Method and device for controlling the steering of a vehicle

Abstract

The present invention relates to a method and a device for controlling the steering of a vehicle, wherein the vehicle has a steering assistance system that, in the activated state, allows the vehicle to follow the lane being driven in and thus carries out lane guidance by determining the lane curvature ahead of the vehicle using a video sensor; and, depending on the detected lane curvature, the steering of the vehicle is controlled such that, depending on the instantaneous speed of the vehicle, the steering actuator system controls the steering of the vehicle such that the vehicle continues to be guided approximately in the centre of the lane, wherein the actuating signals output to the steering actuator system are limited such that they are less than or at most equal to a predefined curvature threshold value and, if it is detected that it is necessary, for lane guidance purposes, to set a curve curvature the actuating signals of which lie above the predefined curvature threshold value, these actuating signals with a greater curve curvature are output to the steering actuator system only if the greater curve curvature has been checked for plausibility using data from a digital map and the current location.

Description

[0001] R. 416780

[0002] Description

[0003] title

[0004] Procedures and a to control the one

[0005] The present invention relates to a method and a device for controlling the steering of a vehicle, wherein the vehicle has a steering assistance system which, when activated, allows the vehicle to follow the lane being traveled and thus performs lane guidance by using a video sensor to determine the curvature of the road ahead of the vehicle;and, depending on the detected track curvature, the vehicle's steering is controlled in such a way that, depending on the vehicle's current speed, the steering actuator is controlled so that the vehicle continues to be guided approximately in the center of the lane, whereby the control signals issued to the steering actuator are limited so that they are less than or at most equal to a predetermined curvature threshold, and if it is detected that a curve curvature must be adjusted for lane guidance, the control signals for which are above the predetermined curvature threshold, these control signals with a greater curve curvature are only issued to the steering actuator if the greater curve curvature has been validated using data from a digital map and the current location.

[0006] State of the art

[0007] From DE 10 2013 213 171 A1, a method and a device for operating a motor vehicle in an automated ferry operation are known, in which a standard trajectory is determined that implements vehicle guidance according to the target setting specified by the driver and the current vehicle environment situation, and a safety trajectory is determined that implements a safe stopping of the vehicle in the event of an emergency depending on the current vehicle environment situation, in which the standard trajectory is further transferred to a first control device.416780 is guided, through which the signals to actuators of the vehicle for vehicle guidance on the basis of the standard trajectory can be forwarded and the safety trajectory is supplied to a second control unit, through which signals to actuators of the vehicle for vehicle guidance on the basis of the safety trajectory can be forwarded, wherein in standard operation the actuators for vehicle guidance are controlled by the first control unit and in the event of safety, if automated ferry operation cannot be ensured, the actuators are controlled by the second control unit in order to stop the vehicle without endangering the vehicle.

[0008] From German patent DE102008035115 A1, a system and a method for detecting a road curve are known, in which a vehicle approaches the curve and road curvature information is automatically provided, and the vehicle speed is controlled. The system uses a tracking device and a map database to determine the vehicle's position. Depending on the vehicle's speed, the system generates a curvature profile for various curvature data points at or around the curve in front of the vehicle. The system then generates a target speed profile for these curvature points. The target speed profile and the actual vehicle speed are compared at each profile point to determine whether the vehicle is traveling too fast for the target speed.The acceleration calculation can be improved by providing a driver cornering mode input, which the vehicle operator can select based on how aggressively the driver wants the system to slow the vehicle down.

[0009] Core and advantages of the invention

[0010] The core of the present invention is to provide a method and a device for controlling the steering of a vehicle, which increases the safety of the occupants and other persons in the vehicle's vicinity and reduces the probability of malfunctions. R. 416780

[0011] Modern driver assistance systems can use a lane keeping function that keeps the vehicle in the currently driven lane. For this purpose, a forward-facing front camera, usually mounted in the center at the top of the windshield, detects the course of the lane markings and calculates a driving trajectory on which the vehicle is kept in the lane, especially in the middle of the lane.

[0012] Such a function can relieve the driver, so that he no longer has to constantly monitor the driving process.

[0013] If the driver becomes unresponsive, the vehicle must be brought to a safe condition. This may be necessary, for example, if the driver has suffered a medical emergency, has been distracted for an extended period, or simply does not respond to the vehicle's prompting to resume control.

[0014] In these cases, the lane keeping function can be supplemented by an emergency stop function, often also referred to as the Emergency Stop Function (EST). With this function, the vehicle is only gently braked or not braked at all, but allowed to coast while the lane keeping function keeps the vehicle in its lane. Shortly before coming to a complete stop, the vehicle is steered to the right-hand side of the road or to a stopping point such as an emergency lane or a lay-by, and the parking brake is engaged once stationary.

