Method and control device for automatic brake control of motor vehicle

Abstract

The invention relates to a method (16) and a control device (6) for automatic brake control of a motor vehicle (1). The invention also relates to a correspondingly arranged motor vehicle (1). In the method (16), whether a standard brake actuation or an emergency brake actuation within a predetermined safety limit is involved is ascertained for the brake actuation to be carried out in each case. According to the invention, if the brake actuation is an emergency brake actuation, only an adjustment feature that is predefined for this purpose is used, which is different from a standard adjustment feature that is predefined for only a standard brake actuation, in order to adjust the actuation of the brake means (2, 3) of the motor vehicle (1) in order to carry out the brake actuation.

Description

Technical Field

[0001] The invention relates to a method and a control device for automatic brake control of a motor vehicle. The invention also relates to a correspondingly configured motor vehicle. Background Art

[0002] Nowadays, efforts are being made to guide motor vehicles with the assistance of assistance systems or in a fully or partially automated manner. To this end, some concepts already exist, such as automated vehicle longitudinal control or emergency braking functions, in order to avoid or otherwise mitigate an unavoidable collision. However, the challenge is that there are different goals that are at least partially opposed to one another. Thus, for example, a relatively weak and smooth deceleration may be desirable for maximum comfort, while for the same desired maximum safety, a deceleration that is as strong and rapid as possible may be optimal.

[0003] As a solution, DE 26 46 288 A1 describes a load-dependent braking force control device for a trailer brake system. An emergency brake valve, a relay valve and a load-dependent braking force controller with a brake pressure control valve are provided. The brake pressure control valve is designed as a relay valve and an emergency brake valve at the same time. However, this is a very special application case and cannot be easily generalized.

[0004] DE 10 2017 209 846 B4 describes a vehicle with an emergency brake system with adaptive override. Here, the emergency brake system can be deactivated depending on the power output of the vehicle motor in the event of manual control intervention by the driver. Likewise, the speed limit system of the vehicle can be deactivated. Here, override thresholds are preset respectively, wherein, if the override threshold for deactivating the speed limit system is greater than the override threshold for deactivating the emergency brake system, the override threshold for deactivating the emergency brake system can be changed to the override threshold for deactivating the speed limit system. This provides a possibility with which the driver can deactivate the autonomous emergency braking performed by the emergency brake system by increasing the power output of the motor even when the speed limit system actively limits the speed of the vehicle. Therefore, for safety reasons, there can also be a corresponding intervention possibility for the driver. Summary of the invention

[0005] The object of the present invention is to enable particularly comfortable and safe operation of a motor vehicle.

[0006] This object is achieved according to the invention by the subject matter of the independent claims. Possible embodiments and improvements of the invention are disclosed in the dependent claims, the description and the drawings. The features, advantages and possible embodiments explained within the scope of the description for one of the subject matters of the independent claims are at least analogously to the features, advantages and possible embodiments of the corresponding subject matter of the other independent claims and any possible combination of the subject matter of the independent claims, if necessary, in combination with one or more of the dependent claims.

[0007] The method according to the invention can be used for automatic brake regulation of a motor vehicle. In other words, the method according to the invention can be used, for example, to regulate the brake system of a motor vehicle or to regulate an actuator for fixing and releasing the brakes or brake means of a motor vehicle. In the method steps of the method according to the invention, for the braking operation currently to be performed or immediately approaching, it is determined that it is a standard braking operation within a preset safety limit or an emergency braking operation. The safety limit preset for the standard braking operation or defining the standard braking operation can be described, for example, by one or more values ​​of corresponding safety parameters. Such safety parameters can be, for example, the distance to an obstacle located ahead in the direction of travel of the motor vehicle, the relative speed of the motor vehicle relative to the obstacle, the deceleration required to avoid a collision, that is, the braking acceleration and / or more similar parameters. The state of the motor vehicle and / or environmental conditions can also be taken into account here. The state of the motor vehicle can, for example, relate to its equipment or the deceleration that is possible in principle or currently in technology, for example due to the tire type, tire pressure, brake system type, switching or adjustment state of the brake system, temperature of the brake system, occupancy or load of the motor vehicle, the presence or absence of a trailer load and / or more similar states. The environmental conditions may include or relate to, for example, the type or state of the local driving surface, ie, road properties or weather conditions that influence road properties and / or other similar conditions.

