Method for avoiding a rollover of a motor vehicle with steer-by-wire, control device, motor vehicle

Abstract

The invention relates to a method and a control device (10) for avoiding a rollover of a motor vehicle (1), and to such a motor vehicle (1) with an electric steering device (3, 4). In the method, the current driving situation of the motor vehicle (1) is monitored and analyzed in terms of a rollover risk. In the event of an identified rollover risk, a predetermined, hierarchical cascade of different automatic control interventions is executed in a hierarchical manner in a cascade in time to influence the driving situation until there is no longer a rollover risk. The cascade is defined here in that in a first stage the steering speed is limited, in a second stage the steering angle is limited, in a third stage the steering angle is further limited and an active brake intervention is effected.

Description

Technical Field

[0001] This invention relates to a method for preventing a motor vehicle from overturning and a control device for preventing a motor vehicle from overturning. The invention also relates to a correspondingly configured motor vehicle. Background Technology

[0002] Especially when manually driving a motor vehicle, there is a risk of the vehicle tilting to the side. This can be caused, for example, by excessive steering intervention at high speeds, sudden and repeated changes in directional and lateral loads, i.e., swaying, etc. Therefore, in the realm of higher safety, there are already means to stabilize the vehicle and avoid such tilting through automatic control intervention.

[0003] For example, document DE 10 2014 202 230 A1 describes a method for preventing the swerving of steerable vehicles, especially rear-wheel steering vehicles. A swerving criterion is determined using the vehicle's steering angle and speed. If the swerving criterion indicates a danger of swerving to the vehicle, a correction signal for the steering angle is provided. This correction signal indicates that the deflection of at least one steerable wheel of the vehicle is less than the steering angle to prevent tilting.

[0004] As another method, sway stabilization in the use of a four-wheel drive system is described in document DE 10 2005 046 776 A1. Specifically, a method for controlling a vehicle with a 4x4 drive system is disclosed here. This involves identifying potential rollover conditions and transmitting drive torque to the front wheels via an electronically controlled center differential or an electronically controlled transfer case to prevent tilting.

[0005] Document DE 10 2018 101 182 A1 describes a method for preventing vehicle rollover during lateral load changes using a torque vectoring device. In this method, the vehicle has a single-wheel drive system designed to drive the wheel subjected to the lateral load change independently of at least one other wheel of the vehicle. The method described therein identifies the critical state of the vehicle during the lateral load change. Furthermore, a driving torque is applied to the wheel subjected to the lateral load change via the single-wheel drive system in such a way that the wheel slips. Additionally, the wheel subjected to the lateral load change is rotated in the direction of travel to prevent vehicle rollover. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to achieve a particularly safe driving characteristic for motor vehicles when the driving power is particularly high.

[0007] The technical problem described herein is solved by a method for preventing motor vehicle rollover, wherein the motor vehicle has an electric steering system, the electric steering system having no mechanical connection between the steering wheel and the wheel being steered, and the method automatically...

[0008] - Monitor and analyze predetermined parameters describing the current driving situation of the motor vehicle in terms of rollover hazard according to predetermined criteria.

[0009] -Upon detecting a rollover hazard, a predetermined cascade structure consisting of multiple different automatic control interventions is executed sequentially at each level to influence the vehicle's driving behavior until the rollover hazard is no longer present. The cascade structure specifies...

[0010] - In the first stage, the steering speed of the electric steering system is limited to a predetermined maximum value.

[0011] - In the second stage, the steering angle of the electric steering system is limited to a predetermined first maximum steering angle.

[0012] - In the third stage, the steering angle is limited to a predetermined smaller second maximum steering angle. If the actual steering angle is greater than the second maximum steering angle, the actual steering angle is actively reduced to at least the second maximum steering angle, and active braking intervention is performed to reduce the vehicle's speed.

