DE102013007543A1 - Method for driver assistance during emergency braking and driver assistance system - Google Patents

Abstract

For driver assistance in emergency braking by automatically applying brake pressure to at least one brake (151) of a vehicle, a signal indicative of potentially impending emergency braking is obtained. In response to receiving the signal, a pump control signal is sent to a pump (161). The pump is configured to deliver brake fluid in a brake fluid circuit (150) of the at least one brake (151). The pump control signal drives the pump (161) such that a speed of the pump (161) reaches a target speed range. Thereby, the pump (161) is placed in a standby state, so that the emergency braking can be initiated comparatively quickly in response to the receipt of another signal requesting the emergency braking.

Description

The invention relates to techniques for driver assistance in emergency braking by means of automatically applying brake pressure to a vehicle's brakes and a driver assistance system. In particular, techniques are discussed in which, responsive to receiving a signal indicative of potentially impending emergency braking, a pump that delivers brake fluid into a brake fluid circuit of the brakes is controlled such that a speed of the pump reaches a target speed range.

Driver assistance systems are known which assist a driver of a vehicle by initiating and / or implementing emergency braking. This support can be carried out fully automatically or semi-automatically. An emergency braking should avoid a collision situation by braking the vehicle. Typical techniques for initiating and executing emergency braking rely on one or more on-vehicle sensors monitoring an environment of the vehicle. If these one or more sensors determine that a collision situation exists with a certain probability, emergency braking is requested. In various reference implementations, a pump and one or more valves in a brake fluid circuit of the brakes are then controlled in such a way that brake fluid of the brake fluid circuit reaches a certain brake pressure at the brakes of the vehicle. As a result, brake shoes can be brought into contact with brake discs of the brakes and thus the emergency braking initiated or carried out. Alternatively or additionally, it is also possible to warn the driver of the vehicle by means of a user interface.

In such a scenario, the sensors monitoring the environment of the vehicle typically accumulate data continuously. For example, at a first point in time, an object which possibly causes a collision situation can be detected for the first time. At the same time, however, the recognition of the object at the first time may be subject to a comparatively high degree of uncertainty. Therefore, the likelihood that the collision situation is imminent may still be comparatively low at the first time and / or a confidence level of probability may be low. After the first time, the sensors monitoring the environment of the vehicle continue to accumulate data. These data can be used to plausibilize the hypothesis that the collision situation is imminent. This plausibility check can increase or decrease the probability that the collision situation is imminent. At a second time, the likelihood that the collision situation is imminent may exceed a certain threshold. Then a signal can be sent that the emergency braking should be carried out. As a result, the emergency braking can be triggered. Characteristic of such a technique is that a first, possibly comparatively uncertain statement that a collision situation is imminent, already at an early first time - while the actual triggering of the emergency braking is delayed until a later second time, z. B. to avoid faulty emergency braking due to a falsely detected collision situation. The time span between the first detection of the collision situation and requesting the emergency braking may, for. B. be referred to as recognition period. Typically, at an earlier (later) second time, when the emergency braking is requested, or a short (long) detection period, the available braking distance is longer (shorter). Therefore, it can often be desirable to request emergency braking early.

However, in such a scenario, it may often be necessary to strike a balance between early deployment and secure detection of the collision situation. If the emergency braking is requested comparatively early (late), on the one hand a confidence with which the collision situation is determined, d. H. a tripping safety, comparatively low (large) and on the other hand be a period of time until the occurrence of the collision situation (English: time to collision, TTC) comparatively long (short). Therefore, it may be necessary to strike a balance between tripping safety and available braking distance for emergency braking.

In either case, it may be desirable to minimize the time between request for emergency braking and the onset of significant braking. Often, the time between requesting the emergency braking and onset of braking is also referred to as dead time. The dead time can be caused by technical limitations. The dead time is followed by the braking time period during which the vehicle is braked with a significant braking effect.

Various techniques for reducing deadtime are known. For example, brakes can be used which are building-related and inherently have a low dead time. Frequently such brakes are expensive and / or consume a large amount of energy and / or require a lot of space in the vehicle. There are also known techniques which, to shorten the dead time, a pre-filling of Make brake fluid circuits in the brake fluid area before actually requesting emergency braking, such as during the detection period. For this purpose, the pump, which promotes the brake fluid in the brake fluid circuit, operated briefly and for a limited time to build up a certain brake pressure. However, the shortening of the dead time by such a pre-fill with brake fluid can be comparatively low.

Therefore, there is a need to provide driver assistance techniques in the event of emergency braking that allow for reduction of dead time after requesting emergency braking. In particular, there is a need for techniques that are inexpensive and low in energy.

This object is solved by the features of the independent claims. The dependent claims define embodiments.

According to one aspect, the invention relates to a method for driver assistance in emergency braking by means of automatic application of brake pressure to at least one brake of a vehicle. The method includes receiving a signal indicating potentially impending emergency braking. Further, in response to receiving the signal, the method comprises: sending a pump control signal to a pump configured to deliver brake fluid in a brake fluid circuit of the at least one brake. The pump control signal drives the pump so that a speed of the pump reaches a target speed range, e.g. B. reaches a target speed with a certain tolerance. In this target speed range, the pump can then z. B. be kept as long as possible.

For example, the pump may be in an idle state, i. H. before receiving the signal, resting, d. H. the speed of the pump may be zero or may be low. In response to receiving the signal, the speed of the pump may then be ramped up to reach the target speed range. In a simple embodiment, the target speed equal to the z. B. within a specified range of the pump maximum speed correspond. It would also be possible for the target speed range to correspond to a different speed within a specification range of the pump. After reaching the target speed range, the speed of the pump z. B. be kept constant or within the target speed range. The method may thus further include: operating the pump in the target speed range.

