DE102013013232A1 - Driver assistance system and operating method for a driver assistance system for vehicle longitudinal steering - Google Patents

Abstract

The invention relates to a driver assistance system (100) for longitudinal vehicle control of a vehicle (1) with regard to a foreign vehicle (2), preferably for speed and / or distance control. The invention further relates to an operating method for a driver assistance system (100) for longitudinal vehicle control of a vehicle (1). The operating method includes a longitudinal vehicle control as a function of at least one current road-specific parameter (107, 108) and / or at least one current vehicle-specific parameter (106).

Description

The invention relates to a driver assistance system for vehicle longitudinal control of a vehicle with respect to a foreign vehicle, preferably for speed and / or distance control. The invention further relates to an operating method for a driver assistance system for vehicle longitudinal control of a vehicle.

In particular, professional drivers have been burdened for several years while driving with an increase of information about the vehicle condition, the road and environmental conditions and with logistics information. This development was taken into account by the vehicle manufacturers by introducing driver assistance systems to relieve the driver of the vehicle. For the area of vehicle longitudinal control, actively intervening control systems have gone into series production, which act both in uncritical - in the sense of an accident risk - driving situations and in critical driving situations.

A system for longitudinal control in uncritical situations, for example, the cruise control with acceleration function and spacing with low delay effect (maximum about -0.3 g). An emergency brake assist, on the other hand, works in critical driving situations to avoid a rear-end collision with a high deceleration effect (maximum about -0.8 g).

However, such current series systems lack sufficient supply of up-to-date driving status and environmental information in order to be able to ensure an equally good effect in different driving situations. Such systems are therefore insufficiently adapted to adapt the vehicle's longitudinal control to the various traffic and driving situations occurring in real traffic. The distance control of such systems is therefore often provided with an additional safety buffer, which adjusts the vehicles to a greater distance than actually necessary, in order to prevent a collision can occur due to unforeseen deviations of the assumptions regarding the braking behavior. However, this leads to an inefficient use of traffic space and a lack of acceptance of such systems, especially when used in commercial vehicles.

A manual readjustment of the respective control system by the driver can take place due to safety only in non-critical situations. In addition, the setting selected by the driver may not be the most appropriate setting for the current driving situation, so that a manual readjustment is error-prone.

It is an object of the invention to provide a driver assistance system and a corresponding operating method that can better adapt the vehicle longitudinal control to different traffic and driving situations in order to reduce the risk of collision with another vehicle by adapting the distance to the situation while at the same time enabling efficient utilization of the traffic space.

The objects described above are achieved according to the invention by an operating method for a driver assistance system for vehicle longitudinal control according to claim 1, and by a driver assistance system for vehicle longitudinal control according to claim 11. Preferred embodiments of the invention are described in the dependent claims.

In the operating method according to the invention for a driver assistance system for longitudinal vehicle control of a vehicle with respect to a foreign vehicle, the vehicle longitudinal control takes place as a function of at least one current road-specific parameter and / or at least one current vehicle-specific parameter. The at least one current vehicle-specific parameter may include, for example, a load state, a state of the brake system and / or a tire-specific parameter of the vehicle.

The term "current" means that the parameter values during operation of the vehicle, for example while driving, are determined virtually in real time and continuously updated. The vehicle longitudinal control is preferably used for speed and / or distance control.

In an advantageous embodiment, the current road-specific parameter describes the current state of the road on which the vehicle is currently driving, in particular a state of the road surface or of the road surface.

A particularly advantageous road-specific parameter is the road friction coefficient, since differences in the road friction coefficient have a high influence on the braking deceleration capacity of both the vehicle and the other vehicle and thus significantly influence the required safety distance.

Furthermore, a predefined number of road condition classes and / or road friction coefficient classes can be provided, wherein at least one of these classes is selected on the basis of the currently determined road-specific parameter and taken into account for vehicle longitudinal regulation.

Preferably, the operating method further comprises the step of determining a vehicle class of a foreign vehicle, wherein the vehicle longitudinal control takes place as a function of at least one derived from the particular vehicle class parameter. For example, depending on the particular vehicle class of the other vehicle, the specific braking deceleration capacity of the vehicle class can be determined. This has the advantage that the determination of the required safety distance in the vehicle longitudinal control can be adapted situationally to the pairings of the vehicle class of the vehicle and foreign vehicle.

A particularly accurate longitudinal control to the actually required safety distance is made possible if the longitudinal control is carried out as a function of both the current road-specific parameter and the vehicle class of the other vehicle. Thus, the present method of operation preferably further comprises adapting a known parameter relating to a braking deceleration capability of the own vehicle as a function of the current road-specific parameter and determining a parameter relating to a braking deceleration capability of the other vehicle depending on the particular vehicle class of the other vehicle and the current road-specific parameter. In this case, the vehicle longitudinal control takes place as a function of the parameters relating to the braking deceleration capacity of the vehicle and the foreign vehicle.

In the case of unfavorable road friction coefficients, in particular during rainfall, above all the comparatively high braking deceleration capacities of sports cars or motorcycles are very heavily leveled due to road friction friction, so that sometimes even a deterioration in comparison to the mass of all vehicles can occur. This results, for example, from the floating of extremely wide tires for lack of rapid water displacement from the tire tread. In such road conditions, a heavy truck may have a comparable or even better braking performance than a sports car, so that the safety distance of a truck to a preceding motorcycle can be shortened in favor of traffic space use compared to a dry asphalt pavement safely. Thus, the actual required safety distance varies greatly depending on the respective vehicle classes of the own vehicle and the foreign vehicle taking into account the current road condition, which can be considered according to the present invention in the longitudinal control.

