DE102023115008A1 - Method for supporting a steering system by wheel-selective braking and drive torques, as well as steering assistance system and vehicle - Google Patents

Abstract

The invention relates to a method for assisting a steering system (2) of a vehicle (1) during a steering process of the vehicle (1), comprising:- providing a steering angle (α) to the steering system,- carrying out the steering process on the basis of the provided steering angle (α) by the steering system (2), and- detecting at least one piece of information about a driving situation relating to the steering process using a detection unit (8), comprising:- determining a target steering angle (β) on the basis of the at least one piece of information about the driving situation detected by an electronic evaluation unit (7),- carrying out a comparison of the target steering angle (β) with the provided steering angle (α) as the actual steering angle by the electronic evaluation unit (7),- assisting the steering system (2) during the steering process by changing a drive torque (14) or a braking torque (13) on at least one wheel (3) of the vehicle (1) based on a result of the comparison carried out. Furthermore, the invention relates to a steering assistance system (6) and a vehicle (1).

Description

The present invention relates to a method for assisting a steering system of a vehicle during a steering process of the vehicle. A steering angle is provided to the steering system, and the steering process is carried out by the steering system on the basis of the provided steering angle. At least one piece of information of a driving situation relating to the steering process is recorded using a recording unit.

Furthermore, the invention relates to a steering assistance system with an electronic evaluation unit. The invention also relates to a vehicle with a steering assistance system.

Modern motor vehicles have various, usually redundant, systems for steering or for setting a yaw rate. In autonomous vehicles, steering is often implemented using a so-called "steer-by-wire" process. In this case, the motor vehicle no longer has a steering wheel at all, but a corresponding control unit of the motor vehicle autonomously carries out the steering of the motor vehicle and the associated steering. If the steering system fails, unpleasant situations can arise if the main steering system fails. For this reason, some approaches provide double redundancy or a second fallback level for a primary steering system or a steer-by-wire system.

Steer-by-wire systems allow the steering wheel to be folded away and retracted during a fully automated journey, in accordance with Level 4 and Level 5 of SAE J3016. This creates more space for the driver, who becomes a passenger during the fully automated journey, to carry out activities such as sleeping, reading the newspaper, surfing the Internet, etc. Likewise, folding away and retracting the steering wheel enables new interior concepts with, for example, rotating seats and fold-out tables. In addition, the mechanical decoupling between the steering wheel and the steering actuator prevents unintentional incorrect operation during the fully automated journey. Even if the steering wheel were not folded away and retracted, accidental touching of the steering wheel would not lead to an unwanted vehicle reaction. In autonomous vehicles according to Level 5, such as robotaxis, there is by definition no driver, so a steer-by-wire system must be installed here.

The use of steer-by-wire also offers various advantages in conventional vehicles without automatic driving functions. Stabilization functions such as sidewall stabilization or trailer stabilization can also be carried out with the steering, as the driver no longer has to intervene in the steering at the steering wheel. With an evasive steering assistant, this can only override a driver in an emergency, for example. This can increase safety. When getting in and out, for example, the steering wheel can be folded away, which makes this process easier. When parking, the steering wheel only needs to be moved slightly when setting the large steering angle required, as this is done by electronically adjusting the gear ratio between the steering angle and the steering wheel angle. The steering behavior can be individually adapted and personalized to the driver. The haptic feedback or steering wheel feedback to the driver can be softer or harder, sportier or more comfortable, direct or dampened. This setting can be transferred from the old to the new vehicle, for example when buying a new vehicle.

With steer-by-wire, the mechanical connection between the steering wheel or steering column module and the steering gear on the axle is broken and replaced by a redundant data line. The steering column, which is rotated by the driver, is no longer required as a "mechanical fallback level". The overall system that influences the lateral dynamics (usually just the steering) must therefore meet the ASIL D safety and availability requirement. To meet this safety requirement, the steer-by-wire system must be designed with at least single redundancy according to the current state of the art. This can be achieved by using double windings in the motor, double control units, double electrical power supply and double data communication. Double redundancy or a second fallback level for a steer-by-wire system would therefore be desirable in principle, as the vehicle could continue to drive after a fault, although in the event of a double fault the requirements for this second fallback level can be significantly reduced compared to the single and zero fault case. Double redundancy can be achieved, for example, by having additional technology available, such as a control unit with three separate windings or a motor with three separate windings. These measures are often associated with high costs.

