Method and vehicle system for controlling a motor vehicle for handling automatically requested braking torques in an additive cooperative operating mode, and correspondingly designed motor vehicle

Abstract

The invention relates to a method (11) for controlling a motor vehicle which can be longitudinally guided both manually by a driver (2) and at least with assistance by a driver assistance system (3). In the method, when a brake control element (5) is actuated by the driver (2) during a target deceleration requested by the driver assistance system (3), an actuator-generated driver-assistance-system torque corresponding to the target deceleration requested by the driver assistance system (3) is automatically frozen. If, while the brake control element (5) continues to be actuated, the speed of the motor vehicle (1) is or falls below a predefined speed threshold, the frozen driver-assistance-system torque is gradually reduced, this reduction being carried out such that it is completed at the latest when the motor vehicle (1) reaches a standstill.

Description

[0001] 24-1737

[0002] 1

[0003] Method and vehicle system for controlling a motor vehicle to handle automatically requested braking torques in an additive-cooperative operating mode and appropriately equipped motor vehicle

[0004] The present invention lies in the field of automotive engineering and relates to a method for controlling a motor vehicle that is configured for both manual longitudinal control by a driver and for at least assisted or at least partially automated longitudinal control by a driver assistance system. The invention also relates to a vehicle system configured for the method and a motor vehicle equipped therewith.

[0005] Motor vehicles are increasingly equipped with functions and systems to improve user comfort or even to automate vehicle operation. This also increases complexity and, at least potentially, the susceptibility to errors or the risk of undesirable effects or behaviors of the respective vehicle. For example, unintentionally or erroneously excessive acceleration or deceleration can be problematic for both the driver and driver assistance systems. Therefore, approaches and rules already exist, for example, regarding functional safety or ensuring the correct control of hydraulic brakes or similar systems. However, such implementations can become more difficult with increasing complexity, especially in cooperative operation where both the driver and a driver assistance system are actively involved in longitudinal control. 24-1737

[0006] 2

[0007] For example, DE 102015 012 377 A1 describes a method for adjusting brake pressures on pneumatically actuated wheel brakes of a motor vehicle. In normal operating mode, a brake pressure is set based on a driver's braking request. When an external braking request, independent of the driver's request, is received, a pressure control mode is used to apply a brake pressure to the respective wheel brakes, taking both the external and driver braking requests into account. The pressure control mode is terminated after the external braking request is withdrawn, based on a comparison of a value representing the driver's braking request with a predefined threshold. This ensures that, when the brake pressure is set in pressure control mode, a continuous braking behavior is maintained after the external braking request is withdrawn.Furthermore, it is described there that the external braking request and the driver's braking request can be additively superimposed if they occur simultaneously. Alternatively, a maximum value can also be calculated from the target braking values ​​already requested internally by a braking system and an external target braking value, whereby the external braking request is only set if it is higher than the internal braking request.

[0008] German patent DE 602 18294 T2 describes a driver assistance system for a motor vehicle with an electrically controlled brake actuation device. Among other things, it describes that a control unit, which monitors the execution of functions for longitudinal control of the motor vehicle, is connected to sensors assigned to a brake pedal and an accelerator pedal, respectively. Each actuation of the brake pedal then deactivates the corresponding longitudinal control function, thereby reactivating the driver's control of the motor vehicle. Conversely, pressing the accelerator pedal allows a set reference speed to be exceeded without the need to deactivate the corresponding longitudinal control function.

[0009] However, existing approaches can present problems. For example, if a driver assistance function for longitudinal control of a vehicle causes a negative torque, i.e., a braking torque, and the driver assistance function is deactivated when the driver presses the brake pedal, the driver is initially released from the braking system. This means that the driver presses the brake pedal, but initially the 24-1737

[0010] 3

[0011] The deceleration of the vehicle may be reduced, which can contradict the driver's actual intention when applying the brake pedal. If, however, the driver assistance function remains active when the driver applies the brake pedal and an additive combination of the corresponding braking effects or torques is provided, then two controllers would be active simultaneously: the driver and the driver assistance function. This would be difficult for the driver to control, meaning they could not precisely and reliably set a specific desired deceleration because they would constantly have to work against a changing input from the driver assistance function. Therefore, there is a need for further improvements in this area.

