A method, control means, vehicle, and computer program for implementing vehicle lane guidance.

Abstract

Method, control means, vehicle, and computer program for implementing lane guidance in a vehicle The present invention relates to a method for implementing lane guidance of a vehicle (1), in which a control variable is determined via a lateral feedback control (7) based on a lateral spacing error describing the lateral deviation (4) of the vehicle (1) relative to a predetermined target trajectory (5), and the lateral position of the vehicle (1) is adjusted to the target trajectory (5) depending on the control variable, wherein at least one calibration value is additionally applied to the control variable, the calibration value being determined by at least one calibration function (12) at least partly depending on the time integral of the lateral spacing error.

Description

Technical Field

[0001] The present invention relates to a method for implementing lane guidance, where a lateral position error that describes the lateral deviation of a vehicle relative to a predefined target trajectory is ite used to determine a control quantity via lateral feedback control, car and the lateral positions of both wheels are adjusted onto the target trajectory according to the control quantity. Furthermore, the present invention also relates to control means, a vehicle, and a computer program.

Background Art

[0002] A vehicle can be equipped with a system or function for automatically implementing lane guidance. Thereby, the lateral position of a moving vehicle can be automatically adjusted to match a predefined trajectory. The lateral position of a vehicle, i.e., the lateral position of the vehicle within a driving lane, can be changed or adjusted to a target position, for example, by automated steering operations.

[0003] Such lane-keeping functions typically use surrounding data obtained from sensors such as cameras, radar or lidar systems, and / or navigation systems such as GPS, to guide the vehicle along a planned trajectory. This trajectory is set to minimize strong or abrupt changes in the vehicle's lateral position, for example, prioritizing a high level of driving comfort. Guiding the vehicle along such a trajectory is usually performed as feedback control, continuously determining the vehicle's lateral deviation from the planned trajectory. Depending on this deviation, appropriate control commands of size and direction are output to the vehicle's, for example, electric steering system. Criteria for judging the quality of such feedback control include, for example, the amplitude and dynamic characteristics of the lateral feedback control deviation, and the frequency of jerky movements of the vehicle's steering wheel. Ideally, the lateral feedback control error should be zero in all driving situations, and steering intervention by lane guide, or the resulting steering motion, should be solely due to the progression of the planned trajectory.

[0004] The performance of such lane guides depends on the quality and performance of the sensors and actuators used in the vehicle. In principle, the overall system performance can be improved to some extent by using multiple sensors or multiple actuators, and / or by implementing appropriate software measures. Yes, it is possible. This is especially true for driver assistance systems, such as those that help maintain the lane.

[0005] However, sensor detection errors, that is, any discrepancies between the sensor signal and its physical counterpart, not only affect the characteristics of the feedback control, but also the quality of the vehicle's lane guide feedback control, particularly because these errors are inherited over generations. To address this, a partially different but partially overlapping action chain is applied depending on the sensor information.

[0006] Image distortion in cameras capturing lane markings can cause, for example, a discrepancy between the calculated curvature of the road and the actual curvature; this is known as ground truth error. Lane guides typically include at least one feedback control means and / or a predictive control means that adjusts the lateral vehicle position according to at least one determined lane curvature. Curvature information describing the lane curvature is often calculated at a predicted point ahead of the vehicle. This information can be used to calculate the steering angle required for each curvature using an inverse vehicle model, and this can be input as a target steering angle component to a steering angle feedback control means, for example, as part of predictive control.

[0007] If the curvature information has an error-induced offset compared to the actual curvature, the predicted target steering angle also has an offset component that acts like a disturbance on the lateral feedback control. This results in the vehicle, when the lane keeping assist is activated, not following the trajectory as expected, but rather, depending on the implementation of lateral feedback control or trajectory-following feedback control—that is, whether a feedback control type that considers static accuracy or not is used—"continuously maintaining a lateral deviation from the planned trajectory" or "deviation at least temporarily until it follows the planned target trajectory after the adjustment process has decayed." The continuous or temporary lateral deviation affects driving comfort, which can then be a factor in the driver's decision whether or not to accept the driver assistance system.

[0008] The degree of image distortion in a camera generally fluctuates constantly while the driver assistance system is in operation, as the camera calibration routine is performed continuously. This means that, depending on the state of camera calibration, even if the camera's transmission characteristics and the resulting curvature offset are not abrupt but bandwidth-limited or gradual changes, the value of the curvature / predictive control offset and the degree of adverse effects on the vehicle's lateral guidance will change over time.

[0009] The steering angle is often a significant auxiliary or feedback control variable within lane tracking assistant systems, and is therefore frequently used in routines for calibrating the steering angle offset. Because the calibration accuracy is finite, the calculated steering angle offset always contains uncompensated components. Several factors can contribute to the offset error remaining in the steering angle signal. Typical calibration routines use signals from yaw rate sensors or wheel rotation speed sensor systems. Errors in these sensors, such as offset and / or linear errors, and in the case of wheel rotation speed sensors, differences in rotation speed due to differences in tire pressure on a single axle, are also inherited by the calculated steering angle offset. In this case, the effect of the steering angle offset is equivalent to that of the curvature offset described above. In this case as well, when the lane keeping assist is activated, the vehicle does not follow the predetermined trajectory as expected, and depending on the implementation of lateral feedback control or trajectory-following feedback control, there is a continuous or temporary lateral deviation from the planned trajectory that negatively affects comfort and the acceptance of the driver assistance system. This also applies to the uncompensated offset between the front and rear axle steering angles.

[0010] The sensor signals for yaw rate, front and rear axle steering angles, and lateral acceleration can also be used for other on-board functions that can, in particular, affect the lateral position or lateral guidance of the vehicle. For example, these sensor signals can be used to estimate disturbance forces and moments acting on the vehicle, as well as the vehicle's sideslip angle due to, for example, road inclination or crosswinds. In such cases, the calculated values ​​contribute as part of the disturbance interruption, as a target steering angle component for lateral vehicle guidance. However, the corresponding offset of the sensor signals, in particular, is similarly passed down as an error to the target steering angle, affecting the vehicle's lateral position. As a result, undesirable temporary or continuous lateral deviations occur in the lane-guided vehicle.

[0011] From DE 10 2008 026 233 B4, a method for compensating for the steering angle offset of an automobile using a vehicle model is known. Here, the yaw rate is calculated depending on the captured steering angle, vehicle speed, and assumed steering angle offset. Subsequently, the calculated yaw rate is compared with the measured yaw rate, and the difference between these forms an error equation for iteratively determining the steering angle offset and feeding it back into the vehicle model to compensate for it.

[0012] The accuracy of such yaw rate and lateral acceleration offset calibrations is finite, and they always try to track the actual offset. Therefore, even with this additional calibration, unwanted steering interventions can still occur. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] DE 10 2008 026 233 B4 [Overview of the Initiative] [Problems that the invention aims to solve]

[0014] Therefore, the objective of the present invention is to improve the accuracy of vehicle lane guidance even under the influence of offset errors, thereby enhancing comfort and driver acceptance of the assistance system. [Means for solving the problem]

[0015] To solve the above problems, the present invention provides a method belonging to the type described at the beginning, wherein at least one calibration value is additionally applied to the control variable, and the calibration value is at least partially lateral by at least one calibration function. position Error Time integral It is determined by the following:

[0016] In other words, feedback control of the vehicle's lateral position is performed using the sum of the controlled variable and at least one calibration value. Depending on the configuration of the lateral feedback control and / or lane guide, other elements may also be applied to the controlled variable in addition to at least one calibration value.

[0017] The controlled variable to which the calibration value is applied affects the lateral position of the vehicle. This controlled variable may be, for example, the target steering angle. For example, this controlled variable can be set by a steering angle interface connected to electric power steering (EPS). Alternatively, the controlled variable can be set in a moment interface that affects the steering torque or steering angle of the EPS.

[0018] The calibration value is particularly incorporated into the lateral direction position The calibration function determines the value depending on the sign and amplitude of the error, but by applying this calibration value to the controlled variable, it is always, Currently Lateral direction position It is used to reduce errors. That is, by applying a calibration value to the controlled variable, the target steering angle is integrated over time in the lateral direction. position The error is corrected or compensated for, resulting in a positive effect.