To support steering systems, “steer-by-brake” systems are used according to the current state of the art. These have a low achievable lateral acceleration in the fallback level through a pure “steer-by-brake”, especially in vehicles with a negative steering radius. Furthermore, mechanical fallback levels with separating clutches are used. These have high Costs and offer no advantage in packaging through steer-by-wire. There are also torque vectoring systems. In this respect, such methods have a second electronic fallback level, i.e. double redundancy. This is often achieved with additional components such as steering actuators. These systems are therefore complex and have a large number of components.

For example, the DE 10 2013 019 472 A1 a method for operating a braking system of a motor vehicle is known. The rotational speed of the left and right wheels can be detected by rotational speed detection means assigned to the left and right wheels of the vehicle, and a braking device and an electric machine can be controlled by a brake mixing device to generate predetermined braking torques for the left and right wheels depending on the detected rotational speeds of the wheels.

Furthermore, the JP 2007 055 358 A a device for detecting or predicting or monitoring a torque on the wheels of a vehicle. This is particularly helpful if, for example, one of the wheels spins.

Furthermore, the DE 10 2019 212 712 A1 a steer-by-wire system and a control method thereof. A reaction motor generates a reaction in a direction opposite to a direction in which a steering wheel is operated by a driver. A current sensor detects a phase current output from the reaction motor. A motor position sensor detects a rotation angle of the reaction motor. A state and disturbance observer estimates a plurality of state variables and a driver torque by receiving information related to the phase current and information related to the rotation angle of the reaction motor.

An object of the present invention is to support a manual or autonomous steering process of a vehicle in such a way that a missing or faulty dynamics of a steering system can be compensated.

This object is achieved by a method, a steering assistance system and a vehicle according to the independent patent claims. Useful further developments arise from the dependent patent claims.

• - Bereitstellen eines Lenkwinkels an das Lenksystem,
• - Durchführen des Lenkvorgangs auf Basis des bereitgestellten Lenkwinkels durch das Lenksystem, und
• - Erfassen zumindest einer Information einer Fahrsituation betreffend des Lenkvorgangs mit einer Erfassungseinheit,
• - Bestimmen eines Soll-Lenkwinkels auf Basis der zumindest einen erfassten Information der Fahrsituation durch eine elektronische Auswerteeinheit,
• - Durchführen eines Vergleichs des Soll-Lenkwinkels mit dem bereitgestellten Lenkwinkel als Ist-Lenkwinkel durch die elektronische Auswerteeinheit,
• - Unterstützen des Lenksystems beim Durchführen des Lenkvorgangs, indem auf Basis eines Ergebnisses des durchgeführten Vergleichs ein Antriebsmoment oder ein Bremsmoment an zumindest einem Rad des Fahrzeugs verändert wird.

One aspect of the invention relates to a method for assisting a steering system of a vehicle during a steering operation of the vehicle, comprising:

• - Providing a steering angle to the steering system,
• - Performing the steering operation based on the steering angle provided by the steering system, and
• - Recording at least one piece of information of a driving situation concerning the steering process with a recording unit,
• - Determining a target steering angle on the basis of the at least one recorded piece of information on the driving situation by an electronic evaluation unit,
• - Carrying out a comparison of the target steering angle with the provided steering angle as the actual steering angle by the electronic evaluation unit,
• - Assisting the steering system in carrying out the steering process by changing a drive torque or a braking torque on at least one wheel of the vehicle based on a result of the comparison carried out.

The proposed method can be used to provide efficient support, in particular automatic support, for the vehicle's steering system. The proposed method is particularly advantageous when, for example, it is determined that the steering process currently being carried out is not sufficient to carry out the steering process safely due to the current situation. For example, the steering angle for carrying out the steering process may be insufficient and the steering system may not be able to achieve the steering angle that is actually required or to be set. For example, the steering system may be faulty in terms of its dynamics. To this end, the steering system can be supported by changing or adjusting a drive torque or a braking torque on at least one wheel of the vehicle or several wheels of the vehicle. By applying an additional braking torque or drive torque to at least one wheel or vehicle wheel of the vehicle, steering performance support for the steering system can be provided.

The proposed method can provide a steering assistance system through wheel-selective braking and/or drive torques.

The proposed method offers advantages especially when steering errors or Steering failures in motor vehicles, particularly those with steer-by-wire steering systems. In such cases, the vehicle can lose the ability to change its position laterally in a translational manner and to influence it rotationally by yaw. This can be done by changing or adjusting a drive torque or a braking torque on at least one wheel based on a comparison between the target steering angle and the actual steering angle.