[0015] During lane keeping or emergency stop functions, only minimal steering torque is applied, which may prevent the vehicle from staying within its lane on tighter curves, i.e., curves with a smaller radius. This poses a risk of the vehicle leaving the roadway.

[0016] The invention uses map information to determine whether the vehicle is in a tight curve, thus validating the track curvature determined from the video image.

[0017] Once the plausibility check has been completed, a higher steering torque can be applied to safely negotiate the curve (R. 416780).

[0018] In the event of a malfunction with the steering assist activated or the emergency stop function activated, it is conceivable that the vehicle, for example in the case of incorrect or non-recognition of the lane (because the lane marking is faded or missing), makes sudden steering movements and steers out of the lane. Therefore, the steering movement or the steering torque that can be applied must be limited.

[0019] In the case of plausible steering movements or steering torques, higher steering torques can be applied, especially in the case of an activated lane keeping function or an active emergency stop function.

[0020] This plausibility check can be performed by using map data. The curve radius, determined from the video data, is validated against map data, and the higher steering torque is only enabled if both the video and map data indicate a tight curve that functionally necessitates the higher steering torque to stay within the lane. If the data from the video images and the map data do not match, the higher steering torque is not enabled.

[0021] After the tight curve has been negotiated, the system switches back to lower steering torques.

[0022] According to the invention, this is solved by the features of the independent claims. Advantageous further developments and embodiments result from the dependent claims.

[0023] In the context of this application, the term "curve curvature" refers to a measure of how tight or wide a road curve is. A very tight curve typically has a small radius. The curve curvature is small and is often used as the inverse of the radius.

[0024] A wide curve typically has a very large curve radius, and the curvature of this wide or gentle curve is expressed as a low value in its inverse.

[0025] A danger to the vehicle and its occupants, and potentially to the surrounding area, usually arises from tight curves with small radii and thus large curvatures, because at higher speeds the greater centrifugal forces make it impossible to follow the tight curve. R. 416780

[0026] Advantageously, the steering assistance system can be designed to activate automatically when an emergency stop function is activated. Lane keeping systems are usually activated by the driver or are automatically activated when the vehicle is started; however, in a particularly advantageous configuration, the lane keeping function can be activated when an emergency stop function is activated, for example, because the driver is experiencing a medical emergency and is unable or unwilling to react.

[0027] Advantageously, the emergency stop function is designed as an automatic vehicle control function that activates if the driver fails to take over control within a specified time after a takeover request. The takeover function's purpose is to terminate any automated driving function due to changes in the driving situation and ensure that the driver resumes control. If this does not occur, the emergency stop function can bring the vehicle to a safe state for everyone (driver, passengers, and the surrounding environment).

[0028] It is particularly advantageous if the emergency stop function slows the vehicle down to a standstill and, during this stopping phase, regulates the vehicle's steering so that it remains within the lane. In the case of multiple parallel lanes, the system may direct the vehicle to the slowest lane (in most countries, the right-hand lane) and stop there, or to a shoulder or lay-by. The vehicle can be slowed down in such a way that the drive system disengages, allowing it to coast slowly. Alternatively, or in driving situations with an anticipated safety risk, the system may prevent the vehicle from coasting and instead bring it to a stop as quickly as possible through active deceleration.However, the vehicle's surroundings should be monitored by sensors to prevent the vehicle's own deceleration, for example by braking too sharply, from endangering other road users in the vicinity. R. 416780.

[0029] Advantageously, the steering signals limited by the curvature threshold can be limited in their steering torque. Alternatively, the steering signals can be limited by the curvature threshold in terms of steering angle or steering deflection. Another alternative is that the steering signals limited by the curvature threshold can be limited in the rate of change of the steering angle or steering angle velocity.

[0030] Alternatively, the steering signals can be limited by the curvature threshold, thereby restricting their steering rate. The steering rate can be defined as the rate of change of the steering angle, thus limiting the steering speed at which the steering angle can be changed per unit of time.

[0031] Furthermore, it is advantageously possible that the steering signals limited by the curvature threshold are limited in any combination of the limitations according to one or more of the possibilities listed.

[0032] Advantageously, the map data can be stored in a database within the vehicle or provided in a data cloud and retrieved by the vehicle via a wireless connection. Storing the map data in a database within the vehicle offers the advantage of very high data availability, whereas retrieving map data from a database in the cloud via a wireless connection ensures that current and potentially corrected map data is always available. Alternatively, it is possible to carry or cloud-provide incomplete map data, focusing instead on the radii of curvature of the curves in conjunction with their location and position. Therefore, it is particularly advantageous if the map data includes the radii of curvature of the curves.