[0008] A standard brake maneuver may occur during normal driving operation of the motor vehicle, in which, for example, a collision can be avoided without initiating maximum deceleration, the collision probability is below a predefined probability threshold value, and / or the like. For such a standard brake maneuver, for example, comfort for the vehicle occupants, maximization of energy recuperation, minimization of wear or emissions (e.g. brake dust or tire wear), and / or the like may take precedence.

[0009] Emergency braking operations can be performed in particular in a situation and / or in braking that exceeds a predefined safety limit. For such emergency braking operations, for example, the maximum possible deceleration can be utilized or sought. Therefore, for emergency braking operations, maximum deceleration or safety can take precedence over passenger comfort, energy recovery, wear, etc. Such emergency braking operations can be performed, for example, when it is determined, for example by a corresponding assistance system of the motor vehicle, that only this can avoid an imminent collision and / or when the corresponding collision probability is above the probability threshold, etc.

[0010] In a further method step of the method according to the invention, if the brake operation to be performed is an emergency brake operation, a control feature which is predefined only for this purpose is used in order to regulate the actuation of the brake means of the motor vehicle in order to perform the brake operation. The control feature which is predefined for the emergency brake operation, which control feature may also be referred to here as the emergency brake control feature, is different from the standard control feature which is predefined only for standard brake operations. At least the emergency brake control feature may in particular predefine or define a certain or specific correlation or characteristic curve for one or more parameters of the corresponding control object or the corresponding control circuit or the corresponding control means, such as a time constant, a dead time and / or other control parameters or route parameters. The standard control feature may accordingly include or define at least one different correlation or characteristic curve of one or more route parameters or control parameters or at least one fixed value which is only used for standard brake operations instead of the corresponding correlation predefined for the emergency brake operation.

[0011] For example, depending on the type of brake actuation to be performed, a corresponding control feature, i.e., a corresponding parameterization of a control loop or a control object or a control means, can be selected and used from a plurality of different control features, i.e., can be set or activated, respectively. For example, a brake control can be performed for an emergency brake actuation according to an emergency brake control feature that is predefined for this purpose, in particular only for this purpose, which can also be referred to as a safety feature or safety control feature, and for a standard brake actuation according to a standard control feature that is predefined for this purpose, in particular only for this purpose, which can also be referred to as a comfort feature.

[0012] The use of the corresponding control feature can, for example, mean or include that the corresponding control device, such as the so-called CVM longitudinal controller (CVM: Central Vehicle Management), is operated using this control feature, that in the case of an emergency braking maneuver, the emergency braking feature or the safety control feature is used instead of the standard or comfort control feature, or that for an emergency braking maneuver, a controller provided according to the emergency braking feature or the safety control feature is used instead of a controller provided for the standard or comfort control feature, and so on.

[0013] In previous automatic braking devices, as already explained at the outset, a compromise is often made between different objectives, for example in order to achieve adequate safety and adequate comfort. However, it should be noted that, for example, when the brake system is new, that is, has not yet been commissioned or braked and / or has not yet reached the optimal operating temperature, the resulting braking characteristics or the resulting following characteristics of the brake controller are not always good enough to actually avoid a collision that is avoidable in principle. On the other hand, the time constants of the brake controller, which are designed as a compromise between safety and comfort, can lead to longitudinal vibrations of the vehicle, especially at relatively low braking torques and relatively low speeds of the vehicle, which in turn can impair comfort or also safety.

[0014] These problems can be solved or at least largely avoided by the invention in that a distinction is made between standard or comfort control features and emergency braking or safety features for various brake actuations with correspondingly different situation-dependent requirements. In other words, it is proposed here that the brake control or the corresponding control object or control means be designed flexibly so that different automatic actions or adjustments can be made in different situations. This makes it possible to achieve optimal comfort depending on the situation without significantly compromising safety in practice, or to achieve optimal safety when it is reasonable and desirable to reduce comfort in order to benefit safety.