To carry out the steering process, the steering system can be provided with an appropriate steering angle as the actual steering angle. For example, a driver of the vehicle can manually specify the steering angle using the vehicle's steering wheel. In an autonomously driving vehicle, the steering angle is specified by the system. Using the steering angle, the steering system can influence a wheel steering angle on the front axle and/or rear axle for the vehicle's lateral guidance in order to impart a lateral or yaw movement to the vehicle. If this is not sufficient to carry out the current steering process in view of the current driving situation of the vehicle, the steering system can be supported on the basis of the changed drive torque and/or braking torque on a wheel.

Steering systems, especially steer-by-wire steering systems, can be limited in their steering performance, for example, by degradation from external circumstances such as temperature or by parts of many individual system components. The reduced steering performance on the vehicle's wheels can lead to driving situations that require high steering dynamics. In such cases, the vehicle can only handle these to a limited extent. With steer-by-wire steering systems, the driver can no longer provide additional steering power via the mechanical control of the steering wheel, as this is not possible with steer-by-wire steering systems. In this situation, the proposed method is advantageous, as additional support of the steering system is provided by the vehicle's wheels being individually subjected to or impressed with a corresponding braking or drive torque. This enables additional intervention in the steering or vehicle lateral guidance. By changing or setting or impressing a yaw moment on the vehicle, the wheel-selective braking interventions and drive torques can also be used. This is also advantageous in various driver assistance systems, such as the ESC. With such systems, the vehicle's steering behavior can usually be influenced or corrected. This would also be advantageous in the event of inadequate steering.

With the help of the proposed method, a driving system, such as a steering support system, can also be provided which can provide additional support with wheel-selective braking and drive torques when the available steering power at the steering angle adjuster is reduced. This means that a higher yaw moment is imposed on the vehicle for a short time, which can defuse critical driving situations with high steering angle gradients. Such a system can be designed in such a way that it can intervene both when operated by the driver as a driver assistance system and during automated journeys by the driving system itself. This driving system or the driver assistance system can identify driving maneuvers with high steering angle gradients and support them with wheel-selective braking and drive torques.

The steering system may in particular be a steer-by-wire steering system.

With the help of the recording unit, which can be designed, for example, from several individual recording devices such as sensors, the driving situation relating to the steering process can be recorded or monitored. A wide variety of information relating to this driving situation can be recorded or detected. In particular, information can be recorded immediately before the steering process is carried out, during the steering process or immediately after the steering process. Information about the driving situation can mean, in particular, information regarding the vehicle, the steering system, the traffic situation, the course of the road and/or other information in the environment of the steering process being carried out or to be carried out. On the basis of this information relating to the driving situation, a target steering angle can be determined, in particular predicted. This means that a target steering angle is determined or identified in a way that is adapted to the respective situation. This is done automatically on the system side, in particular with the help of the electronic evaluation unit. The electronic evaluation unit can be, for example, a computing unit. With the help of the electronic evaluation unit, a target-actual comparison can be carried out on the system side based on the target steering angle and the actual steering angle provided. Based on the result of this comparison, i.e. whether there is a deviation between the target and the actual, the wheels can be turned with a corresponding torque, such as e.g. a drive torque or a braking torque.

Changing the torque on the wheel means, for example, that the torque already currently prevailing or acting on the wheel is strengthened or weakened or, for example, that a braking torque is now applied to a wheel where a drive torque is present in order to be able to defuse the respective situation regarding the steering process or to make it safer.

It is also known that vehicles with a positive steering radius can be steered by braking the wheels on the inside of the curve on the front axle. Trucks, for example, have such a positive steering radius, so this is an effective solution for trucks. Depending on the design, cars can have both a negative and a positive steering radius. With a negative steering radius, the actuation of the steering compensates for the yaw moment from the wheel-selective braking. Lateral guidance through wheel-selective braking on the front axle is therefore not always the effective solution. The proposed method is advantageous in this case and can provide a remedy.

In particular, the proposed method may be a computer-implemented method.

In one embodiment, it is provided that a deviation between the target steering angle and the actual steering angle is determined as a result of the comparison carried out, and if the deviation exceeds a predetermined threshold value, the drive torque or the braking torque of the at least one wheel is changed depending on the deviation.

The comparison can be used to determine whether there is a deviation between the actual steering angle and the target steering angle and, if so, what value, extent and measure the deviation is. The greater the deviation between the target steering angle and the actual steering angle, the more support the steering system needs to carry out the steering process. In particular, if a deviation is detected between the target steering angle and the actual steering angle, the deviation or a value of the deviation can be compared with a specified or predefined threshold value or tolerance. The threshold value can therefore be used to specify when support for the steering system is necessary or should be provided.

In particular, the drive or braking torque of at least one wheel is changed if the deviation between the actual steering angle and the target steering angle is greater than 3%, in particular greater than 4%, in particular greater than 5%.