It is Z. For example, it is possible for the pump control signal to control, in addition to the target speed range itself, a time profile of the speed to reach the target speed range, such as a rate of change of the speed over time or over the time course of the speed itself. Typically, the pump may have some inertia so that reaching the target speed range requires a certain amount of time. In a simple scenario, it is possible for the pump control signal to drive the pump to reach the target speed range as quickly as possible, e.g. Within the pump specifications. However, it would also be possible for the pump control signal to actuate the pump in such a way that a certain length of the time duration is required to reach the target rotational speed range.

The signal can z. B. implicitly or explicitly indicate that the emergency braking is imminent with a certain probability. The certain probability may be included in the signal, but need not be included. The signal can z. B. only consist of a certain voltage level or be a digital signal with a yes / no value. For example, the signal may be obtained via a vehicle bus of the vehicle. The signal may be sent whenever a likelihood that the emergency braking is imminent exceeds a certain threshold.

For example, this certain probability may be comparatively low compared to the case where the emergency braking is actually requested. In other words, the confidence level with which the collision situation is detected can still be comparatively low at the time the signal is received, so that the request for the emergency braking is not yet carried out in accordance with a certain desirable triggering safety. At the same time, however, it may be desirable, by driving the pump so that its speed reaches the target speed range, the pump and optionally various other units of the brake fluid circuit, such. B. valves to put in a ready state. If, subsequently, ie at the end of a recognition time period, a further signal is received which actually requests the emergency braking, the dead time until the onset of the braking effect can be significantly shortened. This may be the case since the pump is already operating at the target speed range. This may be the case, since the dead time due to the startup of the pump to reach a speed which allows a significant flow rate of brake fluid, eliminated or reduced. In other words, it can be achieved by such techniques that the pump is activated in the forefront of an emergency braking such that it is already operated in a useful range with respect to the speed when requesting the emergency braking, which is particularly suitable for performing the emergency braking.

In a simple scenario, it may be possible that on the one hand the pump is controlled such that the speed reaches the target speed range, and on the other hand at least one valve in the brake fluid circuit is controlled such that the brake fluid pressure at the brake is not or not significantly increases. This may have the effect that the brake shoes remain in a rest position and in particular not or not significantly touch the brake discs. In such a case, no or no significant deceleration of the vehicle may be effected. Such an effect can, for. Example, by closing a valve between the pump and the brake and / or by opening a valve between the pump and a brake fluid reservoir.

It is possible that in response to receiving the signal, the method further comprises sending a valve control signal to at least one valve in the brake fluid circuit. The valve control signal may drive the at least one valve to achieve a predetermined brake pressure of the brake fluid at the at least one brake. The predetermined brake pressure can cause a deceleration of the vehicle.

Various arrangements of valves in the brake fluid circuit are possible. For example, a valve may be disposed between the pump and a brake fluid reservoir and / or another valve between the pump and each of the at least one brake. Depending on the arrangement of the valve, the valve can be opened or closed. Is z. For example, when the valve is placed between the pump and the brake fluid reservoir, the valve control signal can drive the valve to close. Is the valve z. B. arranged between the pump and the brakes, the valve control signal can control the valve so that it opens.

The valve may be arranged to have two states - that is, open / close - or may be configured to have more than two states - that is, in addition, partially open. As a result, a certain pressure drop across the valve can be achieved. The valve may alternatively or additionally be configured to achieve the particular pressure drop by opening and closing quickly.

Preferably, the delay achieved by the predetermined brake pressure can be comparatively low. This can be z. B. be achieved in that the predetermined brake pressure causes only a slight contact of the brake shoes and the brake disc and / or the control is so short that the inertia of the system, the touch of the brake shoes through the brake disc do not lead to a noticeable delay in the vehicle , Then the delay of the vehicle z. B. is less than a threshold, this threshold is preferably 1 m / s ² or more preferably 0.1 m / s ² . Depending on the dimensions of the brake fluid circuit, the brake pressure can assume different values. In typical systems, the predetermined brake pressure z. B. be 1.5 bar ± 1 bar, particularly preferably 1.5 bar ± 0.5 bar. It can thereby be achieved that the implementation of such measures for displacing the brakes and the pump into a standby state is not or only to a limited extent discernible by the driver of the vehicle. In particular, the deceleration of the vehicle may be so low that the driver does not perceive it.

By sending the valve control signal according to the techniques described above, in addition to the effect of reaching the target speed range, it can be achieved that pre-filling of the brake fluid circuit already takes place in the brakes with brake fluid. In addition, a preferably comparatively low brake pressure can already be built up so as to further reduce the dead time.

However, by driving the pump so that the rotational speed reaches the target rotational speed range and simultaneously driving the at least one valve, a situation may occur in which the brake fluid pressure of the brake fluid increases continuously with increasing time. If the predetermined brake pressure of the brake fluid at the brakes is reached in such a situation, one or more of the following measures can be taken: for example, the pump can be controlled in such a way that the rotational speed of the pump is reduced; It would also be possible for the at least one valve to be controlled in such a way that the brake pressure of the brake fluid at the brakes is reduced. In the latter case, it may in particular be unnecessary to control the pump, ie it may be possible that the braking pressure of the brake fluid on the brakes does not exceed the predetermined brake pressure or not significantly, while the speed of the pump is increased until reaching the target speed range and or subsequently remains in the target speed range. In this regard, the method z. B. further comprise: depending on the brake pressure of the brake fluid: driving the at least one valve and / or the pump repeatedly by sending corresponding control signals, so that the Brake pressure does not exceed the predetermined brake pressure at the at least one brake.

