Operating a vehicle having a steerable rear axle

Abstract

The invention relates to a method (M1, M2, M3) for operating a vehicle (100) which has a steerable front axle and a steerable rear axle, the method comprising: providing (S21) a data set which contains a plurality of recorded positions of a recording vehicle (100) along a trajectory and, at each position, a recorded rear-axle steering angle of the recording vehicle (100); wherein, when the trajectory is subsequently followed, the following steps are carried out repeatedly (S22): generating (S28) an actuating signal for a rear-axle steering system on the basis of the recorded rear-axle steering angle; and generating (S29) an actuating signal for a front-axle steering system on the basis of the recorded rear-axle steering angle and a detected actual position of the vehicle.

Description

[0001] 2023PF02296

[0002] 1

[0003] OPERATING A VEHICLE WITH A STEERING REAR AXLE

[0004] The present invention relates to a method for operating a vehicle having a steerable front axle and a steerable rear axle. The present invention also relates to a computer program, a driver assistance system, and a vehicle with the driver assistance system.

[0005] A vehicle with a steerable front axle is defined as a vehicle whose front wheels, or whose only front wheel, are steerable. Examples include conventional cars or vans, but also trucks with multiple steerable front axles, motorcycles, or three-wheeled vehicles, including motorcycles with sidecars. A vehicle with a steerable rear axle is defined as a vehicle whose rear wheels, or whose only rear wheel, are steerable. Examples include conventional cars or vans, but also trucks or three-wheeled vehicles. More recently, an increasing number of cars have come onto the market with front wheels that have a large maximum steering angle, for example, up to 35° to the left and right, and rear wheels with a small maximum steering angle, for example, up to 5° to the left and right.

[0006] A vehicle with a steerable front axle and a steerable rear axle, for example, has the advantage of being particularly maneuverable in confined spaces, such as parking garages or parking lots with multiple spaces, including, for example, narrow underground garages.

[0007] If a vehicle has multiple independently steerable axles, this represents an additional degree of freedom for a partially autonomous driving system, such as a parking assistance system. This can lead to current driver assistance systems lacking the computing power to calculate a drivable or optimized route or route solution within a reasonable timeframe. 2023PF02296

[0008] 2

[0009] Against this background, one object of the present invention is to provide a means for calculating a route solution in an acceptable time.

[0010] Accordingly, a method for operating a vehicle is proposed, wherein the vehicle has a steerable front axle and a steerable rear axle. The proposed method includes: providing a data set containing multiple recorded positions of a recording vehicle along a trajectory and, for each position, a recorded rear axle steering angle of the recording vehicle. The proposed method includes: repeatedly executing the following steps while tracing the trajectory: generating a control signal for rear axle steering based on the recorded rear axle steering angle; and generating a control signal for front axle steering based on the recorded rear axle steering angle and a captured actual position of the vehicle.By providing the rear axle steering angle from the recorded drive and playing it back during the subsequent drive, the driver assistance system does not need to account for an additional degree of freedom for the rear axle steering. This reduces the effort required to calculate a permissible route solution. As a result, the same driver assistance system, or a structurally identical driver assistance system, can be used for a vehicle with only front axle steering, a vehicle with only rear axle steering, or a vehicle with both front and rear axle steering.

[0011] The vehicle is, for example, a passenger car or a truck. The vehicle preferably comprises a number of sensor units designed to detect the vehicle's driving state and its surroundings. Examples of such sensor units include imaging devices such as a camera, radar (radio detection and ranging), or lidar (light detection and ranging), ultrasonic sensors, positioning sensors, wheel angle sensors, and / or wheel speed sensors. Each sensor unit is designed to output a 2023PF02296

[0012] 3

[0013] Sensor signals are set up, for example to the driver assistance system, which performs semi-autonomous or fully autonomous driving depending on the detected sensor signals.

[0014] The data set can therefore be described as a trajectory data set. The data set can, for example, be a file. The data set can also contain further information, such as a chosen label, a recording time, at least one piece of information about the recording vehicle, at least one piece of information about a driver during the recording journey, and / or, in particular, at least one other recorded parameter.

[0015] The recorded position is preferably a coordinate pair that is uniquely defined within a roadway plane. The recorded position can also include an elevation value, thus allowing, for example, the unique identification of a parking level in a parking garage. The recorded position can be described as a waypoint of the trajectory.

[0016] The recorded rear axle steering angle can, for example, contain a recorded control signal for the rear axle steering of the recording vehicle, a steering angle, namely preferably in particular a steering angle averaged between right and left, and / or a measurement signal from a rear axle steering angle sensor.

[0017] The trajectory provided by the data set is preferably a trained trajectory. For example, a parking assistance system, a reversing assistance system, or another vehicle assistance system is configured to record and save a manually driven trajectory in a recording or training mode. For example, various sensor signals are recorded that describe a vehicle's driving state, such as speed, position, steering angle, and the like, as unambiguously as possible.