The threshold can be adjusted depending on the prevailing situation and the condition of the vehicle. If the vehicle is on a winding mountain road, for example, the threshold should be set lower, as there is a greater risk of leaving the road and thus, for example, sliding into a ravine.

In one embodiment, it is provided that the drive torque or the braking torque of the at least one wheel is changed depending on the deviation such that the actual steering angle approaches the target steering angle. In other words, depending on the extent of the deviation, a corresponding torque can be changed or impressed or applied to the at least one wheel or multiple wheels of the vehicle such that the current actual steering angle approaches the target steering angle. With the help of the target steering angle, a target value or a target specification can be specified by the system so that the currently existing steering angle approaches this target due to the adjusted torques on the wheels of the vehicle. This intervention on the wheels thus supports the steering system in carrying out the steering process.

In particular, the change in the drive torque or the braking torque of at least one wheel can be carried out until the actual steering angle is essentially adjusted to the target steering angle. While the steering process is being carried out, the target steering angle and the actual steering angle can be continuously determined or checked so that the steering system can be supported in a way that is adapted to the situation.

In one embodiment, it is provided that, depending on the deviation and the at least one piece of information on the driving situation, additional safety measures are activated, with which system-side interventions in the lateral and/or longitudinal guidance of the vehicle can be carried out. This can be done automatically. If, for example, the deviation exceeds a critical threshold and consequently the safety of the vehicle and in particular the safety of the vehicle's occupants is at risk, additional safety measures can be activated automatically in addition to supporting the Steering system, further safety measures or safety systems can be activated. For this purpose, the driver assistance systems can make targeted interventions in the vehicle's lateral guidance and/or longitudinal guidance. In addition to supporting the steering system, targeted braking processes can be initiated. It is also conceivable that a vehicle restraint system is activated accordingly so that the vehicle's occupants are protected with regard to the steering process carried out.

In addition to or instead of this, if the deviation exceeds a critical threshold, an emergency stop procedure or an emergency stop maneuver of the vehicle can be carried out automatically. For this purpose, an appropriate emergency stop safety system, such as a driver assistance system, can be activated, which ensures that the vehicle is brought to a safe stop. This is particularly the case if the discrepancy between the target steering angle and the actual steering angle is so great that the vehicle leaving the road can no longer be ruled out and, for example, there is a high risk that the vehicle will drive into the oncoming lane. For this purpose, an appropriate automatic emergency stop maneuver or an automatic emergency stop procedure can be carried out or initiated.

In one embodiment, it is provided that, depending on the deviation and the at least one piece of information about the driving situation, additional drive torques or braking torques on other wheels of the vehicle are changed, whereby a braking torque or a drive torque can be changed on a respective wheel of the vehicle on a wheel-selective basis. Depending on the current driving situation, in particular depending on the prevailing conditions and in particular depending on the extent of support required by the steering system, the wheels of the vehicle can be subjected to a torque individually, i.e. wheel-selectively. Depending on the current situation, the system can therefore decide which wheels should be controlled accordingly in order to be able to change or adapt a respective torque there. Depending on the extent of the deviation, individual wheels or all of the wheels of the vehicle can be subjected to a drive or braking torque.

In one embodiment, it is provided that a yaw rate of the vehicle is set based on the changed drive torque or the changed braking torque of at least one wheel. With the help of the changed drive torque or the changed braking torque, a yaw rate and thus a yaw moment can be imposed on the vehicle. This additionally set yaw rate can provide a yaw moment of the vehicle in addition to supporting the steering process. Using the set yaw rate of the vehicle, a yaw moment in relation to a vehicle vertical axis of the vehicle can be adjusted or generated to support the braking system. The yaw rate can also be referred to as yaw speed. In particular, the yaw rate refers to the angular speed of the rotation of a vehicle about the vertical axis. The yaw moment of inertia describes the moment of inertia and the vertical axis. The moment about the yaw axis is referred to as the yaw moment. With the help of the set or pre-adjusted yaw rate, the vehicle can be brought in a certain direction accordingly. If the steering is to the left, the yaw rate is set so that the yaw moment moves the vehicle to the left. Likewise, if the steering is to the right, the yaw rate is set so that additional support is provided for moving the vehicle to the right. This can provide additional support for the steering process and thus for the vehicle's lateral guidance.