[0019] Lateral direction position The error describes the lateral or lateral deviation of the vehicle, that is, the lateral deviation of the vehicle from a predetermined target trajectory. Therefore, lateral position Error is also called lateral offset or lateral deviation. In other words, lateral position The error represents the deviation of the vehicle / measurement position at that moment from the desired vehicle / target position described by the target trajectory. The calculation of the vehicle's relative lateral deviation from the target trajectory can be based on an agreed-upon point along the vehicle's longitudinal axis. This allows the lateral deviation to be based on the geometric center of the rear or front axle, or any forward prediction point set along the vehicle's longitudinal axis.

[0020] Lateral direction position The error can be continuously determined, for example, depending on the sensor data of at least one peripheral sensor of the vehicle. The peripheral sensor can be, for example, a camera, a lidar sensor, a radar sensor and / or an ultrasonic sensor. Additionally or alternatively, the lateral direction position The error can also be determined depending on the position data of the navigation system. Lateral direction position The error also has a value that depends on the time integrated by the calibration function.

[0021] The lateral feedback control means used for lateral feedback control can be, for example, trajectory tracking feedback control means, or can include similar means. A calibration function that can also be called centering calibration or centering function is provided additionally to the trajectory tracking feedback control at that time, and constitutes a feedback control loop that is parallel or superior to the control quantity, that is, that affects the lateral position of the vehicle. In particular, the dynamic characteristics of the calibration function are significantly smaller than those of the lateral feedback control at that time, so the lateral position The error has a very slow influence on the control quantity.

[0022] As the calibration function or the basic calculation rule for determining the calibration value, for example, an integrating means having a relatively small Integral gain can be used, whereby the integration of the lateral error having small dynamic characteristics is carried out, and as a result, the influence of the calibration value also has small dynamic characteristics. position

[0023] According to the present invention, at least one calibration function can be implemented as each I element, PT1 element Or PT1 element It can be implemented as. PT1 element has similar integration characteristics compared to pure I element but has the advantage that no measures for restricting the state of the integrating means required in I element are required. This advantage is PT1 element The parameterization degrees of freedom granted to this approach should be compared and considered in each individual application case, as it has the drawback of not being able to achieve strict compensation for the offset amount in transient states.

[0024] The adaptive dynamic characteristics of the calibration value are set to be approximately the same magnitude as the dynamic characteristics of the change in the offset error. An indicator for this is, for example, the maximum expected offset drift caused by the temperature of the sensor used for lateral feedback control, converted to the corresponding steering angle plane. This has the advantage that, for example, when the dynamic characteristics of the calibration function are high, overshoot of the lateral feedback control may occur, which could cause intervention from other compensation functions acting on the steering angle, such as road surface transverse slope compensation or crosswind compensation.

[0025] By using at least one calibration function, or by applying at least one calibration value to the control variable, it is advantageous that offset errors that continuously affect lane guidance are partially or completely reduced over time, or that these offset errors are partially or completely compensated over time. Compensation functions acting on steering angles are often not in continuous operation. For example, lane keeping functions are usually only activated after the driver has activated them. If the compensation function detects an apparent feedback control error due to an offset error when it is activated, the compensation function outputs a control variable in an attempt to reduce this feedback control error. This may cause abrupt steering movements depending on the dynamic characteristics of the compensation function. By compensating for offset errors in advance, it is advantageous that abrupt steering movements to correct accumulated lateral deviations can be avoided, thereby improving occupant comfort while lane guidance is in operation. This also improves the acceptability of lane guidance, or the driver assistance system that performs lane guidance.

[0026] In summary, higher-level calibration functions, in their fundamental concept, are lateral positionThis can also be interpreted as a constant-value feedback control with low dynamic characteristics, where the target value for error is zero. As a result, during automatic lateral guidance or lane guidance, the sum of the direct and indirect offset effects of all sensors used in the system is reduced with respect to the lateral deviation of the vehicle.

[0027] According to the present invention, the time constant of the calibration function may be configured to be at least twice as large as the dominant time constant of the lateral feedback control, particularly preferably. Preferably, the time constant of the calibration function can be set to be at least five times, at least ten times, at least 100 times, or at least 1000 times larger than the dominant time constant of the lateral feedback control. In principle, even larger differences between time constants are conceivable. For example, I element The calibration function achieved is within the range of 0.01 degrees / (m*s) to 0.00005 degrees / (m*s). Integral gain It can have.

[0028] In one preferred embodiment of the present invention, the lateral direction position Error Time integral The integral value of the calibration function is calculated, and this integral value is retained even when the lane guide is stopped, and when the lane guide is restarted, the lateral direction position Error Time integral Used as the initial value.

[0029] In that case, the integral value is the lateral direction up to the point in time associated with the integral value. position Error Time integral It represents the total value formed by the process. In short, the integral value represents the lateral direction up to a specific point in time. position Error Time integral This represents the result. When multiple calibration functions are used, in particular, a separate integral value associated with each calibration function is formed. At least one integral value can be stored in a retrievable form in a storage means of the arithmetic means that performs the method, such as a control device.

[0030] In other words, the state of the calibration function, that is, the state of the integrating means or equivalent function unit that forms the calibration function, is not reset, for example, during the current ignition cycle of the vehicle, and is maintained even if the driver assistant is repeatedly turned on and off, or if there is driver intervention. However, it may be additionally assumed that the integrating means may be reset if an inappropriate activity is recognized, for example, if a jump is detected or reported in the output of one or more offset calibrations of the on-board sensors, or if there is a request via the vehicle's diagnostic interface. The integrated value may also be maintained beyond the vehicle's ignition cycle, i.e., over multiple runs.

[0031] In the present invention, it is conceivable that the lateral feedback control may include predictive control, in which case the predictive control determines the predictive control amount depending on the measured and / or predicted curvature value of the road surface on which the vehicle is traveling, and the control amount includes the predictive control amount as one of its components.

[0032] In this process, the measured curvature value and / or predicted curvature value can be derived, in particular, from sensor data of one or more surrounding sensors of the vehicle. The predictive control, in particular, uses the measured curvature value and / or predicted curvature value to calculate the steering angle required for each curvature via an inverse vehicle model, and this can be used as a predictive control quantity and given, for example, to the control value of the trajectory-following feedback control means of lateral feedback control. The vehicle model changes its transmission behavior according to the vehicle speed. This makes it clear that errors in the measured curvature value affect the lateral guidance of the vehicle in a manner dependent on the vehicle speed.

[0033] In this invention, predictive control can be assumed to be performed depending on a vehicle model that describes the vehicle's natural steering angle gradient, in which case the natural steering angle gradient is adapted during vehicle operation depending on at least one vehicle parameter, in particular the vehicle weight and / or tire stiffness.

[0034] Lateral movement during vehicle cornering as a result of predictive control errors position The error depends not only on the curvature offset error, but also on the inaccuracies of the stored vehicle parameters, particularly the uncertainty of the natural steering angle gradient used in the vehicle model. Errors or deviations in the natural steering angle gradient act as disturbances to the vehicle's lateral feedback control, and therefore, in part, additional lateral feedback. position This can cause errors, which in turn lead to incorrect steering due to the calibration values ​​generated by the calibration function. In such cases, the calibration values ​​respond not only to the sensor offset but also to other factors. As long as the error or deviation in the natural rudder angle gradient is limited, the dynamic characteristics of the calibration function are low and its influence is minor.

[0035] To avoid the effects of errors and / or deviations in large natural steering angle gradients, these can be adjusted, particularly preferably continuously, depending on at least one vehicle parameter. In this case, the adjustment may be, for example, Currently The vehicle mass, and the weight of one or more tires of the vehicle. Currently This is feasible depending on tire stiffness and / or other vehicle parameters.

[0036] In one preferred embodiment of the present invention, the lateral direction position Error Time integral , The weighting factor, which depends on the vehicle's speed, and / or the absolute value of the lateral position error, increases with increasing speed. Weighting factor, particularly preferably, Integral gain Implemented using do This can be anticipated.

[0037] For example, a certain Integral gain The use of this could be an easily feasible compromise for the entire speed range of the vehicle, but speed-dependent Integral gain Alternatively, using an equivalent weighting factor has the advantage of better compensating for velocity-dependent offsets. positionThe impact on the error can arise, for example, from the settings of the feedback control parameters of the lateral feedback control, which are typically used depending on the vehicle's speed. This also changes the disturbance compensation characteristics of the lateral feedback control, and as a result, the sensor offset amount changes laterally. position The effect on the error also changes. To address the above situation, a speed-dependent weighting factor is used, for example, a speed-dependent Integral gain By using, Time integral Furthermore, it becomes possible to make it dependent on the driving speed. Advantageously, this allows for the achievement of ideal and individually adapted dynamic characteristics of the calibration across all driving speed ranges.

