EP1523435A1

EP1523435A1 - Driver assistance system and device for brake control

Info

Publication number: EP1523435A1
Application number: EP03740409A
Authority: EP
Inventors: Steffen Luh
Original assignee: Continental Teves AG and Co OHG
Current assignee: Continental Teves AG and Co OHG
Priority date: 2002-07-05
Filing date: 2003-07-03
Publication date: 2005-04-20
Also published as: DE10392862D2; WO2004005092A1

Abstract

The invention relates to a driver assistance system for assisting the driver of a motor vehicle during dangerous or emergency braking situations, wherein the speed of the vehicle (vref), actuation of an accelerator pedal by the driver, actuation of a brake pedal by the driver and the current driving situation, at least the distance and relative speed in relation to a preceding vehicle, are detected and wherein intervention in the braking control occurs based on all detected values. The invention also relates to a device for controlling or regulating a motor vehicle braking system.

Description

Driver assistance system and device for brake control

The present application relates to a

Driver assistance system to support the driver of a motor vehicle in dangerous and emergency situations and a device for controlling or regulating a motor vehicle brake system.

In modern vehicle control processes and systems, there are various components that can or want to influence the control of the longitudinal dynamics (acceleration or braking in the direction of travel) in order to assist the driver, who previously had to do this task alone. Known are speed controllers (cruise control) controlled by the driver, vehicle sequence controls, with which distances or time gaps to vehicles in front are monitored and maintained or set, curve dynamics controls, which also influence the speed or acceleration in the direction of travel, engine / transmission controls, which regulate an engine from a technical / economic / ecological point of view and brake regulations, in particular brake assistants, which support a driver in the event of emergency or full braking.

There is therefore a need to coordinate the various systems in order to be able to control the motor and brake appropriately.

The object of the invention is to provide a system and a device for supporting the vehicle driver (driver). specify a motor vehicle with which a safe brake control is possible, particularly in dangerous and emergency braking situations.

This object is achieved with the features of the independent claims. Dependent claims are directed on preferred embodiments of the invention.

The object is achieved in that the vehicle speed v _{ref of} the vehicle, the actuation of an accelerator pedal (accelerator pedal) by the vehicle driver (driver), the actuation of a brake pedal by the driver, and the current driving situation, at least the distance and the relative speed of or compared to a vehicle in front, and that an intervention in the brake control takes place on the basis of all recorded values.

The invention is therefore based on the idea of evaluating data from environmental sensors present in the vehicle and linking them to sensor data that describe the overall dynamics of the vehicle and the driver, and then finding a decision in which situation and to what extent the driver is supported by an intervention in the brake control and / or engine electronics is provided. The brake control then takes place in accordance with all recorded values for the vehicle longitudinal dynamics and by specifying an overall target acceleration.

The data of the current driving situation are preferably obtained from an ICC system or ACC system (Intelligent Cruise Control or Adaptive Cruise Control), which measures the distance and the relative speed of or compared to a vehicle in front, recorded, made available.

By taking into account all recorded parameters, which includes driver observation (early human reaction) and environment observation (dynamics of the traffic ahead), critical traffic situations, in particular emergency braking situations in subsequent traffic, can be recognized better and faster and appropriate measures can be initiated quickly. The system particularly supports the inexperienced normal driver, who represents the majority of road users.

In the sense of the invention, it is provided that a hazard potential is ascertained on the basis of all recorded values and that a target value specification for the brake control, in particular a target vehicle acceleration or a target brake pressure, takes place when a hazard potential is determined that is related to a hazard. or emergency braking situation.

The term “vehicle acceleration” is to be interpreted broadly. In the mathematical sense, the term “acceleration” also includes, in particular, negative values, that is to say driving conditions which are referred to as “braking”.

According to the invention, it is provided that the driver's wish to accelerate or decelerate the vehicle is determined and that the brake control is only intervened if it is recognized that the driver does not want to accelerate or decelerate the vehicle.