In one embodiment, it is provided that the steering process is carried out when driving through a curve, the steering system being supported in such a way that a braking torque acts on at least one wheel of the vehicle on the inside of the curve and a drive torque acts on at least one wheel of the vehicle on the outside of the curve. By controlling the wheels accordingly or applying pressure to the respective wheels individually, driving through the curve can be carried out more safely, especially when the actual steering angle is not sufficient to be able to drive through the curve safely. In this case, the corresponding target steering angle can be determined depending on this cornering as a driving situation, and the wheels can be subjected to a torque accordingly in order to be able to drive through the curve without, in particular, leaving the road. Depending on the curve radius of the curve, the at least one wheel or wheels on the inside of the curve and the at least one wheel or wheels on the outside of the curve of the vehicle can be subjected to an individual torque accordingly.

In one embodiment, it is provided that the at least one piece of information relating to the driving situation relating to the steering process includes a route ahead of the vehicle, a curve radius of a curve which the vehicle will drive through during the steering process, a vehicle state of the vehicle, a state of the steering systems, environmental information about the vehicle's surroundings, a braking or acceleration process of the vehicle and/or the condition of the ground in a lane on which the vehicle is moving is recorded. These examples of information relating to the driving situation are intended to provide an overview of possible information that can be recorded and are therefore not to be understood as exhaustive. In particular, the driving situation can be analyzed using this diverse, extensive information. In particular, this information can be used to identify or predict the driving maneuver that is appropriate for the driving situation on the system side, so that the steering system can be effectively supported using this information.

A further aspect of the invention relates to a steering assistance system with an electronic evaluation unit, wherein the steering assistance system is designed to carry out a method according to the previous aspect or an advantageous development thereof. In particular, a method according to the previous aspect can be carried out with the steering assistance system just described.

The steering assistance system can be an electronic system. With the help of the steering assistance system, a steering system, such as a steer-by-wire steering system, can be assisted automatically and in particular on the system side when carrying out a steering process. The steering assistance system is particularly advantageous when the steering system, i.e. the primary steering system of a vehicle, is faulty or has errors and has insufficient dynamics to be able to carry out corresponding steering processes.

A further aspect of the invention relates to a vehicle with a steering assistance system according to the previous aspect or an advantageous development thereof.

In particular, the steering assistance system can be integrated into the vehicle. For example, the steering assistance system can be networked or communicatively connected to vehicle components, driver assistance systems, vehicle guidance systems or the steering system.

The features, examples and advantages mentioned in connection with the method apply analogously and mutatis mutandis to the steering assistance system and the
Vehicle and vice versa. The information on the driving situation can be recorded or measured using the vehicle's corresponding sensors. Inertial sensors, motion sensors, microphones, ultrasonic sensors, cameras and other sensors can be used for this purpose. The invention will now be explained in more detail using the attached drawings.

However, the drawings merely represent exemplary embodiments which do not limit the scope of the invention.

The features, embodiments and their advantages presented in connection with the method according to the first aspect of the invention apply accordingly to the steering assistance system and the vehicle according to the further aspects of the invention and vice versa.

The vehicle preferably has the steering assistance system. The steering assistance system can have a processor device that is configured to carry out an embodiment of a method. For this purpose, the processor device can have at least one microprocessor, at least one microcontroller, at least one FPGA (Field Programmable Gate Array), at least one DSP (Digital Signal Processor) and/or a neural network. Furthermore, the processor device can have program code that is configured to carry out the embodiment of the method when executed by the processor device. The program code can be stored in a data memory of the processor device. The control unit can comprise an internal or external storage unit. The external storage unit can be designed as a cloud unit. The vehicle can comprise a computer program [product] that contains instructions that cause each embodiment of the method to be carried out. The computer program product can be stored on a computer-readable medium.

The invention also includes further developments of the steering assistance system according to the invention and of the vehicle according to the invention, which have features as have already been described in connection with the further developments of the method according to the invention. For this reason, the corresponding further developments of the steering assistance system according to the invention and of the vehicle according to the invention are not described again here.

The invention also includes combinations of the features of the described embodiments.

• 1 eine schematische Darstellung eines Fahrzeugs mit einem Lenkunterstützungssystem zum Unterstützen eines Lenksystems des Fahrzeugs;
• 2 eine schematische Draufsicht auf das Fahrzeug aus 1 bei einem Unterstützungsvorgang des Lenksystems bei einer Kurvenfahrt; und
• 3 eine beispielhafte Darstellung eines Ablaufs hinsichtlich der Regelung zum Durchführen einer Unterstützung des Lenksystems.

It shows:

• 1 a schematic representation of a vehicle with a steering assist system for assisting a steering system of the vehicle;
• 2 a schematic top view of the vehicle 1 when the steering system assists when cornering; and
• 3 an exemplary representation of a sequence regarding the control for carrying out an assistance of the steering system.