[0038] Additionally or alternatively, the weighting factor can be applied laterally. position The absolute value of the error, i.e., the lateral direction to be integrated and / or previously integrated. position It is possible to make it dependent on the error value, but in this case, a larger lateral direction position Errors are weighted more heavily. This includes, for example, nonlinear correspondence rules and / or one or more lateral directions. position Depending on the error threshold, Currently Lateral direction position For the error, one assigned weighting factor, or, Integral gain Determine the horizontal direction position Error Time integral It can be used in the following situations. position The error is weighted progressively by the absolute value of the error, i.e., in the lateral direction. position The weighting factor increases with increasing absolute value of the error. Integral gain By increasing this factor, the calibration speed can be effectively improved.

[0039] This includes, for example, Integral gain Thus, the calibration function adapted can be switched between two or more values, Integral gain In the horizontal direction, position When the absolute value of the error is larger, a larger value is selected. This is advantageous in the lateral direction. position If the absolute value of the error exceeds 0.2m Integral gainSimply doubling the integration constant can enable effective and rapid initial adaptation to the offset situation at the start of the driver assistance function.

[0040] Even in cases where the vehicle has an additional sensor offset calibration function that eliminates the detected offset drift of at least one of the vehicle's sensors by step-like correction for each offset after the confirmation time or vibration isolation time has elapsed, the lateral direction position By increasing the adaptability of the centering calibration depending on the absolute value of the error, rapid adjustment to new offset conditions can be achieved. This means that the longer the vibration isolation time of the sensor offset calibration function, the more the calibration function can adjust laterally during this period. position Error Time integral This becomes more important because, based on this, compensation is performed that must be reintegrated and reversed after the signal update of more sensor offset calibration functions. Integral gain By using this method, it is advantageous that the speed of the correction process can be improved.

[0041] Step-like corrections by the vehicle's sensor offset calibration function cause abrupt movements corresponding to the height of the lateral step of the lane-guided vehicle. Therefore, in a vehicle incorporating control means configured to implement the method of the present invention, all sensor offset calibration functions can be assumed to perform changes to each offset only within a bandwidth limit, rather than in a step-like manner.

[0042] In the present invention, in the following cases, the lateral direction by the calibration function position Error Time integral It is also possible that it will be stopped: - Lateral direction position Error Time integral If the integral value of the calibration function determined by, or determined by, corresponds to a predetermined threshold, - If the curvature value measured and / or predicted on the road surface on which the vehicle is traveling or will travel exceeds a predetermined threshold, - If the curvature value of the target trajectory exceeds a predetermined threshold, - Currently If the product of the square of the vehicle speed and the curvature value of the road surface exceeds a predetermined threshold, and / or, - Currently If the product of the square of the vehicle speed and the curvature value of the target trajectory exceeds a predetermined threshold.

[0043] The contribution of the calibration value to the controlled variable is in the lateral direction of the calibration function. position Error Time integral The integral can be limited to a predetermined threshold by at least temporarily stopping it, or by limiting the total integral to that threshold. This threshold, in this case representing the maximum amplitude, can be determined, for example, based on the sum of the maximum influences that all offsets on the steering angle target value and steering angle measured value can have. Advantageously, this method eliminates the need to take measures to avoid the wind-up effect of the integrating means in the calibration function.

[0044] Integration within the threshold value As an alternative to this limitation, the calibration function may include a low-pass filter, such as a PT-1 filter. This method also avoids the wind-up effect. In this case, although the sensor offset cannot be fully compensated, the centering accuracy achieved by the calibration function can be sufficient.

[0045] Additionally or alternatively, if the measured and / or predicted curvature of the road surface on which the vehicle is traveling exceeds a predetermined threshold, and / or if the curvature of the target trajectory exceeds a predetermined threshold, a calibration function may be performed laterally. position Error Time integral It is possible to stop it.

[0046] Lateral movement as a result of potential errors in predictive control when a vehicle is traveling around a curve position The error depends not only on the curvature offset error, but also on the inaccuracies of stored vehicle parameters, particularly the uncertainty of the vehicle's natural steering angle gradient. Errors in the vehicle's curvature predictive control have a similar effect to disturbances on the vehicle's lateral feedback control, resulting in a partially further lateral impact. position This can cause errors. Such additional lateral position Errors can cause erroneous intervention by the calibration function, which is due to the calibration function or at least the lateral movement caused by the calibration function. position Error Time integral of stop By stopping it, it becomes possible to avoid or reduce the problem, which is advantageous.

[0047] The effect of errors in curvature prediction control on the vehicle's travel and lateral position may be particularly dependent on the vehicle speed. Therefore, in order to consider this speed dependence, the lateral position can be controlled by the calibration function. position Error Time integral of, Currently If the product of the square of the vehicle speed and the curvature value of the road surface exceeds a predetermined threshold, and / or, Currently If the product of the square of the vehicle speed and the curvature value of the target trajectory exceeds a predetermined threshold, stop It is conceivable that it will stop.

[0048] In one preferred embodiment, when steering intervention by the vehicle driver generates a steering moment exceeding a predetermined threshold, and / or, Currently Lateral direction position When a steering moment that increases the error is generated, the lateral direction according to the present invention position Error Time integral but, stop The operation is stopped, and / or the application of the calibration value to the controlled variable is withheld. In this way, lateral movements caused by intentional driving operations that are not due to sensor offset or similar factors, i.e., not due to factors that should be corrected, are stopped. positionThe error is not reflected in the calibration value calculated by the calibration function, therefore, in the lateral direction position This advantageously prevents errors from being reflected in the calibration values ​​calculated by the calibration function. In short, it advantageously prevents lateral deviations from the target trajectory, intentionally caused by the driver rather than being due to the lane guide, from affecting the calibration values.

[0049] In this invention, the vehicle driver, Currently Lateral direction position When steering intervention is performed to generate a steering moment that reduces errors, lateral position Error Time integral This involves, at least for a predetermined time frame, an increased weight, and more preferably, an increased integral. gain It will be carried out using [this method].

[0050] If the driver intervenes in steering to generate a steering moment that acts in the same direction as the calibration value generated by the calibration function, this can be interpreted as confirmation of the direction of adaptation of the calibration function. In this case, increased load or increased Integral gain By using this, it is advantageous that the dynamic characteristics of the improved calibration due to the calibration function can be enhanced. From the driver's perspective, even if he cancels the steering moment he corrects, it will appear that the vehicle's course can be shifted laterally closer to the center of the lane and then maintained.

[0051] In one preferred embodiment, a plurality Calibration function You can use each of these, but here we will Calibration function Each of these has been assigned a different speed zone, and each Calibration function In each assigned speed zone, the vehicle speed is lateral position The error is integrated over time, and the vehicle Currently Corresponds to a speed section that encompasses the speed of Calibration functionThe calibration value, or the total calibration value calculated based on said calibration value, is applied to the controlled variable.

[0052] As mentioned above, the offset amount is in the lateral direction. position The impact on the error is partially dependent on the vehicle's speed. This is effective, for example, on offset errors included in the output of sensor disturbance compensation, or offset errors that are components of curvature prediction control. Lateral position To minimize errors, it is possible to determine a calibration value that is adapted to the controlled variable and depends on the speed. In particular, due to the high integration time constant and the resulting low dynamic characteristics, adapting the calibration value of this unique calibration function to the changing travel speed takes a relatively long time, and it cannot be denied that this may reduce the accuracy of the lane guide.

[0053] To address the above situation, it is advantageous to employ multiple calibration functions rather than using only one calibration function across the vehicle's entire speed range. Each calibration function should ideally be able to determine its own individual calibration values, and in particular, store them independently of other calibration values. By storing these calibration values, for example, in a non-volatile storage device and making them individually storable, these values ​​can be stored during continuous operation. Time integral This allows for sequential expansion, or enables the individual initialization of all states of multiple calibration functions when the vehicle starts up.

[0054] In this case, the entire range of possible vehicle speeds can be divided into multiple sub-sections, each covering a limited speed range and assigned a dedicated calibration function. Currently The calibration value of the assigned calibration function is applied to the speed range within which the speed falls. As a result, only one calibration function is always active, and the remaining calibration functions, in particular, the lateral direction of other calibration functions position Error Time integralThese are stopped, or a zero input signal is applied to their inputs. On the other hand, Currently Active calibration functions include: Currently Lateral direction position You can input the error. In this case, the horizontal direction position Error weighting is a constant weighting factor or Integral gain , or a weighting factor that depends on vehicle speed or Integral gain This can be done using [this method]. Subsequently, the speed section is [a specific speed]. Currently It encompasses the speed of Calibration function The calibration value, or a total calibration value derived based on that calibration value, is applied to the controlled variable. The advantages of using multiple calibration functions, or a bank of calibration functions, over using only one calibration function are most evident during acceleration or braking, and when the speed range changes frequently as a result.