According to the invention, it is provided that the driver's request for vehicle acceleration is considered to be recognized if the driver does not actively actuate the accelerator pedal, in particular if an ascertained accelerator pedal travel is zero or if an ascertained accelerator pedal speed and / or accelerator pedal force is less than or equal to zero. The detection of the driver's request is preferably carried out via a state machine which has the states "driver does not accelerate", "driver accelerates", "driver takes gas back" and "driver holds the accelerator pedal at a constant value (with the hysteresis taken into account accordingly)".

It is provided according to the invention that the driver's request for a vehicle deceleration is considered to be recognized if the driver does not actuate the brake pedal, in particular if the brake pedal travel is zero or a determined brake pedal speed and / or brake pedal force is less than or equal to zero.

In the sense of the invention, it is provided that a current safety distance from a vehicle in front is determined and that an intervention in the brake control takes place only when it is recognized that the current safety distance is undershot. The safety distance is defined in accordance with the respective legal regulations.

Many possible dangerous situations, which include sudden re-entry into a traffic gap (cut-in) and / or falling below a minimum distance (safety distance), can at least be mitigated in an advantageous manner compared to a braking assistant and an (independent) distance and follow-up regulation. An important advantage here is that the intervention can be carried out relatively gently, so that the driver does not have any major ones noticeable pressure jumps or inhomogeneities in brake pressure build-up or reduction.

Braking of the vehicle in front is also advantageously monitored and, in the event that a certain or determinable minimum distance (safety distance) is undershot, the driver's own vehicle is increasingly braked.

According to the invention, it is provided that a relative speed in relation to a vehicle in front is determined and that the intervention is corrected based on the falling below the safety distance in accordance with the determined relative speed, in particular a setpoint value for the vehicle acceleration being corrected or weighted in accordance with the relative speed.

According to the invention, it is provided that the driver's steering wheel actuation is recorded for the purpose of determining an avoidance situation, and that the intervention in the brake control system is not carried out or corrected if an avoidance situation is detected. The term “avoidance situation” here means a driving situation in which the driver dodges an obstacle or changes lanes, typically a rapid lane change on a federal highway. A rapid lane change is defined in particular by (known) significant parameters.

It is provided according to the invention that the steering wheel angular velocity or

Steering wheel angle change speed is detected and that after exceeding a predetermined limit for the Steering wheel angular speed or

Steering wheel angle change speed, preferably in combination with driving state data of a preceding object determined on the basis of an environment sensor system, an evasive situation is considered recognized.

According to the invention, it is provided that a brake pedal characteristic and / or a brake assistant triggering threshold is changed in accordance with the recognized hazard potential. A change in the brake pedal characteristic curve means, for example, a change in the assignment of the brake pedal travel to the system target pressure or target deceleration specification. The brake assist trigger threshold can be adapted by changing the limit values for the brake pedal speed or acceleration.

In the sense of the invention, a warning of the rear traffic can also be given if a dangerous situation is detected with the help of the information from the environment sensors. A suitable unit, for example one or more brake lights, is then activated.

The object is also achieved by a device for controlling a motor vehicle brake system, with sensors for detecting the vehicle speed, pedal travel and / or pedal force sensors for detecting the pedal positions of the accelerator pedal and brake pedal, a distance sensor for detecting the distance and the relative speed of or compared to a vehicle in front, a steering wheel angle sensor for detecting a steering wheel angle speed or steering wheel angle change speed, and with a determining and evaluating device for determining a target acceleration or a target braking pressure in accordance with requirements of the detected values, which cooperate with an acceleration controller that controls the wheel brakes in accordance with the target acceleration or the target brake pressure.

According to the invention, it is provided that the determination and evaluation device has a distance

Monitoring device for monitoring the distance to the vehicle in front, which, in the event that a certain or determinable minimum distance (safety distance) is undershot, outputs control signals for increased activation of the wheel brakes of the vehicle.