The pump control signal may drive the pump so that the speed reaches the target speed range within a predetermined period of time from receipt of the signal.

For example, the predetermined amount of time may be longer than the minimum amount of time required within specifications to reach the target speed range. In other words, the driving of the pump can be carried out in such a way that the pump does not increase the speed as fast as possible. A rate of change of the speed of the pump may be below a maximum possible rate of change of the speed of the pump.

By means of such techniques a variety of effects can be achieved. For example, it may be possible by the appropriate driving of the pump, on the one hand, the speed of the pump, the target speed range within the predetermined time period is reached and on the other hand, the brake fluid pressure at the brakes does not exceed the predetermined brake pressure within the predetermined time or not significantly. With regard to such an effect, therefore, the predetermined period of time can be tuned to certain properties of the brake fluid circuit of the brakes.

Alternatively or additionally, it would also be possible for the predetermined period of time to be matched to operating characteristics of sensors which monitor the environment of the vehicle with regard to the potentially imminent emergency braking. In various reference implementations of such sensors, a certain amount of time may typically be required until the sensors can indicate an imminent collision situation with sufficient probability. This detection period can be predetermined by technical boundary conditions of the operation of the sensors. Typical detection periods may be in the range of 50-200 ms or in about 100 ms. In other words, such a period of time may be required by the sensors to make the upcoming collision situation plausible by further accumulating data describing the environment of the vehicle. In such a situation, it may be desirable for the speed of the pump to reach the target speed range when the sensors request the emergency braking or are able to preclude imminence of the collision situation and subsequently request emergency braking, ie, at the end of the detection period.

By such a tuning of the pump control signal to operating parameters of the sensors and / or to properties of the brake fluid circuit, a particularly efficient driving of the pump can take place. For example, a life of the pump may be increased since it may be unnecessary to achieve the target speed range with a maximum rate of change of the speed. This can also reduce energy consumption of the pump.

The method may further include: sending a further pump control signal to the pump when at least one of the following criteria is met: an abort signal is received; and / or another signal requesting emergency braking is not obtained within a predetermined period of time from receipt of the signal; and / or the brake fluid pressure at the brakes exceeds a predetermined threshold; and / or the speed of the pump reaches the target speed range. The further pump control signal can control the pump in such a way that the rotational speed is reduced relative to the target rotational speed range.

For example, the further pump control signal can control the pump so that the speed is reduced to zero. For example, the abort signal may be obtained if the likelihood of the imminent collision situation falls below a certain lower likelihood threshold - d. H. when the sensors monitoring the environment of the vehicle invalidate the collision situation; this can be z. This may be the case, for example, when an object with which a collision was possible leaves the carriageway or when a collision situation that was previously critically assessed is invalidated as part of the plausibility check.

If the additional signal requesting the emergency braking is not received within the predetermined period of time, this can be equivalent to the fact that the collision situation was invalidated. In particular, in such a case, it may be unnecessary to obtain the dedicated abort signal. This predetermined period of time, which is decisive for the transmission of the further pump control signal, may in particular be chosen the same at the predetermined time interval within which the rotational speed of the pump reaches the target rotational speed range.

By means of such techniques described above, the effect of a termination criterion for driving the pump to place it in the standby state can be achieved by ramping up the speed. It may be desirable to provide such an abort criterion, as not necessarily every received signal, one possibly pending Emergency braking is actually indicated in performing emergency braking. Then it may be desirable to return the pump to the idle state.

It is possible that the method further includes receiving another signal requesting the emergency braking. The method may further include, in response to receiving the further signal: sending a further valve control signal to at least one valve in the brake fluid circuit and / or sending a further pump control signal to the pump. The further valve control signal may actuate the at least one valve to achieve a predetermined additional brake pressure of the brake fluid at the brakes, which is greater than the predetermined brake pressure. The further pump control signal can control the pump such that the speed of the pump reaches the target speed range as quickly as possible.

It would also be possible for the further pump control signal to actuate the pump in such a way that the pump has a further target rotational speed range, for. B. reaches a further target speed with a certain tolerance as quickly as possible, the further target speed range is greater than the target speed range.

For example, the further valve control signal can be sent in particular if the at least one valve was previously in a state which prevents the highest possible brake pressure of the brake fluid from reaching the brakes. This can be z. Example, be the case when a valve, which is located between the pump and a brake fluid reservoir, is open or partially open. The further pump control signal can, for. B. be sent in particular when the pump control signal drives the pump such that a rate of change of the speed to reach the target speed range is less than a maximum possible value. It is possible that only one of the valve control signal and the pump control signal is sent.

In a particularly simple embodiment, it may also be unnecessary to send the valve control signal and send the pump control signal to trigger the emergency braking. This can be z. Example, be the case when the predetermined time to reach the target speed range is designed such that without action at the end of the predetermined period of time, a significant delay is effected.

If the emergency braking is triggered, then a significant deceleration of the vehicle takes place, for example, in the state or up to the walking speed.

For example, the target speed range of the pump may be within a range of a pump characteristic of the pump that is optimized for torque of the pump. Alternatively or additionally, it is also possible for the target rotational speed range to lie within a maximum range of the pump characteristic.