[0055] According to the present invention, the total calibration value is two or more Calibration function The calibration values ​​generated by this process can be calculated to be temporally continuous even when switching between two or more speed intervals. In this way, when the calibration function switches due to changes in vehicle speed, abrupt changes in the calibration values ​​adapted to the control variable, as well as the resulting abrupt intervention, can be avoided.

[0056] In one preferred embodiment, the calibration function is, each, lateral position Error Time integral by, one It belongs to the calibration function. ta product We can determine the minute values, but here, Currently The speed of one or more is outside each speed zone. Calibration function The integral value is continuously, and particularly preferably, within that speed range of the vehicle Currently The speed can be adjusted using a constant rate or a rate dependent on the vehicle speed relative to the integral value of a certain calibration function.

[0057] In cases where the function for automatically implementing lane guidance is mainly used within a narrow speed range, lateral position Only a few, or even just one, calibration functions are loaded for the error, and therefore only Currently To avoid only the offset status being reflected, Currently The inactive calibration function, which is not used at this speed, continues to be used laterally at that point. position It is possible to integrate the error over time. In this case, the integral value, i.e., each Currently The integral means state of the calibration function to which a region adjacent to the velocity range is allocated is, at maximum, Currently It is limited to a value equivalent to the integral value of the calibration function assigned to that speed range. In addition, Integral gain If this is not changed, the advantage of dividing it into multiple integration state states may be lost, Currently Weighting factor of calibration function assigned outside of the speed range Integral gain The advantage is that it can be reduced compared to when it is active. Integral gain The degree of decrease depends on the expected maximum sensor drift, for example, in the range of 10% to 20%. As a result, the inactive calibration function gradually deviates from its current state due to typical drifts in curvature, yaw rate, and lateral acceleration offsets, when entering an adjacent velocity range. Currently Temporary lateral movement until the offset situation is fully adapted. position This makes it possible to avoid an increase in errors and a decrease in driving comfort.

[0058] Currently The speed of one or more is outside each speed zone. Calibration function The continuous integral of the vehicle Currently Adjusting the integral value of the calibration function when the speed is outside that speed range using a constant rate or a rate dependent on the vehicle speed can also be considered as implementing a forgetting factor. In this way, the state of the inactive calibration function is CurrentlyThe system can be brought closer to an active calibration function state, for example, by a constant gradient or a gradient set individually for each speed range.

[0059] A control device according to the present invention for generating a control quantity for at least one lateral guidance actuator of a vehicle is envisioned as a control device configured to carry out the method according to one of the claims. The control device may further be configured to carry out lateral feedback control, to determine a target trajectory, and / or to carry out curvature-predictive control. Alternatively, the control device may carry out only some of these functions. The control device may be connected to at least one sensor of the vehicle, in particular a perimeter sensor that captures at least partially the perimeter of at least one vehicle and / or a speed sensor that captures the speed of at least one vehicle, and / or the vehicle's navigation system.

[0060] The vehicle application of the present invention is assumed to include at least one lateral induction actuator and a control device according to the present invention, wherein the control device is configured to control at least one lateral induction actuator using the above-mentioned control amount. The lateral induction actuator can be, for example, a steering actuator, and more preferably, an electric servo drive for front-axle steering or rear-axle steering.

[0061] The computer program according to the present invention is envisioned to include instructions that cause the control means to carry out the method according to the present invention. The control means may be a control device that can be connected to at least one lateral induction actuator of a vehicle, in particular.

[0062] All the advantages and embodiments described above relating to the method according to the present invention also apply to the control device, the vehicle, and the computer program according to the present invention, and vice versa.

[0063] Further advantages and details of the present invention will become apparent based on the embodiments and drawings described below. The following are schematic diagrams. Figure Description: [Brief explanation of the drawing]

[0064] [Figure 1] Figure 1 shows one embodiment of a vehicle according to the present invention. [Figure 2] Figure 2 is a block diagram of an embodiment of the method according to the invention for implementing vehicle lane guidance, and, [Figure 3] Figure 3 is a block diagram of several calibration functions in an embodiment of the method according to the present invention. [Modes for carrying out the invention]

[0065] Figure 1 shows one embodiment of Vehicle 1. Vehicle 1 can be, for example, an automobile such as a passenger car or a truck. Subsequently, Vehicle 1 can also be a vehicle formation consisting of, for example, a towing vehicle and one or more towed vehicles. Alternatively, this method can be applied to further types of Vehicle 1.

[0066] Vehicle 1 includes control means 2 configured to implement a method for lane guidance of Vehicle 1. Subsequently, Vehicle 1 also includes at least one lateral guidance actuator 3 capable of setting the lateral position of Vehicle 1.

[0067] The lateral guidance actuator 3 may be implemented, for example, as a steering actuator capable of automatically setting the front axle angle of the vehicle 1. The steering actuator may be implemented, for example, as an electric servo motor. Additionally or alternatively, the lateral control actuator 3 may be a steering actuator for automatically setting the rear axle steering angle.

[0068] The control means 2 describes the lateral offset 4 of the vehicle 1 relative to a predetermined target trajectory 5 (shown by a dotted line). position Based on error ite The control variable is determined via lateral feedback control. car The lateral positions of both 1 are configured to be adjusted to the target trajectory 5 according to the control amount. Therefore, the control means 2 controls the lateral guidance actuator 3 using the control amount. In this case, the lateral offset 4 describes, for example, the difference between the target trajectory 5, with respect to the center of the vehicle 1, and the actual travel direction 6 of the vehicle center in the lateral direction of the vehicle.

[0069] In this case, the deviation from the target trajectory can be determined within a defined interval (predicted distance) from the front end of vehicle 1, or any other reference point, as shown in Figure 1. Further candidate reference points include, for example, the height of the rear axle or front axle of vehicle 1. The reference point is preferably located on the long axis of the vehicle, but other fixed reference points can also be considered during the observation period of vehicle 1.

[0070] Figure 2 shows a block diagram relating to an embodiment of a method for implementing automated lane guiding of a vehicle 1, which is performed by a control means 2. The automated lane guiding includes lateral feedback control 7 for feedback control of the lateral position of the vehicle 1 in order to maintain a target trajectory 4. The lateral feedback control 7 generates a control amount delta_set for a lateral guidance actuator 3, which can be controlled, for example, via a total steering angle feedback control means (not shown) installed directly or in between.

[0071] To generate the controlled variable delta_set, the lateral feedback control 7 includes a trajectory-following feedback control means 8, curvature prediction control 9, one or more disturbance compensation means 10 for, for example, crosswinds, road slope, and / or other effects, and steering angle offset calibration 11. Using the trajectory-following feedback control means 8, the controlled variable component delta_regler is determined.

[0072] The curvature prediction control 9 determines the predicted control quantity delta_vorst depending on the measured and / or predicted curvature value of the lane in which the vehicle 1 is traveling, and the control quantity delta_soll includes the predicted control quantity delta_vorst as a control quantity component. Similarly, one or more disturbance compensation means 10 generate one or more control quantity components delta_komp, and the steering angle offset calibration 11 generates the control quantity component delta_offset.

[0073] Subsequently, at least one calibration function 12 is assumed to determine the calibration value delta_kalib. This calibration value delta_kalib is applied to the control variable delta_soll generated by the lateral feedback control 7. The signal processing 13 transmits the yaw rate g and lateral acceleration a_lateral of the vehicle 1 as input variables to at least one disturbance compensation means 10. For this purpose, the signal processing 13 can evaluate the measured values ​​representing the yaw rate and / or lateral acceleration detected by multiple sensors of the vehicle 1.

[0074] The calibration function 12 and the trajectory tracking feedback control means 8 receive information from the position recognition unit and the trajectory planning unit 14 in the lateral direction. position The error delta_y is supplied. In this case, the lateral direction position The error delta_y describes the lateral offset 4 between the target trajectory 5 shown in Figure 1 and the actual direction of movement 6 or actual position of the vehicle 1.

