​​as digital data with the limited bit width for transmission to the secondary control unit, whereby the representable value range of the distance values ​​is limited.The main control unit is further configured to reduce the distance values ​​by scaling prior to transmission to the secondary control unit if the track width is greater than the representable range of the distance values. The secondary control unit is configured to receive and store the driving command, to automatically guide the vehicle to the, in particular safe, stopping position in emergency mode according to the driving command in the event of a failure of the main control unit, and to recalculate the received distance values ​​if they were reduced by scaling prior to transmission to the secondary control unit.

[0015] The solution according to the invention implements a data-based provision of the driving command for the secondary control unit in such a way that the transmission of the driving command to the secondary control unit, in particular a fast, correct, and complete transmission, is enabled with the smallest possible bandwidth and / or is ensured at all times even with a predetermined low bandwidth of a data transmission connection between the main control unit and the secondary control unit. The bandwidth, in particular the data rate, of the data transmission connection is limited, for example, to a maximum value. Therefore, the distance values ​​are provided as digital data with a limited bit width for transmission to the secondary control unit in order to ensure the fast, correct, and complete transmission of the driving command from the main control unit to the secondary control unit.This results in the problem that distance values ​​that exceed the value range representable using this limited bit width cannot be transmitted. The solution according to the invention ensures that even with distance values ​​that exceed the value range representable using this limited bit width, the driving command is transmitted quickly, correctly, and completely. This is achieved by scaling the distance values ​​before transmission to the secondary control unit, thereby reducing them to the value range representable using the limited bit width, thus enabling transmission to the secondary control unit. After transmission, the distance values ​​are recalculated in the secondary control unit, ensuring that the driving command is correct and complete in the secondary control unit.The solution according to the invention also ensures, in particular, that the automated driving of the vehicle, both in regular operating mode and in emergency operating mode, is not limited to lanes with a predetermined maximum track width, but is possible on lanes with any track width, as long as they are sufficiently wide for the vehicle to drive on.

[0016] In one possible embodiment of the method, a scaling factor is determined such that the track width is mapped to the representable range of distance values. In one possible embodiment of the device, the main control unit is configured to determine the scaling factor such that the track width is mapped to the representable range of distance values. This ensures the fast, correct, and complete transmission of the driving command from the main control unit to the secondary control unit.

[0017] In one possible embodiment of the method, the scaling factor is also transmitted to the secondary control unit as an attribute of the driving specification. In one possible embodiment of the device, the main control unit is configured to transmit the scaling factor as an attribute of the driving specification to the secondary control unit, and the secondary control unit is configured to receive the scaling factor as an attribute of the driving specification. This ensures the correct back-calculation in the secondary control unit of the distance values ​​reduced by scaling, in particular in the main control unit, and subsequently transmitted to the secondary control unit, since this ensures that the same scaling factor is used for the scaling in the main control unit and for the back-calculation in the secondary control unit.

[0018] In one possible embodiment of the method, the coordinates of the path points are defined relative to one another in a vehicle-fixed coordinate system. In one possible embodiment of the device, the main control unit is configured to define the coordinates of the path points relative to one another in a vehicle-fixed coordinate system. This ensures correct guidance of the vehicle by means of the secondary control unit in emergency operating mode according to the driving specification into the, in particular safe, stopping position, especially if the secondary control unit also uses the vehicle-fixed coordinate system.

[0019] In one possible embodiment of the method, each path point is assigned a speed value that indicates the desired speed at the respective path point, i.e., the speed the vehicle should have at the respective path point. In one possible embodiment of the device, the main control unit is configured to assign each path point a speed value that indicates the speed the vehicle should have at the respective path point. This enables the vehicle to decelerate safely, in particular until it comes to a standstill in the, in particular, safe, stopping position.