Typically, a flow rate of brake fluid may increase as the speed of the pump increases. Therefore, it may be desirable if the target speed range is selected as high as possible. By setting the target speed range in relation to the pump characteristic, the effect of a specially tuned control of the pump can be achieved.

In the foregoing, various techniques relating to the brakes of the vehicle have been generally discussed. However, it is possible to perform the respective techniques individually for different wheels of the vehicle or equally for all wheels of the vehicle. For example, at least one valve per wheel of the vehicle can be controlled in order to achieve a comparable achievement of the predetermined brake pressure on the brakes of the wheels of the vehicle. In such a case, by controlling the various wheels of the vehicle in the same manner, a particularly high deceleration effect after requesting the emergency braking can be achieved. A braking distance of the vehicle during emergency braking can be reduced.

In another aspect, the invention relates to a driver assistance system for emergency braking by automatically applying brake pressure to brakes of a vehicle. The driver assistance system includes a control unit configured to perform the following steps: receive a signal indicative of a potentially upcoming emergency braking; in response to receiving the signal: sending a pump control signal to a pump. The pump is arranged to deliver brake fluid in a brake fluid circuit of the brakes. The pump control signal drives the pump so that a speed of the pump reaches a target speed range.

For example, the driver assistance system may further include the pump. The pump can furthermore be set up for operation within the framework of driver assistance for electronic driving stability. The person skilled in various driver assistance functionalities for electronic driving stability are known in which automatically a certain brake pressure of the brake fluid is generated at individual brakes of a vehicle to stabilize the vehicle, for. B. in the context of a cornering. For such driver assistance functionality Typically, a corresponding pump is provided in the brake fluid circuit. This pump can be used simultaneously to initiate and perform emergency braking in accordance with various techniques of the present invention.

The driver assistance system can furthermore be set up to carry out the method for driver assistance during emergency braking in accordance with a further aspect of the present invention.

For such a driver assistance system, effects can be achieved which are comparable with the effects that can be achieved for the method for driver assistance in emergency braking according to a further aspect of the present invention.

The features and features set out above, which are described below, can not only be used in the corresponding combinations explicitly stated, but also in other combinations or isolated. The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of embodiments, which will be described in connection with the drawings.

1 is a schematic view of a driver assistance system, which is set up for driving units of a brake fluid circuit.

2 is a signal diagram illustrating signal flows in relation to a control unit of the driver assistance system.

3 FIG. 10 is a flowchart of a driver assistance emergency assistance method according to various embodiments of the present invention. FIG.

4 illustrates a time course of a probability of a collision situation, as it is determined by sensors that monitor an environment of a vehicle.

5A illustrates a time course of a speed of a pump that promotes brake fluid in the brake fluid circuit.

5B illustrates a time course of a brake pressure of the brake fluid to the brakes.

6A illustrates a time course of the speed of the pump.

6B illustrates a time course of the brake fluid pressure at the brakes.

7 illustrates a time course of the deceleration of the vehicle resulting from techniques according to various embodiments of the invention.

8th schematically illustrates a collision situation in which an emergency braking can be performed.

Hereinafter, the present invention will be described with reference to preferred embodiments with reference to the drawings. In the figures, like reference characters designate the same or similar elements. The figures are schematic representations of various embodiments of the invention. Elements shown in figures are not necessarily drawn to scale. Rather, the various elements shown in the figures are reproduced in such a way that their function and general purpose will be understood by those skilled in the art. In the figures, connections and couplings between functional units and elements may also be implemented as indirect connections or couplings. A connection or coupling may be implemented by wire or wireless. Functional units may be implemented as hardware, software or a combination thereof.

Hereinafter, techniques are described which make it possible to put a pump in a brake fluid circuit in a possibly impending emergency braking in a ready state. For this purpose, the pump is controlled such that a speed of the pump reaches a target speed range. Such a target speed range may be defined by, for example, an upper limit and a lower limit. But it can also be defined by a single target speed, which should then be achieved within a predefined or systemic tolerance. If the emergency braking is then actually requested, then the pump is already operating in an optimized speed range. Dead time, which is otherwise required due to the finite inertia of the pump to start the pump to the target speed range, is eliminated or is reduced.

In 1 is a corresponding driver assistance system 100 shown, which is a control unit 103 includes. The control unit 103 can with different components of a brake fluid circuit 150 communicate (in 1 through the Arrows illustrated). The brake fluid circuit 150 can take different forms. In the example of 1 includes the brake fluid circuit 150 a pump 161 , a brake fluid reservoir 153 and different valves 160-1 . 160-2 . 160-3 , Due to the brake fluid can brake 151 be operated so that a delay for the corresponding vehicle is effected in the context of the braking process.

To perform the braking can, for. B. the valve 160-1 and the valve 160-3 be open while the valve 160-2 when operating the pump 161 closed is. Then there is a brake pressure of the brake fluid on the brake 151 , so brake shoes the brake 151 in contact with a brake disc of the brakes 151 to be brought. The brake pressure of the brake fluid may, for. B. by means of a measuring device 151 on the high pressure side of the pump 161 be measured.

In 1 is illustrative only the brake 151 and the brake fluid circuit 150 in relation to a single wheel of the vehicle. However, it should be understood that by appropriate branches of the brake fluid circuit 150 corresponding circuits can be provided for all wheels of the vehicle. It is also possible to provide individual valves so that they have an effect on all brakes, z. B. the valve 160-1 , Alternatively or additionally, it is possible to provide individual valves so that they have an effect only on individual brakes of the several brakes of the vehicle, for. B. the valve 160-3 , This may make it possible to provide brake fluid pressure differently for different brakes; At the same time, only one pump can be used 161 be used.