[0075] The position recognition unit and trajectory planning unit 14 subsequently provide the curvature prediction control 9 with at least one measured and / or predicted curvature information kappa describing the curvature of the target trajectory 5 within a segment of the target trajectory 5 located in front of the direction of travel of the vehicle 1. The position recognition unit and trajectory planning unit 14 also determine the target trajectory 5, and similarly the curvature information kappa, depending on ambient data provided by the ambient sensing unit 15 of the vehicle 1. The ambient sensing unit 15 particularly preferably generates ambient measurement data generated by ambient sensors (not shown) that capture at least one sub-region around the vehicle 1.

[0076] All or part of the functions of blocks 8 to 15 may be implemented within the control means 7. The output values ​​of blocks 8 to 11 are all components of the controlled variable delta_soll. Subsequently, the controlled variable delta_soll is corrected by at least one calibration value delta_kalib of the calibration function 12.

[0077] Each component of the controlled variable delta_soll and at least one calibration value delta_kalib have different effects on the lane guide of vehicle 1, as described below.

[0078] The target steering angle component delta_vorst for curvature prediction control 9 is, for example, (1) delta_vorst=kappa*(l+EG*v^2), It can be calculated as shown, where the parameter l corresponds to the distance between the axles, and EG corresponds to the natural steering angle gradient of vehicle 1. This natural steering angle gradient is, (2) EG=m*(ch*lh-cv*lv) / (ch*cv*(lh+lv)) As described above, it depends on the distance Iv from the center of gravity of vehicle 1 to the front axle, or Ih from the center of gravity to the rear axle, the vehicle weight m of vehicle 1, and the cornering stiffness cv of the front wheels and the cornering stiffness ch of the rear wheels.

[0079] If the curvature information kappa has an offset kappa_offs due to an error compared to the actual curvature, the predicted controlled target steering angle will also be affected. (3)delta_vorst_kappaoff=kappa_offs*(l+EG*v^2) It has an offset component delta_vorst_kappaoff obtained from. The result of the predictive control delta_vorst, including the error due to delta_vorst_kappaoff, acts like a disturbance to the lateral feedback control 7, so to speak, and when the lane keeping assistant is activated, the vehicle 1 does not follow the target trajectory 5 as expected, and instead, depending on the specifications of the trajectory following feedback control means 8 - i.e., depending on the type of feedback control used, such as whether or not it has steady-state accuracy - the vehicle 1 exhibits a continuous lateral offset 4 with respect to the planned target trajectory 5, or at least causes a temporary deviation, until it follows the planned target trajectory 5 after the adjustment process has decayed.

[0080] The degree of image distortion of the camera used as a peripheral sensor to supply peripheral measurement data to the position recognition unit and trajectory planning unit 14 is constantly changing, as the camera calibration routine is typically performed continuously during the operating time of the driver assist system. This means that, depending on the calibration state, the value of the offset of the curvature / predictive control 9, and the degree of adverse effect on vehicle lateral guidance, will change over time, even if the camera's transmission characteristics and the resulting curvature offset are at least not abrupt and are band-limited changes.

[0081] The steering angle can also be used as an auxiliary variable or feedback control value within the lane guide driver assist system. This steering angle may be affected by or corrected by the steering angle calibration routine 11. The calculated steering angle offset delta_offset usually has components that are not fully compensated because the precision of the steering angle calibration routine 11 is finite.

[0082] There are several possible causes for the offset error delta_offset_error remaining in this steering angle signal. Typically, the steering angle calibration routine 11 is based on the signals from the vehicle 1's yaw rate sensor and / or the vehicle 1's wheel rotation speed sensor. In short, errors in these sensors, such as offset errors or linear errors, can be inherited by successive generations in the calculated steering angle offset. In this case, the effect of the steering angle offset is similar to that of the curvature offset described above; the vehicle 1 does not follow the target trajectory 5 as expected, and instead exhibits a continuous lateral offset 4 relative to the planned target trajectory 5, which can adversely affect the comfort and acceptability of the driver assist system, although this also depends on the specifications of the trajectory following feedback control means 8.

[0083] The trajectory tracking feedback control means 8, for example, the transfer function (4)Gr(s)=Kp(v)+s*Kd(v) / (1+s*T), Furthermore, when using PD feedback control means having speed-dependent feedback control factors Kp(v) and Kd(v), Description of lateral offset 4 position Given the error delta_y as the input value, delta_regler as the output value of the trajectory tracking feedback control means 8 is: (5)delta_regler(s)=Gr(s)*delta_y(s) It is obtained by [method].

[0084] As a result, the trajectory-following feedback control means 8 is in a steady equilibrium state during straight-line driving, that is, the physical steering angle is zero degrees, and if lateral disturbances acting on the vehicle 1 are ignored, an uncorrected steering angle offset delta_offset_error is output. The lateral offset 4 required for this is: (6)Delta_y(0)*Gr(0)=Delta_offset_error(0) Obtained from, in the time domain, (7)delta_y=delta_offset_error / Kp(v) This can be expressed as follows. Since the feedback control factor Kp cannot be arbitrarily selected to be large during design, if the uncorrected steering angle offset delta_offset_error is not zero, a lateral offset 4 of vehicle 1 with respect to the target trajectory 5 is always formed. When vehicle 1 is rear-wheel steering, the uncorrected offset of the rear-wheel steering angle has a comparable effect on the lateral offset 4 of vehicle 1, similar to the uncorrected offset of the front-wheel steering.

[0085] Sensor signals for yaw rate, longitudinal steering angle, and lateral acceleration are also used to estimate disturbance forces and load moments acting on vehicle 1, such as road surface inclination or crosswinds acting on vehicle 1. The calculated forces and moments contribute proportionally to the steering angle target value delta_soll through the implementation of disturbance compensation delta_komp.

[0086] Subsequently, these sensors can also be used to estimate the slip angle of vehicle 1, which can also be used as an auxiliary variable for load estimation. Offset errors in yaw rate g, steering angle, or lateral acceleration a_lateral frequently have an effect on the estimated value proportional to the respective offset in steady-state cases, and consequently have a similar effect on disturbance compensation. As a result, yaw rate g, steering angle, and lateral acceleration a_lateral are also inherited by the disturbance compensation component of the steering angle target value delta_sol. Consequently, vehicle 1, which is being guided in the lane, experiences undesirable temporary or continuous lateral deviation from the planned target trajectory 5. The disturbance compensation means 10 for yaw rate g and lateral acceleration a_lateral, like the steering angle correction 11, usually have only finite precision and therefore may lag behind the actual offset. Thus, even with these compensation means in place, the aforementioned adverse effects on the comfort of vehicle 1 may occur when using the lane guide driver assist system.

[0087] These effects are addressed and compensated for at least partially by at least one calibration function 12, thereby improving the ride comfort of the vehicle 1. In this process, the calibration function 12 is superimposed on the lateral feedback control 7 and generates a calibration value delta_kalib that is applied to at least one control quantity delta_soll. The calibration value delta_kalib is at least partially compensated for by at least one calibration function 12 in the lateral direction. position Error Time integral It is determined by the delta_y.

[0088] Lateral direction position Depending on the sign and amplitude of the error delta_kalib, the calibration function 12 is used for the target steering angle delta_soll, and its effect direction is always lateral. position A calibration value delta_kalib is determined to be applied so as to reduce the error delta_y. Subsequently, this calibration value delta_kalib is added together with the control variable delta_soll to the control variable component of the trajectory-following feedback control means 8, the curvature / predictive control 9, one or more disturbance compensation means 10, and the output of the steering angle offset calibration 11, and the calibrated control variable delta_soll_kalib is output as an interrupt to, for example, the target angle interface of the lateral guidance actuator 3. Alternatively, the calibrated control variable can also be output as an interrupt to the moment interface of the lateral guidance actuator 3.

[0089] Calibration function 12 is, for example, an integration means, or a relatively small Integral gain ki I element The calibration function 12 is performed in the lateral direction. position The error is integrated using small dynamic characteristics. Alternatively, the calibration function... is a PT1 element year hand Alternatively, it can be realized as another type of function that exhibits at least partially integral behavior.

[0090] Therefore, the calibration function 12 calibrationThe value delta_kalib is determined using calibration function 12. Integral gain ki possess When implemented as an integration method, for example, (8) Delta_kalib = Delta_y*ki / s It can be expressed as follows.

[0091] The time constant of the calibration function 12 can be set to be at least twice, at least five times, at least ten times, at least 100 times, or at least 1000 times larger than the dominant time constant of the lateral feedback control 7 or the trajectory-following feedback control means 9. Integral gain ki is on the order of, for example, 0.001 Grad / (m*s), and the lateral direction assumed as an example for explanation. position For error delta_y, the gradient of calibration value 12 is only 0.0002 Grad / s from 0.2m.