It is provided according to the invention that the determining and evaluating device has a steering angle monitoring device for monitoring the steering wheel actuation of the driver and determining an avoidance situation which, in the event that an avoidance situation is detected, outputs control signals for the reduced activation of the wheel brakes of the vehicle.

In the sense of the invention, it is provided that the determination and evaluation device has a device for outputting a correction signal for influencing a brake assist system or a brake pedal characteristic curve. Appropriate preconditioning of the brake system by means of targeted pre-filling can already be achieved when a low hazard potential is identified. The hazard potential is a function which preferably measures at least the “distance”, “the

Relative speed "and the" system reaction times (for example, response and threshold times of the brake system) "each weighted in relation to a relevant vehicle in front in such a way that a measure of a potential (Accident) danger is available to the entire system as a benchmark. Further additional information such as, for example, the “required braking distance”, “the jerk” as a derivative of the vehicle deceleration, the vehicle's own deceleration, the deceleration of the relevant object are also taken into account. This enables the determination of the hazard potential to be made much more precise. If a very critical driving situation is recognized, ie if the hazard potential is very large, the function and effect of the brake assist can be improved with this measure. The vehicle can be braked earlier and / or more strongly.

According to the invention, it is provided that the device has a monitoring computer that detects a malfunction of individual sensors and / or controllers and outputs corresponding warning signals and / or switches off parts or the entire system.

An exemplary embodiment of the invention is described below.

The exemplary embodiment relates to a vehicle with an externally controllable wheel brake, here, for example, an electro-hydraulic brake (EMS). This has a brake assistant (BA) implemented, for example by software. The vehicle is also equipped with an environmental sensor system, a radar-based ACC system. The ACC system's bow radar monitors the surroundings and determines the relative distance and relative speed to the relevant front object. The driver's behavior is monitored with the help of brake and accelerator sensors. A special electronic controller, referred to here as a so-called "danger computer", analyzes all relevant information, ie that of the bow radar and the pedal sensors, and uses special algorithms to recognize dangerous situations that result from the driving speed of both vehicles, the distance between them and the Speed or their time derivative with which the distance changes.

Depending on the profile of the dangerous situation, the system initiates staged actions to shorten the stopping distance. These are driver warnings (optically, e.g. using a display, or acoustically, e.g. using a warning buzzer), pre-filling the brake system, a legally compliant pre-deceleration without the driver pressing the brake pedal, and triggering full braking when the driver presses the brake pedal quickly. The brake assistant's trigger thresholds can be adapted to the potential accident risk. Overall, emergency braking is initiated earlier that critical fraction of a second, which may help prevent the accident or help minimize the consequences of the accident.

The embodiment is explained in more detail with reference to drawings (Fig.l to Fig.3).

Show it:

Fig.l An overall view of the brake control system with an assistance system according to the invention,

Fig.2 is a schematic overview of the assistance system according to the invention, and Fig.3 A schematic overview of the hazard calculator of the assistance system.

The overall structure of the system for brake control with function modules of the assistance system according to the invention and their content-related dependencies is shown schematically in a block structure in FIG.

The chain of effects begins logically with the brake pedal or the associated brake pedal simulator, which enables a desired pedal travel pressure assignment, which is carried out in the DRV task (Driver Task) 1, by means of an implemented travel sensor. The pressure setpoint 2 resulting from this task is fed as input to a subsequent arbitration 3, the so-called BFAI task (brake force arbitration). This coordinates the various pressure target specifications of the modules described below and driver task 1 to a requested system target pressure specification for the EBD task (Electronic Brake Force Distribution) 4 and possibly an ABS task 15 for the purpose of regulating the wheel brake 16.

