Patent Application
20180304883
The present invention refers to a method for operating a lateral guidance system adapted for performing automatic transversal guidance interventions on a vehicle, which has a first transversal guidance actuator controlled by a steering handle to be operated on the driver side, in particular a steering wheel, and a vehicle system adapted for setting a target roll angle of the vehicle. The invention also refers to a vehicle.
The known motor vehicles may be steered by the driver in order to perform a transversal guidance, wherein, usually, a steering handle accessible on the driver side, in particular a steering wheel, is used. The steering wheel may be directly mechanically coupled to a transversal guidance actuator, in general a front axle steering; however, it has also been proposed to measure the inputs to the steering handle by means of a steering sensor and to convert these inputs into corresponding control signals for the transversal guidance actuator (keyword: “steer-by-wire”). The position of the steering wheel notifies the driver regarding the intensity and direction of the current steering.
In the context of a progressive automation, vehicle systems have already been proposed, which are completely or partially adapted for an automatic guidance of the motor vehicle. If such a vehicle system is possibly also adapted for the transversal guidance of the motor vehicle, i.e., it may also automatically perform transversal guidance interventions, it is also indicated as a transversal guidance system. Transversal guidance systems are known, for example, which perform transversal guidance interventions when the motor vehicle is at risk of leaving the current driving lane, for example. The transversal guidance systems with central lane tracking try to guide the motor vehicle centrally along the currently followed driving lane. Moreover, transversal guidance systems may also be obviously part of a vehicle guidance system which is at least partially autonomous.
In general, transversal guidance systems evaluate sensor data of the motor vehicle, in particular sensor data of at least one environment sensor, and/or determine properties of the driving lane based on digital map data of a navigation system of a motor vehicle, considering a current position. Central lane transversal guidance systems may, for example, evaluate data of a camera which is directed onto an area in front of the motor vehicle, in order to determine the further driving lane path and/or the transversal position of the motor vehicle on the driving lane and correspondingly determine and perform transversal guidance interventions.
In order to concretely implement transversal guidance interventions, various variants are known in the art. Thus, it is possible, for example, that the transversal guidance intervention is implemented directly through the steering handle, in particular the steering wheel. Motors may be used, for example, which rotate the steering wheel. After these have been coupled to the transversal guidance actuator, the corresponding transversal guidance takes place. The transversal guidance intervention may however also be performed by means of a transversal guidance actuator, which provides the driver indirectly with feedback about the intensity and direction of the intervention, for example when a braking system is used for the lane guidance, which is adapted for differently strong braking interventions on opposed sides of the motor vehicle. Subsequently, a haptic feedback provides information about the requested steering action in case of unilateral braking intervention. Finally, it has already been proposed to perform an intervention onto a transversal guidance actuator, which does not provide any information regarding direction and/or strength of the transversal guidance intervention to the driver. This is particularly used when only smaller steering corrections are performed.
The systems for driver assistance fundamentally require, at least in case of stronger transversal guidance interventions, a (permanently perusable) intuitive display regarding the strength and direction of intervention, since the intervention is otherwise surprising to the driver and thus unacceptable. The only medium suitable for providing a permanent indication of the driving direction is actually the steering handle, in particular the steering wheel, since for instance a haptic channel, which is provided by braking interventions, is only suitable for brief lane deviation alarms and similar, but not for lane tracking.
The different known variants have some disadvantages. A transversal guidance intervention without a coordinated notification is accepted, for example, only in case of minimal steering movements. If for example the transversal guidance system would steer around a curve, without correspondingly moving the steering handle, so that for instance the steering wheel remains in the zero position, then the driver would not accept this due to the inconsistency between the position of the steering handle and the yaw rate.
In case of a transversal guidance intervention by means of a unilateral braking intervention, for example, there is the problem that the braking or deceleration has first of all to be interpreted as a steering. In many motor vehicles, braking jolts occur, which have to be interpreted as a crash warning or similar, which, in case of additional use as a (short) steering notification, may cause confusion in the driver.