[0033] Advantageously, the video camera can be arranged in or on the vehicle and record the area ahead in the direction of travel. This allows for the detection of curves and lane markings in the area to be driven on. R. 416780

[0034] Furthermore, it is advantageous that the video camera in or on the vehicle detects lane markings in the vehicle's surroundings and uses this to create a model for lanes and determine a radius of curvature for the modeled lanes.

[0035] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out, implement and / or control the steps of the method according to one of the embodiments described above, in particular if the program product or program is executed on a computer, a programmable control device or a similar device.

[0036] Further features, applications, and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, which are illustrated in the figures of the drawing. All described or illustrated features, individually or in any combination, constitute the subject matter of the invention, irrespective of their inclusion in the claims or their cross-references, and irrespective of their formulation or representation in the description or in the drawings.

[0037] The process can be implemented, for example, in software or hardware, or in a hybrid form of software and hardware, for example in a control unit.

[0038] The lane keeping system can be an electrical device with at least one processing unit for processing signals or data, at least one storage unit for storing signals or data, and at least one interface and / or a communication interface for reading or outputting data embedded in a communication protocol. The processing unit can be, for example, a signal processor, a so-called system ASIC, or a microcontroller for processing sensor signals and outputting data signals depending on the video signals. The storage unit can be, for example, flash memory, an EPROM, or a magnetic storage device. The interface can be a sensor interface for reading sensor signals from a video sensor and / or as R. 416780.

[0039] The actuator interface is designed to output data signals and / or control signals to an actuator. The communication interface can be configured to read or output data wirelessly and / or via a wired connection. The interfaces can also be software modules, such as those found on a microcontroller alongside other software modules.

[0040] Drawings

[0041] Exemplary embodiments of the invention are explained below with reference to the drawings. The drawings show...

[0042] Figure 1 shows an exemplary driving situation to illustrate the invention,

[0043] Figure 2 shows an exemplary embodiment of a device according to the invention and

[0044] Figures 3a to 3b show exemplary embodiments of the methods according to the invention.

[0045] Description of exemplary implementations

[0046] Figure 1 shows a driving situation in which a road with lanes 1 is depicted. A vehicle 2, equipped with the device and associated method according to the invention, is driving on the road 1 with the lanes. The road with the lanes 1 is curved, so that a first curve 5 with a curve radius r1 is shown in front of the vehicle 2, and further along the road a further curve 6 with a curve curvature r2 is shown. The direction of the curves of these two curves 5 and 6 is not of essential importance. The vehicle 2, which is equipped with a video camera 3 or a video sensor 3, is moving on the road 1. The video camera 3 is mounted and oriented such that the detection field 4 of the camera 3 captures the area of ​​the vehicle 2's surroundings that lies ahead in the direction of travel.This allows the camera to detect three upcoming lane markings and determine future lane paths by evaluating the recorded data.

[0047] Thus, video camera 3 in Figure 1 captures the upcoming curve 5. Based on the video data from video camera 3, the lane 1 of the road can be identified (R. 416780) and the curve radius r1 of curve 5 can be determined. The curve radius r1 indicates the degree of curvature of the upcoming curve 5. A small curve radius r1 describes a very tight curve with a strong curve. A large curve radius r1 describes a curve 5 with only a slight curve. In the example of curve 1 in Figure 1, curve 5 with curve radius r1 is only so slightly curved that the curve curvature r1 is less than a threshold value Rsw.

[0048] Vehicle 2, which may be equipped with a lane-keeping function (often called LKS or Lane-Keeping Support), is able to automatically control its steering while lane guidance is activated, so that vehicle 2 follows the detected lane 1 and adjusts the correct curve curvature r1. With such systems, the adjustable steering radii r are usually limited, so that no curve curvature smaller than the curvature threshold Rsw can be automatically followed. In the case of curve 5 with a curvature radius r1 greater than Rsw (r1 > RSW), i.e., a slightly curved curve, vehicle 2 can follow the curvature and continues along the indicated trajectory 7 of lane 1.

[0049] The vehicle approaches the next curve 6 with a curve radius r2. This radius r2 is smaller than the radius r1 of the previous curve 5 and is also smaller than the curvature threshold RSW, which can be set via the steering system. The video camera 3 detects lane markings, and this information is used to model a lane 1 and determine a steering angle. However, for safety reasons, this angle is limited to a radius Rsw, meaning the vehicle 2 cannot navigate curve 6 independently because the radius r2 is too small. Consequently, the trajectory 7 does not follow lane 1, and the vehicle must inform the driver in time that manual intervention is required.