[0018] 4

[0019] The system also records sensor signals from the vehicle's environmental sensors, which, for example, provide a map of the vehicle's surroundings, particularly the position of obstacles. The recorded or trained trajectory can then be followed, for example, by playing back the vehicle's driving state in a time-synchronized manner. To follow the specified trajectory, it is desirable to consider current environmental sensor data. Therefore, the assistance system receives a sensor signal indicative of the environment.The assistance system can, for example, receive the signal directly from one or more of the vehicle's environmental sensors and combine multiple sensor signals from different environmental sensors, or the assistance system can receive the sensor signal in a pre-processed state, for example in the form of a digital environment map in which detected obstacles in the environment are shown.

[0020] A vehicle's level of automation, for example, corresponds to an automation level according to the SAE classification system. The SAE classification system was published in 2014 by SAE International, a standards organization for motor vehicles, as J3016, "Taxonomy and Definitions for Terms Related to On-Road Motor Vehicle Automated Driving Systems." It is based on six different levels of automation and considers the degree of system intervention required and the driver's attention required. The SAE automation levels range from Level 0, which corresponds to a fully manual system, through driver assistance systems in Levels 1 and 2, to semi-autonomous (Levels 3 and 4) and fully autonomous (Level 5) systems, where no driver is required.An autonomous vehicle (also known as a driverless car, self-driving car, and robotic car) is a vehicle that is able to perceive its surroundings and navigate without human input, and it corresponds to SAE automation level 5.

[0021] Following the provided trajectory is understood to mean, in particular, semi-autonomous or fully autonomous following (SAE levels 2 to 5). Following also includes, for example, the repeated acquisition of features of the vehicle's surroundings.

[0022] 5

[0023] which are contained in or recognizable in sensor signals. Tracking also includes, for example, the repeated acquisition of a global position of the vehicle using a navigation system such as GPS, GALILEO and / or GLONASS. Tracking also includes, for example, the acquisition of an actual position of the vehicle based on the acquired features and / or the acquired global position.

[0024] The control signal for the rear axle steering can, in particular, be and / or contain a control signal for a rear axle steering drive. The control signal for the rear axle steering can, in particular, be a data signal to a control unit for the rear axle steering. The same applies to the front axle steering as to the rear axle steering.

[0025] The vehicle performing the procedure follows the trajectory and can be referred to as a following vehicle. The recording vehicle and the following vehicle may be the same vehicle. Alternatively, the following vehicle may be a different vehicle than the recording vehicle. In this case, both vehicles preferably have a similar or identical wheelbase and similar or identical maximum steering angles of the front and rear axles.

[0026] The fact that the control signal for the rear axle steering is generated based on the recorded rear axle steering angle preferably means that the control signal for the rear axle steering is generated based on a recorded rear axle steering angle selected from the recorded rear axle steering angles of the data set based on the recorded actual position and / or a sequence of the recorded rear axle steering angles of the data set.

[0027] That the control signal for the front axle steering is generated based on the recorded rear axle steering angle preferably means that the control signal for the front axle steering is generated based on a rear axle steering angle that corresponds to the control signal generated for the rear axle steering based on the recorded rear axle steering angle. 2023PF02296

[0028] 6

[0029] That the control signal for the front axle steering is generated based on the detected actual position preferably means that the control signal for the front axle is generated based on a deviation between the detected actual position and a recorded position, which recorded position is selected based on the detected actual position and / or a sequence of the recorded positions of the data set from the recorded rear axle steering angles of the data set.

[0030] The control signal for the rear axle steering may be generated based on an interpolation of the recorded rear axle steering angles. For example, if an actual position lies between two recorded positions, the control signal for the rear axle steering is generated, resulting in a rear axle steering angle that corresponds to the interpolation of the rear axle steering angles recorded at those two positions. Interpolation can, for example, prevent or reduce jerky driving behavior, thus creating a more comfortable driving experience. Ideally, interpolation can generate a continuous curve for the rear axle steering angle, making route calculations easier.The interpolation can, for example, be a linear interpolation between the rear axle steering angles recorded at the two adjacent recorded positions, which is quick and easy to calculate. The interpolation can, for example, be a spline interpolation, preferably at least a cubic spline interpolation, such that both the control signal for the rear axle steering and its derivative(s) are continuous. The interpolation can, for example, be a polynomial interpolation, such that both the control signal for the rear axle steering and its derivative(s) are continuous. Interpolating the recorded rear axle steering angles is a process of modifying the recorded rear axle steering angle data.

[0031] The control signal for the rear axle steering may be generated based on smoothing the recorded rear axle steering angles. For example, a moving average may be calculated. For example, a low-pass filter (2023PF02296) may be used.