[0013] The method according to the invention is used to prevent the rollover of a motor vehicle having an electric steering system, which has no mechanical connection between the steering wheel or steering handle and the wheel being steered. In other words, the method can therefore be used for motor vehicles with so-called steer-by-wire systems. In one step of the method according to the invention, predetermined parameters describing the current driving conditions of the motor vehicle are automatically monitored. These parameters, or their parameter values, are then automatically analyzed against predetermined criteria for the risk of rollover of the motor vehicle. Parameters may include, for example, steering angle, rate of change or speed of change of steering angle, driving speed, roll angle of the motor vehicle about its longitudinal axis, operating status of the braking system, wheel-specific slip, and / or other parameters. The predetermined criteria for the analysis may include, for example, one or more parameter values ​​or variables calculated from one or more parameter values ​​reaching or exceeding a threshold, and / or others. Monitoring and analysis can be performed continuously or periodically during motor vehicle operation, i.e., continuously.

[0014] In particular, the risk of rollover in the sense of this invention exists in the following situations: if the motor vehicle continues to operate according to the corresponding current parameter values ​​extrapolated or without corrective control intervention, it may cause rollover or the probability of rollover to exceed the predetermined intervention threshold.

[0015] In another method step according to the invention, when a rollover hazard is identified in this manner, a predetermined, tiered cascade structure consisting of multiple different automatic control interventions is sequentially executed over time to influence the vehicle's driving behavior, i.e., particularly one or more predetermined parameters, until the rollover hazard is no longer present or until the rollover probability is less than a predetermined safety threshold. In other words, different or additional control interventions can be gradually and automatically initiated or executed to automatically counteract potential rollover or rollover hazards in a stronger or more aggressive manner.

[0016] The predetermined cascaded structure here specifies in the first stage that the steering speed of the electric steering system is limited to a predetermined maximum value. During or at the activation of the first stage, a limit on the maximum rate of change of the steering angle, at least in the direction of the smaller turning radius, can be initiated or set. This avoids or mitigates vehicle swaying caused by steering intervention, lateral load shifting, and / or reduction of the turning radius. Here, for example, compared to automatic changes in the steering angle or relatively strong automatic braking intervention, such as those set in conventional ESC-based or purely brake-based anti-rollover systems, the steering speed limit specified in the first stage can be a relatively weak or mild control intervention. Here, compared to such conventionally set braking intervention, the first stage of the cascaded structure can be initiated or executed particularly earlier than the expected rollover of the vehicle or when there is already a low probability of rollover. This is possible because influencing or controlling the electric steering system is an additional measure, so braking intervention does not have to be the first and only measure. Here, the limitation of steering speed can be achieved particularly simply and transparently to the driver through the corresponding electrical or electronic control of the electric steering system.

[0017] The predetermined cascaded structure, in its second stage, specifies that the steering angle of the electric power steering system be limited to a predetermined first maximum steering angle. In other words, this prevents the driver from manually setting a steering angle greater than the first maximum steering angle, which would result in a smaller turning radius, through appropriate control intervention of the electric power steering system. This, for example, can more effectively avoid or mitigate vehicle sway caused by repeated opposing steering movements. If, when the second stage or its control intervention is activated, the actual steering angle is greater than the first maximum steering angle, the actual steering angle can also be automatically reduced to or withdrawn to the first maximum steering angle.

[0018] The predetermined cascaded structure specifies in the third stage that the steering angle is limited to a predetermined smaller second maximum steering angle. The second maximum steering angle is therefore smaller than the first maximum steering angle, such that the second maximum steering angle matches the vehicle's turning radius, which is larger than the first maximum steering angle. If the actual steering angle is greater than the second maximum steering angle, then in the third stage, corresponding active control intervention reduces the actual steering angle to at least the second maximum steering angle. This weakens or suppresses rollover motion, i.e., the rolling of the vehicle around its longitudinal axis. The third stage of the cascaded structure can be applied or triggered, for example, when such rollover motion, especially exceeding a predetermined threshold, is detected. Automatic active braking intervention is also specified in the third stage to reduce the vehicle's speed. This active braking intervention is used not only to prevent rollover but also affects the electric steering system through the control intervention, allowing the active braking intervention to occur later than conventional anti-rollover systems based solely on ESC or braking for rollover prevention.