[0020] The device is, in particular, a component of the vehicle. It further comprises, for example, an environmental detection sensor system, in particular with a lane detection sensor system and / or lane marking detection sensor system, a position determination unit, in particular for determining a current position of the vehicle using at least one global navigation satellite system, a digital map, an inertial sensor system, a drive actuator system, a brake actuator system, and / or a steering actuator system of the vehicle. The environmental detection sensor system comprises, for example, at least one camera, in particular a stereo camera, at least one lidar sensor, at least one radar sensor, and / or at least one ultrasonic sensor as environmental detection sensors. Multiple environmental detection sensors of the respective sensor type can also be provided.The main control unit and / or the secondary control unit are each coupled to at least one, several, or all components of the device. With regard to the coupling of the respective component, it can be provided that the main control unit is coupled to the respective component either directly or indirectly, in particular via the secondary control unit, and / or that the secondary control unit is coupled to the respective component either directly or indirectly, in particular via the main control unit.

[0021] In regular operating mode, the vehicle is automatically guided to the specified target position along the target trajectory by means of the main control unit, in particular by controlling and / or regulating the vehicle's drive actuators, brake actuators, and / or steering actuators. In emergency operating mode, the vehicle is guided to the, in particular safe, stopping position by means of the secondary control unit, in particular by controlling and / or regulating the vehicle's drive actuators, brake actuators, and / or steering actuators, in accordance with the driving specification.

[0022] Embodiments of the invention are explained in more detail below with reference to drawings.

[0023] Showing: Fig. 1 schematically shows a vehicle with a device for carrying out a method for operating the vehicle in an automated driving mode, Fig. 2 schematically shows a driving specification of the method, Fig. 3 schematically shows an example of a driving specification and lane markings detected by means of an environment detection sensor, Fig. 4 schematically shows a further example of a driving specification and lane markings detected by means of an environment detection sensor, and Fig. 5 schematically shows a further example of a driving specification and lane markings detected by means of an environment detection sensor.

[0024] Corresponding parts are provided with the same reference numerals in all figures.

[0025] Based on the Figures 1 to 5 In the following, a method for operating a vehicle 1 in an automated driving mode and a device 2 for carrying out the method are presented. The device 2 is a component of the vehicle 1 in Figure 1 shown in a highly simplified schematic manner.

[0026] The device 2 comprises in particular a main control unit 3 and a secondary control unit 4, wherein a data transmission connection 5 is provided between the main control unit 3 and the secondary control unit 4, in particular for transmitting a driving instruction, described in more detail below, from the main control unit 3 to the secondary control unit 4.

[0027] The device 2 can additionally comprise further components not shown in detail here, for example an environmental detection sensor system, in particular with a lane detection sensor system and / or lane marking detection sensor system, a position determination unit, in particular for determining a current position of the vehicle 1 by means of at least one global navigation satellite system, a digital map, an inertial sensor system, a drive actuator system, a brake actuator system and / or a steering actuator system of the vehicle 1. The environmental detection sensor system comprises, for example, at least one camera, in particular a stereo camera, at least one lidar sensor, at least one radar sensor and / or at least one ultrasonic sensor as environmental detection sensors. Multiple environmental detection sensors of the respective sensor type can also be provided.The respective environmental detection sensor of the environmental detection sensor system can also be a component of the lane detection sensor system and / or lane marking detection sensor system. Camera and lidar sensor types are particularly suitable for the lane detection sensor system and / or lane marking detection sensor system.

[0028] The main control unit 3 and / or the secondary control unit 4 are each coupled, for example, to at least one, several, or all components of the device 2. With regard to the coupling of the respective component, it can be provided that the main control unit 3 is coupled to the respective component either directly or indirectly, in particular via the secondary control unit 4, and / or that the secondary control unit 4 is coupled to the respective component either directly or indirectly, in particular via the main control unit 3.

[0029] In the method for operating the vehicle 1 in automated driving mode, in particular in highly automated or autonomous driving mode, a target trajectory is regularly, in particular continuously, determined in a regular operating mode by means of the main control unit 3, along which the vehicle 1 is automatically guided, in particular by means of the main control unit 3, to a predetermined target position. This target position is in particular a target position desired by at least one person, in particular by a user of the vehicle 1. It is predetermined, for example, by this person or in some other way. In this regular operating mode, the vehicle 1 is automatically guided along the target trajectory to the predetermined target position by means of the main control unit 3, in particular by controlling and / or regulating the drive actuators, brake actuators and / or steering actuators of the vehicle 1.