[0032] 7

[0033] A forward-backward low-pass filter is applied to the recorded rear axle steering angles. Smoothing also prevents jerks in the control signal. Filter functions can be implemented numerically efficiently. Smoothing the recorded rear axle steering angles is a process of modifying the signal's waveform.

[0034] The control signal for the rear axle steering is preferably generated on the basis of only the recorded rear axle steering angle at or near the actual position of the vehicle, or only the processed progression of the recorded rear axle steering angles at or near the actual position of the vehicle.

[0035] The generation of the control signal for the front axle steering based on the recorded rear axle steering angle preferably includes generating the control signal for the front axle steering based on the recorded rear axle steering angle at or near the actual position of the vehicle or the processed progression of the recorded rear axle steering angles at or near the actual position of the vehicle. The generation of the control signal for the front axle steering based on the recorded rear axle steering angle preferably includes generating the control signal for the front axle steering based on the generated control signal for the rear axle steering. The generation of the control signal for the front axle steering based on the recorded rear axle steering angle preferably includes generating the control signal for the front axle steering based on a rear axle steering angle that is predetermined by the generated control signal for the rear axle steering.

[0036] The trajectory is preferably one that can be followed in the opposite direction to the recording direction. Thus, following the trajectory can be either following in the recording direction or following in the opposite direction. In both cases, the orientation of the following vehicle corresponds to the orientation of the recording vehicle. The orientation of the vehicle can be understood as the direction in which a longitudinal axis of the vehicle points forward, namely 2023PF02296

[0037] 8

[0038] This applies particularly to projections from above onto a road surface and / or horizontal plane. Several scenarios can be distinguished: The trajectory may have been recorded while driving forward and then followed in the same direction while driving forward (following the recording direction). The trajectory may have been recorded while driving forward and then followed in reverse while driving in the same direction (following the recording direction). The trajectory may have been recorded while driving backward and then followed in forward and reverse while driving in the same direction (following the recording direction). The trajectory may have been recorded while driving backward and then followed in reverse while driving in the same direction (following the recording direction).The same applies accordingly to trains on a trajectory that have been recorded traveling in different directions, for example, parking maneuvers involving two vehicles or shunting in confined spaces. It is advantageous that the proposed method reduces the effort required to calculate a permissible route in these cases by using the same step: generating a control signal for the rear axle steering based on the recorded rear axle steering angle.

[0039] The vehicle may have multiple forward gears or forward gear ratios and / or even multiple reverse gears or reverse gear ratios. This is frequently the case, for example, with a range gearbox typical of off-road vehicles or some trucks and / or with a continuously variable transmission (CVT). In this case, the method preferably involves generating the control signal for the rear axle steering in each gear based on the recorded rear axle steering angle. The method is advantageously usable without changing or adjusting to the current gear or gear ratio.

[0040] The data set may contain a recorded orientation of the recording vehicle for each recorded position. For example, the recorded orientation may be used to verify the calculated route. For example, the control signal for the front axle steering may also be based on 2023PF02296.

[0041] 9

[0042] This is generated by a deviation between an actual alignment and a recorded alignment. The measures described above for interpolating and / or smoothing the recorded rear axle steering angle are applicable to the recorded alignment accordingly.

[0043] The orientation can be based on a permanent coordinate system, for example. If the orientation is referenced to a global coordinate system, it can be easily integrated with satellite navigation. Preferably, the orientation is a right-hand angle, which is the angle between a direction of north and, for example, a forward direction along a vehicle's longitudinal axis.

[0044] The orientation can be based on a temporary coordinate system. For example, the orientation can be referenced to a local coordinate system of the vehicle. For example, the orientation can be referenced to a local coordinate system of the vehicle at the start of a current journey (technical term: local zero position at start of vehicle). For example, the orientation can be referenced to a local coordinate system of the vehicle at the start of the follow-up journey (technical term: local zero position at start of record). For example, the orientation can be referenced to a local coordinate system of the vehicle at the furthest / most distant position of the trajectory (technical term: local zero position at start of trajectory), preferably a trajectory cropped to a distance threshold (technical term: reset of local zero position to start of cropped trajectory).

[0045] The presented alignment variants can all be used to advantage in the proposed procedure. The variants concerning a permanent coordinate system are ideal for applications where GPS or similar systems are used for position determination (frequently in parking assistance systems to detect approach to a parking trajectory). The variants concerning a local coordinate system are ideal for applications where position determination is based on environmental features (frequently reversing assistants or parking assistants in parking garages). 2023PF02296

[0046] 10

[0047] The data set may contain the position of at least one feature recorded during the recording run in the vehicle's vicinity. This includes the case where the data set contains the position of a single feature. It also includes the case where the data set contains the position of multiple features, i.e., the position of a first feature, the position of another feature, and possibly the position of yet another feature, and so on. A feature's position contained in the data set is preferably linked to the recorded position of the vehicle during the recording run, from which recorded position the respective feature is or was captured. Thus, the actual position can be determined with greater accuracy, allowing the route solution to be calculated and followed with greater precision.