Another module to be arbitrated in the BFA1 task 3 is the so-called DCM task (Danger Control Module) 5, which contains the actual danger computer. In this task 5, the input variables supplied by the environment sensor system 6, in particular the relative speed 7 and the distance between the vehicles 8, are measured with different system and vehicle variables, for example one

Vehicle speed, linked. Taking into account any external delay requests 9, a delay or pressure set request is generated as an output variable in the DCM task 5 and is sent to an arbitration 11. From the combination of driver / vehicle monitoring and environmental monitoring, a target vehicle deceleration appropriate to the detected danger is adjusted after arbitration 11 with the aid of a depicted longitudinal deceleration controller, the VAC task (Vehicle Acceleration Control) 12. Important criteria for calculating this delay are the relative distances and speeds to the relevant target vehicle or object.

The target pressure 12 requested by the danger computer and the target pressure 2 requested by the driver are coordinated in the described BFAI task 3 and made available to the module of the electrical braking force distribution (EBD task) 4 as an input variable. Possibly. In addition, an external set pressure request 14 is also taken into account 17.

2 shows the assistance system according to the invention in a schematic overview.

If there is an acute danger situation 20 recognized by the system and the driver does not want to accelerate 21 the vehicle, e.g. recognized by evaluating the accelerator pedal acceleration: a <= 0 or the accelerator pedal speed v <= 0, or actively decelerating 22, i.e. the driver is not standing on the brake pedal, then a system intervention is triggered by the aforementioned risk computer 5.

If one of the described conditions for driver behavior (throttle 21, brake 22) is not met or if there is no dangerous situation, then only direct driver access is permitted 23, 24, 25 and the system behaves passively with regard to an intervention. The Danger calculator evaluates the safety distance and the relative movement to the target vehicle (speed, deceleration). If, based on the current vehicle situation, a calculated critical safety distance is undershot 26, then a continuously calculated target deceleration request takes place depending on the determined relative movement of the vehicles to one another 27. This delay requirement can be classified, for example, by two thresholds into a large 28 and a small 29 delay specification, in order to then implement gentle and thus comfortable delay requirements with low delay requirements (gradient limits) or, in the case of a large delay specification, correspondingly additional dynamic components in the printing or Integrate target deceleration and thus keep the existing system reaction times as short as possible.

The hazard calculator is shown in more detail in Fig.3. At least the vehicle speed 40, the steering wheel angle 41, the accelerator pedal travel 42, a recognized object 43, the distance to the object 44, the relative speed to the object 45 and the driver target pressure specification 46 are taken into account as input variables 39. Furthermore, variables related to or derived from these variables, such as a required deceleration 47, an object deceleration 48, a jerk of the object (derivation of the object deceleration) 49, the object speed 50, a stationary object 38 and possibly a driver braking mode, ie whether the driver has not depressed the brake pedal at all, he keeps it almost constant in a detected state, he continues to step towards greater deceleration or releases it again (corresponding hysteresis must be taken into account), supplied as input variables 39. In principle, the driver pedal movement can also take place 52 in the danger computer 5.

A target pressure specification 53 for the brake control is generated from the input variables. In addition, the pedal characteristic curve 4 can be adjusted or the BA trigger threshold can be reduced 55. An overall target pressure specification 59 is determined by an arbitration function 58 from the driver's request acquisition 56, a prepared driver target pressure specification 57 and the hazard calculator target pressure specification 53.

In the danger computer 5, the information from the environment sensors, driver behavior (accelerator, brake pedal) and the entire vehicle are thus combined and evaluated in such a way that a "danger potential" can be assumed and correspondingly staged actions can be initiated. On the basis of the environment sensor data such as distance 44, relative speeds 45, etc., the calculation of a “required deceleration” 47 that is required to avoid a collision with the object in front or to reduce the consequences of an accident to a minimum if this delay occurs can no longer be implemented by the vehicle. Important factors influencing this are the calculated braking distance and the response time of the system or the driver.