The embodiments explained below are preferred embodiments of the invention. In the embodiments, the components described each represent individual features of the invention that are to be considered independently of one another, which also develop the invention independently of one another and are therefore to be viewed as part of the invention individually or in a combination other than that shown. Furthermore, the embodiments described can also be supplemented by other features of the invention already described.

In the figures, functionally identical elements are provided with the same reference symbols.

In 1 For example, a vehicle 1 is shown. The vehicle 1 can be designed as a motor vehicle, a motor vehicle, a manually operated motor vehicle or an autonomously operated motor vehicle. For example, the vehicle 1 can have a steering system 2 with which a steering process of the vehicle 1 can be carried out. The steering system 2 can in turn be coupled to wheels 3 of the vehicle 1 in order to be able to carry out corresponding steering or steering processes. The steering system 2 can be an electromechanical steering system. In particular, the steering system 2 is a steer-by-wire steering system.

For example, the steering system 2 can be assigned a steering angle α (compare 2 ) or provided in data format. A steering operation can be carried out on the basis of the steering angle α. In a manually operated vehicle, the steering angle α can be set by a user, such as a driver, operating a steering wheel 4 of the vehicle 1. In an autonomously driving vehicle, the steering angle α can be specified or provided by the steering system 2 itself or by a vehicle guidance system of the vehicle 1.

Depending on the situation and in particular depending on which driving maneuver is carried out during the steering process, it may happen that the steering system 2 cannot carry out the steering process adequately. The reason for this may be an error in the steering system 2 or due to the situation. For this purpose, according to the invention, the steering system 2 can be supported in carrying out the steering process.

In the 1 Furthermore, the vehicle transverse axis x, vehicle vertical axis z and vehicle longitudinal axis y are shown, in particular in the form of a coordinate system.

For this purpose, the 2 a schematic plan view of the vehicle 1 is shown.

For example, the vehicle 1 can perform a steering maneuver when driving through a curve 5 or a turn or bend. A steering assistance system 6 can be integrated into the vehicle 1 to support the steering system 2 and thus the steering maneuver. This serves to support the steering system 2. With the help of the steering assistance system 6, which can have an electronic evaluation unit 7, it can first be checked whether the steering angle α, which can be referred to as the actual steering angle, is sufficient for driving through the curve 5. For this purpose, a wide variety of information can be made available to the evaluation unit 7 in order to be able to evaluate or analyze the information available, in particular when driving through the curve.

For example, information on the driving situation relating to the steering process can be made available to the evaluation unit 7 as input variables. This can be done with the help of a recording unit 8 (see 1 ) can be recorded. In this case, a wide variety of information can be recorded in and/or outside the vehicle 1 immediately before, during or immediately after driving through the curve 5 and when carrying out the steering process. In this case, for example, a route ahead of the vehicle, i.e. here the curve 5, a curve radius of the curve 5, a vehicle state of the vehicle 1, a state of the steering system 2, environmental information of an environment 9 of the vehicle 1 and/or a ground condition of a lane 10 on which the vehicle 1 is located, in particular when driving through the curve 5.

Furthermore, additional information can be made available to the evaluation unit 7 by vehicle systems or external information points. Based on the information collected, the system can The target steering angle β can be determined or predicted. This target steering angle β can be used as a target specification, particularly an optimal one, for safely driving through curve 5.

In order to be able to support the steering system 2 accordingly, the electronic evaluation unit 7 can carry out a comparison, in particular a target-actual comparison. The target steering angle β can be compared with the actual steering angle α. On the basis of this comparison, a corresponding support or support measure can be provided for the steering process to be carried out. For this purpose, wheel-selective braking and drive torques can be set or imposed. A braking torque or a drive torque can be changed or set or imposed on at least one or more of the wheels 3 of the vehicle 1.