[0048] The proposed procedure may have a recording mode and a tracking mode. In tracking mode, the procedure includes the steps described above. In recording mode, the procedure includes the following steps: repeatedly recording the vehicle's actual position and the rear axle steering angle at each recorded actual position during a drive or recording run; and saving the recording as a data set.

[0049] The trajectory can be either an entry trajectory or an exit trajectory. An entry trajectory can be identified, for example, by the fact that the journey ends in a parking space, in a public parking facility such as a parking garage, and / or on private property. An exit trajectory can be identified, for example, by the fact that the journey begins in a parking space, in a public parking facility, and / or on private property.

[0050] The method may include in the recording mode: offering to save the recording in response to the detection of a successful parking or unparking maneuver, preferably with the recording only being triggered by user input. 2023PF02296

[0051] 11

[0052] The data is stored there. A successful parking maneuver can be defined as a trip that ends in a parking space. A successful exit from a parking space can be defined as a trip that begins at a parking space and whose distance exceeds a distance threshold or whose maximum speed exceeds a speed threshold. This achieves two things simultaneously: firstly, it prevents the user or driver from being confronted with a nonsensical trajectory, and secondly, the user or driver can control the saving of the data records.

[0053] Furthermore, the recording mode can be initiated only if the vehicle's speed falls below a predefined threshold. This threshold is preferably up to 55 km / h and more preferably up to 35 km / h. The primary application of the proposed method is precise maneuvering in confined spaces using rear-axle steering. Since such maneuvers are typically initiated and performed at low speeds, recording irrelevant sections of the journey can be avoided.

[0054] As described above, the trajectory can be recorded while driving forwards or backwards and then followed in the same or opposite direction. A particularly preferred application is a reversing assistance system. The trajectory may be a reversing trajectory. A primary use case for a reversing trajectory is to relieve a driver of the need for extended reversing maneuvers in narrow streets, for example, when there is oncoming traffic on a single-lane road. For this purpose, the recording mode is preferably performed continuously or while driving at a speed up to a certain speed threshold. The speed threshold can be, for example, up to 80 km / h, more preferably up to 65 km / h, and even more preferably up to 55 km / h.Preferably, recorded positions, recorded rear axle steering angles and, if applicable, other recorded data such as recorded orientations, recorded positions of features and the like are removed from the recording if the corresponding recorded position is different from an actual-2023PF02296.

[0055] 12

[0056] The vehicle's position along the trajectory is further than a distance threshold. The distance threshold is preferably up to 500 m and more preferably up to 300 m. This option allows the data set to always retain the preceding 500 m in order to operate a reversing assistant or reversing assistance system upon request.

[0057] It should be mentioned here that, according to one aspect of the invention, a method for operating the vehicle is proposed which only includes the steps of the recording mode. These steps provide a data set that makes it possible to trace the trajectory of the data set without having to calculate the rear axle steering angle as a degree of freedom. Thus, this method also represents a means of determining the route solution in an acceptable time.

[0058] It should also be mentioned here that, according to another aspect of the invention, a data set is proposed which contains several recorded positions of a vehicle along a trajectory and, for each recorded position, a recorded rear axle steering angle of the recording vehicle. Such a data set makes it possible to trace the trajectory without having to calculate the rear axle steering angle as a degree of freedom. Thus, this data set also represents a means of determining the route solution in an acceptable time.

[0059] Furthermore, a computer program product is proposed which includes instructions that, when the program is executed by a computer, cause it to perform the procedure described above.

[0060] A computer program product, such as a computer program tool, can be provided or delivered from a server on a network, for example, as a storage medium such as a memory card, USB stick, CD-ROM, DVD, or as a downloadable file. This can be done, for example, in a wireless communication network using the 2023PF02296

[0061] 13

[0062] Transfer of a corresponding file using the computer program product or computer program tool.

[0063] Furthermore, a driver assistance system for a vehicle is proposed. The driver assistance system is configured to execute the method described above. The driver assistance system can be implemented as a control unit, a part of a control unit, and / or a circuit consisting of several control units. In particular, the driver assistance system can include or implement additional driver assistance features. The embodiments and features described for the proposed method apply accordingly to the proposed driver assistance system.

[0064] The driver assistance system is specifically designed for semi-autonomous or fully autonomous driving of the vehicle. Semi-autonomous driving means, for example, that the driver assistance system controls the steering and / or the automatic transmission. Fully autonomous driving means, for example, that the driver assistance system also controls the drive system and the braking system.