The vehicle classification of the foreign vehicle is preferably based on a determination of the rear silhouette of the preceding foreign vehicle. For example, a distance, a height and / or a width of the other vehicle can be determined in order to determine the rear silhouette of the other vehicle. Since different classes of vehicles, such as motorcycles, sports cars, cars or trucks have different typical heights and / or widths, the vehicle class can be determined for example by means of radar sensors based on these dimensions or the resulting rear skyline.

According to an alternative embodiment, vehicle-specific parameters of the foreign vehicle, such as its class or its braking deceleration, can be received directly by vehicle-to-vehicle communication from this other vehicle, so that the vehicle longitudinal control takes place depending on the received vehicle-specific parameters of the other vehicle. This has the advantage that such parameters need not be determined by the vehicle itself, but can be received directly from the other vehicle while avoiding any measurement inaccuracies. However, this presupposes that both the vehicle and the foreign vehicle are set up to transmit or receive such data. Alternatively, the vehicle could also receive such vehicle-specific parameters of the other vehicle from a stationary roadside transmit station.

The accuracy of the vehicle's longitudinal control can also be improved by determining one or more current vehicle-specific parameters that affect the vehicle's deceleration capability and are incorporated into the vehicle's longitudinal control.

Preferably, a current vehicle-specific parameter includes the vehicle type of the own vehicle. The vehicle type of the own vehicle is by design known from the outset and either fixed in the driver assistance system or is set once when starting operation.

Furthermore, the current vehicle-specific parameter may include a load state. The load condition may be determined as the current weight of the vehicle, the current weight of a trailer, and / or the current weight of a load. In particular, in commercial vehicles, the current vehicle weight can vary greatly by loading or people. Since the vehicle-specific deceleration capacity is dependent on the current load, a more accurate longitudinal vehicle control can be achieved when the vehicle load is currently detected and incorporated into the vehicle longitudinal control. Similarly, the accuracy of the vehicle longitudinal control can be improved if the presence of a trailer is detected and incorporated into the vehicle's longitudinal control.

Furthermore, the current vehicle-specific parameter may also specify whether a trailer is attached or uncoupled. By coupling or uncoupling a trailer or trailer arise strong differences in braking (acceleration) assets, so that it is advantageous to recognize the true state of the entire vehicle and to consider when setting the safety distance.

According to a further advantageous embodiment, one or more tire-specific parameters of the own vehicle are recorded, which flow into the longitudinal control. Examples of tire-specific parameters are the tire air pressure, the tire condition and / or a tire class. Thus, variations in road-tire friction caused solely by the tire type or the tire class can greatly affect the braking deceleration capability of the vehicle. Depending on the tire type, summer, winter, year-round or off-road tires have different friction characteristics between the road and the tire. Consequently, with an additional consideration of the tire type as a parameter in the longitudinal control, improved accuracy can be achieved. In a comparable manner, fluctuations in the friction between the road surface and the tire result, in particular in the event of precipitation, for different tire tread depths.

Furthermore, it is advantageous if in addition the state of the brake system as a vehicle-specific parameters flows into the longitudinal control. Both the current load and the maintenance condition of the brake system on your own vehicle can have a significant impact on the deceleration of your own vehicle. For example, drum brakes under load greatly reduce the sometimes unequal extent of the pot-shaped drum under load. Likewise, the effect of the brake pads can be reduced by heat and wear.

Preferably, the operating method is further set up to determine a three-dimensional trajectory of the foreign vehicle and a three-dimensional trajectory of the own vehicle and to calculate the vehicle longitudinal control as a function of the determined trajectories. By taking into account the three-dimensional trajectories of both the own vehicle and the other vehicle slopes and gradients and the associated changes in the braking deceleration of both the vehicle and the other vehicle by the influence of Hangab- / slope buoyancy force can be considered. Additionally or alternatively, the road type and the three-dimensional course of the trajectory of the road can be determined and incorporated into the longitudinal control.

The driver assistance system according to the invention for longitudinal vehicle control of a vehicle with respect to a foreign vehicle comprises, in particular, a control unit which is set up to carry out the operating method as described above. The aspects of the operating method described above thus also apply to the control unit of the driver assistance system.

Preferred embodiments of the present invention will be described below, by way of example and by way of example, with reference to the accompanying drawings.