[0019] The first and / or second maximum steering angles can be fixed or predetermined, or adjusted or predetermined dynamically based on conditions, such as speed, lane inclination, and / or other factors. For example, the maximum steering angle can be smaller or reduced at higher vehicle speeds, and / or reduced asymmetrically, especially for the two steering directions, when the lane inclination along the vehicle's lateral direction is greater. For example, the reduction of the maximum steering angle can be set or activated only for uphill oriented steering directions, or the maximum angle can be greater for uphill oriented steering directions than for downhill oriented steering directions. This effectively prevents rollover by minimizing the reduction in the vehicle's manual controllability or range of manual control.

[0020] Compared to traditional rollover avoidance systems that rely solely on ESC or braking intervention, this invention allows for earlier control intervention to avoid rollover, yet this earlier intervention can less forcefully interfere with the vehicle's driving characteristics. This invention achieves particularly linear driving characteristics of the vehicle over a particularly wide range of limits, with the vehicle's control device configured to execute the method according to the invention intervening to avoid rollover. This invention can avoid or reduce sudden changes in the vehicle's driving characteristics. This results in improved driving or usability comfort within the limits and better or simpler controllability of the vehicle. Furthermore, better safety can be achieved through earlier intervention.

[0021] A combination of multiple different types of control interventions—namely, control interventions for the electric steering system and braking interventions specified at least in Level 3—also contributes to improved safety. This prescribed combination of multiple different types of control interventions allows for the realization or full utilization of greater corrective potential, thereby permitting higher driving dynamics—i.e., larger steering angles, higher speeds, and / or larger rollover angles—without compromising vehicle safety. Compared to stability systems without steer-by-wire support, Level 3 or the highest level of the cascaded control interventions can be engaged significantly later because, in the corresponding critical situations, the front wheels of the vehicle on the outside of the curve are no longer adequately braked if necessary through the corresponding purely ESC-based or braking-based control interventions, and therefore, conventional rollover avoidance based on this must correspondingly introduce full braking of that wheel earlier to prevent vehicle rollover.

[0022] According to the additional limitations specified in the invention, and where necessary, the reduction of the steering angle can be accomplished more quickly (e.g., compared to a purely mechanical steering system) due to the electrical design or control of the steering, and thus activated later, while still preventing vehicle rollover.

[0023] In a possible design of the invention, the predetermined cascaded structure also specifies automatic active braking intervention in the first and / or second stages, where the braking intervention is weaker than that specified in the third stage. This weakened braking intervention at a correspondingly earlier time point reduces the kinetic energy of the vehicle particularly early, thereby preventing or mitigating vehicle swaying accordingly. This weakened braking intervention occurs relatively early, thus it can be weaker than the braking intervention specified in the third stage, thereby avoiding sudden or abrupt changes in the vehicle's driving characteristics or driving state. Therefore, the design proposed herein not only achieves improved safety but also improved comfort and, when necessary, automatic control of the vehicle to avoid rollover, i.e., better acceptability of the corresponding driver assistance system. If corresponding active braking interventions are specified in all stages of the cascaded structure, they can progressively increase in strength, thereby achieving or assisting a particularly uniform or linear change in the vehicle's driving characteristics, even though the cascaded structure of the control intervention is hierarchical.