But also, the notification of a transversal guidance intervention on the steering handle, in particular the steering wheel, has problems. If the transversal guidance system sets off its information, that a transversal guidance intervention takes place, through the steering handle and/or if the steering handle itself is used, in order to perform the intervention, this overlaps, in an undefined and not reproducible way, with the existing desire for a nominal course by the driver, which uses the steering wheel, in fact, for implementing his or her own driving desires. In this way, the control sovereignty of the guider is influenced, so that the transversal guidance intervention may be perceived by the driver even as patronizing. Moreover, confusion may be caused regarding the responsibility of the vehicle guidance. For example, it may be unclear whether the transversal guidance system takes over the transversal guidance or even the entire vehicle control or whether a recommendation has to be reproduced. The driving direction is determined by an undefined mixed behavior; moreover, the use of the steering handle for back communicating regarding a performed transversal guidance intervention disturb the relationship between the steering moment and the steering angle, so that an inconsistent steering behavior is caused.
The object of the invention is thus to provide an improved possible implementation of transversal guidance interventions which do not patronize and/or confuse the driver and to provide the driver with information regarding transversal guidance interventions.
In order to achieve this object, in a method of above said type according to the invention, it is envisaged that for performing a transversal guidance intervention, a second transversal guidance actuator not acting on the steering handle in case of transversal guidance interventions is used and for notifying the transversal guidance intervention to the driver a notification roll angle of motor vehicle, which depends on at least one intervention parameter describing the transversal guidance intervention, instead of an influence on the steering handle is set up.
According to the invention, it is thus proposed that two separate complete channels (actuator and display) are formed for the transversal guidance, i.e., the first channel with the steering handle, in particular the steering wheel, and the first transversal guidance actuator and the second channel with the driving system and the second transversal guidance actuator. Both channels are thus independent from each other, at least with reference to the display, ideally also to the actuator. The transversal guidance system does therefore not engage the transversal guidance through the steering handle, but uses a transversal guidance actuator which cannot be felt on the steering handle. The steering handle is not used for displaying strength and direction of the transversal guidance intervention, too, while instead the direction and strength of the transversal guidance intervention are notified to the driver by means of a roll angle of the frame included in the motor vehicle. The control over the steering handle and thus also over the first channel remains exclusively to the driver.
Thus, it is possible for the driver to completely separate the transversal guidance by the driver from the transversal guidance by the transversal guidance system, since the transversal guidance system uses transversal guidance actuators, which are not felt on the steering handle, i.e., they don't influence neither the steering perception nor the steering wheel angle. In order to display the transversal guidance interventions, instead of the notification “steering wheel angle”, a roll angle is actively introduced in the motor vehicle and used as a display. The roll angle of the vehicle frame (and thus also of the motor hood) advantageously corresponds to the direction in which the transversal guidance system controls the motor vehicle. The roll angle is perceived by the driver in a visual and partially haptic/vestibular way. This notification through the roll angle is readily accepted by the river, since it is very intuitive (see the flight in an airplane).
As already mentioned, it is important that the steering handle remains untouched in case of transversal guidance interventions by the transversal guidance system, hence it remains in the zero position or in the position preset by the driver, after the used second transversal guidance intervention is notified through the alternative channel “roll angle” or “hood inclination relative to road”. Thus, no disturbance of the delicate relationship between driver and steering handle takes place. The steering feeling remains consistent. The driver may overlap the transversal guidance intervention as she wishes by means of her own channel, thus the steering handle, without perceiving corrective steering moments. A curve cutting during central lane tracking may for example be easily implemented by the transversal guidance system. In general, in central lane tracking the transversal guidance may keep the steering wheel essentially always in the zero position. Thus, the further advantage is obtained, that, for example, in case of highly automatic driving of the motor vehicle, it is possible to use the steering handle in another way, for instance as a support for mobile devices, in particular tablets and similar. Moreover, during vehicle driving, no question regarding competence or responsibility arise, since the driver keeps unbothered his sovereignty over the steering wheel.
Therefore, a clear separation between the potentials and responsibilities during a vehicle transversal guidance is provided. The vehicle guidance is determined by a defined behavior, since no unpredictable mixed reactions on the steering handle take place.