[0050] Limiting the steering radius is intended to increase the safety of the lane-keeping function, as excessively sharp steering inputs are not possible. At the same time, this limitation creates an additional hazard in specific driving situations. This hazard is mitigated by allowing sharper steering inputs, i.e., smaller radii of curvature (Rsw), when a sharp curvature (i.e., small radii of curvature, r < RSW) has been detected and its accuracy has been further verified. This additional verification enhances driving safety. R. 416780

[0051] Another application of this device and method according to the invention is an emergency stop function. An active lane keeping support system is not explicitly required for this. Vehicles 2 equipped with highly automated driving systems (see SAE Automation Levels 2 to 4) can drive themselves autonomously for extended periods. However, the driver must be ready to take over the driving task at any time and therefore be monitored to determine whether they can be called upon within a predetermined time period of x seconds. This can be achieved, for example, by monitoring the driver using a driver monitoring camera (DMC), an infrared system, or electromagnetic waves (e.g., infrared radiation or low-power microwaves).Alternatively or additionally, fitness watches or fitness trackers can also record the driver's vital signs.

[0052] If it is determined that the driver is experiencing a medical emergency or that a transfer of driving duties to another driver is necessary, but the driver fails to assume driving duties within the allotted time, the vehicle 2 must be brought to a safe state to ensure safety. Such functions, which bring the vehicle 2 to a safe state, are referred to as emergency stop functions. These functions slow the vehicle 2 down, for example, by disabling the propulsion systems and allowing the vehicle to coast without endangering following vehicles, or by actively applying the brakes to bring the vehicle 2 to a standstill as quickly as possible. During such emergency stop functions, the vehicle 2 is guided along its lane and may also be forced to avoid other objects.Before the vehicle 2 comes to a complete stop, it is steered to the edge of the roadway or, on a multi-lane road, into the right-hand (slower) lane. If a hard shoulder or a lay-by is available, the emergency stop function brings the vehicle 2 to a stop there. These steering actions require intervention in the vehicle 2's steering system. In cases where the lane markings are not visible or where the road has sharp curves (i.e., small curve radii r), the steering may make large deflections, which could endanger the vehicle occupants, the vehicle 2 itself, and people and objects in the vicinity 4. Therefore, even with emergency stop functions, a limitation of the steering angle of the steering system R. 416780 is necessary, unless the sharp curve (the small curve radius r) can be plausibly explained by other data according to the invention.

[0053] Figure 2 shows an embodiment of the device 10 according to the invention. The device 10 has an input circuit 11 through which input signals 12 to 16 from upstream devices 3, 17 to 20 can be supplied to the device 10. Upstream devices 3, 17 to 20 are devices that provide the device 10 with data to enable the method according to the invention to be carried out and to provide output signals according to the invention.

[0054] A video camera 3 or a video system 3 is provided as a device 3, which captures the environment 4 of the vehicle 2 and performs evaluations on the optically captured data. This allows for the detection of upcoming lane markings of the roadway 1, the modeling of a lane 1, and the determination of curve curvatures r1, r2 of upcoming curves 5, 6. It is possible that the data 12 output by the video camera 3 or the video system 3, which is supplied to the device 10 as input data, is already pre-processed data containing lane markings and / or curve curvatures and / or trajectory data, or alternatively, some of this data has not yet been determined and the video data from the video camera 3 is transmitted as input data 12 in the form of raw video data, and the evaluation of the video images is carried out as part of the processing in the device 10.

[0055] A further input signal 13 is a speed signal v, which originates from a speed sensor 17 and supplies the device 10 with a signal 13 representing the currently driven speed v of the vehicle 2.

[0056] Another input signal for the device 10 is a signal 14 from a digital card 18. The digital card is a database that is either carried in the vehicle 2 or located on an external data server, and whose data is transmitted to the vehicle 2 via a radio interface. The device 10 can communicate bidirectionally with the digital card 18 and selectively retrieve data from the digital card that will be needed for driving operations in the near future. Alternatively, the digital card 18 can know the current location of the vehicle 2 and automatically provide the data 14 stored for this location as an input signal 14.

[0057] Another input signal 15, which supplies the device 10 input signals, is a position sensor 19, which determines the current location of the vehicle 2, for example by means of a satellite navigation system such as GPS, and transmits the determined position data of the vehicle 2 as an input signal 15.

[0058] Another possible (optional) input signal 16 could be the signal from a sensor 20 for determining the driver's health status. This sensor could, for example, be a pulse monitor that measures the driver's vital activity, or a so-called wearable device, usually in the form of a wristwatch, that records and stores the wearer's activity and health data. Alternatively, it is also possible to use systems installed in the vehicle 2 as health sensors 20 that monitor the driver's health status and activity. These could be, for example, infrared or microwave systems that can detect heartbeat or driver movement, or detect and interpret the driver's posture.