As in the example in the 2 When driving through the curve 5, the steering system 2 can be supported in such a way that a braking torque 12 is set or impressed on the wheels 11 on the inside of the curve. In contrast, a drive torque 14 can be carried out or set or impressed on the wheels 13 on the outside of the curve. Consequently, the steering system 2 and thus the vehicle 1 can be supported when driving through the curve 5, so that in particular the actual steering angle α adapts to the target steering angle β or approaches it. By this exemplary control or application of the wheels 3, a yaw moment 15 can be impressed on the vehicle 1. As a result, the vehicle 1 is deflected or moved to the left as viewed in the vehicle's longitudinal direction x. In order to be able to better support the steering process depending on the situation or the driving maneuver, in particular to be able to defuse critical situations, an additional yaw moment 16 can be applied. For this purpose, a yaw rate can be set by the changed drive torques 14 and/or changed braking torques 11 on the wheels 3. This in turn allows the yaw moment or additional yaw moment 16 to be adjusted. The yaw moment 15, 16 acts in relation to the vehicle's vertical axis z. In order to support the vehicle's lateral and yaw movements in the event of a fault or faulty case of the steering system 2, wheel-selective braking and drive torques 12, 14 are used in the fallback level. The steering forces impart a yaw moment 15, 16 to the vehicle 1 about the vertical axis z, which in turn can support the vehicle control or the steering process. The imposed or yaw moment 15, 16 can be used to control the vehicle's lateral and yaw movements. For example, forces 17 (shown with the arrows) can be caused by the set or applied torques 12, 14 on the wheels 3 of the front axle. As can be seen here, these have the same direction as the yaw moment 15, 16. This allows the vehicle 1 to be steered further to the left, as in this example. In particular, the wheel-selective adjustment of the moments on the wheels takes place especially when, for example, transverse forces from the steering movement cannot build up the desired yaw moment. This is where the present invention comes into play to advantage.

Depending on the drive concept of the vehicle 1, the drive torques 14 with which the wheels 3 can be driven in the vehicle's longitudinal direction x can be specified wheel-selectively or via a differential. The braking interventions can generally be performed wheel-selectively up to the locking limit. With the braking torque 12, the wheels 3 can therefore be set against the direction of travel, the opposite vehicle's longitudinal direction x. Another control option can be applied via open differential drive forces in order to synthetically increase the braking force that can be applied on one side. In this way, a higher yaw moment can be generated even with low adhesion values.

A deviation between the target steering angle β and the actual steering angle α can be determined for controlling the wheels 3 and for applying a corresponding torque. The system can check, in particular with the help of the evaluation unit 7, whether the deviation has exceeded a specified threshold or limit value. If this is the case, the drive torques 14 and/or the braking torques 12 can be set or specified individually on the wheels.

In addition, depending on the situation and the support required by the steering system 2, additional safety measures can be activated, in which system-side interventions in the vehicle's lateral guidance and/or longitudinal guidance can be carried out. In this case, the deviation between the target steering angle β and the actual steering angle α can be checked. If a critical threshold is exceeded here, an emergency stop maneuver can be initiated or carried out, for example. The critical threshold is to be understood as meaning that, for example, vehicle 1 when driving through For example, in curve 5, the vehicle veers off its lane and, in the worst case, drives into oncoming traffic. An emergency stop should be carried out automatically and as quickly as possible.

For example, with the help of the steering support system 6, the actual steering angle α can be influenced via wheel-selective braking and acceleration interventions. This is possible without complex hardware or a large number of additional components. This is applicable to vehicles with front-wheel drive, rear-wheel drive and all-wheel drive.

Furthermore, with the help of the steering support system 6, which can be referred to as a driving system, it is possible to identify during a manual or automated driving maneuver that cannot be represented by the steering in its dynamics due to an error. Wheel-selective braking and drive torques can be used for this purpose. The interventions go beyond those of an ESC system in terms of their level and prediction. The present invention thus offers an additional extension for the vehicle 1

By applying a respective moment to the wheels 3, the steering dynamics of the steering system 2 can be influenced. In particular, environmental situations can be recorded and analyzed. This can support the steering system 2 in particular if it is faulty, especially if the dynamic requirements are too great, such as when driving around a sharp curve. If the actual steering angle α is to be adjusted by changing the moments present on the wheels 3 and the vehicle 1 is an automated or autonomous vehicle, a trajectory planning can also be adjusted using a trajectory of the vehicle 1.

In the 3 an exemplary sequence, in particular of a control system for supporting the steering system 2, is shown. In a step S1, the target steering angle β can be determined or calculated using a vehicle model, in particular one that can be represented with the aid of the evaluation unit 7. For this purpose, a target vehicle reaction with regard to the current situation can be provided in the vehicle model. For this purpose, a steering wheel angle of the steering wheel 4 and information regarding the steering system 2 can be taken into account. In the following exemplary step S2, the target steering angle β is calculated. This can be passed on to a model in a subsequent optional step S3. This model can calculate the steering angle dynamics depending on the availability of the steering system 2. This can determine the available actual steering angle α in a step S4. This can in turn be passed on to the vehicle 1 in an optional step S5 or provided in order to carry out steering accordingly. In order to check whether the available actual steering angle α matches the required target steering angle β, the difference or deviation between these two is calculated and transmitted to the steering support system 6 in an optional step S6. The steering support system 6 can be referred to, for example, as the driving control system for steering performance support. Here, based on the calculated difference, it can be determined whether wheel-selective braking and drive torques are necessary to support vehicle control. This can again be done in a step S7. This can in turn be fed back to the vehicle, i.e. in step S5. In an optional step S8, the actual vehicle reaction can be advantageously adjusted accordingly in order to be able to carry out a safe steering process, for example.