It is to be noted that embodiments may be devised, in which as a second transversal guidance actuator the first transversal guidance actuator is used, which is decoupled or may be decoupled from the steering handle. If for instance a front axle steering is influenced through the steering handle, as usually happens, no mechanical fixed coupling has to be necessarily present between the steering handle and the first transversal guidance actuator, but instead a so called “steer-by-wire” system may be implemented, which measures actuations of the steering handle and converts them in corresponding control commands for the first transversal guidance actuator. The control commands for the first transversal guidance actuator however may originate also from other vehicle systems, thus also from the transversal guidance system, so that the first transversal guidance actuator may also be used as a second transversal guidance actuator, since no feedback is provided from the transversal guidance actuator to the steering handle. In other cases, embodiments may also be provided, where, instead of “steer-by-wire” systems, in which the first transversal guidance actuator is not fixedly coupled to the steering handle, the first transversal guidance actuator is also used as a second transversal guidance actuator.
Within the scope of the present invention it is however preferred if an additional transversal guidance actuator, different from the first transversal guidance actuator, is uses as a second transversal guidance actuator. Then, also regarding the transversal guidance actuator a decoupling is provided, since a transversal guidance actuator, which cannot be perceived through the steering handle, may be used in a targeted way, such as a rear axle steering and similar, for example. Neither the steering feeling nor the angle of the steering handle are thus influenced, so that the separate complete channels may act in a completely separated way, with regard to intervention and notification.
Concretely, it may be that as a first transversal guidance actuator a front axle steering coupled in particular mechanically to the steering handle and/or as a second transversal guidance actuator a rear axle steering and/or a braking system and/or an overlapping steering and/or an active lane adjustment system and/or as a vehicle system for setting the notification roll angle an active propulsion system is used. In this context, the present invention thus uses the fact that modern motor vehicles are already provided with a plurality of transversal guidance actuators, for example, the usual power steering, an overlapping steering, a rear axle steering, the possibility of unilateral braking interventions, the so-called torque vectoring, wherein different torques are transmitted to opposed wheels, a tensioning steering, a possible active lane adjustment, or even a steering by roll angle introduction. Interventions through some of these transversal guidance actuators are not perceived by the driver on the steering handle, for example, interventions via del rear axle steering and similar. Such transversal guidance actuators are in particular suitable as second transversal guidance actuators, according to the above. Active transversal guidance systems may thus use one or more of the transversal guidance actuators as second transversal guidance actuators, in order to implement their transversal guidance intervention. Fundamentally, active drive systems are also already known in the art, wherein these systems may be provided with active stabilizers and/or full active driving units, which allow the setting of a roll angle independently from the driving situation and which may advantageously be used in the context of the present invention, in order to implement the notification system for transversal guidance interventions to be performed automatically.
The required notification roll angle, which visually corresponds ultimately to an inclination angle of the motor hood with respect to the road, should be selected to be sufficiently large, in order to provide a clear perception by the driver. In the context of the present invention, two special, particularly advantageous embodiments may be envisaged.
A first preferred embodiment of the present invention consists in that the notification roll angle is selected according to a virtual steering angle of the steering handle, which causes the same current transversal guidance effect provided by the transversal guidance intervention, in particular proportional to the virtual steering angle. For each transversal guidance intervention, at every time during the transversal guidance intervention, it may thus be determined which steering angle of the steering handle, in particular of the steering wheel, would be necessary in order to achieve the same transversal guidance effect. This virtual steering angle forms the base for the notification regarding the notification roll angle, so that the inclination of the motor vehicle caused by the notification is in particular proportional to a quasi-steering wheel angle as a virtual steering angle. The notification roll angle thus indicates a yaw rate initiated by the transversal guidance system, the value of which is similar to the steering angle of the steering handle, which would cause the same yaw rate in case of manual driving.
This has the advantage that ultimately a sort of “virtual steering handle rotation” is provided. In fact, the steering handle is also inclined relative to the environment in case of a vehicle inclination, so that the driver may peripherally perceive that for example the steering wheel, in particular by observing the steering wheel spoke, is, as usual, pointed in the direction of the curve. A consistent relationship between the yaw rate and the perceived steering angle is thus provided. However, no rotation has taken place with respect to the vehicle interior, so that there is no intervention on the steering handle and no influence on the steering sensation.