[0015] In a possible design of the present invention, the regulation feature preset for emergency brake operation defines or determines the preset correlation between the dead time of the regulation object of the brake regulation and the braking torque. The braking torque can be, in particular, the corresponding current braking torque, for example, measured or actually applied at the beginning of the brake operation and / or during the brake operation. Therefore, as part of the method, the corresponding current braking torque can be measured or the currently measured braking torque can be detected as an input for the brake regulation, that is, the corresponding regulating device. In order to define or determine the correlation, the regulation feature can, in particular, include a corresponding preset characteristic curve. By the correlation between the regulation object dead time and the braking torque proposed here, it can be considered, for example, that the brake device can react differently depending on whether the brake lining is very far or slightly away from the brake disc, or has already been abutted against the brake disc. Similarly, the regulation deviation can be particularly quickly identified during the emergency brake operation, so that the brake regulation can also react accordingly and quickly. This can achieve particularly effective brake regulation, and thus achieve particularly fast and reliable parking of the motor vehicle. In contrast, for standard brake actuations, for example, a permanently longer or on average longer control object dead time can be set or used, which can achieve improved comfort. Furthermore, the correlation proposed here can avoid or reduce longitudinal vibrations or jolts of the vehicle that were possible in previous brake control. This can also achieve improved controllability of the vehicle during emergency brake actuations, if necessary.

[0016] In a possible development of the invention, the correlation provides a smaller control object dead time at a greater value of the braking torque. The control object dead time can also decrease with increasing value of the braking torque. In other words, an inversely proportional relationship or correlation between the control object dead time and the value of the braking torque can be provided here, for example. This makes it possible to avoid or reduce the shaking or longitudinal vibration of the motor vehicle particularly effectively.

[0017] In another possible embodiment of the present invention, the control characteristic predefined for the emergency brake operation defines or determines a predefined correlation of one or more controller time constants of the corresponding control object or control device with the corresponding target deceleration of the brake operation. For this purpose, the target deceleration for the corresponding brake operation or during the corresponding brake operation can be detected as part of the method as an input for the brake control, that is, the corresponding control device. The target deceleration can be output or provided, for example, by a corresponding auxiliary function of the motor vehicle, such as an AEB function (automatic emergency braking function). In order to realize the embodiment of the present invention proposed here, the control characteristic can in particular include a corresponding characteristic curve. Through the correlation proposed here, the brake control can react to changes particularly quickly and at the same time particularly reliably during the emergency brake operation, which is particularly relevant for the effective, controlled and safe parking of the motor vehicle when the target deceleration is typically greater in the emergency brake operation than in the standard brake operation.

[0018] In a possible improvement of the present invention, the correlation sets a smaller regulator time constant when the target deceleration value is larger. Therefore, the regulator time constant may decrease with the increase of the target deceleration, so that the regulating device can react faster or can be more quickly manifested in terms of its regulating characteristics. In other words, an inverse proportional relationship or correlation between the regulator time constant and the target deceleration can be given here, for example. Here, a target deceleration with a larger value means more intense braking. On the contrary, a larger regulator time constant can be set or used when the target deceleration value is smaller, that is, when the braking of the motor vehicle is correspondingly weaker. This can avoid or reduce the longitudinal vibration or shaking of the motor vehicle and react faster to changes, interference effects or regulation deviations when the target deceleration that may be particularly relevant to safety is larger. This can generally achieve a particularly effective and particularly safe parking of the motor vehicle during emergency braking.

[0019] In another possible design of the present invention, the regulation characteristic preset for the emergency brake operation defines or determines the preset correlation of the regulator time constant or a regulator time constant with the gradient of the corresponding target deceleration. The regulator time constant can be in particular the regulator time constant mentioned in other positions. The corresponding target deceleration can be in particular the target deceleration mentioned in other positions. The gradient of the target deceleration for the corresponding braking operation or during the corresponding braking operation can be detected as part of the method as an input for the braking regulation, that is, the corresponding regulating device or the regulating object, or for example, by means of the detected value of the target deceleration during the braking operation, in particular, in real time, calculated. The gradient of the target deceleration can be determined or obtained, for example, by the AEB function or by the braking regulation, that is, the corresponding regulating device. In order to realize the design of the present invention proposed here, the regulation characteristic can in particular include, define or realize the corresponding characteristic curve. Through the correlation proposed here, it is possible to automatically react to relatively slowly changing states or situations and to rapidly changing states or situations in a correspondingly adaptive manner. This can achieve particularly effective and reliable parking of the motor vehicle.