In particular, the steps mentioned can be carried out within an environment of the steering assistance system 6 and in particular the evaluation unit 7 on the system side or by software.

For example, the 3 a vehicle lateral control, which is extended by a feedforward control for longitudinal forces.

list of reference symbols

1

vehicle

2

steering system

3

Wheels

4

steering wheel

5

curve

6

steering assistance system

7

electronic evaluation unit

8

registration unit

9

Vicinity

10

roadway

11

wheels on the inside of the curve

12

braking torque

13

outside wheels

14

drive torque

15

yaw moment

16

additional yaw moment

17

forces

α

actual steering angle

β

target steering angle

x

vehicle transverse axle

y

vehicle's longitudinal axis

z

vehicle vertical axis

S1 to S8

steps

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• DE 10 2013 019 472 A1 [0008]
• JP 2007 055 358 A [0009]
• DE 10 2019 212 712 A1 [0010]

Claims (10)

Method for assisting a steering system (2) of a vehicle (1) during a steering process of the vehicle (1), comprising: - providing a steering angle (α) to the steering system, - carrying out the steering process on the basis of the provided steering angle (α) by the steering system (2), and - detecting at least one piece of information about a driving situation relating to the steering process with a detection unit (8), characterized by - determining a target steering angle (β) on the basis of the at least one piece of information about the driving situation detected by an electronic evaluation unit (7), - carrying out a comparison of the target steering angle (β) with the provided steering angle (α) as the actual steering angle by the electronic evaluation unit (7), - assisting the steering system (2) during the steering process by changing a drive torque (14) or a braking torque (12) on at least one wheel (3) of the vehicle (1) on the basis of a result of the comparison carried out. becomes. procedure according to claim 1 , characterized in that as a result of the comparison carried out, a deviation between the desired steering angle (β) and the actual steering angle (α) is determined, and if the deviation exceeds a predetermined threshold value, the drive torque (14) or the braking torque (12) of the at least one wheel (3) is changed depending on the deviation. procedure according to claim 2 , characterized in that the drive torque (14) or the braking torque (12) of the at least one wheel (3) is changed depending on the deviation such that the actual steering angle (α) approaches the desired steering angle (β). procedure according to claim 2 or 3 , characterized in that , depending on the deviation and the at least one piece of information on the driving situation, additional safety measures with which system-side interventions in a vehicle lateral guidance and/or vehicle longitudinal guidance of the vehicle (1) can be carried out are activated, in particular if the deviation exceeds a critical threshold value, an emergency stop procedure of the vehicle (1) is automatically carried out. Method according to one of the preceding Claims 2 until 4 , characterized in that , depending on the deviation and the at least one piece of information on the driving situation, additional drive torques (14) or braking torques (12) on further wheels (3) of the vehicle (1) are changed, wherein a braking torque (12) or a drive torque (14) can be changed on a respective wheel (3) of the vehicle (1) in a wheel-selective manner. Method according to one of the preceding claims, characterized in that a yaw rate of the vehicle (1) is set on the basis of the changed drive torque (14) or the changed braking torque (12) of the at least one wheel (3), in particular by means of the set yaw rate of the vehicle (1) a yaw moment (15, 16) in relation to a vehicle vertical axis (Z) of the vehicle (1) can be adjusted to support the steering system (2). Method according to one of the preceding claims, characterized in that the steering process is carried out when driving through a curve (5), the steering system (2) being assisted in such a way that a braking torque (12) acts on at least one wheel (11) of the vehicle (1) on the inside of the curve and a drive torque (14) acts on at least one wheel (13) of the vehicle (1) on the outside of the curve. Method according to one of the preceding claims, characterized in that with the at least one piece of information of the driving situation relating to the steering process, a route ahead of the vehicle (1), a curve radius of a curve (5) through which the vehicle (1) is driven during the steering process, a vehicle state of the vehicle (1), a state of the steering system (2), environmental information of an environment (9) of the vehicle (1), a braking or acceleration process of the vehicle (1) and/or a ground condition of a lane (10) on which the vehicle (1) is moving is recorded. Steering assistance system (6) with an electronic evaluation unit (7), wherein the steering assistance system (6) is designed to carry out a method according to one of the preceding claims. Vehicle (1) with a steering assistance system (6) according to claim 9 .

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