[0030] In addition, in this regular operating mode, a driving specification for an emergency operating mode is determined regularly, in particular continuously, for example at a time interval of 40 ms, by means of the main control unit 3, in particular in parallel with the determination of the target trajectory, and is transmitted to the secondary control unit 4 and stored there. This driving specification is also referred to as a fallback path. In the event of a failure of the main control unit 3, the vehicle 1 is guided into a, in particular safe, stopping position by means of the secondary control unit 4 in emergency operating mode in accordance with the driving specification. The stopping position is therefore in particular an emergency stopping position. The driving specification is thus determined in such a way that this, i.e. guiding the vehicle 1 in emergency operating mode into the, in particular safe, stopping position, is achieved.In emergency operating mode, the vehicle 1 is guided into the, in particular safe, stopping position by means of the secondary control unit 4, in particular by controlling and / or regulating the drive actuators, brake actuators and / or steering actuators of the vehicle 1 in accordance with the driving specification.

[0031] The driving specification includes information about a course of a path P on which the vehicle 1 is to be guided into the, in particular safe, stopping position, about a course of a speed with which the vehicle 1 is to be guided on the path P, and about a position of at least one lane marking SLFV, SRFV or several lane markings SLFV, SRFV relative to the path P. As in Figure 2As shown by way of example, the course of path P is determined by a series of path points PP. Each path point PP is assigned a distance value that corresponds to a distance ALFV, ARFV of the respective path point PP to the left or right lane marking SLFV, SRFV. This results in the position of at least one lane marking SLFV, SRFV or the multiple lane markings SLFV, SRFV relative to path P.

[0032] For example, coordinates dx, dy of the path points PP are defined relative to each other in a vehicle-fixed coordinate system. The vehicle-fixed coordinate system is defined in Figure 2 with the x-axis X and the y-axis Y.

[0033] For example, it is also intended that each path point PP is assigned a speed value that indicates the desired speed at the respective path point PP, ie, the speed that vehicle 1 should have at the respective path point PP. These speed values ​​define the speed profile and are therefore also a component of the driving specification. Figure 2 For example, the speed value assigned to the last path point PP, starting from vehicle 1, is 0 m / s, i.e., the standstill of vehicle 1 is to be reached here. For example, the speed value 10 m / s is assigned to one of the intermediate path points PP.

[0034] The distance values ​​are provided as digital data, albeit with a limited bit width, for transmission to the secondary control unit 4. This limits the representable range of distance values. For example, this range is limited to four meters. Figures 3 and 4 show two examples in which this limited value range is sufficient. Shown here are the path P of the driving specification, vehicle 1, which is schematically represented as an arrow, lane markings SLFV, SRFV according to the driving specification, and real lane markings SLR, SRR detected by the environment detection sensor system, in particular lane detection sensor system and / or lane marking detection sensor system, for example, using a camera. As shown, the lane markings SLFV, SRFV according to the driving specification and the real lane markings SLR, SRR detected by the environment detection sensor system overlap or, more precisely, are positioned on an inner edge of the real lane markings SLR, SRR.

[0035] However, if the lane width, which is determined, for example, from the digital map and / or by means of the environmental detection sensors, becomes so large that the distance values ​​for the distance ALFV, ARFV of the driving specification to the respective lane marking SLFV, SRFV according to the driving specification exceed or could exceed the representable value range, then correct transmission of the distance ALFV, ARFV of the driving specification would no longer be possible. Therefore, the method described here provides that, if the lane width is larger than the representable value range of the distance values, the distance values ​​are reduced by scaling before transmission to the secondary control unit 4, in particular, they are reduced to the value range representable using the limited bit width, and are recalculated in the secondary control unit 4 after transmission. The scaling of the distance values ​​takes place, in particular, in the main control unit 3.The track width refers in particular to the lane that vehicle 1 is to use, ie, on which path P runs. The track width is specified in particular by the left and right real lane markings SLR, SRR, ie by a marking distance between the left and right real lane markings SLR, SRR.