[0024] In another feasible design of the invention, the predetermined cascaded structure also specifies, in at least one stage, a limitation on the vehicle's response to the driver's acceleration signals. In other words, the vehicle's fuel supply or the power output of its traction battery is limited to the corresponding operational action, such as the driver pressing the accelerator pedal, or reduced compared to normal operation outside the limits. This method can particularly easily and effectively avoid the formation of additional kinetic energy that would cause the vehicle to sway further or more rapidly. Here, this limitation on the response can be a proportionate reduction in the vehicle's driving characteristics or driving state, such as a less intense or abrupt intervention of active braking. Therefore, by limiting the vehicle's response as suggested herein, the uniformity or linearization of the vehicle's driving characteristics within the limits or across multiple stages of the cascaded structure can also be achieved, which can improve the vehicle's safety, controllability, and comfort. As described elsewhere in conjunction with braking intervention, corresponding limitations can be specified in one or more stages of the cascaded structure. This limitation can here progressively increase in intensity. In a feasible improved design of the invention, the predetermined cascaded structure may specify a weaker first limitation on the response in the first and / or second stages, and a stronger second limitation on the response in the third stage. For example, in the first stage, the response to an acceleration signal or the action of an acceleration signal may be reduced or limited to about 50%, in the second stage, for example, to about 25%, and / or in the third stage, for example, to about 0% to 10%. Similarly, other values ​​or levels are also feasible, for example, depending on the design or required characteristics for the corresponding application purpose. By limiting the vehicle's response to acceleration signals as suggested herein, further control or intervention options are provided to prevent vehicle rollover, thereby achieving overall improved safety and improved comfort of the vehicle.

[0025] In another feasible design of the invention, the cascading automatic progression of the structure is based on a predetermined association with a predicted rollover time point at which the vehicle is expected to rollover without control intervention. In other words, an association can be predetermined, indicating which level of measures or control intervention will be automatically applied or triggered at which time interval relative to the rollover time point. Specifically, it can be specified that at a given time interval relative to the rollover time point, the highest level to be executed or applied up to that time point according to the predetermined association can be executed or applied. If a higher level has been specified for application or execution at a determined first time interval relative to the rollover time point, then lower levels can then be skipped if necessary. With the design proposed herein, on the one hand, the characteristic of the vehicle being particularly predictable, i.e., the same across multiple rollover events, can be achieved at least in most cases; on the other hand, improved safety can be achieved, because in critical situations, lower levels of control intervention are not necessarily executed or passed first.

[0026] In another feasible embodiment of the invention, the vehicle is monitored by sensors to identify one or more wheels lifting off the road surface, and a cascade structure is applied accordingly. For example, a Dynamic Chassis Control (DCC) device and / or a sensor for, for example, the headlight range adjustment device of the vehicle can be used. Lifting at least one wheel off the road surface can be identified, for example, by observing or monitoring the contraction state of the corresponding part of the vehicle or the sensor or the vehicle's damping system. The application of the cascade structure for control intervention can be made, for example, based on the monitoring results or based on the detected lifting of one or more wheels. This can mean, for example, that when a lifting is detected or when a threshold, for example, for an intervention limit is predetermined based on the range or extent of such lifting, adjustments, particularly strengthening or aggravating the aforementioned limit or maximum steering angle and / or others, can be made, and / or automatically added to the next level of the cascade structure when a lifting is detected or when the detected lifting reaches or exceeds the predetermined threshold or limit.

[0027] Adjustments to thresholds, limits, maximum steering angle, and / or other parameters can be made, for example, only for the corresponding current driving or rollover hazard situation or permanently. In the latter case, the method can, for example, automatically adjust for the personalized characteristics or features of the corresponding motor vehicle, i.e., automatically learn such characteristics or features. For example, user-related modifications to the motor vehicle or other aspects that may affect the driving or rollover characteristics of the motor vehicle can be automatically taken into account.

[0028] The proposed use of sensors to identify one or more wheel lifts of a motor vehicle enables a particularly accurate and reliable determination of rollover risk, because, for example, the risk of rollover does not need to be inferred solely from the vehicle's speed and current steering angle, without considering other influencing variables such as the characteristics of the road surface, the effects of crosswinds, the vehicle's load, and / or others. Instead, sensors can detect or consider the vehicle's current state, which is actually relevant to a possible rollover. The use of adaptive chassis control devices and / or headlight range adjustment devices, or their sensors, enables the invention to be implemented particularly effectively, especially in terms of saving components and cost, through the corresponding dual use of sensors.