1 shows a block diagram and illustrates by way of example the determined data and calculated functional quantities of a driver assistance system according to an embodiment;

2 shows a table with typical braking deceleration capability depending on various lane and vehicle specific parameters according to an embodiment;

3 illustrates the distance and angle of incidence between the vehicle and other vehicle and the recognition of the vehicle class according to an embodiment;

4 shows a flowchart for illustrating a control sequence for a typical driving situation according to an embodiment;

5A and 5B illustrate schematically the recognition of the road course on the basis of the change of the vehicle silhouettes according to an embodiment;

6 shows a flowchart for illustrating a control sequence for a further driving situation according to an embodiment;

7A schematically illustrates the in the flowchart of 6 described driving situation;

7B schematically illustrates a reaction phase that the driver in the flowchart according to 6 is granted;

8th shows a flowchart for illustrating a control sequence for a further driving situation according to an embodiment; and

9 schematically illustrates the driving situation according to the flowchart 8th ,

The block diagram of 1 illustrates the sensors and data used 101 and the functional variables determined therewith 103 to 112 that can be included in the distance regulation. The sensors and data used 101 include the current wheel speed, suspension speed, outside temperature, tire temperature and axle load. The sensors and data used 101 Furthermore, GPS data, navigation data or data, which are determined by means of laser sensors, radar sensors, an inclination sensor, ultrasonic sensor, a camera sensor or other sensor variables. In the aforementioned data and sensors 101 These are measured variables and sensors known from the automotive industry.

This collected data 101 be over a data connection 102 to a driver assistance system for vehicle longitudinal control 100 transmitted. By means of the transmitted data 101 become several function variables or lane and vehicle-specific parameters 103 to 112 determined in the distance control of a controller unit 114 incorporated.

A known from the prior art function variable for longitudinal control is the own driving speed 103 of the vehicle 1 , This can be determined by the wheel speed and / or GPS data.

The most recently measured shortest distance 104 to the foreign vehicle 2 and its change can be determined, for example, by means of radar signals, which at the other vehicle 2 be reflected. From your own driving speed 103 and the time course of the measured distance to the other vehicle 2 can the driving speed 103 of the foreign vehicle 2 as well as a timely braking or acceleration behavior of the other vehicle 2 and the vehicle 1 be determined. The shortest distance is in 3 as the length of the arrow 104 shown. In a straight or slightly laterally offset third party vehicle 2 (upper vehicle in 3 ), the distance is substantially equal to the distance from the front of the vehicle 1 to the middle of the rear silhouette of the other vehicle 2 , In a laterally approaching from behind another vehicle 2 (lower vehicle in 3 ), the shortest distance becomes substantially different from that of the vehicle 1 facing, front side body portion of the other vehicle 2 certainly.

If the direction of travel between your own vehicle 1 and foreign vehicle 2 is not identical, is the angle of incidence 105 between vehicle 1 and foreign vehicle 2 an important for the longitudinal control size, especially in lateral approach or Einschervorgängen of foreign vehicles 2 , As in 3 illustrated, is the angle of incidence 105 the angle between the direction of travel 3 of the vehicle 1 and the distance vector 104 to the foreign vehicle 2 and can, for example, by means of a radar sensor 6A be determined. The angle of incidence 105 and the measured shortest distance 104 or their chronological course significantly determine the danger and the risk of collision of the temporal course of the traffic situation.

As in 1 further shown, will continue to be different vehicle parameters 106 of your own vehicle 1 determined for determining the current braking deceleration capacity of the vehicle 1 be used.

For example, the vehicle type can be detected. The own vehicle type and the technical vehicle design is based on a design-related deceleration (and acceleration) assets. This forms the basis for further calculations for the longitudinal control of the respective driving situation. The type of vehicle or the technical vehicle design is typically already in the driver assistance system 100 preset so that it does not need to be recalculated or updated.

Other possible current vehicle parameters 106 based on the current load of the vehicle 1 or indicate if a trailer is docked. The load condition may be considered the current weight of the vehicle 1 , are determined as the current weight of a trailer and / or as the current weight of a load. The total weight is distributed over the axles and can be calculated with their compression height on the basis of the spring characteristic of the struts.

Other current vehicle parameters 106 describe the condition of the tires, and include several tire-specific parameters of the own vehicle 1 such as tire condition and tire type with defined tire classes, e.g. B. summer, winter, year-round or off-road tires. The tire condition can be recorded as tread depth, for example as a percentage of new condition. This also applies in the case of a re-cut tire. Wear condition detection of the tire is possible from the difference between the vehicle speed calculated from the rolling circumference and the speed detected via GPS, so that the state of wear of the tires is automatically determined and does not have to be entered manually.

Other possible current vehicle parameters 106 specify the state of the brake system, for example, based on the current maintenance condition or the current load condition of the brake system 116 , The latter, in particular the situational and timely heating of such vulnerable brake systems 116 , can be detected by local temperature and wear sensors and taken into account accordingly in the vehicle longitudinal control.

Another class of functional variables that feed into the vehicle's longitudinal control are parameters that affect the current roadway 5 describe. This becomes a current road condition 107 determined. The road condition 107 may result from the immediate detection of road parameters, such as roughness of the surface, waviness of the road surface 5 , Surface temperature on the road surface 5 , etc., are derived, for example, derived from the work or movement of the spring and damping elements for stabilizing the sprung suspension and body dimensions of the vehicle 1 ,

In addition, for a more accurate assessment of height differences of the transverse profile of the road 5 Ultrasonic sensors are used. By means of appropriate sensor data, the condition of the roadway 5 be classified, for example by means of a three-stage classification of the road 5 in "good", "medium" and "bad". The determined road condition can then be used in the determination of the braking deceleration capacity of the own vehicle 1 and the foreign vehicle 2 For example, be taken into account via a correction factor or by using corresponding experimentally determined experimental data.