[0012] The object of the invention is to enable a driver of a motor vehicle to precisely and comfortably control the longitudinal guidance of the vehicle, even when an active driving assistance system is in use.

[0013] This problem is solved by the subject matter of the main claim and the dependent claims or independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments set forth in the description for one of the subject matter of the independent claims are to be regarded, at least analogously, as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as of any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the dependent claims.

[0014] The method according to the invention can be used for or in the control of a motor vehicle that is equipped for both manual longitudinal control by a driver and for at least assisted or at least partially automated longitudinal control by a driver assistance system. In particular, a braking system or a braking and drive system of the motor vehicle can be controlled. The motor vehicle or its braking system can, for example, include at least one brake actuator for generating a braking torque, i.e., a decelerating or negative torque. Such a brake actuator can, in particular, be or include a hydraulic friction brake. Likewise, corresponding braking torques or negative drive torques can be generated by means of an electric drive motor. (24-1737)

[0015] 4 Such an electric drive motor can also generate accelerating, i.e. positive, torques, and thus be part of the drive system of the motor vehicle.

[0016] In the respective motor vehicle in which the procedure is applied, continuous monitoring can be carried out for positive or negative accelerations or corresponding torques requested by the driver assistance system and for manual actuations of a brake control element of the motor vehicle. Thus, the driver assistance system can, for example, initiate a target deceleration or corresponding torque, i.e., a decelerating torque, to slow down the motor vehicle.Braking torque is requested. That the driver assistance system requests a specific target deceleration can mean, for example, that the driver assistance system calculates a specific target deceleration or a corresponding torque for at least assisted or at least partially automated longitudinal guidance or for the execution of a specific driving maneuver and then outputs a corresponding control or request signal, for example to the braking and drive system or a corresponding actuator or control unit, here in particular to a brake actuator or a brake control unit of the motor vehicle.

[0017] A brake control element can be, in particular, a brake pedal. It is therefore possible to monitor whether the driver of the vehicle manually operates the brake control element. Monitoring can also be carried out for the actuation of an acceleration control element, in particular an accelerator or drive pedal, and any resulting driver-initiated acceleration torque can be taken into account. A driver-initiated braking torque can be determined from each actuation of the brake control element. This can consist of an actual driver contribution, which is zero without actuation of the brake control element and increases with increasing actuation, and, if applicable, a predefined offset or foot point torque. Such an offset or foot point torque can, for example, be or include a predefined creep torque or recuperation torque that is present even without actuation of the brake control element, i.e., at its foot point.The zero position can be different from zero. 24-1737.

[0018] 5

[0019] In the method according to the invention, it is detected when, during a target deceleration requested by the driver assistance system, i.e., during a deceleration of the vehicle caused by the driver assistance system, or when the driver assistance system or a speed controller of the driver assistance system has requested or set a non-zero deceleration or a corresponding braking torque, i.e., simultaneously with a corresponding activity of the driver assistance system, the brake control element is manually actuated by the driver. Upon such actuation or its detection, an actuator-set torque corresponding to the target deceleration requested by the driver assistance system, i.e., the current target deceleration of the driver assistance system, which is referred to here as the driver assistance system torque (driver assistance system torque), is automatically frozen, that is, its value is fixed, i.e., kept constant.The frozen FAS torque can therefore be set to a constant value until further notice. Thus, the frozen FAS torque can effectively be defined as a new or temporary foot point torque for the driver or a corresponding control element, in particular the brake control element, or, together with the offset or foot point torque that is standard when the brake control element is not actuated, it can form a temporary foot point torque used during actuation of the brake control element. The FAS torque can be determined, for example, by the driver assistance system itself, or by the braking and drive system, an actuator control unit of the vehicle, or a vehicle system configured to carry out the method according to the invention.