[0029] In another feasible embodiment of the invention, the rollover motion of the vehicle is detected or monitored by an acceleration sensor and / or a rotation sensor. The application of the cascaded structure is then precisely controlled based on the detected rollover motion. This may, for example, mean that for each level of control intervention or corresponding intervention intensity, threshold, limit, maximum steering angle, and / or other factors, a corresponding control or adjustment range is predetermined around the corresponding value, and the control intervention can be controlled, adjusted, or shifted within this range. The control or adjustment ranges for different levels may, in particular, be non-overlapping. By applying the cascaded structure, i.e., the fine control proposed herein to execute the corresponding control intervention, the control intervention can be set or executed such that the rollover motion of the vehicle is limited or reduced only to the degree necessary to avoid rollover or to achieve or set a specific predetermined or particularly uniform or consistent characteristic of the vehicle. This allows for automatic responses to particularly unpredictable, situation-specific conditions or realities through appropriate adjustments, such as given lane inclination, uneven load on the vehicle if necessary, tire pressure, user-related influences on the vehicle's driving characteristics, crosswind conditions or effects, and / or more. In this way, not only can the characteristics of the vehicle remain as constant as possible under different circumstances, but safety can also be improved through adjusted or adjustable control or regulation ranges. To achieve the proposed design of this invention particularly effectively, sensing devices of the vehicle's adaptive chassis control system can be used, for example.

[0030] In another feasible design of the invention, the application or execution of different control interventions configured according to the cascade structure is automatically coordinated by the vehicle's driving dynamics controller. The driving dynamics controller is configured to simulate whether the vehicle can travel on its corresponding current trajectory using current operating parameters and / or with the use of a determined control intervention, without overturning. The driving dynamics controller may be, for example, a control device configured to coordinate different control interventions, for example, with each other, e.g., in terms of their intensity and / or the timing and / or duration of execution or application. The driving dynamics controller can therefore take into account the effects or combined effects of different control interventions on the vehicle's driving or overturning characteristics or trajectory. This simulation or corresponding simulation may be performed, for example, considering a corresponding level or corresponding current level of control intervention, or considering multiple levels of control intervention or control interventions at multiple levels in the cascade structure. If simulations show that, with the corresponding current operating parameters and / or control interventions, the vehicle cannot travel on its current trajectory without the possibility of rollover, or can only travel on its current trajectory with a rollover probability higher than a predetermined probability threshold, then control interventions are then executed or adjusted by the driving dynamics controller to avoid rollover or reduce the rollover probability below the probability threshold. This can be achieved, for example, based on iterative simulations with correspondingly modified parameters representing the control intervention, its intensity, application timing, and / or application duration. Different optimal or particularly effective combinations of control interventions can be found or applied through the coordination of different prescribed or feasible control interventions suggested herein. This not only achieves improved rollover safety but also, for example, improved vehicle controllability or maneuverability. For example, combining multiple different control interventions within a correspondingly central range of its control or regulation interval allows for greater flexibility or responsiveness for additional automatic or driver-manual control interventions compared to applying one or more control interventions at the edge range, i.e., the end or maximum value of its control or regulation interval.

[0031] Another aspect of the invention is a control device for a motor vehicle. The control device according to the invention has an interface for detecting parameter values ​​describing the corresponding current driving conditions or driving states of the motor vehicle, and the interface is used to output control signals to control the motor vehicle. Here, a unique or common interface can be provided for detection and output, or an input interface and separate output interfaces. Furthermore, the control device according to the invention has a data processing device to automatically process the detected parameter values ​​in order to determine the rollover hazard of the motor vehicle and generate control signals according to a predetermined cascade structure of control intervention. The control device according to the invention is configured to automatically execute at least one embodiment or variation of the method according to the invention. For this purpose, the data processing device may include a processor device, such as a microprocessor, microchip, or microcontroller, and a data memory connected thereto. Running or computer programs, which encode or implement the processes, measures, or method steps described in conjunction with the method according to the invention, can be stored on the data memory and can be executed by the processor device to implement or cause the execution of the corresponding method. The detected parameter values ​​may, as described in conjunction with the method according to the invention, be, for example, measurements or sensor values ​​of driving speed, steering angle, acceleration sensing devices, rotation sensing devices, and / or other sensors of the motor vehicle and / or more.