Another road parameter is the current road friction coefficient 108 , This results on the one hand from the road surface and on the other hand from the influence of weather. Both influencing factors can be combined with radar sensors, camera systems (also infrared) or laser scanners in combination with a road surface recognition for performing image comparisons based on a roadway database, and / or data on the brightness, echo evaluation (strength and scattering of an acoustic reflection) and the Outdoor temperature can be obtained.

The data evaluation leads to friction coefficient detection with defined or specified friction coefficient classes. Depending on the friction coefficient μF of the roadways 5 For example, the following road friction coefficient classes are formed: μF_1>0.8;μF_2> 0.5 to 0.8; μF_3 = 0.2 to 0.5; μF_4 <0.2.

For further details on the determination of tire wear, road condition and road friction coefficient is to the document DE 10 2011 108 110 A1 directed.

Another feature that is included in the vehicle's longitudinal control is the vehicle class 109 of the foreign vehicle 2 , Different vehicle classes 109 generally have different braking deceleration capabilities. By determining the vehicle class 109 of the foreign vehicle 2 can the safety distance to the vehicle in front 2 to the present vehicle class 109 customized become. For example, cars, but also motorcycles, compared to trucks or buses usually have a significantly higher braking deceleration.

3 Illustrates schematically how the class 109 of the preceding vehicle 2 determined by the vehicle silhouette. 3 shows different possible dimensions of rear silhouettes 4A to 4G of a preceding foreign vehicle 2 , With 4A designated silhouette corresponds due to the low height of a sports car, the silhouette 4B with comparable width, but greater height a car. The silhouette 4C narrow width corresponds to a motorcycle; the silhouette 4D with similar width as sports cars and cars, but larger height, equivalent to an SUV. The silhouette 4E corresponds to a van, the silhouette 4F a small truck or city bus while the largest silhouette 4G a truck or coach.

In the longitudinal regulator is a predetermined number of vehicle classes 109 deposited. By means of a radar or camera sensor, the height and width of the other vehicle 2 determined and thus the vehicle class 109 of the foreign vehicle 2 from the given number of vehicle classes 109 certainly. Taking into account further variables such as the lateral silhouette, the length of the other vehicle 2 , and / or the angle of incidence 113 For example, additional geometry correction may be required if the detected heights and widths of the rear silhouette are affected by, for example, cornering.

Further, the trajectory becomes 110 of your own vehicle 1 determined in all three levels. The traveled and the up to the preceding vehicle 2 projected trajectory 110 of your own vehicle 1 become exact estimates of the driving situation and the distance to the vehicle in front 2 calculated. The trajectory 110 can for example by means of radar 6 , an inclination sensor and / or GPS data are determined.

Furthermore, as far as can be determined by the vehicle's own sensor system, the trajectory is also determined 111 of the preceding vehicle 2 calculated. This can be done for example by means of radar 6 or laser sensors. For example, a cornering from the distance to the preceding foreign vehicle 2 and the changed width of the rear silhouette of the foreign vehicle 2 , which is detected by means of radar or laser data can be determined. This is also possible for driving on uphill or downhill gradients. For this, the change in height of the rear silhouette of the preceding foreign vehicle 2 determines what follows from the 5A and 5B is explained. Instead of the trajectory 111 of the foreign vehicle 2 This data can also be determined by means of data transmission from the other vehicle 2 or from a stationary transmitting station (not shown).

Further, the road type and the trajectory 112 the streets are determined in three levels as a function variable. This can be done using the following sub-steps: First, from (timely) navigation data, the current road type 112 be determined. The current street type 112 may include the following values: Bundesautobahn, expressway, main road, provincial road, side street, city street - multi-lane, city street - single lane, main street, side street, if necessary construction site. Below is the number of lanes in the direction of travel, taking into account the determined road type 112 and / or determined from an image comparison with images from a road type database. The following may be based on the determined road type 112 and the number of lanes the lane width are calculated. Thus, to determine the right and possibly the left edge of the driving band by means of image analysis, it can be determined whether lane markings are present and / or the background is detected by scanning (for example by means of ultrasound sensors).

Based on the determined road type 112 , the number of lanes and the calculated lane width is then preceded by the lane 5 , for example by radar 6 or laser. A preliminary determination of the road gradient 5A can then be done by changing the length of the scanning beam. A gradient 5B The road can then be done by sensing the horizon shift by image comparison taking into account the vehicle pitch or the vehicle position. Becomes a gradient 5B Sensing the axle load shift (compression travel), decreasing the engine pulling power (tension diagram), changing the length of the road scanning beam, changing the altitude (over NN) over a longer second period, or Change the GPS position. By means of this calculated data, a precalculation of the trajectory is then carried out 112 the street.

The described functional variables 103 to 112 be over a data connection 113 to a controller unit 114 the driver assistance system for longitudinal control 100 transfer.

Based on these functional sizes 103 to 112 determines the controller unit 114 the current braking deceleration capacity of the vehicle 1 or the foreign vehicle 2 Based on stored controller tables 200 , Based on this deceleration capacity then the currently required safety distance is determined as in known longitudinal control systems. If an adjustment of the safety distance is necessary, the longitudinal controller controls 114 through an output signal 115 for example, the brake control 116 of the vehicle 1 ,

In the vehicle controller 114 are different regulation tables 200 deposited, by means of which the current braking deceleration capacity of the vehicle based on the specific function variables 1 and the foreign vehicle 2 is determined in order to calculate an actual safety distance on this basis. This is based on 2 explained in more detail.