[0020] In a possible improvement of the invention, the correlation sets a smaller regulator time constant in the case of a larger numerical gradient of the target deceleration. The regulator time constant may therefore decrease as the numerical value of the gradient of the target deceleration increases. In other words, an inversely proportional relationship between the regulator time constant and the gradient of the target deceleration or the numerical value of the gradient of the target deceleration may also be given here, for example. By means of the correlation proposed here, the brake control can react particularly quickly to faster changes of the target deceleration that are particularly relevant for safety, while in the case of slower changes of the target deceleration, unnecessary hasty reactions that could lead to uncontrolled behavior or shaking or longitudinal vibrations of the motor vehicle can be avoided or reduced.

[0021] In another possible design of the present invention, for a standard brake operation, a preset fixed value is used for the dead time of the regulating object or a dead time of the regulating object and / or for the regulator time constant or a regulator time constant. The dead time of the regulating object and / or the regulator time constant can be in particular the dead time of the regulating object or the regulator time constant mentioned elsewhere. Here, if it is found that the corresponding brake operation is a standard brake operation, the correlation or characteristic curve for the dead time of the regulating object and / or the regulator time constant is not used, but the corresponding fixed preset value is used in the brake regulation. Therefore, the brake regulation is performed while using the dead time of the regulating object and / or the regulator time constant that is constant according to the corresponding preset value. The corresponding fixed value of the dead time of the regulating object and / or the regulator time constant can be described, included or defined, for example, in the standard feature or comfort feature preset for the standard brake operation. The design of the present invention proposed here can realize a particularly simple implementation and execution of the brake regulation for the standard brake operation. Since such standard braking maneuvers (e.g. due to a smaller target deceleration and a smaller target deceleration gradient) are typically less safety-critical than emergency braking maneuvers, comfortable and reliable parking or braking of the motor vehicle can also be achieved within the scope of standard braking maneuvers according to the knowledge on which the present invention is based using fixed preset values ​​for the control object dead time and / or the regulator time constant.

[0022] The present invention also relates to a regulating device for a motor vehicle, which is used to automatically regulate the brake device of the corresponding motor vehicle. The regulating device according to the present invention is hereby arranged to implement the method according to the present invention in particular automatically. The regulating device according to the present invention can be designed, for example, as a controller, a regulating circuit, a regulator implemented in software and / or in hardware, or the like. The regulating device according to the present invention can be or include, for example, an electronic circuit, which implements or depicts the method steps, flow or process described in conjunction with the method according to the present invention. Likewise, the regulating device according to the present invention can include, for example, a processor device (i.e., for example, a microchip, a microcontroller or a microprocessor or the like) and a data memory. In the data memory, a run or computer program that can be implemented by the processor device to implement or apply the corresponding method can then be stored, which runs or computer programs encode or implement at least a part of the method steps, flow or process described in conjunction with the method according to the present invention. The regulating device according to the present invention can be, in particular, a regulating device or regulating object mentioned in association with the method according to the present invention or corresponding to the regulating device or regulating object.

[0023] The invention also relates to a motor vehicle having an automatically actuatable brake device or brake system and a control device according to the invention coupled thereto. The motor vehicle according to the invention can in particular be a motor vehicle as described in conjunction with the method according to the invention and / or in conjunction with the control device according to the invention or can correspond thereto. Accordingly, the motor vehicle according to the invention can have some or all of the properties or features mentioned in these contexts, such as a CVM longitudinal controller, an AEB function and / or the like.