[0032] Another aspect of the invention is a motor vehicle having an electric steering device, i.e., a steer-by-wire system, without mechanical connection between the steering wheel or steering handle and the wheels of the vehicle, and also having a controllable braking device and a control device according to the invention. The control device is configured herein to control the electric steering device and the braking device according to the method according to the invention, i.e., connected or coupled, for example, to the braking device and the control device accordingly. The motor vehicle according to the invention may also have sensors mentioned elsewhere and / or other sensors coupled to the control device, as well as some or all of the mentioned devices and / or additional devices, such as an adaptive chassis control device, a headlight range adjustment device, a ride dynamics controller, and / or others. The motor vehicle according to the invention is particularly a motor vehicle combining the method according to the invention and / or the control device according to the invention. Therefore, the motor vehicle according to the invention may have some or all of the characteristics or features mentioned in this context. Attached Figure Description

[0033] Further features of the present invention can be derived from the following description and from the accompanying drawings. The features and combinations of features mentioned in the foregoing description, as well as the features and combinations of features shown in the description and / or alone in the accompanying drawings, can be used not only in the given combinations, but also in other combinations or alone, as long as they do not depart from the scope of protection of the present invention.

[0034] Figure 1This diagram shows a partial schematic of a motor vehicle equipped with an electric steering system, which is designed to automatically prevent rollover. Detailed Implementation

[0035] Figure 1 A partial schematic diagram of a motor vehicle 1 equipped with an electric steering system is shown. Here, the steering wheel 2 is coupled to a steering signal transmitter 3, which generates corresponding steering signals based on the driver's operation or manipulation of the steering wheel 2 and transmits them to an electromechanical actuator 4. The electromechanical actuator 4 converts the steering signals into mechanical steering movements of the wheels 5 of the motor vehicle 1.

[0036] The motor vehicle 1 also has a braking device 6, which can brake the wheels, such as the steering wheels 5. The braking device 6 can also be controlled by an electromechanical actuator 4.

[0037] In addition, a driving status sensing device 7 is provided here, which can detect the driving status of the vehicle 1, such as the vehicle's current speed and steering angle. The driving status sensing device can also detect the operating or control status of the braking device 6. Furthermore, the vehicle 1 here has a height sensing device 8 and a rotation sensing device 9. The height sensing device 8 can monitor or identify, for example, the lifting of individual wheels of the vehicle 1 from the corresponding driving ground by observing the retraction state. The tilting or rolling motion of the vehicle 1, especially around the vehicle's central longitudinal axis, can be detected by the rotation sensing device 9. The rotation sensing device 9 may, for example, have a dedicated rotation sensor and / or one or more acceleration sensors.

[0038] The vehicle 1 is also equipped with an anti-rollover device 10. It is also schematically connected to the vehicle network 11, like the other components mentioned here, through which data, signals and control commands can be transmitted.

[0039] The anti-rollover device 10 has an interface 12 for acquiring data or signals from one or more of the other devices mentioned above, particularly the steering signal transmitter 3, the driving status sensor 7, the height sensor 8, and the rotation sensor 9. The data or signals acquired through the interface can be processed by the anti-rollover device 10 via the processor 13 and the data memory 14 to generate signals or control commands for initiating control interventions, namely, automatic control of the electric steering and / or braking devices 6. These control signals can be output via the interface 12 and transmitted via the vehicle network 11, for example, to the electromechanical actuator 4. The anti-rollover device 10 is configured to automatically execute predetermined methods during the operation of the vehicle 1 to prevent the vehicle 1 from rolling over.

[0040] The so-called rollover intervention, namely the control intervention to prevent the vehicle 1 from rolling over or to prevent or limit the lifting of one or more wheels of the vehicle 1, can be automatically executed or activated by the anti-rollover device 10. The time window for identifying whether such rollover intervention is necessary is usually relatively short. If the rollover of the vehicle 1 is avoided solely by using the braking device 6, a very sudden and strong intervention or a change in the characteristics or driving state of the vehicle 1 will occur. To avoid this situation, electric steering is also included in the anti-rollover mechanism.