The control unit 103 is still in communication with at least one sensor 101 of the vehicle monitoring an environment of the vehicle, e.g. B. via a vehicle bus. Furthermore, the control unit communicates 103 with a user interface 102 which allows input and output of information from and to a user, again e.g. B. via the vehicle bus.

The sensors 101 are set up to detect any impending emergency braking. This can be done by the sensors 101 determine a probability value of a collision situation. If this probability value exceeds a certain threshold value, ie if the collision is particularly probable, then the sensors can 101 a signal to the control unit 103 send the emergency braking request. The control unit 103 then can the various components of the brake fluid circuit 150 trigger accordingly to trigger or carry out emergency braking. The vehicle is braked.

Typically, it is desirable that the dead time between the signal, the emergency braking at the control unit 103 request and minimize the onset of the delay. In this regard, the at least one sensor 101 be set to send a signal to the control unit before sending the signal that requests the actual emergency braking 103 to send a potentially impending emergency braking indicated. Then the control unit 103 already take appropriate measures to put the various components of the brake fluid circuit in a ready state. During a recognition period, z. B. in particular the speed of the pump can be started up. As a result, the dead time can be reduced in the event of a subsequent emergency braking request.

The ready state of the pump 161 In particular, it includes increasing the speed of the pump 161 so that the speed of the pump finally reaches a predetermined target speed range and z. B. retains, for. B. retains for a predetermined period of time. Hereinafter, with reference to the other figures, techniques will be explained which involve a corresponding activation of the pump 161 through the control unit 103 affect. As a result, when the emergency braking is actually requested, it can be avoided that due to the inertia of the pump 161 the dead time by the time it takes to start the pump 161 is needed is extended. As a result, a significant braking effect can be achieved earlier. This reduces a braking distance of the vehicle. This increases the safety of the occupants and other road users. In one embodiment, the control of the pump takes place 161 in such a way that the most effective target speed range is achieved, the target speed range is kept as long as possible and the control for vehicle occupants in the case in which then no braking is initiated, as little as possible. Actually used control of the pump 161 can be a compromise between these criteria.

In 2 a signal flow diagram is shown schematically illustrating the corresponding communication between the various units. First, in step X1, the at least one sensor is shipped 101 a signal 301 to the control unit 103 , which indicates a possible impending emergency braking. For example, the at least one sensor 101 the signal 301 then send in step X1 if the Probability for the collision situation exceeds a first threshold.

In response to receiving the signal 301 leads the control unit 103 through steps X2 and X3. In step X2, a pump control signal 302 to the pump 161 Posted. By means of the pump control signal 302 becomes the pump 161 controlled such that a speed of the pump 161 reaches a target speed range. This can be the driving of the pump 161 be done so that the speed of the target speed range within a predetermined period of time, eg. B. from receiving the signal 301 or from getting the signal 302 at the pump 161 , reached. This may mean that the signal specifies a rate of change of the speed over time. For example, this rate of change may be less than a maximum possible rate of change. It is also possible that the signal 302 the specified time period is explicitly indicated. It would also be possible for the signal 302 the indicated period of time only implicitly indicated, for example by reference to previously set operating parameters of the pump 161 ,

In step X3, the control unit sends 103 a valve control signal 303 to at least one valve 160-1 . 160-2 . 160-3 , The valve control signal 303 instructs that at least one valve 160-1 . 160-2 . 160-3 in that a predetermined brake pressure of the brake fluid on the brake 151 is reached. This predetermined brake pressure can z. B. cause the brake shoe of the brake 151 just in contact with the brake disc of the brake 151 comes. Thereby, a deceleration of the vehicle can be effected, which however is comparatively small, preferably in particular so small that it is not perceived by the driver of the vehicle. For example, the delay may be less than 0.5 m / s ² . To achieve the predetermined brake pressure z. B. the valve 160-1 to be opened, the valve 160-2 be closed and the valve 160-3 be opened. In alternative arrangements of the at least one valve 160-1 . 160-2 . 160-3 in the brake fluid circuit 150 , according to other configurations of the valves 160-1 . 160-2 . 160-3 to be possible.

By steps X2 and X3 is thus achieved that the pump 161 and the valves 160-1 . 160-2 . 160-3 , or the brake fluid circuit 150 be put into a standby state. As a result, the dead time can be reduced when the emergency braking is actually triggered.

In step X4, the meter represents 155 the brake pressure of the brake fluid on the brake 151 the control unit 103 ready. Step X4 is an optional step. Depending on the measured brake pressure of the brake fluid on the brake 151 , the control unit can 103 take further action. For example, in a scenario in which the measured brake pressure exceeds the predetermined brake pressure, in step X5, a command to the at least one valve 160-1 . 160-2 . 160-3 be sent, which causes the brake pressure does not increase further. This can be z. B. can be achieved by partial or cyclic or complete opening or closing of one or more valves. For example, in the scenario of 1 the valve 160-2 be opened partially or in a certain period to achieve such that, despite operating the pump 161 at a finite speed, z. B. in the target speed range, the brake fluid pressure of the brake 151 does not rise above the specified brake pressure.