[0059] Alternatively, or in combination with a health status sensor, the sensor 20 can also include a timer which, after issuing a driver takeover request 31, determines a time period within which the driver must take over the driving task. If the driver has not taken over the driving task by the end of a predetermined takeover time, the duration of which can be fixed or derived from the current driving situation, this may indicate a medical emergency of the driver. In this case, or also in the case of a driver falling asleep or deliberately inactive, the highly automated driving function must be terminated without endangering the vehicle's surroundings or its occupants by automatically bringing the vehicle to a safe state using the emergency stop functions, as already explained with regard to Figure 1.

[0060] If the function according to the invention is not implemented within the framework of an emergency stop function but within the framework of a conventional lane keeping system (LKS system), a sensor in the form of monitoring driver health or detecting driver activity can be dispensed with and this sensor 20 can be designed purely as a timer that monitors driver takeover within a certain period of time.

[0061] The data 12, 13, 14, 15, 16 supplied to the input circuit 11 of the device 10 are forwarded to a computing device 22 via a data exchange device, which can be implemented in particular as a data bus system. The computing device 22 can be implemented as a microprocessor, as a microcontroller, as a system ASIC (this is an application-specific semiconductor component in which predefined functions are integrated as semiconductor circuits), or as an FPGA (freely programmable semiconductor component).

[0062] In the computing device 22, the functions according to the invention are implemented as software and are processed by means of a programmed algorithm or by means of an artificial intelligence, for example as a Bayesian network or as a CNN (convolutional neural network) that has been previously trained with suitable training data sets.

[0063] This generates output data 24, 25, 26, 27 from the input data 12, 13, 14, 15, 16, 17, which are output by the computing device 22 to a data exchange system 21 and passed on to an output circuit 23 of the device 10.

[0064] The computing device 22 outputs a signal 24, which is then sent to a downstream steering actuator 28. The steering actuator 28 is a steering control system that, based on signals 24 from the computing device 22 representing a requested steering angle, steering speed, or steering angle or radius to be driven by the vehicle, controls the steerable wheels of the vehicle 2 so that the vehicle 2 follows the desired trajectory 7, and in particular remains within the detected lane 1.

[0065] As a further possible (optional) output signal 25, the output circuit 23 outputs a signal 25 that controls the propulsion device 29 of the vehicle 2. The propulsion device is, for example, a vehicle engine that can accelerate the vehicle 2 or maintain a constant vehicle speed. Thus, in the event of an activated emergency stop function (EST function), the propulsion can be switched off and the vehicle 2 can coast to a stop. R. 416780

[0066] Losing speed v. Alternatively, the propulsion of vehicle 2 can be slowly reduced in order to guide vehicle 2 in a controlled manner to a safe location and to be able to park it there automatically.

[0067] Another possible (optional) output signal of the output circuit 23 is a delay signal 26 for the deceleration devices 30 of the vehicle 2. The deceleration devices 30 of the vehicle 2 could be, in particular, the braking devices such as a friction brake of the vehicle 2, but in the case of electric or hybrid vehicles, they could also be a generator that, through its generator effect, decelerates the vehicle 2 in a controlled manner and stores the energy generated in a battery. By controlling the deceleration devices 30 of the vehicle 2, the vehicle 2 can be guided along the travel trajectory 7 or, in the case of an activated emergency stop function (EST function), brought to a safe state and parked in a safe location.

[0068] Furthermore, a possible (optional) output signal 27 of the output circuit 23 is provided, which can trigger a takeover request ÜA of a takeover request device 31. The takeover request ÜA can be an acoustic or an optical signal or a combination of both types of signals, which prompts the driver during the operation of an automated driving function to take over the driving task within a predetermined time period, for example, because the system is unable to safely navigate an upcoming driving situation independently due to external conditions.

[0069] Alternatively, the takeover request may also be necessary if the driver does not react during the emergency stop function and the vehicle 2 needs to be safely braked and stopped at the side of the road, in a stopping bay or on a hard shoulder.

[0070] Figures 3a to 3c show two variants of the implementation of the method according to the invention, which start from different initial states but employ the same inventive process. A first variant begins in Figure 3a and continues this process up to transition point A, and is then continued in the process of Figure 3c. At the end of the process according to Figure 3c, the process jumps at point A to the beginning of the process in Figure 3c, thus forming a loop. 416780

[0071] A processing loop that is repeated over and over again.

[0072] The second variant shown begins in Figure 3b, goes through the procedure of Figure 3b up to transfer point A, and is then continued at transfer point A of Figure 3c until the end of the procedure in Figure 3c, and then jumps back to the beginning of the procedure of Figure 3c in the sense of a repeatedly executed processing loop.