A second further advantageous embodiment of the present invention consists in that the notification roll angle is selected according to a currently acting transversal force due the transversal guidance intervention, in particular proportional to the transversal force. In this embodiment, the inclination of the motor vehicle is thus determined by the transversal force caused by the transversal guidance intervention of the transversal guidance system, so that the inclination may ultimately be understood—in connection with the previously discussed first concrete embodiment—for example as proportional to a quasi-steering wheel angle multiplied by the actual speed of the motor vehicle.
This embodiment has the particular advantage that the transversal guidance intervention can only be perceived in a purely visual way, since no transversal force is involved. The passengers driving in the vehicle along with the driver thus do not notice the transversal guidance intervention, which is advantageous in particular when the transversal guidance system corrects a driving error in the transversal guidance by the driver. The driving error by the driver thus remains undetected and the driving comfort of the passengers is not negatively impacted by the transversal guidance intervention.
A general advantageous embodiment of the present invention consists in that the notification steering angle is scaled depending on a preset by the driver. The use of the roll angle as a notification means for transversal guidance interventions thus also has the further advantage that the notification effect may be scaled, so that, in particular, going from a comfortable inclination of the vehicle chassis to a clearly perceivable abrupt inclination, based on the notification roll angle, a multitude of different intensities of the notification may be set, in particular in a driver-selectable way.
The inventive concept may be used in a variety of transversal guidance systems, so that as a transversal guidance system a lane tracking system and/or a safety system and/or a vehicle guidance system used for full automatic motor vehicle guidance may be used. In functional terms, the described concept may thus be used, for example, for a lane centering guidance, in active lane-abandoning alerts, in active lane-change warnings, in active lane change assistance and in avoidance maneuvers, in order to avoid collisions and/or in order to reduce the consequences of collisions. Obviously, the use for highly automated and fully automated motor vehicles may also be envisaged, wherein, even in the case where interventions by the driver are prevented, the steering handle, in particular a steering wheel, may remain in the zero position, so that for example surfaces of the steering handle, such as a steering wheel surface, may be used as a display or similar.
An elaboration of the method consists in that, in case of fulfillment of a criticality criterion indicating a situation that requires the attention of the driver, for a planned transversal guidance intervention by the transversal guidance system, the latter controls the steering handle in order to output an indication signal, which attracts the attention of the driver. This means that in rare exceptional situations, the complete separation of the transversal guidance system from the steering handle may be deactivated, i.e., when a particular critical traffic situation ensues, which requires a particular attention by the driver, who thus has to monitor the same. It has been shown that exactly when interventions by the transversal guidance system are not indicated through the steering handle, the steering handle represents an excellent medium for informing the driver about an exceptional situation occurring, which requires her full attention. This holds in particular when the steering wheel is very near to the driver and possibly used, as already mentioned, for other tasks, such as a support.
Concretely, it may be envisaged, that a deviation of the steering handle is outputted, which indicates the direction of the planned transversal guidance intervention, in particular when this deviation does not influence the first transversal guidance actuator (steer-by-wire). Within this concept the case is also included, where the transversal guidance intervention is notified through the steering handle, alternatively or additionally to the notification roll angle. In addition, or as an alternative, the steering wheel signal may be outputted as a vibration and/or oscillation of the steering handle.
In an embodiment, the or at least one criticality criterion may describe the system approaching a limit of the transversal guidance system, while dropping below at least one threshold value. In particular when the capacities of the transversal guidance system are almost completely exhausted, a higher attention by the driver is appropriate.
The invention also refers to a motor vehicle, which is provided with a first transversal guidance actuator, which is controlled by a steering handle operated by the driver, in particular a steering wheel, at least one transversal guidance system adapted for performing automatic transversal guidance interventions, which is characterized in that the transversal guidance system is adapted for performing automatic transversal guidance interventions by means of an additional second transversal guidance actuator, which does not act on the steering handle in case of transversal guidance interventions, and for notifying the transversal guidance intervention by setting a notification roll angle by means of the vehicle system. The transversal guidance system may in particular have a control device, which is adapted for performing the inventive method. All embodiments regarding the inventive method may be analogously be applied to the inventive motor vehicle, which therefore provides the same already mentioned advantages of the inventive method.