After a predetermined period of time 250 from sending the pump control signal 302 in step X2 to the pump 161 , the control unit takes steps in steps X6 and X7 to allow the pump 161 and the at least one valve 160-1 . 160-2 . 160-3 return to a state of rest. This may in particular mean that the speed of the pump 161 is lowered back to zero. To do this, the control unit sends 103 in step X6 another pump control signal 302b to the pump 161 , Furthermore, the control unit sends 103 in step X7 another valve control signal 303b to the at least one valve 160-1 . 160-2 . 160-3 , For example, the other valve control signal 303b cause the valve 160-2 permanently open, causing the brake fluid pressure on the brake 151 by fluid communication with the brake fluid reservoir 152 is reduced. This can cause the brake shoes of the brake 151 from the brake disc and there is no delay of the vehicle.

In the above with respect to the 2 Although the case discussed becomes the signal 301 sent indicating the potentially imminent emergency braking. However, no further signal is sent which actually requests the emergency braking. It does not trigger the emergency braking. Such a situation can z. B. arise when the at least one sensor 101 perceives a comparatively critical situation in the environment of the vehicle, but then defuses this situation or is weakened by further data. In a situation where emergency braking is actually requested, the at least one sensor sends 101 another signal to the control unit 103 , preferably during the period of time 250 , Then the control unit 103 Take appropriate measures to initiate emergency braking. In a particularly simple embodiment, these measures may be that steps X6 and X7 are not performed. In such a case can itself through Operating the pump 161 in the target speed range, the brake fluid pressure at the brake 151 continue to build without the appropriate valve 161-2 would be opened, which would lead to a reduction of the brake pressure. However, it would also be possible for the control unit 103 another signal to the pump 161 and / or the at least one valve 160-1 . 160-2 . 160-3 sends, which causes the brake pressure is increased faster and / or maintained.

In 3 FIG. 3 is a flowchart of a driver assistance emergency assistance method according to various embodiments of the present invention. The procedure begins in step A1. First, it is checked in step A2 whether there is an increased probability of emergency braking. This review can z. B. by means of at least one sensor 101 , which monitors the environment of the vehicle, take place. Only when there is an increased likelihood of imminent danger braking, the method continues with step A3. In step A3, the signal becomes 301 to the control unit 103 of the driver assistance system 100 which indicates an increased likelihood of impending emergency braking.

In response to receiving this signal 301 , controls the control unit 103 the pump 161 such that the speed of the pump 161 reaches the target speed range (step A4). This happens z. B. by sending the pump control signal 302 ,

Optionally, in step A5, the activation of the at least one valve 160-1 . 160-2 . 160-3 through the valve control signal 303 done so that the brake pressure of the brake fluid to the brake 151 reached the predetermined brake pressure.

By such techniques it is achieved that due to the execution of steps A4 (and optional step A5) on the brake, a certain brake pressure is present and the pump is operated at a certain speed. As a result, the dead time can be significantly reduced in a subsequent triggering of the emergency braking.

First, however, it is checked in step A6 whether an abort criterion is met. The termination criterion may have various configurations. So it is z. B. possible that the termination criterion by expiration of the specified period 250 is fulfilled. It would also be possible for the at least one sensor 101 an abort signal to the control unit 103 sends. Alternatively or additionally, the termination criterion in step A6 may be that the brake fluid pressure at the brake 151 exceeds the predetermined brake pressure.

If the termination criterion is met in step A6, then in step A8, the pump 161 from the control unit 103 controlled so that the speed is reduced compared to the target speed range. This can z. B. the further pump control signal 302b (Cf. 2 ). Preferably, in step A8, the driving of the pump takes place in such a way that the rotational speed is reduced to zero or the pump is returned to the idle state. Subsequently, the method may end in step A10.

However, if it is determined in step A6 that the abort criterion is not met, it is checked in step A7 whether a triggering criterion is met. The trigger criterion can be fulfilled in particular when the emergency braking by sending a further signal to the control unit 103 from the at least one sensor 101 is actually requested. It would also be possible for the triggering criterion to be due to the expiration of the given time period 250 , z. B. from step A3, is realized.

If the triggering criterion is not met in step A7, step A6 is carried out again. Otherwise, the method continues with step A9. Step A9 is an optional step. In step A9, the driving of the pump takes place 161 and / or the driving of the at least one valve 160-1 . 160-2 . 160-3 for performing the emergency braking. For example, the driving of the pump can be such that the target speed range is reached faster or that the speed is maximized. Accordingly, a position of the various valves 160-1 . 160-2 . 160-3 be adapted so that the brake pressure of the brake fluid to the brake 151 is maximized. Alternatively, it would also be possible for the emergency braking to be carried out without further implementation of different activation steps. This may be the case if by operating the pump in the target speed range as a result of step A4 and by the corresponding driving of the valve in step A5, the brake fluid pressure at the brake 151 steadily increased, so that the emergency braking takes place - unless step A8 is carried out as an abort - without further control commands, in particular without step A9.

After step A9, the process ends in step A10.

Various techniques for driver assistance in emergency braking have been discussed above. Hereinafter, various operating parameters will be discussed with respect to the various components discussed above. as a function of time 201 discussed. This is in particular to the different triggering criteria that lead to the implementation of the various steps, or various advantageous effects, such. As the reduction of dead time to explain in more detail.

In 4 is the probability 205 for an imminent collision situation over time 201 applied. For example, the probability 205 by means of the at least one sensor 101 be determined. At a first time 201-1 the probability exceeds a first threshold (in 4 represented by the horizontal dashed line). At a second time 201-2 exceeds the probability 205 a second threshold (in 4 also represented by a horizontal dashed line). The probability 205 at the second time 201-2 is greater than the probability 205 at the first time 201-1 , This means that with greater security at the second time 201-2 can be predicted that a collision situation is imminent. At the time 201-2 requesting the emergency braking can be carried out, for. B. by sending the further signal from the at least one sensor 101 to the control unit 103 , The time span between the first and second time 201-1 and 201-2 may also be referred to as the detection period. During the recognition period, the at least one sensor makes itself plausible 101 the presence of the collision situation and / or it is waited, whether the collision situation defused, z. For example, because an object with which the collision is possible leaves the road. Accordingly, it is possible that the time interval between the times 201-1 . 201-2 in various embodiments has very different magnitudes, from about a few milliseconds to a few seconds.