[0092] The adaptive dynamic characteristics of the calibration value 12 are preferably set to be of a magnitude similar to the dynamic characteristics of the change in the offset error described above. An indicator for this is, for example, the maximum expected offset drift due to the temperature of the sensor used in the lateral feedback control 7, converted to, for example, the corresponding steering angle plane. If the dynamic characteristics are selected to be significantly large, the calibration will partially compete with the convergence characteristics of the compensation function 10 for road transverse slope and crosswind, resulting in a typical overshoot in the signal for delta_kalib. However, this may limit the comfort improvement obtained by the calibration function 12.

[0093] Calibration function 12 is lateral position Error delta_y Time integral The integral value of calibration function 12 is calculated accordingly. This integral value represents the lateral direction at a specific point in time. position Error delta_y Time integral This represents the result. This integral value is retained even when the lane guide is stopped, and when the lane guide is restarted, the lateral direction position New error delta_y Time integral It is used as the initial value. For example, the state of calibration function 12 implemented as an integration means is Currently Rather than being reset during the ignition cycle, it is maintained even if the driver assistance system is repeatedly stopped and started due to the end of driving and / or driver intervention that overrides the automatic lane guidance.

[0094] In calibration function 12, a constant Integral gain Using ki could be a compromise for the entire speed range that vehicle 1 can reach, but this is because the offset amount is lateral position This is because the effect on the error delta_y may depend on the travel speed. Furthermore, this may be due to the travel speed-dependent controller parameter control commonly used in the trajectory-following feedback control means 8. This also changes the disturbance compensation characteristics of the trajectory-following feedback control means 8, and as a result, the sensor offset amount changes laterally. position The effect on the error delta_y also changes.

[0095] To address the above situation and extend the potential of the calibration function, a weighting factor, particularly preferably one that depends on the vehicle speed, is required. Integral gain Lateral direction using ki position Error delta_y Time integral It can be assumed that this will be implemented. Therefore, Integral gain ki is vehicle 1 Currently It can be implemented as ki(v) which depends on the speed. This advantageously realizes the dynamic characteristics of the calibration of the individually adjustable calibration function 12, which is optimized for each driving speed range.

[0096] Additional or alternative, weighted factors or Integral gain ki, horizontally position It is conceivable that the value may increase as the absolute value of the error delta_y increases. The calibration speed of calibration function 12 is lateral. positionThe error delta_y can be effectively improved by applying additional nonlinear or incremental weighting to its absolute value.

[0097] This includes, for example, Integral gain ki, and thereby the adaptation rate, can be switched between two or more values, Integral gain In terms of ki, horizontal direction position When the absolute value of the error delta_y is greater, a larger value is selected. For example, in the horizontal direction. position If the absolute value of the error delta_y exceeds 0.2m, doubling the integration constant ki allows for faster initial adaptation to the offset situation present when the driver assistant function is activated.

[0098] Even if the sensor compensation means 10 and / or other sensor offset calibration functions within the vehicle 1 finally eliminate the detected sensor offset drift by correcting each offset in a step-by-step manner after the vibration isolation time has elapsed, the adaptation rate of the calibration function 12 is lateral position By defining it according to the absolute value of the error delta_y, it becomes possible to quickly adapt to new offset conditions. This is particularly advantageous when the vibration isolation time of the sensor compensation means 10 and / or other sensor offset calibration functions is relatively long, because during such vibration isolation time the calibration function 12 performs compensation one after another, and after the signal update of the sensor compensation means or sensor offset calibration function, these compensations need to be integrated back again.

[0099] Step-like correction of the sensor offset directly causes abrupt lateral movement of vehicle 1 depending on the step height. As a favorable extension, it can be assumed that all sensor offset calibration functions within vehicle 1 perform changes to each sensor offset only within a bandwidth limit, rather than in a step-like manner. If offset compensation for on-board sensors is performed, for example, only by a defined maximum gradient, and the output delta_kalib of the centering calibration can always follow this with only a small tracking error of about 0.03 degrees, then the lateral movement in calibration function 12 position The nonlinear or gradual weighting of the absolute value of the error delta_y can be omitted as a measure to improve the dynamics.

[0100] Subsequently, the contribution of delta_kalib to the total controlled quantity delta_soll_kalib is favorably limited in its maximum amplitude due to the constraints on the integration means state in calibration function 12. Therefore, the lateral direction of calibration function 12 position Error delta_y Time integral However, when a predetermined threshold is reached, the lateral direction is controlled by the calibration function 12. position Error delta_y Time integral It is expected that it will be shut down.

[0101] The threshold or maximum amplitude of the integration means or calibration function 12 is, for example, based on the sum of the maximum influences of all offset amounts on the steering angle target value delta_soll and the measured steering angle. Here, if delta_komp, delta_vorst and delta_offset each have, for example, a maximum offset error of 0.05 degrees, then delta_kalib should be limited to a range of + / - 0.15 degrees. These angle notations are based on the steering angle of the vehicle, for example, the steering angle of the vehicle's front wheels. Advantageously, this method eliminates the need to take other necessary measures to avoid the wind-up effect of the integration means within the calibration function 12.

[0102] As an alternative to limiting the integration state, a low-pass filter such as a PT-1 filter can be used. This method also avoids the wind-up effect. In this case, although the offset situation cannot be completely eliminated, the centering accuracy can be sufficient.

[0103] Lateral movement during cornering as a result of predictive control errors position The error depends not only on the curvature offset error but also on the inaccuracies of the stored vehicle parameters, particularly the uncertainty of the natural steering angle gradient EG. The error component of predictive control due to the error in the natural steering angle gradient EG can be evaluated with respect to EG or its error EG_err by applying the total differential to equation (1). (8)delta_vorst_EG_err=(d delta_vorst / d EG)*EG_err =(d(kappa*(l+EG*v^2)) / d EG)*EG_err =kappa*v^2*EG_err It is obtained as follows.

[0104] The contribution of delta_vorst_EG_err acts as a disturbance to the lateral feedback control of vehicle 1, resulting in lateral steering errors of delta_kalib. position An error delta_y is introduced proportionally. That is, the signal delta_kalib does not only respond to the sensor offset amount. As long as EG_err is limited, the effect of EG_err on the vehicle level is small due to the large integration time constant of the centering calibration. In this case, the integration time constant is Integral gain It is defined as the reciprocal of ki.

[0105] This is also true because the incorrect steering of delta_kalib on curves is corrected again on the straight sections of the lane. As a countermeasure when EG_err fluctuations are significant, the EG value within the vehicle is adjusted based on the vehicle mass m and tire stiffness, etc. CurrentlyThe adaptive algorithm can be continuously adjusted to match the conditions, which reduces EG_err and consequently lowers the contribution of delta_vorst_EG_err.

[0106] If the fluctuations in EG_err remain significant, and the product of kappa * v^2 takes a large value, the calibration function 12 can be interrupted. That is, Currently If the product of the square of the vehicle speed v and the curvature value kappa of the target trajectory 5, and / or the curvature value of the lane, exceeds a predetermined threshold, the lateral direction of the calibration function 12 is corrected. position Error delta_y Time integral It is conceivable that this will be interrupted.

[0107] To achieve this, the curvature value kappa is subjected to low-pass filtering using, for example, the PT-1 algorithm, and then compared with a threshold value that depends on the driving speed v. If the filtered curvature exceeds the threshold value, the calibration function 12 is temporarily stopped.

[0108] Subsequently, if the measured and / or predicted curvature value kappa of the road surface on which vehicle 1 is traveling exceeds a predetermined threshold, and / or if the curvature value of the target trajectory 5 exceeds a predetermined threshold, the lateral direction of the calibration function 12 is corrected. position Error delta_y Time integral It is also conceivable that it may need to be stopped.

[0109] If the curvature itself temporarily has a large offset error, this may reduce the calibration work of the high-speed calibration function 12 until the camera calibration compensates for this error. However, since the adaptive region is displaced only by the amount of the curvature offset, the calibration work does not completely stop. Furthermore, when the travel speed v decreases and kappa * v^2 decreases accordingly, the calibration is performed again intensibly.

[0110] Calibration disturbances can occur, for example, by steering the steering wheel of vehicle 1 in a lateral direction. position It can also be caused by driver intervention that can directly affect the error delta_y. To address this, calibration function 12, i.e., lateral position The integral of the error delta_y is obtained when there is driver intervention with respect to the steering wheel. stop It can be stopped. This is especially true when steering intervention by the driver of vehicle 1 generates a steering moment M that exceeds a predetermined threshold, and / or, Currently Lateral direction position When a steering moment M that increases the error delta_y is generated, the lateral direction position Error delta_y Time integral but, stop The process is stopped, and / or the application of the calibration value delta_kalib to the controlled variable delta_soll is suspended.