[0065] Furthermore, a vehicle is proposed which incorporates the proposed driver assistance system. The embodiments and features described for the proposed method and the proposed driver assistance system apply accordingly to the proposed vehicle.

[0066] Other possible implementations of the invention also include combinations of features or embodiments described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In such cases, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0067] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. Im2023PF02296

[0068] 14

[0069] Furthermore, the invention will be explained in more detail with reference to preferred embodiments and the accompanying figures.

[0070] Fig. 1 shows a schematic top view of a proposed vehicle incorporating a proposed driver assistance system configured to perform the proposed method for operating the vehicle according to an embodiment of the invention;

[0071] Fig. 2 schematically shows a flowchart of the proposed method for operating the vehicle, wherein the method is designed as a parking assistance method and a provided trajectory is processed during a following maneuver, according to one embodiment;

[0072] Fig. 3 schematically shows a flowchart of the proposed method for operating the vehicle, wherein the method is designed as a parking assistance method and the trajectory is prepared before following, according to one embodiment; and

[0073] Fig. 4 schematically shows a flowchart of the proposed method for operating the vehicle, wherein the method is designed as a reversing assistance method and the trajectory is prepared before following, according to one embodiment.

[0074] In the figures, identical or functionally equivalent elements have been given the same reference symbols, unless otherwise indicated.

[0075] Fig. 1 shows a schematic bird's-eye view of a vehicle 100. The vehicle 100 is, for example, a car located in an environment 140. The car 100 has a driver assistance system 110, which is, for example, a control system 2023PF02296.

[0076] 15

[0077] The device is designed. Furthermore, a plurality of environmental sensor devices 120, 130 are arranged on the car 100, including, for example, optical sensors 120 and ultrasonic sensors 130. The optical sensors 120 include, for example, visual cameras, a radar, and / or a lidar. The optical sensors 120 can each capture an image of a respective area from the environment 140 of the car 100 and output it as an optical sensor signal. The ultrasonic sensors 130 are configured to detect the distance to objects arranged in the environment 140 and to output a corresponding sensor signal. By means of the sensor signals detected by the sensors 120, 130, the driver assistance system 110 is able to drive the car 100 semi-autonomously or even fully autonomously. In addition to those shown in Fig.In addition to the optical sensors 120 and ultrasonic sensors 130 shown in Figure 1, the vehicle may also have 100 different additional sensor devices 120, 130. Examples include a microphone, an accelerometer, an antenna with a coupled receiver for receiving electromagnetically transmitted data signals, and the like.

[0078] Figures 2 to 4 each show an embodiment M1 - M3 of a proposed method for operating the vehicle 100, which has a steerable front axle and a steerable rear axle.

[0079] First, an embodiment M1 of the method is presented with reference to Fig. 2, wherein the method is used as a parking assistance system and a provided trajectory is processed during a following maneuver.

[0080] Operating procedure M1 has a recording mode A and a tracking mode N. Recording mode A is an operating mode of procedure M1 or of the driver assistance system 110, which executes procedure M1 operationally. Recording mode A is used to record a trajectory in the form of a data set. Tracking mode N is another operating mode of procedure M1 or of the driver assistance system 110. Tracking mode N is used to track a trajectory that is provided in the form of a data set. 2023PF02296

[0081] 16

[0082] In step S10, recording mode A is started. For example, in step S10, a navigation system might detect that the vehicle is entering a parking lot, parking garage, and / or non-public area. Similarly, in step S10, a speed measuring device might detect that the vehicle is traveling at a low speed, typical for driving in parking lots and the like, such as up to 35 km / h.

[0083] In step S11, several steps S12 to S17 are repeatedly executed during a vehicle journey. The vehicle typically drives under the control of a human or another external driver assistance system, such as remote control by an external driver or remote control by an external valet parking system.

[0084] In step S12, the actual position of vehicle 100 is recorded. The actual position is unique. It contains, for example, two linearly independent coordinates, such as latitude and longitude. The recorded actual position can also include altitude information to uniquely identify a floor in a multi-story parking garage or underground parking facility. The position can be determined, for example, using an updated environmental image based on sensor signals from environmental sensors 120 and 130, and / or using a navigation system.

[0085] In step S13, at least one feature of the environment 140 is recorded. The feature is detected in a sensor signal from the environment sensors 130, 140. The feature is preferably recorded in conjunction with the actual position(s) from which it is detectable. 2023PF02296

[0086] 17

[0087] In step S14, a rear axle steering angle is recorded at the current actual position. The recorded value can, for example, be or contain a logged control signal to a rear axle steering system. The recorded value can, for example, contain or be the steering angle of the steerable rear wheel(s), or the average steering angle of the steerable rear wheels. The recorded value can, for example, be or contain a sensor output of a sensor signal that is indicative of a rear axle steering angle.