[0024] Further features of the invention can be derived from the claims, the drawings and the description of the drawings. The features and feature combinations mentioned in the description and the features and feature combinations shown individually in the following description of the drawings and / or in the drawings can be used not only in the respectively indicated combination but also in other combinations or individually without departing from the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings show:

[0026] Figure 1 A schematic diagram of a detail of a motor vehicle is shown, which is provided with a control device for automatic brake control with different control characteristics; and

[0027] Figure 2 An exemplary schematic flow chart of a method for a corresponding brake control is shown. DETAILED DESCRIPTION

[0028] In the vehicles or vehicle assistance systems so far, for example, the longitudinal adjustment of the vehicle and the front protection function for automatically slowing down or stopping the vehicle in the case of a collision risk can be realized. Here, for example, the corresponding function or auxiliary device can determine and output or preset the deceleration suitable for avoiding or mitigating the collision or to be applied when a frontal collision is about to occur. The corresponding regulator can then convert or transmit the deceleration into a matching, i.e. corresponding braking torque, so as to adjust the interference parameters or interference effects that occur as quickly as possible. However, it is typical that in the brake regulation, different situations or requirements are not distinguished, but a unified adjustment feature is used. It has been shown that the follow-up characteristics of the brake regulation for safety-critical braking or emergency braking are not always good enough to actually avoid or mitigate collisions that can be avoided in principle with maximum efficiency and safety. In addition, optimal comfort may not be achieved in the case of standard braking that is not or is not safety-critical.

[0029] These problems may have various causes, such as the lack of differentiation between standard or comfort features of standard brake actuation and safety features of emergency brake actuation. Furthermore, the dead time of control objects previously designed for comfort may be too long for emergency brake actuation or safety-critical situations, so that control deviations may be detected too late in terms of maximum safety. Relatively high values ​​of the time constants of the corresponding controllers may also lead to longitudinal vibrations of the vehicle, especially at relatively low braking torques and vehicle speeds.

[0030] These problems can be counteracted by correspondingly adapted brake control. Figure 1 A schematic diagram of a section of a motor vehicle 1 having a brake device 2 is shown. The brake device 2 can include, for example, a brake disk and thus a brake lining that can be contacted for braking. Likewise, the brake device 2 can include, for example, a sensor for determining or measuring the respective currently applied braking torque. The motor vehicle 1 also has at least one brake actuator 3, for example as a component of the brake device 2 or coupled to the brake device. The at least one brake actuator 3 can be automatically controlled or adjusted in order to actuate and release the brake device 2 in a correspondingly controlled manner.

[0031] Furthermore, motor vehicle 1 has an environment sensor system 4 and an assistance system 5 for assisting or at least partially automatically carrying out a longitudinal control of motor vehicle 1 .

[0032] In addition, the motor vehicle 1 is equipped with a control device 6. The control device 6 is provided for automatic brake control, that is, for example, for controlling the brake actuator 3. For this purpose, the control device 6 comprises, for example, an interface 7, a processor 8 and a data memory 9. Via the interface 7, for example, the deceleration to be set, which is determined or required by the assistance system 5, the current braking torque, information about whether the respective brake operation to be performed is classified or performed as a comfort standard brake operation, or a safety or emergency brake operation, and / or the like can be detected.

[0033] At least one regulating object or regulating logic can be implemented in the regulating device 6, which is shown here by way of example and in part. The corresponding actual braking torque 10 can be detected and used as an input variable. A safety trigger 11 and a respectively required target deceleration 12 can be used as further input variables. If the braking operation to be implemented is an emergency braking operation, that is, a braking operation to be implemented with corresponding safety regulating features, the safety trigger 11 can be given or activated. In addition, the regulating object can include a plurality of preset characteristic curve modules 13, combination or calculation modules 14 and / or the like. From this, for example, at least one regulating parameter 15 can then be determined, such as a regulating dead time and / or a regulator time constant, which can then be used for brake regulation. The characteristic curve module 13 can, for example, give or implement a preset characteristic curve of the correlation of the regulator time constant with the target deceleration 12 and the gradient of the target deceleration 12 and the correlation of the regulating object dead time with the measured actual braking torque 10 and / or the like.

[0034] The regulating device 6 can implement both comfort or standard regulating features for standard brake actuations and safety or emergency brake regulating features for emergency brake actuations, which can be calibrated differently, for example with regard to regulator time constants and controlled object dead times.