[0020] According to the invention, if, with the set FAS torque frozen, the vehicle's speed falls below a predetermined speed threshold while the driver continues to operate the brake control, the frozen FAS torque is gradually reduced, i.e., not instantaneously or abruptly, and in particular continuously. This reduction is carried out automatically, i.e., automatically parameterized, so that it is completed, or will be completed, at the latest when the vehicle comes to a standstill, or would be completed at least if the driver continues to apply sufficient force to stop the vehicle manually. During this reduction of the FAS torque, the corresponding portion of the set total torque can therefore be automatically reduced. 24-1737

[0021] 6. In particular, if necessary, down to zero. During this time, any further dynamic or controlling influence of the driver assistance system on the longitudinal guidance of the vehicle is deactivated or suspended. In other words, the driver assistance system or its cruise control cannot control the longitudinal guidance or speed of the vehicle while the driver assistance system is automatically dissipating the FAS torque that was frozen upon initial detection of brake control activation, provided the brake control is still being applied. For example, the cruise control may be automatically frozen or continuously reset, or control requests or corresponding control signals from the driver assistance system may be blocked or rejected.

[0022] While the FAS torque is frozen and dissipating, the driver can adjust the deceleration—that is, the braking torque—by varying the application of the brake lever, thus manually applying the brakes. This allows for any possible increase in deceleration relative to the current FAS torque value, i.e., any correspondingly more negative braking torque. Because the driver assistance system and its cruise control cannot intervene in the longitudinal control (i.e., the actual deceleration or total deceleration of the vehicle) during this time, the driver is the sole controlling factor. This enables the driver to precisely and consistently set or control a desired deceleration by applying the brake lever.At the same time, the present invention prevents the actual deceleration of the motor vehicle from initially decreasing when the driver activates the brake control. This can already lead to or contribute to improved safety and more intuitive, comfortable handling of the motor vehicle.

[0023] By appropriately selecting the predetermined speed threshold, sufficient time can be provided for a relatively slow and therefore comfortable reduction of the FAS torque, which is easily controllable for the driver. During this time, the driver can, if necessary, further reduce the FAS torque—that is, decrease the vehicle's deceleration—by gradually applying more force to the brake control (24-1737).

[0024] 7. Compensate. This would not be easily possible if, for example, the FAS torque were reduced almost instantaneously only when the brake control is released or at or immediately before coming to a standstill. Furthermore, the gradual reduction of the FAS torque during the additional manual braking, as proposed here, avoids disturbing noises or acoustic abnormalities that occur with a sudden reduction of the entire FAS torque and could, for example, impair comfort or unsettle the driver.

[0025] In principle, an alternative approach to avoiding such acoustic anomalies could be to initiate the torque reduction only when the vehicle comes to a standstill or enters a near-standstill speed range with a frozen or applied FAS torque, and even then, to gradually reduce it over time. However, this could lead to delayed vehicle reactions. For example, the vehicle might come to a standstill during the FAS torque reduction and remain stationary for a certain period until the torque reduction is complete. Subsequently, the vehicle might then start rolling again or increase its speed. This could be surprising or unintuitive for the driver and / or compromise safety. Such problems can be avoided by the present invention.

[0026] The gradual reduction of the FAS torque proposed according to the invention can, for example, be linear, which allows for simple implementation and is easily comprehensible and compensable for the driver. Likewise, the reduction of the FAS torque can be carried out according to another predefined function or rule, or with a different predefined curve. Thus, the method can be flexibly adapted to various needs or requirements.

[0027] The cruise control or a controlling influence of the driver assistance system on longitudinal guidance can, for example, be automatically released when the brake control is fully released, i.e., no longer operated by the driver, and / or when the vehicle has come to a standstill. 24-1737

[0028] 8

[0029] It can be provided that the method according to the invention is only used in an additive operating mode, or that the currently set FAS torque is only frozen in such an additive operating mode when the driver acts the brake control. In such an additive operating mode, both the driving assistance system, in particular including its cruise control, and a driver-requested deceleration or corresponding driver-requested torque indicated by actuating the brake control contribute to the actual deceleration or the actual or total torque by being additively combined. In other words, in the additive operating mode, the FAS torque and the driver-requested torque resulting from or determined by actuating at least the brake control or the acceleration control can be added together.The resulting sum of these moments can then be applied as a total moment or combined with other contributing moments to achieve the total moment to be applied. In additive operating mode, for example, when the driver assistance system and the driver are active simultaneously, there is no overlap or partial consideration of the driver assistance system's target deceleration and the driver's desired deceleration indicated by the brake control. Additive operating mode can be requested by the driver assistance system or detected or set based on a corresponding signal from the system. Similarly, additive operating mode can be manually set or activated by the driver, or in some other way.Outside of additive operating mode, a different operating mode can be used, i.e., a different, non-additive combination of the FAS target deceleration and the driver's desired deceleration, or corresponding torques. In this mode, for example, a gradual blend can be performed from the FAS target deceleration or the sum of the FAS target deceleration and the driver's desired deceleration to the pure driver's desired deceleration. Alternatively, a maximum selection can be made, so that only the greater deceleration or only the torque with the larger magnitude is used or considered for the longitudinal guidance of the vehicle.