A basic distinction is made between two driving situations. Firstly, a critical safety distance is not reached at a low relative speed and secondly, a driving situation with a high relative speed (see Fig. 2, 27, 28, 29) First, using the current

Vehicle speed 40, the distance 44 and further status information of the environment sensor (for example the validity of the target object 43, etc.) divided the current situation into two critical areas. These are indicated by danger thresholds, by status bits, and are used in the course of the program

Decision making whether an action needs to be initiated at all.

This is followed by an investigation and evaluation of the driver's accelerator behavior. The gas positions are stored there and evaluated in a status detection as to whether the driver is actively accelerating (s> 0 and v> = 0 or s (new)> s (old)) or the accelerator pedal (accelerator pedal) is approximately constant (v ~ = 0) or whether he releases the accelerator pedal (v <= 0 or s (new) <s (old)).

It has been shown that the tolerance ranges to be set for the individual conditions depend on the driver's behavior and are therefore to be adapted in accordance with personal specifications. It is only important that the driver's wish to "actively accelerate" must be recognized and implemented quickly in order to avoid a feeling of "braking". Otherwise a sufficient acceptance of the assistance function by the driver cannot be guaranteed. These are essentially the basic requirements that require "autonomous" intervention in the braking system.

If the critical safety distance is undershot, the method works as described below. Are the basic requirements for a possible intervention given above, ie are the conditions Object recognized by the environment detection, the driver does not actively accelerate (see automatic accelerator pedal state machine), the driver does not brake actively (see automatic brake pedal state machine) and the relative speed is above a threshold value (depending on the vehicle speed and the distance) are met in this situation Relative speed-dependent factors are calculated in order to then determine a target pressure as a function of the distance to the target vehicle. A distinction is also made as to whether the driver is on the accelerator pedal or the so-called "empty gas information" is available, ie the driver is not accelerating. In the latter case, a higher pressure can be permitted since it is reliably recognized that the driver at least does not want to actively accelerate the vehicle. The pressures are then converted into a required delay due to a critical safety distance.

The system intervention described below, which is caused by large driving situations

Relative speeds between own and target vehicle results. The first step is to recognize these situations, which take into account the distance and the relative speed to the target vehicle. The "required deceleration" calculated at the beginning serves as a reference value and is continuously corrected by observing the distance and relative speed values. This delay value is arbitrated with the target specification described in the previous section, so that the maximum value always serves as the system input variable.

If the driver steps on the accelerator or the environment sensor has lost the relevant target object, this is detected accordingly and the system reduces the Target deceleration in such a way that the driver does not feel the feeling of a braking effect. At the end there is again the conversion of the pressure into a delay specification.

In the case of an autonomously braking vehicle or a vehicle that can detect the objects located in the lane ahead and can provide status feedback about a possible collision, it is possible to control a brake light independently of the driver. In our case, a separate, third brake light is advantageously installed. This enables the following traffic to be informed about a dangerous situation, which can then be perceived as early as possible and consequently possible reactions, possibly decisive fractions of a second, can be initiated earlier.

In principle, two situations are to be distinguished: first, a situation when a dangerous situation is perceived by the surrounding system with subsequent preparation, the driver does not react and the system is not allowed to intervene, e.g. due to the driver pressing the accelerator pedal, and a second situation, if a dangerous situation is recognized accordingly and the vehicle is braked by the assistance system.

In the first case, the additional brake light is controlled with an adjustable flashing frequency to visually warn the traffic behind. In the second case, the brake light is permanently activated as long as the assistance function actively brakes the vehicle. Particular advantages of the invention result from the interaction of an existing environment sensor system with an externally controllable service brake. The inventive processing of the sensor signals (distance, relative speed, deceleration and object status) enables the surroundings of the vehicle to be examined for possible dangers, the driver to be warned and the braking system to be preconditioned. To avoid rear-end collisions and to mitigate critical traffic situations, there is the option of warning the following traffic in the event of a recognized dangerous situation, for example by activating the brake lights. With this system, numerous accidents can be prevented or the severity of the accident reduced.