[0111] However, improving the availability of calibration function 12, and consequently, speeding up convergence, means that the driver is lateral position This can be achieved by stopping the calibration function 12 only when steering in a direction that increases the error delta_y. This is due to the driver steering moment M and the lateral direction. position This can be done by comparing the signs of the error delta_y. For example, the counting arrow for the driver steering moment M indicates that steering to the left in the direction of travel produces a positive moment and a positive lateral direction. position If the error is defined to mean that the vehicle is positioned to the right of the direction of travel of the planned target trajectory 5, then the stopping conditions for the calibration function are the sign and lateral direction of the driver steering moment M. position The signs of the errors must be different.

[0112] Integral gainFirst, ki is evaluated using, for example, the magnitude of the measured driver steering moment M, for the implementation of the lane keeping assistant when the driver's steering intervention is below a predetermined intensity, and this is set as the basic specification. Additionally or alternatively, the driver of vehicle 1, Currently Lateral direction position When steering intervention is performed to generate a steering moment M that reduces the error delta_y, the lateral direction position Error delta_y Time integral This involves, at least for a predetermined time frame, an increased weight, and more preferably, an increased integral. gain This is performed using [a specific method / tool]. This allows for the detection of driver intervention, and also enables the driver to move laterally. position If steering is being performed in a direction that reduces the error delta_y, Integral gain It becomes possible to intentionally increase this value beyond the basic specification value. In this case, the driver's steering can be considered as acceptance of the calibration process by calibration function 12, Integral gain Increasing ki justifies enhancing calibration dynamics.

[0113] As mentioned above, the offset amount is in the lateral direction. position The impact on the error delta_y depends in part on the vehicle speed v. This is effective, for example, on the offset error included in the output delta_komp of the disturbance compensation means, or the offset error that is a component of the curvature prediction control delta_vorst. Therefore, if the travel speed changes, for example, in the lateral direction... position Even assuming that the yaw rate g, lateral acceleration a_lateral, and the offset value of the predictive control curvature kappa, which cause errors, are constant, position To keep the error small, delta_kalib must be constantly changed. The integration time constant of calibration function 12 is high, and therefore even if the dynamic characteristics of calibration function 12 are low, it takes a relatively long time to adapt to the changed driving speed v, during which time the accuracy of lane following decreases.

[0114] To address the above situation, it is advantageous to adopt a configuration consisting of multiple integration or storage means, as illustrated in Figure 3, rather than using a single integration means as the memory device for delta_kalib across the entire speed range of the vehicle.

[0115] Figure 3 shows multiple Calibration function The use of 12_1 to 12_N is shown. Furthermore, interpolation unit 16, initialization unit 17, Integral gain The decision unit 18 and the sequence control unit 19 are depicted as components of the control means 2.

[0116] Calibration function Each of 12_1 through 12_N is assigned a different speed interval, but here, Calibration function 12_1 to 12_N respectively indicate that when the speed of vehicle 1 is within the assigned speed range, the lateral direction position Error delta_y Time integral The system is configured to perform the following. In this configuration, the entire range of vehicle speed is divided into N>1 subsections, each covering only a limited speed range, to which a dedicated calibration function 12 is assigned. Therefore, at any given time, only one calibration function 12 is active, while the remaining calibration functions 12 are either in a dormant state or have an input signal of zero applied to their input terminals. On the other hand, one of the calibration functions 12_1 to 12_N, which are currently active, is assigned a weighted lateral direction position An error delta_y is input, and each integration method generates individual delta_kalib_v(k), k=[1...N]. Each velocity interval is Currently The corresponding calibration values ​​delta_kalib_v(1) to delta_kalib_v(N) of one of the calibration functions 12_1 to 12_N that encompass the speed of vehicle 1 are used to directly apply the resulting delta_kalib to the controlled variable delta_soll. Lateral position The weighting of the error delta_y is constant in each case. Integral gain This can be done using ki or a coefficient ki(v) that depends on the vehicle speed.

[0117] Integral gain ki to ki(v) are the individual calibration functions 12_1 to 12_N, Integral gain This can be determined by the decision unit 18. For this purpose, Integral gain The decision unit 18 takes the following as input values, for example, vehicle speed v, steering moment M of the driver of vehicle 1, Currently Lateral direction position The error delta_y, as well as the measured or predicted curvature kappa, can be obtained.

[0118] The centers of the N travel speed intervals effectively constitute nodes of the output value delta_kalib_v(k). To obtain the resulting delta_kalib from each contribution delta_kalib_v(k), the total calibration value delta_kalib_ges, derived by the interpolation unit 16 from the calibration values ​​delta_kalib_v(1) to delta_kalib_v(N), can be applied to the control variable delta_soll, either additionally or alternatively. The total calibration value delta_kalib_ges is then calculated using two or more Calibration function The total calibration value delta_kalib_ges is derived from the calibration values ​​delta_kalib_v(1) and delta_kalib_v(N) generated by 12, but it is particularly preferable that the total calibration value delta_kalib_ges is derived in such a way that it is continuous even when switching between two or more speed intervals. This can be achieved, for example, by linear interpolation by the interpolation unit 16, which takes the vehicle speed v as an input value.

[0119] In this case, for example, Currently Depending on the distance between the velocity and the center of the adjacent velocity range, delta_kalib_ges is linearly combined from delta_kalib_v(k) and delta_kalib_v(k+1). That is, (9)delta_kalib_ges=delta_kalib_v(k)*a+delta_kalib_v(k+1)*(1-a) However, in the formula: a=(vv(k)) / (v(k+1)-v(k)),v>v(k),v <v(k+1)となる。

[0120] Interpolation between individual integration means states delta_kalib_v(k) is advantageous because it avoids step-like discontinuous changes in delta_kalib_ges when transitioning from one speed range to another. A step in the steering angle target value delta_soll_kalib would cause the vehicle 1 to move abruptly laterally, which must be avoided from the standpoint of ride comfort. The advantages of using multiple banks of calibration functions 12_1 to 12_N, or multiple banks of integration means, over using only one integration means, are most evident during acceleration or braking, and when the speed range is frequently changed as a result.

[0121] When the driver assistance function is operating primarily within a single speed range, only one of the calibration functions 12 is set to lateral position Given an error delta_y, only this calibration function 12 is used. Currently It is possible that the offset situation may not be accurately reflected. Due to the typical drift of the offset values ​​for curvature kappa, yaw rate g, and lateral acceleration a_lateral, the state of the remaining integration means gradually becomes inconsistent with the current state.

[0122] When entering an adjacent speed range, temporarily move laterally position As the error delta_y increases, Currently Ride comfort will decrease until adaptation to the offset situation is complete. As a remedy, it is advantageous to implement a forgetting coefficient. To do this, calibration functions 12_1 to 12_N are, respectively, lateral position Error Time integral The calibration functions 12_1 through 12_N were assigned accordingly. 、 It is conceivable that we would need to determine the integral value of calibration functions 12_1 to 12_N, but here, CurrentlyThe speed of one or more is outside each speed zone. Calibration function The integral value of is continuously, and particularly preferably, within the speed range of vehicle 1 Currently The speed can be adjusted using a constant rate or a rate dependent on the vehicle speed relative to the integral value of a certain calibration function 12_1 to 12_N.

[0123] In this case, for example, all integration means states, or calibration functions 12_1 to 12_N that are not operating Integral gain teeth, Currently The state or integral value of the operating calibration functions 12_1 to 12_N is asymptotically approached by a uniform or individually predetermined gradient for each velocity range. This gradient can be set, for example, according to the fluctuation characteristics of the offset value. In the application, this means that 25% of the gradient set for delta_kalib_v(k) is 0.2m lateral. position It is advantageous to estimate in a way that accommodates errors. If a leveling gradient that is too steep is selected, the advantage of using a bank of multiple calibration functions 12_1 to 12_N instead of using only one calibration function 12 is lost.

[0124] As an alternative to the gradient method described above, Currently Calibration function for unrelated speed ranges, for example, reduced by 10% to 20% Integral gain One possible approach is to continue the process using the following. In this approach, the integral means state is Currently The integration means state exceeding the operating speed range is avoided by corresponding limitations.