[0030] In one possible embodiment of the present invention, the reduction of the frozen FAS torque depends on the speed of the motor vehicle and the size, i.e., the magnitude of the FAS torque, in particular the initially frozen magnitude, i.e., upon initial detection of the actuation of the brake control element, of the 24-1737

[0031] 9

[0032] FAS torque. A lower vehicle speed, as well as a larger FAS torque value, results in a greater rate of reduction. In other words, the rate of reduction, i.e., the gradient of the FAS torque reduction, can be determined as a function of the vehicle speed and the magnitude of the initial FAS torque. Because the rate of reduction is not fixed but rather determined or arises situationally, it can be ensured that the reduction of the FAS torque is completed by the time the vehicle comes to a standstill in all situations. Furthermore, this ensures that the rate of reduction of the FAS torque is not excessively high or unnecessarily large. This allows for maximum comfort and controllability in various situations.

[0033] In another possible embodiment of the present invention, the predetermined speed threshold is greater than the maximum creep speed of the respective vehicle. In other words, the speed threshold can be above a creep speed range of the respective vehicle. The maximum creep speed can form an upper limit or upper limit speed of the creep speed range. The creep speed range can be a speed range in which the vehicle can or would move without driver intervention, i.e., without manual operation of a brake and / or acceleration control element and without a longitudinal control request from a driver assistance system, due to an active creep function or a creep torque specified – for example, as a foot-point torque.The proposed high speed threshold ensures particularly reliable dissipation of even relatively large frozen FAS moments without excessively steep gradients, thus keeping them easily controllable for the driver. Simultaneously, the speed threshold prevents the FAS moment, which is likely to be particularly safety-relevant, from being dissipated at very high speeds (i.e., speeds above the threshold) and thus potentially reducing the vehicle's braking performance, when particularly high braking forces are required. 24-1737.

[0034] 10

[0035] In a possible further development of the present invention, if the vehicle's speed is greater than the predetermined speed threshold when the brake control is initially applied, the frozen FAS torque is reduced, i.e., the reduction is parameterized such that the FAS torque is completed upon reaching the maximum creep speed or upon reaching the creep speed range, or at least would be completed with continued, sufficiently strong application of the brake control to stop the vehicle. This can apply at least, or only, if a predetermined maximum gradient for the reduction, i.e., for the change in the FAS torque, is not exceeded.Otherwise, the maximum gradient can be maintained, and, for example, the endpoint or completion of the reduction of the FAS torque can be shifted into the creep speed range, but at most until the vehicle comes to a complete stop. The further development of the present invention proposed here allows for particularly comfortable and consistent vehicle behavior. In this way, the creep function or creep behavior of the vehicle can be as unaffected as possible by the FAS torque. This can be particularly useful because it can be expected that the driver will release the brake pedal relatively frequently within the creep speed range, i.e., before reaching a complete stop, and / or that there are often only very minor changes in the position of the brake control element within the creep speed range.For example, the deflection angle of a brake pedal may be so small that a correspondingly fine control of the FAS torque may be difficult, or there may not be enough scope for a comfortably slow reduction of the initially frozen FAS torque.

[0036] In a possible further development of the present invention, if the vehicle's speed at the time of initial actuation of the brake control element corresponds at most to the maximum creep speed, i.e., lies within the creep speed range, the FAS torque is reduced in such a way that the reduction is only completed when the vehicle comes to a standstill, or at least would be completed if the brake control element were actuated with sufficient force to stop the vehicle. Thus, the maximum time available for reducing the FAS torque until the vehicle comes to a standstill can be utilized. This allows the gradient of the corresponding change in deceleration 24-1737 to be reduced.