[0073] The first method shown begins in Figure 3a in step 41 by activating an assistance system 10 with lane guidance, for example by starting the vehicle 2 or by activating the assistance system by the driver.

[0074] The process continuously checks whether the driver is experiencing a medical emergency. If the driver is not experiencing a medical emergency, step 42 branches to "no" and continues by rechecking the driver's health status in step 42 after a waiting period. Alternatively or additionally, step 42 can check whether the driver takes over the driving task within a specified time after a takeover request (ÜN) is issued. If the driver takes over the driving task within the takeover timeframe, step 42 branches to "no," and the driver continues to drive vehicle 2 manually. The process then resumes in step 42 as soon as the assistance system, particularly the lane keeping system, is active.

[0075] If a medical emergency of the driver was detected in step 42, step 42 branches to 'yes' and the procedure continues in step 43, in which an emergency stop function (EST function) is activated.

[0076] If, in the alternative or combined case of the takeover request in step 42, the driver has not taken over the driving task in time after the issue of takeover request 27, the emergency stop function is also activated in step 43.

[0077] The procedure is further continued in step 44 of Figure 3c by reading video data 12 from the video sensor 3 in step 47 and determining a radius of curvature r of the detected lane 1.

[0078] In the following step 48, it is checked whether the determined radius of curvature r is smaller than a predetermined radius of curvature threshold Rsw, which is defined by the vehicle as R. 416780

[0079] Steering signals 24 can be output to the steering actuator 28. If the determined radius of curvature r is greater than the radius of curvature threshold Rsw, step 48 branches to "no" and the determined steering angles are output as signals 24 to the steering actuator 28. In the following step 49, the steering signals 24 output to the steering actuator 28 are adjusted by the steering actuator 28 and the vehicle 2 follows the determined trajectory 7.

[0080] If, in step 48, it was determined that the radius of curvature r, which vehicle 2 must follow in order to follow trajectory 7, is smaller than the radius of curvature threshold Rsw, this smaller radius of curvature r will not be adjusted, since a strong steering deflection can represent a factor of uncertainty and, in the event of incorrect detection of lane markings, vehicle 2, its occupants and the surroundings could be endangered.

[0081] Therefore, in the next step 50, the current vehicle position is determined. For this purpose, a position signal 15 is supplied by the position sensor 19, which indicates the current vehicle position, for example in world coordinates.

[0082] In the following step 51, an input signal 14 of the digital card 18 is received from the digital card 18, wherein this signal 14 from the digital card contains the radius of curvature r1 , r2 of the preceding curve.

[0083] In the following step 52, it is checked whether the radius of curvature r determined using the video data 12 from the video sensor 3 is plausible with the curvature data 14 of the digital map 18 for the preceding curve r1, r2. Both values ​​are plausible if their deviation lies within a predefined tolerance range. If the values ​​of the track curvature radius r determined by the video sensor 3 and the radii of curvature r1, r2 provided by the digital map 18 are plausible, i.e., within the predefined, permissible deviation limits, then step 52 branches to "yes" and a steering signal 24 is output to the steering actuator 28. This signal allows for smaller radii of curvature r (stronger curve curvature) than the curvature radius threshold Rsw, since this smaller radius r has been validated by an additional data source.In step 49, the steering signal 24 with the smaller radius of curvature r than the radius of curvature threshold Rsw is then converted in the steering actuator 28 into a steering activity of the vehicle 2, so that even narrow R. 416780.

[0084] Curves such as the curve 6 shown in Figure 2 with radius r2 can be followed.

[0085] After adjusting the steering signal in the steering control and following the lane, the procedure continues in step 44, the transfer point A, and the procedure jumps back to the transfer point A at the beginning of the procedure according to Figure 3 and goes through the part of the procedure of Figure 3c again.

[0086] If, in step 52, it was determined that the radius of curvature r determined using the video data 12 of the video sensor 3 is not plausible with the curvature data 14 of the digital map 18 for the preceding curve r1 , r2, because both values ​​deviate too much from each other and are outside the specified tolerance range, step 52 branches to "no" and the procedure is continued in step 53.

[0087] In step 53, if the radii of curvature between r and r1, r2 are implausible, a safe procedure must be implemented to prevent accidents caused by incorrect steering signals 24. For this purpose, in step 53, for example, the output steering signal is limited to the steering signal threshold value Rsw to prevent excessively strong and implausible steering inputs 28. Simultaneously, in the immediately following step 54, the vehicle speed v is reduced by the deceleration devices 30, for example, to allow the vehicle 2 to stop in time and / or to enable more reliable and accurate detection of the lane markings in the following seconds due to a slower vehicle speed v.