[0041] On the one hand, rollover intervention can thus be used later with full effect or intensity than in conventional systems, which generally allows for higher driving dynamics. On the other hand, a relatively weak first rollover intervention can be applied earlier than in conventional systems, so that the driving characteristics of vehicle 1 do not change abruptly, and vehicle 1 becomes controllable or remains controllable within its limits.

[0042] Therefore, the anti-rollover device 10 can control the electric steering system, especially the electromechanical actuator 4, to limit the steering speed in a rollover critical situation where the vehicle 1 is about to roll over without control intervention. This avoids unnecessary swaying of the vehicle 1. This can be done at a relatively early point in time, i.e., in the first stage of the predetermined cascade structure of control intervention or rollover intervention. It is also possible to reduce or limit the fuel supply to the vehicle 1, and / or to generate a relatively weak first braking intervention to reduce the kinetic energy of the vehicle 1.

[0043] At a later point in time, such as in the second stage of the cascaded structure, the anti-rollover device 10 can be activated to limit the steering angle as appropriate, in order to avoid or reduce oversteer and lateral acceleration peaks. This can be assisted by reducing fuel and / or braking intervention, i.e., automatic control braking device 6, to further reduce the energy of vehicle 1.

[0044] However, if the rolling or overturning motion of vehicle 1, particularly reaching or exceeding a predetermined threshold, occurs, then, for example, in the third stage of the cascaded structure, additional limiting and / or reduction of the steering angle to a predetermined maximum steering angle is initiated by the anti-rollover device 10 to suppress the overturning motion. This is combined here with vehicle deceleration also initiated by the anti-rollover device 10, i.e., a stronger second or third braking intervention. This allows the driver of vehicle 1 to continue following the desired target trajectory. Compared to the final control measures of conventional roll stabilization systems without steer-by-wire assistance or integration, this third intervention stage of the cascaded structure can here begin significantly later, i.e., significantly closer to the expected rollover time.

[0045] The rollover intervention can be coordinated here by a driving dynamics controller, which can be integrated or implemented, for example, in the anti-rollover device 10. This driving dynamics controller can permanently simulate whether the current trajectory of the vehicle 1 is still safe to drive without risk of rollover, or whether a critical situation for rollover has already occurred. At the corresponding critical rollover time point, if the vehicle 1 is expected to rollover without control or rollover intervention, the rollover intervention can be introduced according to the time interval relative to the corresponding critical rollover time point, and if necessary, matched, coordinated, or paired with each other by the driving dynamics controllers. The electrical or electronic control of steering and, if necessary, braking device 6 provided here achieves relatively late restraint of the vehicle 1 and prevents one or more wheels of the vehicle 1 from rolling over or lifting.

[0046] In the manner described here, automatic anti-rollover intervention can be assisted by a corresponding steer-by-wire system. Especially early prevention of swaying of vehicle 1 can be achieved by limiting steering speed, and especially early prevention of potential critical situations can be achieved by preventing oversteer. Here, there is a possibility of relatively late intervention when the rolling motion of vehicle 1 is imminent, thereby allowing for particularly high driving forces of vehicle 1 even within its extreme range without compromising its rollover safety. Furthermore, particularly linear vehicle characteristics of vehicle 1 can be achieved across the entire extreme range.

[0047] In summary, the examples illustrate how to achieve agility in rollover avoidance maneuvers or rollover stabilization maneuvers by using a vehicle's steer-by-wire system.