[0035] To further illustrate, Figure 2 An exemplary schematic flow chart shows a corresponding method for automatic brake control of motor vehicle 1 . In method step S1 , motor vehicle 1 can be put into operation and, for example, state monitoring can be activated, for example for continuous or regular monitoring or measurement of actual braking torque 10 .

[0036] During operation of motor vehicle 1 , a brake actuation can then be set by assistance system 5 and a corresponding target deceleration 12 can be determined.

[0037] In method step S2 , target deceleration 12 can be detected by control device 6 .

[0038] In method step S3a, it can be determined or detected, for example, by the assistance system 5 or the regulating device 6, whether the corresponding brake operation is to be implemented as a standard brake operation, that is, a standard brake operation with comfort characteristics or standard regulation characteristics, or as an emergency brake operation, that is, an emergency brake operation with safety characteristics or emergency brake regulation characteristics. In method step S3b, the regulating device 6 can determine the corresponding braking torque as a function of the detected target deceleration 12.

[0039] In method step S4, the regulating device 6 can select or set the regulating characteristic to be used for the respective brake maneuver. In method step S5, the regulating device 6 can actuate or regulate the brake device 2 or the brake actuator 3 according to the selected or set regulating characteristic to perform the respective brake maneuver until the brake maneuver is ended. The brake maneuver can be ended, for example, when the motor vehicle 1 is stationary, i.e., its speed is set to zero, when the assistance system 5 signals the end of the brake maneuver, or the like.

[0040] Overall, the example described shows how a CVM longitudinal control of a vehicle can be implemented with safety-related restrictions.

[0041] Reference numerals list

[0042] 1 Motor Vehicle

[0043] 2 Braking devices

[0044] 3 Brake actuator

[0045] 4 Environmental sensing device

[0046] 5. Auxiliary systems

[0047] 6. Regulating devices

[0048] 7 Interfaces

[0049] 8 Processors

[0050] 9 Data storage

[0051] 10 Actual braking torque

[0052] 11 Safety Trigger

[0053] 12 Target deceleration

[0054] 13 Characteristic curve module

[0055] 14 Computing Module

[0056] 15 Adjustment parameters

[0057] 16 Flowchart

[0058] S1-S5 method steps.

Claims

1. A method (16) for automatic brake control of a motor vehicle (1), wherein: respectively - for the brake actuation to be performed, ascertaining whether the brake actuation is a standard brake actuation within predefined safety limits or an emergency brake actuation, If the brake actuation is an emergency brake actuation, a control feature which is predefined only for emergency brake actuation and which differs from a standard control feature which is predefined only for standard brake actuation is used in order to control the actuation of the brake means of the motor vehicle (1) for carrying out the brake actuation.

2. The method (16) according to claim 1, characterized in that: The control characteristic predefined for the emergency brake operation determines the correlation (13) between the dead time of the control object and the braking torque (10).

3. The method (16) according to claim 2, characterized in that: When the braking torque (10) is greater in value, the dependency (13) sets a smaller controlled object dead time.

4. The method (16) according to any one of the preceding claims, characterized in that The control characteristic predefined for the emergency brake actuation determines a dependency (13) of a controller time constant on a corresponding target deceleration (12).

5. The method (16) according to claim 4, characterized in that In the case of a greater value of the target deceleration (12), the dependency (13) sets a smaller controller time constant.

6. The method (16) according to any one of the preceding claims, characterized in that The control characteristic predefined for the emergency brake actuation determines a dependency (13) of a controller time constant on the gradient of a corresponding target deceleration (12).

7. The method (16) according to claim 6, characterized in that If the gradient of the target deceleration (12) is greater in value, the dependency (13) sets a smaller controller time constant.

8. The method (16) according to any one of the preceding claims, characterized in that For standard brake maneuvers, predefined fixed values ​​are used for the control object dead time and / or the controller time constant.

9. An adjusting device (6) for a motor vehicle (1) for automatically adjusting brake means (2, 3), wherein the adjusting device (6) is designed to carry out a method (16) according to any one of the preceding claims.

10. A motor vehicle (1) having automatically actuatable brake means (2, 3) and an adjusting means (6) according to claim 9 coupled to the brake means.

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