[0088] The procedure is then continued in step 44, at transfer point A, by continuing the procedure at transfer point A as shown in Figure 4c. Here, the radius of curvature r is again determined, and its conformity with the radius of curvature threshold Rsw and its plausibility with the values ​​r1, r2 from the digital map 18 are checked.

[0089] In another embodiment, which begins in the method according to Figure 3b, the method according to the invention is not implemented as part of an emergency stopping function, but in a lane-keeping system, in which the driver requests a driver takeover request ÜNA 27, 31 in cases where the vehicle can no longer be driven automatically within the next time.

[0090] For this purpose, the procedure in Figure 3b begins in step 45, in which a lane keeping system 10 with lane guidance can be activated, either by another vehicle system of the same vehicle 2 or by the driver of vehicle 2 manually starting the lane keeping system.

[0091] In the next step, 46, it is checked whether the lane keeping system is activated. If this system is not activated, the procedure branches to "no" after step 46 and jumps back to step 46, going through a waiting loop until it is activated.

[0092] If step 46 detects that the lane keeping system is active, step 46 branches to 'yes' and continues at transfer point A 44 by following the procedure shown in Figure 3c.

[0093] The procedure is further continued in step 44 of Figure 3c by reading video data 12 from the video sensor 3 in step 47 and determining a radius of curvature r of the detected lane 1.

[0094] In the following step 48, it is checked whether the determined radius of curvature r is smaller than a predetermined radius of curvature threshold Rsw, which can be output by the vehicle as steering signals 24 to the steering actuator 28. If the determined radius of curvature r is larger than the radius of curvature threshold Rsw, step 48 branches to "no" and the determined steering angles are output as signals 24 to the steering actuator 28. In the following step 49, the steering signals 24 output to the steering actuator 28 are adjusted by the steering actuator 28 and the vehicle 2 follows the determined trajectory 7.

[0095] If, in step 48, it was determined that the radius of curvature r, which vehicle 2 must follow to maintain trajectory 7, is smaller than the radius of curvature threshold Rsw, this smaller radius of curvature r will not be adjusted, as a large steering deflection can represent an uncertainty factor and, in the event of incorrect detection of lane markings, vehicle 2, its occupants, and the surrounding area could be endangered. R. 416780

[0096] Therefore, in the next step 50, the current vehicle position is determined. For this purpose, a position signal 15 is supplied by the position sensor 19, which indicates the current vehicle position, for example in world coordinates.

[0097] In the following step 51, an input signal 14 of the digital card 18 is received from the digital card 18, wherein this signal 14 from the digital card contains the radius of curvature r1 , r2 of the preceding curve.

[0098] In the following step 52, it is checked whether the radius of curvature r determined using the video data 12 of the video sensor 3 is plausible with the curvature data 14 of the digital map 18 for the preceding curve r1, r2. Plausibility of both values ​​exists if the deviation of both values ​​lies within a predefined tolerance range. If the values ​​of the track curvature radius r determined by the video sensor 3 and the radii of curvature r1, r2 provided by the digital map 18 are plausible, i.e., lie within the predefined, permissible deviation limits, then step 52 branches to "yes" and a steering signal 24 is output to the steering actuator 28, which also allows smaller radii of curvature r (stronger curve curvature) than the radius of curvature threshold Rsw, since this smaller radius r has been validated by another data source.In step 49, the steering signal 24 with the smaller radius of curvature r than the radius of curvature threshold Rsw is then converted in the steering actuator 28 into a steering activity of the vehicle 2, so that even tight curves such as the curve 6 shown in Figure 2 with radius r2 can be followed.

[0099] After adjusting the steering signal in the steering control and following the lane, the procedure continues in step 44, the transfer point A, and the procedure jumps back to the transfer point A at the beginning of the procedure according to Figure 3 and goes through the part of the procedure of Figure 3c again.

[0100] If, in step 52, it was determined that the radius of curvature r determined using the video data 12 of the video sensor 3 is not plausible with the curvature data 14 of the digital map 18 for the preceding curve r1, r2, because both values ​​deviate too much from each other and are outside the specified tolerance range, step 52 branches to "no" and the procedure continues in step 53. R. 416780

[0101] In step 53, if the radii of curvature between r and r1, r2 are implausible, a safe procedure must be implemented to prevent accidents caused by incorrect steering signals 24. For this purpose, in step 53, for example, the steering signal output is limited to the steering signal threshold value Rsw to avoid excessively strong and implausible steering inputs 28. Simultaneously, in the immediately following step 54, the vehicle speed v is reduced by the deceleration devices 30, for example, to allow the vehicle 2 to stop in time and / or to enable more reliable and accurate detection of the lane markings in the following seconds due to a slower vehicle speed v.