[0037] 11. Braking effect, i.e., the rate at which the FAS torque dissipates, should be kept as low as possible. This allows for the most comfortable and controllable vehicle behavior for the driver, without accepting somewhat unintuitive and unpredictable behavior of the vehicle after coming to a standstill.

[0038] In a further possible embodiment of the present invention, the predetermined speed threshold is automatically adjusted, i.e., changed, and in particular increased, depending on the magnitude of the FAS torque applied or frozen upon initial application of the brake pedal. This is achieved such that a larger initial FAS torque results in a higher speed threshold. In other words, with a larger FAS torque, i.e., a stronger decelerating torque, the reduction of the FAS torque can begin at a higher vehicle speed. This allows the corresponding gradient, i.e., the rate at which the FAS torque is reduced, to be limited, and an exceedance of a maximum reduction rate or gradient can be prevented, at least in most situations. This enables particularly comfortable and easily controllable vehicle handling.In particular, it can be provided that the speed threshold can only be increased from an initially predefined standard value. This ensures that, at least from a speed corresponding to the standard speed threshold value, a sufficient minimum time is available for the FAS torque to dissipate. The adjusted speed threshold can then be reset to its standard value, for example, when or after the vehicle comes to a standstill, is switched off, the brake lever is released, or the FAS torque has completely dissipated. This ensures consistent vehicle behavior for the next driving situation.

[0039] In a possible further development of the present invention, the speed threshold is adjusted only if the magnitude of the FAS torque initially frozen when the brake control element is actuated corresponds to at least a predetermined threshold, which is referred to here as the adjustment threshold. If the initially frozen FAS torque is therefore less than the 24-1737

[0040] 12

[0041] The adaptation threshold value means that the standard speed threshold can be sufficient for a comfortable and easily controllable reduction of the FAS torque, or at least provide enough time. This avoids an initially unnecessary reduction in the vehicle's deceleration at speeds above the speed threshold, which can ultimately benefit safety. At the same time, in this case, no significant loss of comfort due to an excessively rapid reduction of the FAS torque needs to be accepted. This can result in a particularly good compromise between safety and comfort, or rather, controllability for the driver.

[0042] In a further possible embodiment of the present invention, the reduction of the FAS torque is achieved by means of a fader, i.e., a crossfade control. This crossfade control, when determining the torque to be set at any given time, such as the total torque mentioned elsewhere, gradually blends the sum of the FAS torque frozen upon initial actuation of the brake control element and the driver-desired torque resulting, at least in part, from the actuation (i.e., the position of the brake control element) to the pure driver-desired torque. The crossfade control can thus vary a corresponding input variable for determining the torque to be set at any given time, or, if applicable, the torque to be set itself, accordingly during the reduction process, i.e., over time.

[0043] For example, a corresponding blending factor, which can vary between two predefined values, such as 0 and 1, can be used. When initially freezing the FAS torque, the factor can be set to the second value, for example, 1. To reduce the FAS torque, the factor can then be gradually reduced back to the first value, for example, 0. When the factor reaches the first value, for example, 0, the FAS torque can be completely reduced. The factor can thus specify or determine a blending ratio between the sum of the frozen FAS torque and the driver-requested torque, or a respective proportion of the total torque. The use of a blending controller proposed here can represent a simple and practical way to implement the automatic and gradual or continuous reduction of the FAS torque. 24-1737

[0044] 13

[0045] The present invention also relates to a vehicle system for a motor vehicle. The vehicle system according to the invention has an input interface for acquiring input data. This input data can, for example, include a positive or negative target acceleration from the driver assistance system (FAS), in particular a requested target deceleration, and / or a corresponding FAS torque for implementing the target acceleration, on the one hand, and an actuation signal that can indicate the current actuation position of the brake control element or the acceleration control element, and / or a driver-requested deceleration or a corresponding driver-requested torque derived therefrom. Furthermore, the input data can, for example, include the current speed of the motor vehicle or, depending on requirements or implementation, also other parameter values.