Claims

Expectations

1. Driver assistance system to support the vehicle driver (driver) of a motor vehicle in dangerous and emergency braking situations, characterized in that the vehicle _speed v _{rβf of} the vehicle, the actuation of an accelerator pedal by the driver, the actuation of a brake pedal by the driver, and the current driving situation, at least the distance and the relative speed from or with respect to a vehicle in front are detected, and that an intervention in the brake control takes place on the basis of all recorded values.

2. The method according to claim 1, characterized in that a hazard potential is determined on the basis of all recorded values and that a target value specification for brake control, in particular a target vehicle acceleration or a target brake pressure, takes place when a hazard potential is determined that on a Indicates a dangerous or emergency braking situation.

3. The method according to claim 1 or 2, characterized in that the driver's wish to accelerate or decelerate the vehicle is determined and that an intervention in the brake control takes place only when it is recognized that the driver neither wants to accelerate nor decelerate the vehicle. A method according to claim 3, characterized in that the driver's request for a vehicle acceleration is considered recognized if the driver does not actively actuate the accelerator pedal, in particular if a determined accelerator pedal travel is zero or if an determined accelerator pedal speed and / or accelerator pedal force is less than or equal to zero.

A method according to claim 3 or 4, characterized in that the driver's request for a vehicle deceleration is considered recognized if the driver does not actuate the brake pedal, in particular if the brake pedal travel is zero or a determined brake pedal speed and / or brake pedal force is less than or equal to zero.

Method according to one of claims 1 to 5, characterized in that a current safety distance from a vehicle in front is determined and that an intervention in the brake control takes place only when it is recognized that the current safety distance is undershot.

A method according to claim 6, characterized in that a

Relative speed compared to a vehicle in front is determined and that the intervention is corrected due to the falling below the safety distance in accordance with the determined relative speed.

8. The method according to any one of claims 1 to 7, characterized in that the steering wheel actuation of the driver is detected for the purpose of determining an avoidance situation, and that the intervention in the brake control is not carried out or corrected when an avoidance situation is detected.

9. The method according to claim 8, characterized in that the steering wheel angular velocity or

Steering wheel angle change speed is detected and that after a predetermined limit value for the steering wheel angle speed or steering wheel angle change speed, an evasive situation is recognized.

10. The method according to any one of claims 1 to 9, characterized in that a brake pedal characteristic and / or a brake assistant triggering threshold is changed in accordance with the recognized hazard potential.

11. Device for controlling or regulating a motor vehicle brake system, with sensors for detecting the vehicle speed, pedal travel and / or pedal force sensors for detecting the pedal positions of the accelerator pedal and brake pedal, a distance sensor for detecting the distance and the relative speed from or in front of a driver Vehicle, a steering wheel angle sensor for detecting a steering wheel angle speed or steering wheel angle change speed, and with a determining and evaluating device for determining a target acceleration or a target braking pressure in accordance with the detected values, which cooperate with an acceleration controller, which controls the wheel brakes in accordance with the target acceleration or the target brake pressure.

12. The apparatus according to claim 11, characterized in that the determination and evaluation device has a distance

13. The apparatus of claim 11 or 12, characterized in that the determination and evaluation device has a steering angle monitoring device for monitoring the steering wheel actuation of the driver and determining an avoidance situation, which, in the event that an avoidance situation is detected, control signals for reducing the control of the wheel brakes Vehicle.

14. Device according to one of claims 11 to 13, characterized in that the determination and evaluation device has a device for outputting a correction signal for influencing a brake assist system or a brake pedal characteristic.

15. The device according to one of claims 11 to 14, characterized in that it has a Monitoring computer that detects a malfunction of individual sensors and / or controllers and outputs corresponding warning signals and / or switches off parts or the entire system.