[0088] In step S15, the orientation of vehicle 100 is recorded. The orientation is, for example, a right-hand angle, which is the angle between a vehicle normal direction running forward along a longitudinal axis of vehicle 100 and a north direction running from a vehicle center point to true north. The orientation recorded here is therefore an orientation about a vehicle vertical axis.

[0089] In step S16, the position of a rear axle center point is recorded. This is determined, for example, using the vehicle's position and orientation. The rear axle center point position can be determined, for example, by at least one distance to an environmental feature, calculated from sensor signals.

[0090] It is possible that other parameters will also be recorded, such as the path of a vehicle hose, speed, vehicle orientation around a transverse axis (i.e., whether the vehicle, or for example its front, is pointing up or down), and / or the position of a movable object. This list is not exhaustive. These additional parameters are also preferably recorded with respect to the actual position. 2023PF02296

[0091] 18

[0092] In step S17, a successful parking maneuver or a successful exit from a parking space is detected. A successful parking maneuver is detected, for example, if the vehicle remains stationary for longer than a threshold time. Stopping can mean that the speed is below a threshold speed, for example, below 0.5 km / h. A successful parking maneuver is detected, for example, if a driver exits the vehicle, for example, by means of a door opening sensor and / or a driver's seat occupancy sensor and / or a driver's seatbelt sensor. A successful exit from a parking space is detected, for example, when the vehicle leaves the parking space / parking garage / private property. A successful exit from a parking space is detected, for example, if the vehicle speed exceeds a minimum speed, such as 35 km / h. A successful exit from a parking space is also detected, for example, if a minimum distance has been traveled, for example, 200 meters.This list is not exhaustive.

[0093] Preferably, the detection of a successful parking maneuver in step S17 means that recording in step S11 ends and the process continues with step S18. Preferably, the failure to detect a successful parking maneuver in step S17 means that steps S12 to S17 are repeated.

[0094] In step S18, the user is offered the option to save the recording. For example, a message is displayed on a screen, a mobile device, and / or audibly, and the system waits for user input via a button, touchscreen, other touch-sensitive surface, gesture, mobile device, and / or audible command. This allows the number of stored trajectory records to be kept small. For example, a user can determine whether a given parking space is a regularly visited (and therefore worthy of being saved) parking space or an exceptionally visited (and therefore not worthy of being saved) parking space. The aforementioned examples of output to and input from a user apply to the entire description. 2023PF02296

[0095] 19

[0096] In step S19, the recorded values ​​are stored in a data record. Step S19 may only be executed upon detection of corresponding user input.

[0097] In an alternative configuration, each parking trajectory and exit trajectory, or each trajectory completed with a successful parking or exit maneuver, is automatically saved. Saving the data ends recording mode A.

[0098] In step S20, the following mode N is started. For example, the following mode is triggered by the detection of a user input that indicates the start of a following journey. For example, the following mode is triggered by the detection of approaching a trajectory starting point, such as approaching a driveway to a private property or an entrance to a parking garage.

[0099] In step S21, a data set is provided containing multiple recorded positions and, for each position, a recorded rear axle steering angle. Step S21 can occur before and / or after step S20 and / or simultaneously with it. The data set provided in S21 is a data set stored in S18.

[0100] It is possible that only data records recorded by the same vehicle and / or the same driver assistance system are provided. Preferably, however, the data records are transferable in such a way that a data record recorded by the same user is provided, for example, via a network connection to a server of a vehicle fleet or a data service provider. Preferably, the data records are transferable in such a way that a data record recorded in the same parking facility (parking lot, parking garage, underground parking facility, and / or private property) is provided, for example, via the network connection, thus enabling valet parking. If a data record is to be transferable, vehicle data of the recording vehicle 100, such as wheelbase, steering circle diameter, and a Wen-2023PF02296, are preferably included.

[0101] 20

[0102] The following data is stored as metadata in the data set: the diameter of the turning circle, a maximum front axle steering angle, a maximum rear axle steering angle, a vehicle width, a vehicle height, a recording date, and / or the like, in order to select a provided data set depending on a comparison of such data set metadata with stored corresponding data of the potentially following vehicle 100.

[0103] In step S22, several steps S23 to S29 are repeated during a follow-through of the trajectory.

[0104] In step S23, the actual position of vehicle 100 is recorded. Reference is made to S12 and S13. For example, in substep S24, a feature of the environment 140 is compared with a feature recorded in S13.

[0105] In step S25, the trajectory is processed. For example, in substep S26, the rear axle steering angles are interpolated, for instance, using polynomial interpolation. This avoids abrupt changes in the rear axle steering angle, which would often be accompanied by abrupt changes in the front axle steering angle. The result is a smooth ride with consistent lateral accelerations. In another substep, S27, the rear axle steering angles are smoothed, for example, using a moving average. Step S27 is preferably performed as an alternative to step S26, but offers the same advantages.