[0046] The vehicle system also includes a data processing unit for processing the input data, for example, to generate respective results and / or corresponding control signals. Furthermore, the vehicle system has an output interface for outputting corresponding results and / or control signals. The input interface and the output interface can be separate interfaces or combined or integrated in a common, bidirectional interface. The input interface and the output interface can each be implemented wholly or partially in hardware and / or in software. According to the invention, the vehicle system is configured to automatically execute the method according to the invention.

[0047] The vehicle system, in particular its data processing unit, can, for example, comprise a processing unit, such as a microprocessor, microchip, microcontroller, or the like, and a computer-readable data storage device coupled thereto. This data storage device can then, for example, contain a corresponding operating or computer program that encodes or implements the process steps, measures, or sequences described in connection with the method according to the invention, or corresponding control instructions. This operating or computer program can then be executed by means of the processing unit to carry out the corresponding method or to effect its execution. The vehicle system according to the invention can 24-1737

[0048] 14 In particular, the vehicle system mentioned in connection with the method according to the invention. The vehicle system according to the invention can be a separate system, for example, its own control unit, or it can comprise such a system. Likewise, the vehicle system according to the invention can, for example, be combined or integrated with the driver assistance system and / or with a control system or control unit for brake or drive control.

[0049] The present invention also relates to a motor vehicle that is equipped for both manual longitudinal control, i.e., control by a driver, and for at least assisted or at least partially automated longitudinal control by a driver assistance system. The motor vehicle according to the invention can therefore, in particular, have a corresponding driver assistance system. The motor vehicle according to the invention is equipped with the vehicle system according to the invention and can accordingly, in particular, be configured for the automatic execution or application of the method according to the invention. The motor vehicle according to the invention can therefore, in particular, be the motor vehicle mentioned in connection with the vehicle system according to the invention and / or in connection with the method according to the invention.

[0050] Further features of the invention may become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures themselves, can be used not only in the combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0051] The drawing shows in:

[0052] Fig. 1 shows a partial schematic representation of a motor vehicle equipped for manual and automated operation, as well as for the automatic reduction of braking torques generated by a driver assistance system during simultaneous manual braking in an additive operating mode; and 24-1737

[0053] 15

[0054] Fig. 2 shows an exemplary schematic flow chart for a corresponding procedure.

[0055] If a vehicle can simultaneously operate an automatic longitudinal control function alongside manual longitudinal control, various possibilities exist for corresponding cooperation between human and machine, or between manual and at least assisted or at least partially automated driving. One example is additive behavior, i.e., an additive operating mode in which torques generated by the driver assistance function and torques generated by manual controls are additively incorporated into the longitudinal control. To avoid a conflict between two controllers or two simultaneously and potentially opposing influences, the torque generated by the driver assistance function (DAS torque) can be frozen, i.e., initially fixed during a manual longitudinal control intervention.

[0056] However, it can be desirable to offer a driver the option, at low speeds, such as in a creep speed range, to allow the vehicle to creep forward using a predefined creep torque or automatic creep function, and to counteract this creep by manually operating a brake control. The creep speed range, or near-standstill speed range, could, for example, be a speed range from 0 km / h to approximately 7 km / h.

[0057] Figure 1 shows a partial schematic representation of a motor vehicle 1, which can be controlled and longitudinally guided by a driver 2 in a manual operating mode and by a driver assistance system 3 in an automated operating mode. For manual driving, the motor vehicle 1 is shown here as an example with an accelerator pedal 4 and a brake pedal 5, which can be operated by the driver 2. When the accelerator pedal 4 and / or the brake pedal 5 is pressed, a corresponding signal can be sent to a drive system 6 of the motor vehicle 1 to implement the corresponding driver request. Likewise, the driver assistance system 3 can send signals to the drive system 6 for automated longitudinal guidance. The drive system 6 can then control corresponding actuators to provide corresponding torques or to achieve corresponding positive or negative accelerations. When the driver 2 or the driver 2...However, if the vehicle 1 is now approaching a near-standstill speed range, such as the creep speed range, with a frozen FAS torque, this can be particularly problematic if, in response to manual application of the brake pedal 5, a relatively high negative, i.e., decelerating, FAS torque was previously frozen in an additive operating mode, and the driver 2 only lightly applies the brake pedal 5. The frozen FAS torque would then potentially have to be reduced over a correspondingly short actuation distance, i.e., over a few degrees of brake pedal angle. This would be practically impossible for the driver 2 to compensate for or manage precisely and reliably by adjusting the brake pedal application. Furthermore, a correspondingly high pressure reduction in the brakes can, for example, be noticeably loud.Alternatively, if the FAS torque reduction were gradual over time, potentially disruptive acoustic artifacts or effects could be avoided, but this could also lead to an undesirable delayed vehicle response. For example, vehicle 1 might initially remain stationary while the FAS torque reduction is taking effect and then start rolling once the torque reduction is complete.