[0102] The procedure is then continued in step 44, at transfer point A, by continuing the procedure at transfer point A as shown in Figure 4c. Here, the radius of curvature r is again determined, and its conformity with the radius of curvature threshold Rsw and its plausibility with the values ​​r1, r2 from the digital map 18 are checked.

Claims

R. 416780 Claims 1. Method for controlling the steering (28) of a vehicle (2), - wherein the vehicle (2) has a steering assistance system (10, 28) which, when activated, allows the vehicle (2) to follow the lane (1) being traveled and thus performs lane guidance, - by using a video sensor (3) to determine the track curvature (r1 , r2) in front of the vehicle (2); - and depending on the detected track curvature (r1 , r2) the steering (28) of the vehicle (2) is controlled such that, depending on the current speed (v) of the vehicle (2), the steering actuator (28) is controlled so that the vehicle (2) is guided approximately in the center of the lane (7), - wherein the control signals (24) output to the steering actuator (28) are limited such that they are smaller than or at most equal to a predetermined curvature threshold (Rsw), characterized in that - if it is recognized that for track guidance 87) a curve curvature (r1 , r2) must be adjusted, the control signals (24) of which are above the specified curvature threshold (Rsw), - these control signals (24) with greater curve curvature (r1 , r2) to the steering actuator (28) will only be output if the larger curve curvature (r1 , r2) has been validated using data from a digital map (18) and the current location (15).

2. Method according to claim 1 , characterized in that the steering assistance system (10, 28) is automatically activated when an emergency stop function (EST, 41 - 43) is activated.

3. Method according to claim 2, characterized in that the emergency stop function (EST, 41-43) is an automatic vehicle control function that is activated when the driver of the vehicle does not take over the vehicle control task within a specified time after a takeover request (42). R. 416780 4. Method according to one of the preceding claims, characterized in that the emergency stop function (EST, 41-43) slows the vehicle (2) down to a standstill and during this stopping phase controls the vehicle steering (28) so that the vehicle stops within the lane (1) being driven on, or, in the case of several parallel lanes, transfers the vehicle (2) to the slowest lane (1) or steers it onto a shoulder or onto a lay-by next to the roadway (1).

5. Method according to one of the preceding claims, characterized in that the steering signals (24) limited by the curvature threshold (Rsw) are limited in their steering torque.

6. Method according to one of the preceding claims, characterized in that the steering signals (24) limited by the curvature threshold (Rsw) are limited in their steering deflection or steering angle.

7. Method according to one of the preceding claims, characterized in that the steering signals (24) limited by the curvature threshold (Rsw) are limited in the temporal change of the steering angle or the steering angle speed.

8. Method according to one of the preceding claims, characterized in that the steering signals (24) limited by the curvature threshold (Rsw) are limited in a combination of the limitations according to one or more of claims 5 to 7.

9. Method according to one of the preceding claims, characterized in that the map data (18) - are stored in a database in the vehicle (2) or - are provided in a data cloud and are accessed by the vehicle (2) via a radio connection. R. 416780 10. Method according to one of the preceding claims, characterized in that the map data (18) include the radii of curvature (r1 , r2) of the curves.

11. Method according to one of the preceding claims, characterized in that the video camera (3) is arranged in or on the vehicle (2) and captures the vehicle environment (4) in the direction of travel.

12. Method according to claim 11, characterized in that the video camera (3) detects lane markings in the vehicle environment (4) and models lanes (1) and determines a radius of curvature (r1 , r2) for the modeled lanes (1).

13. Device for controlling the steering (10, 28) of a vehicle (2), - wherein the vehicle (2) has a steering assistance system (10, 28) which, when activated, allows the vehicle (2) to follow the lane (1) being traveled and thus performs lane guidance (7), - a video sensor (3) is provided by means of which the track curvature (1) in front of the vehicle (2) is determined; - and a steering actuator (28) is provided which, depending on the detected track curvature (r1 , r2), controls the steering of the vehicle in such a way (24) that, depending on the current speed (v) of the vehicle (2), the steering actuator (28) continues to guide the vehicle (29) approximately in the center of the lane, - wherein the device (10) outputs control signals (24) to the steering actuator (28) which are limited such that they are smaller than or at most equal to a predetermined curvature threshold (Rsw), characterized in that - if it is recognized that a curve curvature (r1 , r2) must be adjusted for track guidance (7), the control signals (24) of which are above the specified curvature threshold (Rsw), - these control signals (24) with greater curve curvature (r1 , r2) to the steering actuator (28) will only be output if the larger curve curvature (r1 , r2) has been validated using data (14) from a digital map (18) and the current location (15, 19). R. 416780 14. Computer program product configured to execute, implement and / or control the method according to any one of claims 1 to 12.

15. Machine-readable storage medium on which the computer program product according to claim 14 is stored.

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