In the 2 shown table 200 lists values for typical braking deceleration depending on various lane and vehicle specific parameters 103 to 112 on.

According to the in 2 described embodiment is for the determination of the braking deceleration of a preceding foreign vehicle 2 between seven different vehicle classes 109 of the foreign vehicle 2 distinguished in the second row of the table 200 are listed. For example, in a first class trucks up to 40 t or high-build coaches fall. In the third line are those for the respective vehicle class 109 typical dimensions of the height and width of the rear vehicle silhouette listed. The typical height of such trucks and coaches is between 35 and 40 decimetres and the width is between 23 and 25 decimetres. In a comparable way, the height and width dimensions of cars with caravans, SUVs, vans, trucks from 12 to 24 t and buses, sports cars and motorbikes are listed for vehicle classes 2 to 7.

In table 200 are for different vehicle classes 109 typical braking deceleration listed, assuming a typical driving speed of the other vehicle 2 , Equipped with ABS, suitable tires and medium load. It is here in particular between three road condition classes 107 "Good", "medium" and "bad". Furthermore, between four different Fahrreibreibwertklassen μF 108 Differences that take into account the different coefficients of friction on dry roads, wet roads without stagnant water, wet roads with stagnant water or with grippy snow or roads with smooth snow or ice.

Each row in the field "Road friction coefficient classes μF" of the table 200 gives the braking deceleration capacity for one of the friction coefficient classes 1 to 4 for the respective vehicle class 109 "1" to "7" of the foreign vehicle 2 in which the values in each table field are again differentiated according to the road conditions good / medium / bad.

By determining the current road condition 107 and the current road friction coefficient 108 as related to 1 Thus, the currently applicable braking deceleration capacity of the preceding foreign vehicle can be described 2 be determined.

For example, was the preceding vehicle 2 recognized as a car class 2, the current road condition 107 determined as "good" and the current road friction coefficient μF 108 with a value> 0.8 (road friction coefficient class "1"), then you remove from the associated field of the table 200 the value 0.95 g for the braking deceleration of the preceding car. In a bad road condition 107 (Road condition class "bad"), the value would be 0.8 g.

In bad road condition 107 and a road friction coefficient "3", the braking deceleration would be reduced to 0.35 g. Is it in these road conditions in the preceding vehicle 2 By contrast, a transporter (vehicle class 4), the corresponding braking deceleration would be 0.42 g.

The table 200 illustrates that the brake deceleration capacity underlying the distance control system is highly dependent on the current road condition 107 and the current road friction coefficient 108 that can change constantly during a journey. As a result of the constant determination of these roadway parameters, the distance control can thus be constantly adapted to the current roadway state, so that the distance control is based on a currently valid braking deceleration capacity.

Used in determining the braking deceleration capacity of the other vehicle 2 additionally the vehicle class 109 of the preceding vehicle 2 the accuracy of the particular deceleration capacity can be significantly increased.

This is how a motorcycle (vehicle class 7, see last column in Table 200 ) in good road conditions 107 and a current road friction class 108 of "1" (dry lane), compared to a heavy truck of the vehicle class "1" better braking deceleration of 1.1 g compared to 0.62 g for the truck on. On the other hand, the braking deceleration capability of the motorcycle deteriorates in poor road conditions 107 and a current road friction class 108 from "3" (stagnant or grippy snow) to 0.12 g. By contrast, the weight of the heavy truck only deteriorates to 0.4 g, so that the braking deceleration capacity of the truck is greater than that of the motorcycle in these road conditions. The simultaneous consideration of the current roadway parameters and the respective vehicle class 109 of the foreign vehicle 2 thus allows a much more accurate distance control that can adapt to the current driving environment.

2 further illustrates the dependence of the braking deceleration capacity of the own vehicle 1 depending on vehicle-specific parameters 106 and of lane-specific parameters, again distinguishing between the different vehicle classes 1 to 7. 2 shows only partial example values for individual parameter combinations.

The column "1" gives an example of a car with the values specified in parentheses for the vehicle-specific parameters vehicle class (PKW), assumed tire type (all-season tires), tire condition (profile condition of 50% of new condition), loading condition (4 persons), condition of brake system ( Factor 1) the braking deceleration capacity. Here are only values for an assumed road condition 107 represented by the value "good", which can be seen by selecting "x" in the line "Road grade". For these parameters, the lower four lines of the "possible delay" field now give the braking deceleration capability of the vehicle for the four different road friction coefficient classes 108 at.

Similarly, in column "3" or "transporter", for example, the respective braking deceleration capacities for a transporter as a preceding third party vehicle 2 "medium" grade, one-person loading and brake factor "1", braking deceleration values being given separately for summer and winter tires (marked by "S" and "W").

Further, the table 200 It should be noted that, in the case of a car, 100% laden, whose condition of the braking system was rated by a factor of "1" and fitted with summer tires whose tread condition is 90% of new condition, the current braking capacity for a dry lane of the Class "1" has the value 0.74.

It is noted that 2 only by way of example and in part in the memory of the driver assistance system 100 stored braking deceleration for a foreign vehicle 2 and your own vehicle 1 for the different value ranges of the determined function variables 103 to 112 represents.