Further advantages and details of the present invention may be obtained from the following exemplary embodiments as well as from the drawings. In particular:
The steering handle 2 and the first transversal guidance actuator 3 thus form a complete channel for transversal guidance of the motor vehicle, which is completely under the control of the driver 1.
The motor vehicle, in the present case, also has a transversal guidance system 6, which is adapted for performing automatic transversal guidance interventions, for example a driver assistance system for central lane guidance. In order to implement the transversal guidance interventions, a second transversal guidance channel, completely independent from the described first transversal guidance channel is provided, in which the transversal guidance system 6 initially uses, in order to implement the transversal guidance intervention, according to arrow 7, a second transversal guidance actuator 8 different from the first transversal guidance actuator 3, such as a rear axle steering, for example. This means that the implementation of the transversal guidance interventions does not influence the steering handle 2 in any way.
In order to nonetheless inform the driver 1 about the transversal guidance intervention by the transversal guidance system 6, according to arrow 9, a vehicle system 10, in this case an active driving system, is controlled in such a way that a notification roll angle for the motor vehicle, which indicates the strength and direction of the transversal guidance intervention, is set, and this angle is perceived by the driver 11 according to arrow 11. This means that the steering handle 2 is used neither based on the implementation of the transversal guidance intervention nor by direct control, in order to convey to the driver 1 the strength and direction of the automatic transversal guidance intervention, but through a lateral inclination of the chassis of the motor vehicle, which may be perceived and interpreted by the driver in particular by means of the inclination of the motor hood with respect to the environment surrounding the motor vehicle.
Due to the fact that the first transversal guidance channel with the steering handle 2 remains completely untouched, the delicate interaction between the driver and this manual transversal guidance channel does not vary. The driver may use it as normal and according to their experience, even without feeling patronized. At the same time, however an extremely intuitive feedback is provided by the notification roll angle.
It is to also to be noted, at this point, that embodiments may also be envisaged, in which the first transversal guidance actuator 3 corresponds to the second transversal guidance actuator 8, if the first transversal guidance actuator 3 is decoupled or may be decoupled from the steering handle 2, since then transversal guidance interventions performed by the first transversal guidance actuator 3 do not necessarily cause a feedback to the steering handle 2; in order to get the steering feeling it is however preferred that the first transversal guidance actuator 3 and the second transversal guidance actuator 8 are different from each other.
In order to indicate the direction of the transversal guidance intervention, the motor vehicle is ultimately tilted towards the curve inner side, i.e., according to the direction of the transversal guidance intervention by a corresponding sign of the notification roll angle. In order to intuitively indicate the strength of the transversal guidance intervention via the notification roll angle, two possibilities exist. On one hand, the notification roll angle may be selected to be proportional to a virtual steering angle of the steering handle 2. This may be readily derived from the known properties of the first transversal guidance channel. Alternatively, it is possible to select the notification roll angle to be proportional to the transversal force, which is caused by the transversal guidance intervention.
It is also possible to render the strength of the notification regarding the notification roll angle to be influenced by the driver, since it may be scaled. This may be accomplished, for example, through a corresponding setting on a human-machine-interface.
The motor vehicle 13 is provided, completely independently from the above, with a transversal guidance system 6, in this case a driver assistance system for lane central tracking, the operation of which is controlled by a control device 12, which is adapted for performing the inventive method. To this end, the control device 12 is connected to the second transversal guidance actuator 8 configured as a rear axle steering, and the vehicle system 10, which is configured as an active driving system.
Finally, it is also to be noted that embodiments may be envisaged, which, in situations requiring the attention of the driver, may differ from a strict separation of formed channels. Exactly because of the fact, that usually transversal guidance interventions by the transversal guidance system 6 are not notified on the steering handle 2, these embodiments are particularly suitable for indicating critical situations. Since transversal guidance interventions are usually pre-planned (pre-control), for example based on predictive data regarding the track profile, transversal guidance interventions may also be judged in an early stage, on whether the attention of the driver is required, for example, because the transversal guidance system 6 is approaching the limits of the system. This can be described by at least one criticality criterion. If this criterion is fulfilled, then the transversal guidance system 6 outputs an indication signal regarding the steering handle 2.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 005 975.0 | May 2015 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/000438 | 3/11/2016 | WO | 00 |