[0058] To avoid these problems, the vehicle 1 also has a vehicle system 7, which is shown separately for illustrative purposes only. The vehicle system 7 is connected, at least indirectly, via an interface 8 to the accelerator pedal 4 and the brake pedal 5, or corresponding sensors or signal transmitters, to the driver assistance system 3, and to the drive system 6. The vehicle system 7 can acquire various data or signals via the interface 8. These can, for example, indicate or determine the accelerator pedal 4 and the brake pedal 5 operated by the driver 2, as well as positive or negative accelerations or corresponding torques requested by the driver assistance system 3. The vehicle system 7 can also, for example, acquire the current speed of the vehicle 1 via the interface 8.

[0059] The vehicle system 7 is now configured to freeze braking torques or decelerations caused or requested by the driver assistance system 3 (i.e., one or more driver assistance functions) at the beginning of a detected braking action by the driver 2, i.e., upon detection of brake pedal 5 activation. Furthermore, the vehicle system 7 is configured to completely dissipate a frozen driver assistance system torque no later than when the vehicle comes to a standstill, and in particular, where possible, before or upon reaching the near-standstill speed range or the creep speed range from a higher speed. For this purpose, the frozen driver assistance system torque can be controlled – at least primarily – via the speed of the vehicle 1, i.e., depending on the speed, during braking in additive operating mode in good time before reaching the creep speed range or the near-standstill speed range.The standstill torque is gradually reduced, i.e., gradually, and in particular continuously or quasi-continuously, automatically. This reduction – for example, linear – i.e., a corresponding ramping down of the frozen FAS torque from a set total torque, can begin when an upper speed threshold is reached or fallen below. The reduction can then be as slow as possible, i.e., at a maximum predetermined rate, so that the driver 2 is able to compensate for this – i.e., a corresponding, non-abrupt deceleration – by pressing the brake pedal 5 again if necessary or desired.

[0060] To implement this functionality or behavior, the vehicle system 7 can, for example, include a processor 9 and a computer-readable data storage device 10 coupled to it, in order to process the acquired data or signals and generate corresponding control signals and output them, for example, also via interface 8, to the driver assistance system 3 and / or the drive system 6. For example, the vehicle system 7 can implement a corresponding crossfade controller or feed a value of a reduction or crossfade factor to a speed controller of the driver assistance system 3 or, for example, to a torque controller of the drive system 6. This reduction or crossfade factor, or its value, can begin at the upper speed threshold orIf, during the initial freezing of the FAS torque, the speed of the vehicle 1 is already below the set value, the value gradually decreases from 1 to 0 from the moment the driver 2 presses the brake pedal 5. A value of 1 means that the initially frozen FAS torque is fully released. A value of 0, on the other hand, means that the FAS torque is completely released and therefore no longer contributes to longitudinal control. 18.

[0061] For further illustration, Fig. 2 shows an exemplary schematic flowchart 11 for a corresponding procedure for operating or controlling the motor vehicle 1. The procedure can be started in a process step S1. Here, for example, the motor vehicle 1, the driver assistance system 3 and the vehicle system 7 can be commissioned and / or the additive operating mode can be requested or activated.

[0062] In process step S2, continuous monitoring can then be activated (i.e., started) – if not already active – to detect whether a longitudinal guidance request, in particular a deceleration request from the driver assistance system 3, and a manual actuation of the brake pedal 5 by the driver 2, or a deceleration request from the driver, are present simultaneously. If this is not the case, i.e., if there is only a longitudinal guidance request from the driver assistance system 3 or only a longitudinal guidance request from the driver 2, such as a deceleration request from the driver, then in process step S3 the corresponding request can be implemented by the drive system 6.