[0036] Figure 5 This is demonstrated in an example. The track width between the left and right real lane markings SLR, SRR is five meters here, for example. As mentioned above, the displayable range of the distance values ​​is limited to four meters, for example. Scaling is therefore performed. In particular, it is intended that a scaling factor is determined such that the track width is mapped to the displayable range of the distance values.

[0037] The scaling factor is thus calculated as a quotient with the maximum value of the representable value range, in this example, four meters, in the numerator and the track width, in this example, five meters, in the denominator. The scaling factor in this example is therefore 4 / 5, or 0.8.

[0038] With this scaling factor, the respective actual distance ALT, ART to the respective real lane marking SLR, SRR is converted into the respective reduced distance ALFV, ARFV of the driving specification. In the example shown, the actual left distance ALT of path P to the real left lane marking SLR is 4.5 m and the actual right distance ART of path P to the real right lane marking SRR is 0.5 m. By converting using the scaling factor 0.8, i.e. by multiplying the respective actual distance ALT, ART by this scaling factor, the reduced left distance ALFV of path P to the left lane marking SLFV according to the driving specification is 3.6 m and the reduced right distance ARFV of path P to the right lane marking SRFV according to the driving specification is 0.4 m. As a result, the respective lane marking SLFV, SRFV is spaced from the respective real lane marking SLR, SRR according to the driving specification, as in Figure 5 shown.

[0039] These determined reduced distance values ​​are transmitted from the main control unit 3 to the secondary control unit 4 and recalculated there. For this purpose, it is particularly intended that the scaling factor, as an attribute of the driving specification, is also transmitted to the secondary control unit 4. By recalculating the distance values ​​in the secondary control unit 4, it is ensured that the lane markings SLFV, SRFV now correspond to the respective real lane markings SLR, SRR according to the driving specification, ie they overlay them or, as in the Figures 3 and 4 shown, are positioned on the inner edge of the respective real lane marking SLR, SRR, so that an exact and safe guidance of the vehicle 1 is ensured by means of the driving specification.

[0040] The described solution implements data provision of the driving command for the secondary control unit 4 in such a way that the transmission of the driving command to the secondary control unit 4, in particular a fast, correct, and complete transmission, is enabled with the smallest possible bandwidth and / or is ensured at all times even with a predetermined low bandwidth of the data transmission connection 5 between the main control unit 3 and the secondary control unit 4. The bandwidth, in particular the data rate, of the data transmission connection 5 is limited, for example, to a maximum value. Therefore, the distance values ​​are provided as digital data with a limited bit width for transmission to the secondary control unit 4 in order to ensure the fast, correct, and complete transmission of the driving command from the main control unit 3 to the secondary control unit 4.This results in the problem that distance values ​​that exceed the value range representable using this limited bit width cannot be transmitted. The described solution ensures that the driving command is transmitted quickly, correctly, and completely, even for distance values ​​that exceed the value range representable using this limited bit width. This is achieved by scaling the distance values ​​before transmission to the secondary control unit 4, thereby reducing them to the value range representable using the limited bit width, thus enabling transmission to the secondary control unit 4. After transmission, the distance values ​​are recalculated in the secondary control unit 4, ensuring that the driving command is correct and complete in the secondary control unit 4.The described solution also ensures, in particular, that the automated driving of vehicle 1, both in regular operating mode and in emergency operating mode, is not limited to lanes with a predetermined maximum track width, but is possible on lanes with any track width, as long as they are sufficiently wide for vehicle 1 to drive on.

[0041] For example, the driving specification comprises 64 data records for 64 path points PP, with the respective information described above, in particular regarding the respective path point PP. By using fewer data records, in particular a smaller bit width, regarding the distance value of the respective path point PP and thus of the respective data record, the amount of data to be transmitted via the data transmission connection 5 and thus the bandwidth required for this purpose can be significantly reduced.

[0042] The method, in particular the automated driving of the vehicle 1, can also be carried out if only one real lane marking SLR, SRR is detected by means of the environment detection sensor system and / or only the driving specification has only one lane marking SLFV, SRFV, at least if the track width is constant.

