METHOD FOR PROVIDING ASSISTANCE TO A DRIVER OF A VEHICLE AND DRIVING ASSISTANCE SYSTEM

Abstract

A method for providing assistance to a driver of a vehicle, the vehicle including a driver assistance system that enables at least temporary autonomous driving, and that, after the termination of the autonomous driving, requests the driver to take over at least the lateral guidance of the vehicle via a signal. It is further provided that the steering of the vehicle is stiffened for a specified time span after the request to take over the lateral guidance. A computer program and a device that are set up to carry out the method, are also described.

Claims

1-10. (canceled)

11. A method for assisting a driver of a vehicle, the vehicle including a driver assistance system that enables at least temporary autonomous driving, the method comprising: after the termination of the autonomous driving, requesting, via a signal, the driver to take over the guidance of the vehicle; and stiffening steering of the vehicle for a specified time span after the request to take over the lateral guidance.

12. The method as recited in claim 11, wherein the stiffening of the steering takes place through at least one of: (i) reduction of a steering support within the specified time span, and (ii) application of a counter-torque that is opposed to a steering movement of the driver when the steering movement takes place within the specified time span.

13. The method as recited in claim 11, wherein, to stiffen the steering during the specified time span, a steering ratio is changed in such a way that steering wheel rotations result in reduced wheel steering angle rotations.

14. The method as recited in claim 11, wherein a strength of the stiffening is carried out as a function of the driving speed of the vehicle, the stiffening increasing as the speed of the vehicle increases.

15. The method as recited in claim 11, wherein the stiffening of the steering of the vehicle takes place as a function of the steering direction, the stiffening being stronger when steering takes place in a direction of an obstacle or a lane boundary than when steering takes place in the direction of an open surface.

16. The method as recited claim 11, wherein one of: (i) the specified time span for the stiffening of the steering begins at a time at which the driver grasps a steering wheel, or (ii) the specified time span begins at a time at which the driver begins steering.

17. The method as recited in claim 11, wherein the specified time span is selected as a function of at least one of a speed of the vehicle, a distance from an obstacle, and a distance from a lane boundary.

18. A non-transitory computer readable storage medium on which is stored a computer program for assisting a driver of a vehicle, the vehicle including a driver assistance system that enables at least temporary autonomous driving, the computer program, when executed by a computer, causing the computer to perform: after the termination of the autonomous driving, requesting, via a signal, the driver to take over the guidance of the vehicle; and stiffening steering of the vehicle for a specified time span after the request to take over the lateral guidance.

19. A driver assistance system, the driver assistance system including a control device that permits at least temporary autonomous driving of a vehicle, wherein the control device is set up to stiffen a steering of the vehicle for a specified time span.

20. The driver assistance system as recited in claim 19, wherein the control device is designed to: after the termination of the autonomous driving, request, via a signal, a driver to take over the guidance of the vehicle; and stiffen steering of the vehicle for the specified time span after the request to take over the lateral guidance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Exemplary embodiments of the present invention are shown in the figures and are explained in more detail below.

[0038] FIG. 1 shows a vehicle driving into a construction site area.

[0039] FIG. 2 shows the stiffening of the steering by reducing the steering support.

[0040] FIG. 3 shows the stiffening of the steering through the application of a counter-torque.

[0041] FIGS. 4A and 4B show the stiffening of the steering by reducing the steering ratio.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0042] In the following description of exemplary embodiments of the present invention, identical or similar components have been designated with identical reference characters, and a repeated description of these components in individual cases is omitted. The Figures represent the subject matter of the present invention only schematically.

[0043] FIG. 1 shows a vehicle entering a construction site area.

[0044] FIG. 1 shows a vehicle 10 traveling on a street 12. On street 12 there are situated markings 14, 15. Roadway boundaries 14 limit the drivable area of street 12. Lane markings 15 divide street 12 into two lanes. Vehicle 10 is situated in the right lane.

[0045] Vehicle 10 includes a control device 20 that is connected to distance sensors 26 and a camera 24. In addition, control device 20 is set up to take over both the longitudinal guidance and the lateral guidance of vehicle 10, so that fully autonomous driving is enabled. The possibility of lateral guidance is indicated in FIG. 1 by a connection between control device 20 and a steering wheel 22 of vehicle 10. The vehicle further includes a GPS receiver 28 in order to provide satellite navigation data to control device 20.

[0046] For fully autonomous driving of vehicle 10, the environment surrounding vehicle 10 is monitored for obstacles using distance sensors 26. In addition, camera 24 acquires both lane boundary 14 and lane markings 15 on street 12, so that vehicle 10 can follow the right lane of street 12 without intervention by the driver. Vehicle 10 thus automatically follows the course of street 12, and the driver of vehicle 10 merely has to monitor the driving process.

[0047] In a construction site area 18 on street 12, however, neither roadway boundaries 14 nor lane markings 15 are available. Instead, in construction site area 18 the lane is identified by traffic cones 16.