At the first time 201-1 the signal is sent 301 indicating an impending emergency braking from the sensor 101 to the control unit 103 , Then the control unit 103 the measures described above take to the pump 161 in a standby state at an increased speed. Will be at the second time 201-2 the emergency braking actually triggered, is the pump 161 already in the state of increased speed, so that the dead time can be reduced.

With the dotted line in 4 is presented a situation where the probability 205 does not exceed the threshold for requesting emergency braking. In such a case, appropriate measures can be taken that the control unit 103 the pump 161 returned to the idle state, ie, for example, the speed is reset to zero.

The temporal change of the probability 205 between the first and second time 201-1 . 202-2 can be based on various effects. For one thing, the situation around the vehicle may change over time. In a simple case, for. B. a pedestrian, who has previously entered the street, leave the road again, so that the collision situation is averted. Another reason for changing the probability 205 over time 201 can in a certain latency in the operation of the at least one sensor 101 lie. In a simple example, the at least one sensor 101 z. Example, be an optical camera, which monitors an area in front of the vehicle. For example, at the first time 201-1 the optical camera has processed two captured images and on this data basis the probability 205 determine for the upcoming collision situation. At the first time 201-1 then the optical camera can evaluate further acquired images and the probability 205 adapt or make plausible the upcoming collision situation due to the extended data basis. Typically, this can reduce an uncertainty of the recognition of the collision situation. This can increase the tripping safety.

In 5A is the speed 202 the pump 161 over time 201 applied. At first 201-1 Following is the speed 202 increases until it reaches the target speed range (represented by a target speed 202a ; in 5A shown as a dashed horizontal line). This happens at a second time 201-2 ,

In 5B is the brake pressure 203 the brake fluid on the brake 151 over time for the scenario of 5A shown. As a result of increasing the speed 202 the pump 161 (please refer 5A ) increases the brake pressure 203 over time 201 , After a period of time 250 after the first time 201-1 ie at the second time 201-2 , the brake pressure reaches 203 a certain value, eg. B. the predetermined brake pressure (in 5B represented by the dashed horizontal line). Subsequently, the brake pressure 203 continue to increase (solid line in 5B ) and a significant deceleration of the vehicle during emergency braking; this may require an action or it may be necessary to omit an abort action. It is also possible that the brake pressure 203 is dismantled again (dotted line in 5A and 5B ). Then no emergency braking takes place. The low brake pressure previously applied to the brake 151 applied can cause no or no significant delay.

In 6A is one with the 5A comparable situation shown, in 6A with the dotted line the speed 202 the pump 161 is shown according to various reference implementations. According to various reference implementations, the speed becomes 202 the pump 161 only from the second time 201-2 increases, in which the emergency braking is actually requested, ie after the detection period. The solid line shows an implementation according to the teachings of the present invention. Already from the first time 201-1 is the speed 202 the pump 161 increased to the target speed 202a to reach.

The embodiment of the 6A stands out - in contrast to the embodiment of 5A - characterized in that the speed 202 the pump 161 the target speed 202a already before the second time 201-2 reached.

In 6B is for the situation of 6A the brake pressure 203 on the brake 171 over time 201 shown. In particular, in 6B presented a situation in which the brake pressure 203 already before the expiry of the time span 250 the predetermined brake pressure 203a reached. To make sure the brake pressure 203 during the time span 250 , ie before requesting the emergency braking, the predetermined brake pressure 203a does not exceed, a corresponding valve control signal to the at least one valve 160-1 . 160-2 . 160-3 be sent. Such a signal can ensure that despite further increasing the speed (see 6A ) is achieved, that the brake pressure 203 on the brake 151 does not continue to rise. This can be the at least one valve 160-1 . 160-2 . 160-3 z. B. be cyclically opened and closed or partially opened. Corresponding effects may alternatively or additionally to such a control of the valve 160-1 . 160-2 . 160-3 also by a suitable dimensioning of the brake fluid circuit 150 be achieved.

In 7 is the delay 204 of the vehicle over time 201 for those in the 6A and 6B described situation. How out 7 can be seen, is by increasing the brake pressure 203 during the time span 250 ie before the second time 201-2 already reached a delay of the vehicle. This delay is comparatively small and does not cause significant deceleration of the vehicle. Only at the time 201-2 following is the delay 204 of the vehicle significantly increased, which corresponds to the emergency braking. For the case of the reference implementation (dotted line in 7 ) sets a significant delay 204 only after a certain dead time 260 from the second time 201-2 to which the emergency braking is required. The solid line shows the delay 204 for an implementation of the techniques of the present invention. In particular, a significant braking effect occurs very soon after the second time 201-2 one. The dead time 260 is significantly reduced and a particularly short braking distance during emergency braking can be achieved.

In 8th is a collision situation 520 shown. The vehicle 500 moves to an object 501 to. The vehicle 500 has a certain distance 510 from the object 501 , Along with the speed of the vehicle 500 so can a time to collision TTC with the object 501 be determined. For example, the probability of the occurrence of the collision situation of the distance 510 and / or depend on the time to collision. Furthermore, the probability 205 for the occurrence of the collision situation also of an accuracy of the recognition of the object 501 by means of the sensor 101 of the vehicle 500 depend.