[0048] List of reference numerals in the attached diagram:

[0049] 1 motor vehicle

[0050] 2 steering wheels

[0051] 3 Turn Signal Transmitters

[0052] 4. Electromechanical actuators

[0053] 5-wheel steering

[0054] 6. Braking device

[0055] 7 Driving Status Sensors

[0056] 8 Altitude Sensors

[0057] 9 Rotary sensor

[0058] 10 Anti-rollover devices

[0059] 11 Vehicle Networks

[0060] 12 interfaces

[0061] 13 processor

[0062] 14 Data Storage

Claims

1. A method for preventing a motor vehicle (1) from overturning, the motor vehicle having an electric steering device (3, 4), the electric steering device (3, 4) not having a mechanical connection between a steering wheel (2) of the motor vehicle (1) and a wheel (5) being steered, wherein the method automatically... - Monitor and analyze predetermined parameters describing the current driving conditions of the motor vehicle (1) in terms of rollover hazard according to predetermined standards. - Upon recognizing a rollover hazard, a predetermined cascade of automated control interventions, consisting of multiple different levels, is executed sequentially in a cascaded manner to influence the driving behavior of the motor vehicle (1) until the rollover hazard is no longer present. The cascade structure specifies - In the first stage, the steering speed of the electric steering devices (3, 4) is limited to a predetermined maximum value. - In the second stage, the steering angle of the electric steering devices (3, 4) is limited to a predetermined first maximum steering angle. - In the third stage, the steering angle is limited to a predetermined second maximum steering angle, wherein the second maximum steering angle is less than the first maximum steering angle. If the actual steering angle is greater than the second maximum steering angle, the actual steering angle is actively reduced to at least the second maximum steering angle, and active braking intervention is performed to reduce the speed of the motor vehicle (1).

2. The method according to claim 1, Its features are, The cascaded structure also specifies active braking intervention in the first and / or second stages, wherein the active braking intervention specified in the first and / or second stages is weaker than the active braking intervention specified in the third stage.

3. The method according to any one of the preceding claims, Its features are, The cascaded structure also specifies, in at least one stage, a limitation on the response of the motor vehicle (1) to the driver's acceleration signals.

4. The method according to claim 3, Its features are, The cascade structure specifies a first restriction on the reaction in the first and / or second stages, and a second restriction on the reaction in the third stage, wherein the second restriction is stronger than the first restriction.

5. The method according to claim 1 or 2, Its features are, The incremental increase is based on the expected rollover time point, at which the vehicle (1) is expected to rollover without control intervention.

6. The method according to claim 1 or 2, Its features are, The vehicle (1) is monitored by a sensing device to identify when the wheels are lifted off the ground, and the cascade structure is applied accordingly.

7. The method according to claim 1 or 2, Its features are, The overturning motion of the motor vehicle (1) is detected by an acceleration sensor and / or by a rotation sensor (9) of the motor vehicle (1), and the application of the cascade structure is precisely controlled based on the detected overturning motion.

8. The method according to claim 1 or 2, Its features are, The application of different control interventions as specified in the cascade structure is coordinated by the driving dynamics controller of the motor vehicle (1), which is set to simulate whether the motor vehicle (1) can travel on the corresponding current trajectory of the motor vehicle by means of the current operating parameters and / or by means of the determined control intervention, without the motor vehicle (1) overturning.

9. The method according to claim 6, Its features are, The sensing devices of the motor vehicle (1) include an adaptive chassis control device and / or a headlight range adjustment device.

10. The method according to claim 7, Its features are, The acceleration sensing device includes an adaptive chassis control device (8).

11. A control device for a motor vehicle (1), the control device having an interface (12) for detecting parameter values ​​describing the current driving conditions of the motor vehicle (1), the interface for outputting control signals to control the motor vehicle (1), the control device having data processing means (13, 14) for processing the detected parameter values ​​to determine a rollover hazard of the motor vehicle (1) and generate control signals according to a predetermined cascade structure of control intervention, wherein, The control device is configured to automatically execute the method according to any one of the preceding claims.

12. A motor vehicle having an electric steering device (3, 4) that is not mechanically connected between a steering wheel (2) and a steering wheel (5) of the motor vehicle (1), the motor vehicle also having a controllable braking device (6) and a control device according to claim 9, the control device being configured to control the electric steering device (3, 4) and the braking device (6).

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