So is in 2 not shown that the three-dimensional trajectories and road courses can be additionally taken into account in the form of further tables or a correction factor. From the trajectories can the difference of the slopes of the roadway 5A of the vehicle 1 and foreign vehicle 2 determining from which a correction factor due to the additional slope driving force can be derived, by the value for the braking deceleration capability of the vehicle 1 and foreign vehicle 2 to the roadway slope 5A adapt.

On the basis of the so determined braking deceleration of the own vehicle 1 and the foreign vehicle 2 can take into account the current driving speed and the angle of incidence 105 of the foreign vehicle 2 an accurate safety margin can be calculated on which the driver assistance system 100 then adjusts.

The influence of different functional sizes 103 to 112 on the braking deceleration can by means of test series for different vehicle classes 109 be determined. For example, a deterioration of the road condition has an effect 107 or the road friction coefficient 109 Negative on the braking deceleration of vehicles.

The determined brake deceleration values for different combinations of roadway and vehicle specific parameters 103 to 112 are then used as control tables in the vehicle 1 deposited, on the controller unit 114 accesses.

The following figures exemplify the vehicle longitudinal control for some typical driving situations.

In 4 is described the control sequence for a driving situation in which a truck semitrailer 1 a sports car 2 follows (see also 5 ). The vehicles 1 . 2 driving on a federal highway at dry asphalt and daylight. The driving speed of the sports car 2 is 80 km / h because the driver enters a replacement engine while the tractor-trailer 1 with a gross vehicle weight of 40 t, slowly with 85 km / h of the vehicle in front 2 approaches.

In a step S400, the preceding foreign vehicle becomes 2 (the sports car) from the radar 6 detected. In the next step S401, the distance becomes 104 between the tractor trailer 1 and the sports car 2 determined. Subsequently, in step S402, the vehicle class 109 of the preceding vehicle 2 based on the distance 104 , which determines the width and height of the object. The width and height of the object is determined by radar reflection on the back silhouette of the vehicle ahead 2 detected. In the present example, the silhouette 4a recognized and thus as a sports car 2 identified.

Subsequently, in step S403, the angle of incidence 105 to the preceding sports car 2 due to distance 104 and vehicle width determined. In the present embodiment, the angle of incidence is <5 °, thus driving the vehicle in front 2 in the same lane. In step S404, the own traveling speed becomes 103 queried and then in step S405 own three-dimensional trajectory 110 calculated. In the example assumed, a straight-ahead journey takes place in the plane.

In step S406, the current road type and the trajectory 112 calculated the road. In the present example, there is a federal highway and a straight road. Subsequently, in step S407, as previously explained, the road condition is calculated. In the present example is a flat good road 5 in front. In step S408, the road friction coefficient class is determined: the road friction coefficient class μF_1> 0.8. On the basis of these data, the own current braking deceleration capacity is determined from the stored characteristic value tables in step S409, which corresponds to a value of 0.62 g on the basis of the current function variables. Subsequently, in step S410, the braking delay capacity for the other vehicle 2 determines what corresponds to a value of 1.05 g on the basis of the available function variables. On the basis of the determined braking deceleration capacity, the safety distance for the vehicle longitudinal control for a speed of 80 km / h of the preceding vehicle is subsequently in step S411 2 calculated.

For the calculation of the safety distances and for comparison purposes continue to be the vehicle-typical threshold duration of the brake system 116 considered until the application of the brake pads and until the further increase of the brake pressure until reaching the Radblockierdrucks (beginning of the anti-skid control). Typical reference values for vehicle categories Passenger cars and motorcycles or trucks or semi-trailers are 0.2, 0.3 and 0.7 seconds respectively. Furthermore, the reaction time of the driver to be considered by the gas on the brake pedal or handle, with an exemplary guide value is 0.2 seconds; but this is not relevant to the regulations. A guideline value of the safety distance to the vehicle in front 2 As a time gap t = _Sich can then typically be 1.8 seconds, but is also not relevant to the regulator but is only used for comparative calculations. However, there is still the calculation or cycle time of the controller 114 to be considered, which is assumed to be 400 ms.

t_RBreak = Gesamtansprechdauer Fahrerassistenzsystem 100 und Bremse 116
a₁ = Mindestverzögerung Folgefahrzeug 2
a₂ = Verzögerung vorausfahrendes Fremdfahrzeug 2
v₁ = Geschwindigkeit 103 Folgefahrzeug 2
v₂ = Geschwindigkeit vorausfahrendes Fremdfahrzeug 2
errechnet sich der Sicherheitsabstand von 41 m entsprechend einer Zeitlücke t_Sich = 1,85 s. Das Fahrerassistenzsystem 100 regelt daraufhin die Folgefahrt auf dem errechneten Sicherheitsabstand bei gleichen Geschwindigkeiten ein.For a 40 t truck trailer, the brake threshold is 0.7 s, plus the computation time of the controller 114 of 0.4 s, this results in a total response time t _break for the controller of 1.1 s. From the formula

t _RBreak = total response time driver assistance system 100 and brake 116
a ₁ = minimum delay following vehicle 2
a ₂ = delay preceding foreign vehicle 2
v ₁ = speed 103 the following vehicle 2
v ₂ = speed preceding foreign vehicle 2
the safety distance of 41 m is calculated according to a time gap t _Sich = 1.85 s. The driver assistance system 100 then regulates the following trip to the calculated safety distance at the same speeds.