[0106] In step S28, a control signal for the rear axle steering of vehicle 100 is generated. The control signal is preferably generated such that the rear axle steering angle of the follow-up journey at the actual position is as close as possible to the (interpolated / smoothed) rear axle steering angle of the recording journey at this position.

[0107] If the tracking takes place in reverse (i.e., tracking in reverse while recording in forward gear) or forward (i.e., tracking in forward gear while recording in reverse), then the 2023PF02296

[0108] 21

[0109] The rear axle steering angle is preferably predetermined by the control signal in order to correspond to the recorded rear axle steering angle at a position up to one wheelbase later.

[0110] In step S29, a control signal for front axle steering is generated so that the vehicle follows the positions of the recorded trajectory 100. This is achieved using a steering method that takes the following into account:

[0111] - the rear axle steering angle as a predetermined value;

[0112] a deviation of the actual position of vehicle 100 determined in step S23 from the next recorded position in the data set sequence; a deviation of an actual orientation from an orientation recorded in step S15 at the next recorded position in the data set sequence; and

[0113] a deviation of a currently determined position of the rear axle center from a position of the rear axle center recorded in step S16, corresponding to the next recorded position in the order of the data set.

[0114] Thus, the method M1 can guide the following vehicle 100 with high accuracy along the recorded trajectory.

[0115] By repeatedly performing steps S23 to S29, the vehicle is guided 100% semi-autonomously or - if an additional step is applied to generate an acceleration control signal - fully autonomously and safely along the recorded trajectory.

[0116] Figure 3 schematically shows a flowchart of another embodiment M2 of the proposed method. Method M2 is also used as a parking assistance system. In contrast to method M1 according to the first embodiment, the trajectory processing in S25 to S27 does not take place during the following maneuver in S22, but before the following maneuver, but after the provision in S21. Otherwise, the description for the first embodiment M1 of the proposed method applies. 2023PF02296

[0117] 22

[0118] Figure 4 schematically shows a flowchart of a further embodiment M3 of the proposed method. Method M3 is used for a reversing assistance system or back drive assist system. The differences between this method and embodiments M1 and M2 shown in Figures 2 and 3 are discussed below.

[0119] The purpose of a reversing assistance procedure is to enable autonomous reversing in unforeseen situations. Therefore, the procedure is started by default in S10 when the vehicle begins a journey.

[0120] Step S11 repeats steps S30, S12 to S16, and S31. Steps S12 to S16 have already been described.

[0121] In step S30, the vehicle's current speed (100) is recorded. A low current speed can indicate a driving situation where a semi-autonomous reverse maneuver may subsequently occur. The current speed is compared, for example, to a speed limit, and if the limit is not exceeded, the reverse trajectory is recorded (continued). The speed limit could, for example, be 55 km / h.

[0122] In step S31, recorded values ​​are deleted from the log if their position is further than a distance threshold from the current position. For example, if the reversing assistance procedure is configured to allow the vehicle to reverse semi-autonomously for up to 500 meters, all recorded values ​​from past positions of the vehicle that are more than 500 meters back will be deleted. 500 meters is one example of a distance threshold; 550 meters, 250 meters, and 200 meters are other preferred examples.

[0123] Repeated execution in S11 thus constitutes the provision of the data set, which contains at least the recorded positions and the recorded rear axle steering angles. Step S11 therefore also serves as step S21. 2023PF02296

[0124] 23

[0125] If an input to start following is detected from a driver in step S20, the following mode N begins.

[0126] For example, the trajectory is then prepared with steps S25 to S27, before the tracking follows in S22 with steps S23, S24, S28 and S29. As a result, vehicle 100 successfully travels back along the desired route.

[0127] In a variant not shown, the trajectory is prepared during the return journey in tracking mode N, so that the start in step S20 is followed by the repeated execution of steps S23 to S29 in step S22.

[0128] Although the present invention has been described using exemplary embodiments, it can be modified in many ways. 2023PF02296

[0129] 24

[0130] REFERENCE MARK LIST

[0131] 100 vehicles

[0132] 110 Driver assistance system

[0133] 120 optical sensor

[0134] 130 ultrasound equipment

[0135] 140 surroundings

[0136] M1, M2, M3 Procedures for operating a vehicle

[0137] A recording mode

[0138] N Following mode

[0139] 510 Starting recording mode depending on vehicle speed

[0140] 511 Repeatedly performing the following steps during a journey

[0141] 512 Recording an actual position

[0142] 513 Recording a feature of the environment

[0143] 514 Recording a rear axle steering angle

[0144] 515 Recording a vehicle alignment

[0145] 516 Recording a rear axle center point

[0146] 517 Recognizing a successful parking maneuver

[0147] 518 Offering to save the recording

[0148] 519 Saving the recorded values ​​to a data record

[0149] 520 Starting the follow mode

[0150] 521 Providing a data set containing multiple recorded positions and, for each position, a recorded rear axle steering angle. 522 Repeated execution during a follow-up of the trajectory.

