Longitudinal Control System for a Motor Vehicle

Abstract

A longitudinal control system is provided for a motor vehicle equipped with a sensor system for detecting a traffic event lying ahead, in particular in order to locate vehicles traveling ahead, and a control unit for automatically controlling the speed or the acceleration of the motor vehicle to a standstill on the basis of the traffic event lying ahead. An automatic drive-off is allowed without a driver confirmation within a specified time interval after reaching the standstill, and after the time interval has expired, an automatic start-up is allowed after a start-up confirmation is triggered by the driver. A start-up confirmation is triggered if a contacted state of the steering wheel is detected starting from a non-contacted state of the steering wheel.

Claims

1. A longitudinal control system for a motor vehicle having a sensor system that detects a traffic event lying ahead and having a control unit that automatically controls a speed or acceleration of the motor vehicle to a standstill state and out of the standstill state based on the traffic event lying ahead, wherein automatic driving off is allowed without a driver confirmation within a predefined time interval from a time when the standstill state has been reached, and after the predefined time interval has expired the automatic driving off is not allowed until a driver triggered starting confirmation is provided, the method comprising the acts of: starting from a non-contact state of a steering wheel of the motor vehicle, detecting a contacted state of the steering wheel; and triggering a starting confirmation if the contacted state of the steering wheel is detected starting from the non-contacted state of the steering wheel.

2. The longitudinal control system as claimed in claim 1, wherein the starting confirmation is triggered if a contacted state of the steering wheel is detected in a defined activation mode starting from the non-contacted state of the steering wheel.

3. The longitudinal control system as claimed in claim 2, wherein the defined activation mode is a defined contact position and/or a defined contact sequence with respect to the steering wheel.

4. The longitudinal control system as claimed in claim 1, wherein the contacted state is detected if the driver touches the steering wheel in a defined contact region with at least one hand.

5. The longitudinal control system as claimed in claim 1, wherein the contacted state is detected when the driver applies a predefined contact pressure when touching the steering wheel with at least one hand.

6. The longitudinal control system as claimed in claim 1, wherein the contacted state is detected when the driver performs a predefined contact sequence at the steering wheel with at least one hand.

7. The longitudinal control system as claimed in claim 6, wherein the predefined contact sequence is performed in combination with defined contact positions with respect to the steering wheel.

8. The longitudinal control system as claimed in claim 1, wherein a contacted state is detected when the driver lets go of the steering wheel within a time interval which starts when the steering wheel is first touched, and the driver then touches the steering wheel again at least one more time.

9. The longitudinal control system as claimed in claim 1, wherein a contacted state is detected with a sensor system which is arranged in the steering wheel and/or with a camera system which captures at least a region of the steering wheel.

10. The longitudinal control system as claimed in claim 9, wherein the sensor system which is arranged in the steering wheel is a sensor system which measures capacitance in the steering wheel.

11. The longitudinal control system as claimed in claim 4, wherein the contacted state is detected if the driver touches the steering wheel in the defined contact region with both hands.

12. The longitudinal control system as claimed in claim 5, wherein the contacted state is detected when the driver applies the predefined contact pressure when touching the steering wheel with both hands.

13. The longitudinal control system as claimed in claim 1, wherein the traffic event lying ahead is a location of a vehicle traveling ahead.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is a simplified design of a longitudinal control system which serves as an example of the invention.

[0019] FIG. 2 is a flow chart of a possible refinement of the longitudinal control system for convenient automatic starting from a standstill state.

DETAILED DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 shows, as a central element of the longitudinal control and speed control system, a control unit SE which receives various input signals sHOS, sKS, fv, sS and v and generates an output signal and a.