5A Illustrates how the trajectory 111 of the preceding vehicle 2 based on the changing rear silhouette of the vehicle 2 can be determined. The rear silhouette of the preceding foreign vehicle 2 gets off the vehicle 1 by means of a radar beam 6 detected. The recorded height 7 the rear silhouette of the foreign vehicle 2 varies depending on slope 5A and gradient 5B the roadway 5 ,

For example, the detected height of the rear silhouette 7 compared to the situation where both vehicles 1 . 2 in one plane, at the entrance of the preceding vehicle 2 in a slope seemingly larger, so the rising trajectory 111 of the preceding foreign vehicle 2 from the following vehicle 1 can be detected by the increasing rear silhouette. Similarly, the detectable height of the rear silhouette 7 of the preceding foreign vehicle 2 smaller if the preceding foreign vehicle 2 enters a gradient. This is in 5B illustrated. In a similar way (not shown), right or left turns 111 the roadway of the preceding foreign vehicle 2 by the changing width of the rear silhouette of the foreign vehicle 2 be detected and corrected by the calculated trajectory.

6 illustrates the control sequence for another typical driving situation. In this example, a truck is driving 1 on the right lane of a federal highway with a speed of 75 km / h in heavy rain and poor visibility. A foreign vehicle 2 in the form of a truck approaches from the rear right, as in 7A illustrated, for threading at 85 km / h and thus gets into the radar angle of incidence of trucks 1 ,

In step S600, the other vehicle laterally approaching from behind becomes 2 from the radar 6 detected. In step S601, the shortest distance becomes 104 to the foreign vehicle 2 measured. Then, in step S602, the vehicle class becomes 109 of the approaching vehicle 2 determined by the distance and altitude and identified as a truck or bus. In step S603, the incident angle becomes 105 due to the distance 104 determined by the left front vehicle limit, which has a value of 150 ° in the present example. Subsequently, in step S604, the own traveling speed 103 which is generally known at all times. In step S605, the own three-dimensional trajectory becomes 110 calculated, which in the following example corresponds to a straight-ahead travel in the plane. Subsequently, in step S606, the road type and the trajectory 112 calculated the road. According to the assumed driving situation, the road type becomes 112 determined as federal highway. Subsequently, in step S607, the road condition 107 calculated according to the assumed driving situation, a good road 5 with a smooth course.

Subsequently, in step S608, the road friction coefficient class 108 determined, in the present case μF_2 with values of 0.5 to 0.8. In the following step S609, the three-dimensional trajectory 111 of the truck 2 calculated. In step S610, depending on the determined trajectories 110 . 111 determines whether a time period or a distance to a possible side collision between the vehicle 1 and the side approaching other vehicle 2 has fallen below a predetermined threshold. If NO, there is no immediate danger of collision, and the control flow goes back to step S600 to further observe the danger situation. However, if there is a time or distance up to a possible side collision between the own vehicle 1 and the foreign vehicle 2 has fallen below a predetermined threshold, ie, a collision could be imminent, a warning signal is output in step S611. In the present example, the risk of lateral collision or cutting was determined in 3 to 4 seconds and thus an acoustic warning from the loudspeaker was issued to the driver in step S611.

Subsequently, it is determined in step S613 whether the driver performs a steering and / or braking operation or a speed change or change of the accelerator pedal during a predetermined reaction phase. For this purpose, the driver can be given a reaction time of 2 seconds, for example by means of a timer, to give the driver himself the opportunity to steer or brake in a steering manner. Such dangerous situations can usually be best solved by a lateral control of the driver, so that before engaging the longitudinal control advantageously the driver is given a reaction time. 7B illustrates the reaction phase given to the driver in step S612 between times t1 and t2. The length of the reaction phase may be determined depending on the particular duration of the particular distance up to a possible side collision.

If a driver's reaction is detected in step S613, there is no controller intervention S614. However, the vehicle longitudinal control remains in principle in order to capture the traffic situation on. If the driver does not respond within the predetermined reaction time and it is detected in step S615 that a predetermined minimum safety distance is exceeded, the vehicle longitudinal control feeds the maximum brake pressure in step S616, in addition, the ABS control is started because the coefficient of friction at 0.55 is.

In step S617, due to the close contour of the lateral approaching foreign vehicle 2 the foreign vehicle 2 recognized and classified as a truck. In step S618, the deceleration takes place until the safety distance to the classified truck 2 is reached. After reaching the required safety distance, an end of the longitudinal control follows in step S619, since the immediate side collision danger no longer exists and the safety distance is reached.

8th and 9 illustrate the longitudinal control for another typical driving situation. As in 9 shown, follows in the present example, a truck vehicle 1 a preceding car other vehicle 2 along a roadway 5 on a section 5B with a slope. In this example, the truck drives 1 at a speed of 50 km / h in snowfall and a snowy road and poor visibility. As in the picture below 9 shown drives the preceding car 2 then in a plane. Due to the entrance of the car in front 2 in a plane improves its braking deceleration by eliminating the slope force, so that the safety distance from the subsequent truck 1 who is still on the slope, to this car 2 must be increased.