[0151] 523 Recording the actual position of the vehicle

[0152] 524 Comparing a feature of the environment with a recorded feature

[0153] 525 Processing the trajectory

[0154] 526 Interpolating the rear axle steering angles 2023PF02296

[0155] 25

[0156] 527 Smoothing the rear axle steering angles

[0157] 528 Generating a control signal for a rear axle steering system

[0158] 529 Generating a control signal for a front axle steering system

[0159] 530 Recording a return trajectory if a speed threshold is not exceeded

[0160] 531 Remove recorded values ​​whose position is further away from the actual position than a distance threshold.

Claims

2023PF02296 26 PATENT CLAIMS 1. Method (M1 , M2, M3) for operating a vehicle (100) having a steerable front axle and a steerable rear axle, comprising: Providing (S21) a data set containing multiple recorded positions of a recording vehicle (100) along a trajectory and, for each position, a recorded rear axle steering angle of the recording vehicle (100); where the following steps are repeated during a trajectory retracing (S22): Generating (S28) a control signal for a rear axle steering system based on the recorded rear axle steering angle; and Generating (S29) a control signal for a front axle steering system based on the recorded rear axle steering angle and a detected actual position of the vehicle (100).

2. Method according to claim 1, characterized in that the control signal for the rear axle steering is generated (S28) on the basis of an interpolation (S26) of the recorded rear axle steering angles.

3. Method according to claim 2, characterized in that the interpolation (S26) is a linear interpolation, a spline interpolation, namely preferably an at least cubic spline interpolation, and / or a polynomial interpolation.

4. Method according to one of the preceding claims, characterized in that the control signal for the rear axle steering is generated (S28) on the basis of a smoothing (S27) of the recorded rear axle steering angles.

5. Method according to one of the preceding claims, characterized in that the following is a following in a recording direction of the trajectory or a 2023PF02296 27 Following is in the opposite direction to the recording direction, whereby in both cases an orientation of the following vehicle corresponds to an orientation of the recording vehicle (100).

6. Method according to one of the preceding claims, characterized in that the data set contains an orientation of the recording vehicle (100) for each position, wherein the control signal for the front axle steering is additionally generated on the basis of a deviation of an actual orientation to a recorded orientation.

7. Method according to one of the preceding claims, characterized in that the data set contains a position of at least one feature recorded during the recording journey in the vicinity of the vehicle (100), wherein the position of the feature is preferably linked to the recorded position from which the feature is recorded.

8. Method according to one of the preceding claims, characterized in that the method (M1 , M2, M3) has a recording mode (A) and a following mode (N), wherein in the recording mode (A) during driving an actual position of the vehicle (100) and a rear axle steering angle at each actual position are repeatedly recorded (S11 , S12, S14) and the recording is stored as a data set (S19), and wherein in the following mode (N) the steps of the method according to one of the preceding claims are carried out.

9. Method according to one of the preceding claims, characterized in that the trajectory is a parking trajectory and / or an exit trajectory.

10. Method according to claims 8 and 9, characterized in that the method (M1, M2) in recording mode (A) includes: offering (S18) the option to save the recording upon detection of a successful parking or unparking maneuver, wherein the recording is saved only upon input. 2023PF02296 28 11. Method according to one of claims 9 or 10, characterized in that the recording mode (A) is started if the speed of the vehicle (100) falls below a speed threshold, which is preferably up to 55 km / h and preferably up to 35 km / h.

12. Method according to claim 8, characterized in that the trajectory is a return trajectory, wherein the recording mode (A) is performed continuously or during a journey at a speed up to a speed threshold, wherein the speed threshold is preferably up to 80 km / h, more preferably up to 65 km / h and more preferably up to 55 km / h, and wherein recorded positions, recorded rear axle steering angles and optionally recorded orientations or positions of features are removed from the recording (S31) if the corresponding recorded position is further away from an actual position of the vehicle along the trajectory than a distance threshold, wherein the distance threshold is preferably up to 500 meters and more preferably up to 300 meters.

13. Computer program product comprising instructions which, when the program is executed by a computer, cause it to execute the method (M1 , M2, M3) according to any one of claims 1 - 12.

14. Driver assistance system for a vehicle (100) configured to perform the method (M1 , M2, M3) according to one of claims 1 - 12.

15. Vehicle (100) with a driver assistance system according to claim 14.

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