Of course, the features of the previously described embodiments and aspects of the invention may be combined. In particular, the features may be used not only in the described combinations but also in other combinations or per se, without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

100

Driver assistance system

101

Sensor evaluation unit

102

User interface

103

control unit

150

Brake fluid circulation

151

brake

152

Brake fluid reservoir

155

gauge

160

Valve

160-1

Valve

160-2

Valve

160-3

Valve

161

pump

201

Time

201-1

time

201-2

time

202

rotation speed

202a

Target speed

203

brake pressure

203a

predetermined brake pressure

204

delay

205

probability

250

Period of time

260

dead

301

signal

302

Pump control signal

302b

another pump control signal

303

Valve control signal

303a

another valve control signal

303b

another valve control signal

500

vehicle

501

object

510

distance

520

collision situation

Claims (10)

Method for driver assistance during emergency braking by automatic application of brake pressure ( 203 ) on at least one brake ( 151 ) of a vehicle ( 500 ), the method comprising: - obtaining a signal ( 301 ) indicating a possible emergency braking, in response to the signal being received ( 301 ): Sending a pump control signal ( 302 ) to a pump ( 161 ), which is adapted to brake fluid in a brake fluid circuit ( 150 ) of the at least one brake ( 151 ), wherein the pump control signal is the pump ( 161 ) such that a speed ( 203 ) of the pump ( 161 ) a target speed range ( 202a ) reached. Method according to claim 1, characterized in that it further comprises: - in response to the receipt of the signal ( 301 ): Sending a valve control signal ( 303 ) to at least one valve ( 160-1 . 160-2 . 160-3 ) in the brake fluid circuit ( 150 ), wherein the valve control signal ( 303 ) the at least one valve ( 160-1 . 160-2 . 160-3 ) to achieve a predetermined brake pressure ( 203a ) of the brake fluid at the at least one brake ( 151 ), wherein the predetermined brake pressure is a deceleration of the vehicle ( 500 ) causes. Method according to one of claims 1 or 2, characterized in that the pump control signal the pump ( 161 ) such that the rotational speed ( 203 ) the target speed range ( 202a ) and / or the brake pressure ( 203 ) a predetermined brake pressure ( 203a ) within a given period of time ( 250 ) and / or the speed for a predetermined period in the target speed range ( 202a ) holds. Method according to one of the preceding claims, characterized in that it further comprises: - sending a further pump control signal ( 302b ) to the pump ( 161 ) if at least one of the following criteria is met: - an abort signal is received; - another signal requesting emergency braking will not be given within a given period ( 250 ) from receiving the signal ( 301 ) receive; - the brake pressure ( 203 ) of the brake fluid at the at least one brake ( 151 ) exceeds a predetermined threshold, - the speed ( 203 ) of the pump ( 161 ) reaches the target speed range ( 202a ) and / or has held the target speed range for a further predetermined period of time, the further pump control signal ( 302b ) the pump ( 161 ) such that the rotational speed ( 203 ) relative to the target speed range ( 202a ) is reduced. Method according to one of the preceding claims, characterized in that it further comprises: - receiving a further signal requesting the emergency braking, - in response to receiving the further signal: sending a further valve control signal ( 303 ) to at least one valve ( 160-1 . 160-2 . 160-3 ) in the brake fluid circuit ( 150 ) and / or sending another pump control signal to the pump ( 161 ), wherein the further valve control signal ( 303 ) the at least one valve ( 160-1 . 160-2 . 160-3 ) for achieving a predetermined further brake pressure of the brake fluid at the at least one brake ( 151 ), which is greater than the predetermined brake pressure, wherein the further pump control signal, the pump ( 161 ) such that the rotational speed ( 203 ) of the pump ( 161 ) the target speed range ( 202a ) achieved as quickly as possible. Method according to one of the preceding claims, characterized in that the target speed range ( 202a ) in an area of a pump characteristic of the pump ( 161 ), which with respect to a torque of the pump ( 161 ), and / or the target speed range ( 202a ) lies in a maximum range of the pump characteristic. Method according to one of the preceding claims, characterized in that at least one valve ( 160-1 . 160-2 . 160-3 ) per wheel of the vehicle ( 500 ) is controlled to a comparable achievement of the predetermined brake pressure ( 203a ) on the brakes ( 151 ) of the wheels of the vehicle ( 500 ) to reach. Driver assistance system ( 100 ) for emergency braking by automatic application of brake pressure ( 203 ) on at least one brake ( 151 ) of a vehicle ( 500 ), the driver assistance system ( 100 ) comprises: - a control unit ( 103 ), which is set up to carry out the following steps: - receiving a signal ( 301 ) indicating a possible emergency braking, in response to the receipt of the signal ( 301 ): Sending a pump control signal ( 302 ) to a pump ( 161 ), which is adapted to brake fluid in a brake fluid circuit ( 150 ) of the at least one brake ( 151 ), wherein the pump control signal is the pump ( 161 ) such that a speed ( 203 ) of the pump ( 161 ) a target speed range ( 202a ) reached. Driver assistance system ( 100 ) according to claim 7, characterized in that the driver assistance system ( 100 ) continue to pump ( 161 ), which is further adapted for operation in the context of driver assistance for electronic stability. Driver assistance system ( 100 ) according to one of claims 8 or 9, characterized in that the driver assistance system ( 100 ) is further adapted to perform a method according to any one of claims 1-7.

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