[0048] In the situation shown in FIG. 1, the driver assistance system of vehicle 10 implemented by control device 20 must hand over at least the lateral guidance to the driver of vehicle 10, because the further course of the lane is no longer guaranteed by the acquisition of roadway boundaries 14 and lane markings 15 by camera 24. The necessity of taking over the lateral guidance is communicated to the driver via corresponding means, such as an acoustic or an optical signal.

[0049] In order to give the driver an adequately long takeover time within which, after the signal has been made to take over the lateral guidance, the driver can orient himself and gain an overview of the traffic situation, in the case of known construction site areas 18 the signal for this can be outputted already before reaching construction site area 18. For this purpose, the position of vehicle 10 is ascertained using GPS receiver 28 and, as the vehicle approaches construction site area 18, the time of the request to take over lateral guidance is given when, taking into account the speed of vehicle 10, vehicle 10 is for example 7 seconds away from construction site area 18.

[0050] When the driver of vehicle 10 grasps steering wheel 22, an inadvertent steering wheel rotation, or oversteering, may occur. It is then possible that vehicle 10 will depart from the lane, and will either move from the right lane into the region of the left lane, or will completely leave street 12, which could result in an accident. In order to avoid an unintentional steering wheel rotation or oversteering, according to the present invention it is provided to stiffen the steering of vehicle 10 temporarily for a specified time span.

[0051] For the stiffening of the steering, control device 20 can act on a steering support unit 23. Such a steering support 23, for example realized as a servo steering, acquires the torque, for example 1.5 Nm, applied to the steering linkage by the driver through rotation of steering wheel 22. Subsequently, as a function of a gain factor a steering actuator is actuated by steering support 23, and an additional steering torque is produced. If for example the gain factor is 10, then, in the example, for a steering torque of 1.5 Nm applied by the driver, an additional steering torque of 15 Nm is produced by the steering actuator. For the stiffening of the steering, the gain factor is set to a lower value, for example a value of 1, for a specified time span, for example 700 ms. Within the specified time span in which the steering is stiffened, the driver then has to exert a significantly larger steering torque than in the normal state. In this way, it is made more difficult for the driver to rotate the steering wheel, which prevents inadvertent rotation or oversteering. In further specific embodiments of the present invention, it is in addition possible, in order to stiffen the steering, to produce a counter-torque opposed to the steering torque applied by the driver, or to reduce the steering ratio between the deflection of the steering wheel and the resulting rotation of the front wheels of vehicle 10.

[0052] FIG. 2 shows the stiffening of the steering through the reduction of a steering support.

[0053] In FIG. 2, a diagram is shown that shows the gain factor of a steering support, in particular a servo steering, as a function of time. In FIG. 2, the temporal curve of gain factor F is identified with reference character 30.

[0054] In the depicted example, gain factor F is normally 7, and at time t.sub.0, at which specified time span T begins, it is reduced to the factor 1. The specified time span T ends at time t.sub.1, and here gain factor F again reaches its normal value of 7. Within specified time span T, gain factor F varies, increasing over time.

[0055] FIG. 3 shows the stiffening of the steering through the application of a counter-torque.

[0056] FIG. 3 shows the curve of a steering torque 32 applied by the driver, as well as of a counter-torque 32, over time t, torques M being indicated in units Nm. Here it is provided to set the gain factor of the steering support, or the servo steering, to a value of for example −0.8 within specified time span T. In this way it is achieved that an opposite counter-torque is produced corresponding to steering torque 32 applied by the driver. The counter-torque increases in its magnitude when the steering torque applied by the driver increases, and decreases when steering torque 32 applied by the driver decreases. Here, the maximum magnitude of −2 Nm of counter-torque 34 corresponds to the maximum value of steering torque 32 of 2.5 Nm for the case in which the gain factor is set at −0.8. In the example shown in FIG. 3, during specified time span T, which begins at time t.sub.0 and ends at time t.sub.1, the gain factor is held constant at the value −0.8. In further specific embodiments, however, it would be possible to select the gain factor to be variable, similar to the manner described with reference to FIG. 2.

[0057] FIGS. 4A and 4B show the stiffening of the steering through the reduction of the steering ratio.

[0058] In FIG. 4A, steering wheel angle α for the steering wheel rotation over time t is shown as curve 36. In FIG. 4B, for this purpose the actual rotation of the front wheels is shown in the form of a wheel steering angle β, as curve 38. In the example shown in FIGS. 4A and 4B, the steering ratio is changed by a factor of 4 during specified time span T, and is thus 56:1. Normally, the steering ratio is 14:1. Due to the reduced steering ratio during specified time span T, a steering movement of the driver is transmitted to the front wheels only to a reduced degree. Thus, for example, given a steering wheel rotation of 16°, a wheel steering angle rotation of only 0.25°, instead of 1°, is transmitted to the front wheels of the vehicle.

[0059] The present invention is not limited to the exemplary embodiments described here or to the aspects emphasized therein. Rather, within the scope of the present invention, a large number of modifications are possible that are within the competence of those skilled in the art.