In step S800, the passing slope of the current lane becomes 5 determined. The pass was made from the three-dimensional tram curves 112 and / or from the three-dimensional trajectories 110 . 111 of the vehicle 1 or the foreign vehicle 2 determined. In step S801, the current safety distance is controlled to pass-off taking into account the braking deceleration capabilities of the vehicle 1 and the foreign vehicle 2 as before, based on the different functional sizes 103 to 112 were determined. In step S802, an end of the grade is detected by horizon shift and object change. The rear silhouette and the visible front of the vehicle result from the perspective of the truck 1 a larger object height 7 ,

In step S803, the vehicle longitudinal control brakes the truck 1 as long as the distance to the car in front 2 adapted according to the extended braking distance due to the known downgrade force. In step S804, a new adjustment of the safety distance after retraction of the truck 1 into the plane.

The individual features of the invention are of course not limited to the described combinations of features in the context of the presented embodiments and can be used in other combinations depending on existing vehicle sensors. This applies in particular to the combinations of in 1 to illustrated functional sizes, which can be combined differently. For example, only one or more current lane-specific parameters may be used in the calculation of the deceleration capability of the vehicle as well as the foreign vehicle. The same applies to the vehicle-specific parameters.

Furthermore, it is advantageous, but not absolutely necessary, to calculate further parameters such as the determination of the vehicle class of the preceding vehicle, the trajectories of the vehicles, etc. Depending on the selected embodiment, the determined function variables in the driver assistance system then become 100 the corresponding adjusted control tables are stored. Further, of course, as needed and required accuracy, the number of classes used may be adjusted for each parameter, such as vehicle class, road condition class, road friction coefficient class, etc.

LIST OF REFERENCE NUMBERS

1

vehicle

2

foreign vehicle

3

direction of travel

4A

Sports car silhouette

4B

Car silhouette

4C

Motorcycle Silhouette

4D

SUV silhouette

4F

small truck or city bus silhouette

4G

Truck or coach silhouette

5

roadway

5A

Road with slope

5B

Road with gradient

6

radar beam

6A

radar sensor

7

Height rear silhouette

100

Driver assistance system for vehicle longitudinal control

101

Sensors and data

102

Data Connection

103

speed

104

shortest distance to the other vehicle

105

angle of incidence

106

vehicle parameters

107

current road condition

108

current road friction coefficient

109

Vehicle class foreign vehicle

110

3D orbit vehicle

111

3D trajectory foreign vehicle

112

Road type and 3D lane roadway

113

data line

114

controller unit

115

control line

116

braking system

200

Table with road-specific and vehicle-specific braking deceleration capacity

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011108110 A1 [0051]

Claims (12)

Operating method for a driver assistance system ( 100 ) for vehicle longitudinal control of a vehicle ( 1 ) with regard to a foreign vehicle ( 2 ), preferably for speed and / or distance control, characterized in that the vehicle longitudinal control in dependence on at least one current road-specific parameter and / or at least one current vehicle-specific parameter takes place. The operating method of claim 1, wherein the at least one current lane-specific parameter has a current lane state. 107 ) and / or a current road friction coefficient ( 108 ) describes. Operating method according to one of claims 1 or 2, comprising the step: determining a vehicle class ( 109 ) of the foreign vehicle ( 2 ), wherein the vehicle longitudinal control as a function of at least one of the particular vehicle class ( 109 ) derivable parameter takes place. Operating method according to claim 3, further comprising the steps of: adapting a previously known parameter relating to a braking deceleration capacity of the vehicle ( 1 ) depending on the current lane-specific parameter; Determining a parameter relating to a braking deceleration capability of the foreign vehicle ( 2 ) depending on the particular vehicle class ( 109 ) of the foreign vehicle ( 2 ) and the current lane-specific parameter, the vehicle longitudinal control depending on the parameters relating to the braking deceleration capacity of the vehicle ( 1 ) and the foreign vehicle ( 2 ) he follows. Operating method according to one of the preceding claims 3 or 4, further comprising the step: determining a rear silhouette of the preceding foreign vehicle ( 2 ), on the basis of which the classification of the other vehicle ( 2 ) he follows. Operating method according to claim 5, wherein a distance, a height and / or a width of the foreign vehicle ( 2 ) to determine the rear silhouette of the other vehicle ( 2 ). Operating method according to one of claims 1 to 4, further comprising the steps: receiving, from the foreign vehicle ( 2 ), of vehicle-specific parameters of the other vehicle ( 2 ) and performing the vehicle longitudinal control depending on the received vehicle-specific parameters. Operating method according to one of the preceding claims, wherein the at least one current vehicle-specific parameter comprises at least one vehicle type, a load state, a state of the vehicle brake system and / or a tire-specific parameters. The operating method of claim 8, wherein the tire-specific parameter describes a tire air pressure, a tire condition, and / or a tire class. Operating method according to claim 8 or 9, wherein the loading state the current weight of the vehicle ( 1 ), which describes the current weight of a trailer and / or the current weight of a load. Driver assistance system ( 100 ) for vehicle longitudinal control of a vehicle ( 1 ) with regard to a foreign vehicle ( 2 ), preferably for speed and / or distance control, in particular for carrying out the operating method according to one of the preceding claims, characterized in that the driver assistance system ( 100 ) Comprises: - a provisioning device, which is designed to provide at least one current lane-specific parameter and / or at least one vehicle-specific parameter; and - a control device, which is designed to perform the vehicle longitudinal control in dependence on the at least one current road-specific parameter and / or the at least one vehicle-specific parameter. Commercial vehicle, preferably a truck or bus, with a driver assistance system ( 100 ) according to claim 11.

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