Claims

1. Method for operating a vehicle (1) in an automated driving operation, - in a regular operating mode, by means of a main control unit (3), a target trajectory being regularly ascertained, along which target trajectory the vehicle (1) is guided in an automated manner to a predetermined target position, and a driving specification for an emergency operating mode being regularly ascertained, which driving specification is transmitted to a secondary control unit (4) and stored there, - the vehicle (1) being guided in an automated manner, in the event of a failure of the main control unit (3), into a stop position by means of the secondary control unit (4) in emergency mode according to the driving specification and - the driving specification comprising information about a course of a path (P) on which the vehicle (1) is to be guided into the stop position and information about a course of a speed at which the vehicle (1) is to be guided on the path (P), the course of the path (P) being determined by a series of path points (PP), characterized in that - the driving specification additionally comprises information about a position of at least one lane marking (SLFV, SRFV) relative to the path (P), - each path point (PP) of the path (P) being assigned at least one distance value which corresponds to a distance (ALFV, ARFV) of the relevant path point (PP) to the left or right lane marking (SLFV, SRFV), - the distance values being provided as digital data which have a limited bit width for transmission to the secondary control unit (4), thereby limiting a representable value range of the distance values, - the distance values being reduced by scaling before transmission to the secondary control unit (4) and being recalculated in the secondary control unit (4) after transmission if a lane width is greater than the representable value range of the distance values.

2. Method according to claim 1, characterized in that a scaling factor is determined such that the lane width is mapped to the representable value range of the distance values.

3. Method according to claim 2, characterized in that the scaling factor is transmitted to the secondary control unit (4) as an attribute of the driving specification.

4. Method according to any of the preceding claims, characterized in that coordinates (dx, dy) of the path points (PP) are defined relative to one another in a vehicle-fixed coordinate system.

5. Method according to any of the preceding claims, characterized in that each path point (PP) is assigned a speed value which indicates the speed that the vehicle (1) should have at the relevant path point (PP).

6. Device (2) for carrying out a method according to any of the preceding claims, comprising a main control unit (3) and a secondary control unit (4), wherein the main control unit (3) is configured to: - in a regular operating mode, regularly ascertain a target trajectory and guide the vehicle (1) in an automated manner along the ascertained target trajectory to a predetermined target position, - regularly ascertain a driving specification for an emergency operating mode and transmit it to the secondary control unit (4), wherein the driving specification comprises information about a course of a path (P) on which the vehicle (1) is to be guided into a stop position, about a course of a speed at which the vehicle (1) is to be guided on the path (P) and about a position of at least one lane marking (SLFV, SRFV) relative to the path (P), wherein the course of the path (P) is determined by a series of path points (PP), wherein each path point (PP) is assigned at least one distance value which corresponds to a distance (ALFV, ARFV) of the relevant path point (PP) to the left or right lane marking (SLFV, SRFV), - provide the distance values as digital data which have a limited bit width for transmission to the secondary control unit (4), thereby limiting a representable value range of the distance values, - reduce the distance values by scaling before transmission to the secondary control unit (4) if a lane width is greater than the representable value range of the distance values, wherein the secondary control device (4) is configured to: - receive and store the driving specification, - guide the vehicle (1) in an automated manner into the stop position in emergency mode according to the driving specification in the event of a failure of the main control unit (3), - recalculate the received distance values if they have been reduced by scaling before transmission to the secondary control unit (4).

7. Device (2) according to claim 6, characterized in that the main control unit (3) is configured to determine a scaling factor such that the lane width is mapped to the representable value range of the distance values.

8. Device (2) according to claim 7, characterized in that the main control unit (3) is configured to transmit the scaling factor to the secondary control unit (4) as an attribute of the driving specification and the secondary control unit (4) is configured to receive the scaling factor as an attribute of the driving specification.

9. Device (2) according to any of claims 6 to 8, characterized in that the main control unit (3) is configured to define coordinates (dx, dy) of the path points (PP) relative to one another in a vehicle-fixed coordinate system.

10. Device (2) according to any of claims 6 to 9, characterized in that the main control unit (3) is configured to assign to each path point (PP) a speed value which indicates the speed that the vehicle (1) should have at the relevant path point (PP).