[0063] In the case of simultaneous, especially decelerating, longitudinal guidance requirements of the driver 2 and the driving assistance system 3, the FAS moment can be frozen in a process step S4 when the activation of the longitudinal guidance requirement of the driver 2 is detected, i.e. in particular when the activation of the brake pedal 5 is detected, which is then used to implement the longitudinal guidance requirement of the driving assistance system 3.

[0064] In process step S5, it can then be continuously checked whether the current speed of vehicle 1 is below the speed threshold. If this is the case, the FAS torque can then be gradually reduced in process step S6 as described.

[0065] The continued execution of a specific function or process step can occur only if no other process step, for example, one that is also being executed continuously, conflicts with it, i.e., if no other process step has led to the termination of the process or to a diversion of the process flow into another branch of flowchart 11. 24-1737

[0066] 19

[0067] Overall, the examples described show how a reduction of frozen torque during braking in additive braking situations towards the creep speed range can be realized and applied.

[0068] 24-1737

[0069] 20

[0070] Reference number list 1 Motor vehicle

[0071] 2 drivers

[0072] 3 Driver assistance systems

[0073] 4 Accelerator pedal

[0074] 5 Brake pedal 6 Drive system

[0075] 7 Vehicle system

[0076] 8 Interface

[0077] 9 processor

[0078] 10 Data storage 11 Flowchart

[0079] S1 - S6 process steps

Claims

24-1737 21 Patent claims 1. Method (11) for controlling a motor vehicle (1) which is equipped for manual longitudinal control by a driver (2) and for at least assisted longitudinal control by a driver assistance system (3), wherein automatically - when the driver (2) activates a brake control element (5) during a target deceleration requested by the driver assistance system (3), an actuator-set FAS torque corresponding to the target deceleration requested by the driver assistance system (3) is frozen, and - if the speed of the motor vehicle (1) is or becomes less than a predetermined speed threshold value while the brake control element (5) is still being activated, the frozen FAS torque is gradually reduced, with this reduction occurring in such a way that it is completed at the latest when the motor vehicle (1) comes to a standstill.

2. Method (11) according to claim 1, characterized in that the reduction of the frozen FAS moment is carried out depending on the speed of the motor vehicle (1) and the magnitude of the FAS moment, wherein a lower speed as well as a larger magnitude leads to a greater reduction rate.

3. Method (11) according to one of the preceding claims, characterized in that the speed threshold is greater than a maximum creep speed of the motor vehicle (1).

4. Method (11) according to claim 3, characterized in that when the speed of the motor vehicle (1) is greater than the predetermined speed threshold when the brake control element (5) is actuated, the removal of the frozen FAS- 24-1737 22 Moments is such that it is completed upon reaching the maximum creep speed.

5. Method (11) according to claim 3 or 4, characterized in that when the speed of the motor vehicle (1) corresponds at most to the maximum creep speed when the brake control element (5) is actuated, the reduction of the frozen FAS torque takes place in such a way that it is only completed when the vehicle comes to a standstill.

6. Method (11) according to one of the preceding claims, characterized in that the predetermined speed threshold is automatically adjusted by the amount of the FAS torque frozen when the brake control element (5) is actuated, such that a larger amount leads to a larger speed threshold.

7. Method (11) according to claim 6, characterized in that the speed threshold is only adjusted if the amount of the FAS torque frozen when the brake control element (5) is actuated corresponds to at least a predetermined threshold.

8. Method (11) according to one of the preceding claims, characterized in that the reduction of the FAS torque is carried out by means of a crossfade controller, by which, when determining a torque to be set at any given time, the sum of the FAS torque frozen when the brake control element (5) is actuated and a driver request torque resulting from the actuating of the brake control element (5) is gradually crossfaded to the driver request torque.

9. Vehicle system (7) for a motor vehicle (1), comprising an input interface (8) for acquiring input data, a data processing device (9, 10) for processing the input data and An output interface (8) for outputting resulting results and / or control signals, wherein the vehicle system (7) is configured to automatically execute the method (11) according to any of the preceding claims.

10. Motor vehicle (1) configured for manual longitudinal control by a driver (2) and for at least assisted longitudinal control by a driver assistance system (3), and comprising a vehicle system (7) according to claim 9.

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