[0021] Basically, the control unit SE is configured in such a way that, on the basis of the signals sS of a sensor system S and of the driver inputs fv predefined by the driver by means of a manual input unit mEE (e.g. target speed and/or distance range to be maintained from a vehicle traveling ahead), it outputs an acceleration signal a to a corresponding actuator system Ak. The actuator system Ak comprises a drive unit A and a brake unit B, for implementing the acceleration request. The sensor system S is configured here in such a way that the traffic event lying ahead can be detected by way of a radar system and/or a camera system, and therefore vehicles ahead which are relevant, in particular, for the speed control can be identified. These relevant data sS are transmitted to the control unit SE for further processing, with a result that in the case of so-called unobstructed travel the control takes place in such a way that the target speed fv which is predefined by the driver is set, and in the case of so-called follow-on travel (relatively slow vehicle traveling ahead) the control is carried out in such a way that a distance which is to be maintained in accordance with the driver setting fv is ensured. Basically, the control can be carried out as far as the stationary state and from the stationary state.

[0022] Furthermore, the control unit SE receives a speed signal v so that a standstill state of the vehicle which is reached on the basis of the speed control can be detected. The control unit SE is also connected to a sensor system HOS which is arranged in the steering wheel L. In addition, the control unit SE can be connected to a passenger compartment camera system KS (illustrated by dashes here). These sensor systems transmit a signal sHOS and, if appropriate, a signal sKS to the control unit SE in order to transmit information as to whether the driver has his hands on the steering wheel and/or when the driver has his hands on the steering wheel (at a defined position).

[0023] One possible refinement of the longitudinal control system for comfortable automatic starting out of the standstill state is now illustrated on the basis of the following description with respect to FIG. 2, wherein it is assumed that the relevant control unit is correspondingly designed to detect and process relevant input signals and output corresponding output signals to the actuator system for controlling the speed.

[0024] The flow chart starts in step 10 as soon as the distance-controlled speed control system ACC is switched on and active. As soon as the speed control system is activated, in step 20 the speed or acceleration control process a starts as a function of the target speed set by the driver, taking into account the traffic event lying ahead. The result is that in the case of unobstructed travel the target speed which has been set is maintained, and in the case of follow-on travel a necessary distance from the vehicle traveling ahead is maintained.

[0025] If the vehicle is itself controlled to a standstill statefor example owing to braking of the vehicle traveling ahead to the standstill stateso that the speed v of the vehicle is zero, a timer T is started when the standstill state (v=0 in step 30) is reached in the next step 40.

[0026] As soon as it is detected in the next step 50 that the vehicle could drive off again (in the near future) owing to the changed traffic situation (driving off condition satisfied), in the next step 60 it is interrogated whether the time dt which has passed since the starting of the timer T is (still) shorter than a predefined first time interval T1 within which automatic starting without a driving off confirmation is permitted. If this is the case, the system jumps back from step 60 to step 20, and automatic driving off, that is to say a corresponding speed control process, is brought about.

[0027] However, if it is determined in step 60 that the time dt which has passed since the starting of the timer T is not shorter than a predefined first time interval T1, in the next step 70 a message (visual and/or haptic and/or acoustic) requesting the vehicle to permit the automatic starting is output. The system then progresses to step 80.

[0028] The system stays in step 80 until a starting confirmation from the driver is registered. Depending on the configuration of the system, various possible ways for outputting a starting confirmation can be provided. According to the invention, e.g. a starting confirmation is registered if a contacted state H-On of the steering wheel is detected starting from a non-contacted state H-Off of the steering wheel. In this example, a contacted state H-On is detected if the driver grasps the steering wheel rim with both hands. Alternatively, a starting confirmation is also registered if (slight) activation of the accelerator pedal is detected.

[0029] As soon as a corresponding starting confirmation is detected, the system jumps back from step 80 to step 20 and automatic driving off, that is to say a corresponding speed control process, is brought about.

[0030] Many advantages can be achieved by means of the longitudinal control system according to the invention as proposed here. For example, the inventive configuration of the starting confirmation has a positive effect on the traffic flow, since a driver who has firstly taken his hands off the steering wheel in the standstill state will initially return his hands to the steering wheel before he triggers another action to confirm automatic starting.

[0031] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.