[0125] Depending on the dynamic characteristics of the offset effect, it is advantageous to store the states of individual calibration functions 12 or multiple calibration functions 12_1 to 12_N in a non-volatile storage means, such as a storage means of the control means 3, so that when the vehicle 1 is restarted, it can be set to one or more calibration functions 12 to 12_1 to 12_N already calibrated. This is particularly advantageous when the majority of the offset error has little to no temporal drift.

[0126] The stored states or integral values ​​of one or more calibration functions 12_1 to 12_N can be performed by the initialization unit 17. The initialization unit 17 performs the initialization of calibration functions 12_1 to 12_N, as well as the initialization of calibration functions 12_1 to 12_N, Currently We will perform a state comparison of the integral values.

[0127] The flow control unit 19 activates and / or stops the automatic lane guide. Time integral The system can monitor for the occurrence of stop conditions and / or the application of at least one calibration value delta_kalib to the controlled variable delta_soll, switching between speed intervals, and / or other events, and control the operation of at least one calibration function 12 accordingly.

[0128] The calibration function 12 can be considered, in its basic function, as a form of the integral component of the trajectory-following feedback control means 8, preferably in the lateral direction. position Error delta_y Time integral Used Integral gain Alternatively, other weighting factors may be significantly smaller compared to the lateral feedback control 7, which differs from typical specification conditions, and / or the calibration function 12 or lateral position Error delta_y Time integralHowever, it has essential characteristics or fundamental differences, such as not being initialized to zero when the assistant system is restarted, but rather starting or continuing from the last reached state. The advantage of this is that when the vehicle 1 activates the driver assistance function, it can immediately travel along the planned target trajectory 5 without substantially having a lateral convergence process. The extension of at least one of the calibration functions 12 described above is a further difference from the conventional integral component of the lateral guidance feedback control means.

[0129] At least one calibration function 12 can be implemented as an independent function or implemented in the trajectory-following feedback control means 8 as an alternative to or additional to an existing integral component. In this case, at least one calibration function 12 is adapted, in particular, only during the activation phase of the driver assist system, so that the integral component of the trajectory-following feedback control means 8 is lateral position This is performed until the error delta_y equals zero, or when the integral component of the trajectory-following feedback control means 8 must be reset and rebuilt. This can occur, for example, in a Level 2 autonomous driving system when the driver intervenes with steering.

[0130] In general, the dynamic characteristics of the calibration of the calibration function 12, namely the lateral displacement 4 of the vehicle 1, Currently The time required to adjust for the offset situation is longer than in the case of a driver assist system in which the trajectory tracking feedback control means 8 does not have an integral component. This problem arises, at least in part, when using one or more calibration functions 12 with a trajectory tracking feedback control means 8 that does not have an integral component. Integral gain or more Integral gainThis can be addressed by increasing the value. Furthermore, when an integral component is used in the trajectory-following feedback control means 8, it is possible to omit one or more disturbance compensations 10 for crosswinds and / or road surface inclination. This eliminates one of the main causes of offset errors, resulting in a reduction in the number of offset effects that the calibration function 12 must consider, and furthermore, the advantage of reducing the requirements for the dynamic characteristics of the calibration of at least one calibration function 12.

Claims

1. A method for performing lane guiding for a vehicle (1), wherein a control amount is determined via lateral feedback control (7) based on a lateral position error that describes the lateral deviation (4) of the vehicle (1) from a predetermined target trajectory (5), and the lateral position of the vehicle (1) is adjusted to the target trajectory (5) according to the control amount, At least one calibration value is determined by at least one calibration function (12) at least in part depending on the time integral of the lateral position error, and the at least one calibration value is additionally applied to the controlled variable, and the lateral position of the vehicle (1) is adjusted depending on the controlled variable to which the at least one calibration value is applied. Characterized by Methods for implementing lane guidance.

2. The time constant of the calibration function (12) is configured to be at least twice as large as the dominant time constant of the lateral feedback control (7), which is particularly preferable. Characterized by The method according to claim 1.

3. The integral value of the calibration function (12) is calculated by the time integral of the lateral position error. However, this integral value is retained even when the lane guide is stopped and is used as the initial value of the time integral of the lateral position error when the lane guide is restarted. Characterized by The method according to claim 1.

4. Lateral feedback control (7) includes predictive control (9), wherein the predictive control (9) determines the predictive control amount depending on the measured and / or predicted curvature value of the road surface on which the vehicle (1) is traveling, and the control amount includes the predictive control amount as one of its components. Characterized by The method according to claim 1.

5. Predictive control is implemented based on a vehicle model that describes the vehicle's natural steering angle gradient, provided that this natural steering angle gradient is adapted during vehicle operation depending on at least one vehicle parameter, particularly vehicle weight and / or tire stiffness. Characterized by The method according to claim 4.

6. The time integral of the lateral position error is performed using a weighting factor that depends on the speed of the vehicle (1), and / or a weighting factor that increases with increasing absolute value of the lateral position error. Characterized by The method according to claim 1.

7. The weighting factor is the integral gain ki in the formula Delta_kalib = Delta_y * ki / s, where Delta_kalib is the calibration value, Delta_y is the lateral position error, and s is the Laplace operator. The method according to claim 6, characterized in that

8. In the following cases, The time integral of the lateral position error by the calibration function (12) is stopped. The method according to feature 1: - If the integral value of the calibration function (12) obtained by the time integral of the lateral position error corresponds to a predetermined threshold, - If the curvature value measured and / or predicted on the road surface on which vehicle (1) is traveling or is likely to travel exceeds a predetermined threshold, - If the curvature value of the target trajectory (5) exceeds a predetermined threshold, - If the product of the square of the current vehicle speed and the curvature value of the road surface exceeds a predetermined threshold, and / or, - When the product of the square of the current vehicle speed and the curvature value of the target trajectory (5) exceeds a predetermined threshold.

9. If steering intervention by the driver of vehicle (1) generates a steering moment exceeding a predetermined threshold, and / or generates a steering moment that increases the current lateral position error, the time integral of the lateral position error is stopped, and / or the application of a calibration value to the control variable is suspended. Characterized by The method according to claim 1.

10. When the driver of vehicle (1) performs a steering intervention that generates a steering moment to reduce the current lateral position error, the time integral of the lateral position error is performed with an increased load, particularly preferably with an increased integral gain, for at least a predetermined time frame. Characterized by The method according to claim 1.

11. Multiple calibration functions (12) are used, however each calibration function (12) is assigned a different speed interval, and each calibration function (12) integrates the lateral position error over time at the speed of the vehicle (1) within its assigned speed interval, and the calibration value of the calibration function (12) corresponding to the speed interval encompassing the current speed of the vehicle (1), or the total calibration value calculated based on said calibration value, is applied to the control variable. Characterized by The method according to claim 1.

12. The total calibration value is determined from calibration values ​​generated by two or more calibration functions (12) such that it is temporally continuous even when switching between two or more speed sections. Characterized by The method according to claim 11.

13. Each of the multiple calibration functions (12) determines an integral value attributed to one calibration function (12) by the time integral of the lateral position error, provided that the integral values ​​of one or more calibration functions whose current speed is outside their respective speed ranges are continuously adjusted, particularly preferably, by a constant rate or a rate dependent on the vehicle speed relative to the integral value of the calibration function (12) whose current speed of the vehicle (1) is within that speed range. Characterized by The method according to claim 11.

14. At least one calibration function (12) is implemented as either an I element or a PT1 element. Characterized by The method according to claim 1.

15. A control device (2) for generating a control amount for at least one lateral guide actuator (3) of a vehicle (1), characterized in that it is configured to carry out the method according to claim 1.

16. A control device (2) for generating a control amount for at least one lateral guide actuator (3) of a vehicle (1), characterized in that it is configured to carry out the method according to claim 10.

17. A control device (2) for generating a control amount for at least one lateral guide actuator (3) of a vehicle (1), characterized in that it is configured to carry out the method according to claim 11.

18. A vehicle comprising a lateral guide actuator (3) and a control device (2) as described in claim 15, wherein the control device (2) is configured to control at least one of the lateral guide actuators (3) using a control variable.

19. A vehicle comprising a lateral guide actuator (3) and a control device (2) as described in claim 16, wherein the control device (2) is configured to control at least one of the lateral guide actuators (3) using a control quantity.

20. A vehicle comprising a lateral guide actuator (3) and a control device (2) as described in claim 17, wherein the control device (2) is configured to control at least one of the lateral guide actuators (3) using a control quantity.

21. A computer program comprising an instruction prompting a control means to carry out the method described in any one of claims 1 to 15.

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