Method for steering a motor vehicle using a steer-by-wire steering system, and steer-by-wires steering system

Abstract

The invention relates to a method for steering a motor vehicle using a steer-by-wire steering system (100), said method having the steps of: - detecting (10) at least one state variable (z1,…, z4) of the motor vehicle and / or of at least one component of the motor vehicle by means of at least one detection device (1, 1-1), - determining (20) at least one power characteristic (pA, pB) on the basis of the at least one detected state variable (z1,…, z4) by means of a controller (2), - ascertaining (30) at least one steering parameter (s1, s2, s3) on the basis of the at least one determined power characteristic (pA, pB) by means of the controller (2), and - setting (40) the ascertained at least one steering parameter (s1, s2, s3) by means of the controller (2). The invention also relates to a steer-by-wire steering system (100).

Description

[0001] Description

[0002] Method for steering a motor vehicle by means of a steer-by-wire steering system and steer-by-wire steering system

[0003] The invention relates to a method for steering a motor vehicle by means of a steer-by-wire steering system and a steer-by-wire steering system.

[0004] Steer-by-wire steering systems do not require a mechanical coupling between the steering wheel and the wheels, for example, via an intermediate steering shaft. Instead, a wheel actuator, for example, steers the wheels according to the driver's steering input. Due to the mechanical decoupling, steer-by-wire steering systems allow for variable steering behavior, especially the steering ratio.

[0005] For example, using a steer-by-wire steering system, the steering ratio between the steering wheel and the wheel actuator can be set in such a way that just half a turn of the steering wheel is sufficient to specify maximum steering deflection of the wheels. A steering ratio set in this way can offer the driver very comfortable steering behavior when parking, for example, since only half a turn of the steering wheel is sufficient to turn the wheels fully. The problem is that such a steering ratio places a great deal of strain on the wheel actuator, particularly when the wheels have to be deflected synchronously with the steering input and a particularly rapid wheel movement is to be achieved. This requires a high wheel steering force, especially when the vehicle is stationary. The resulting strain on the components of the motor vehicle, in particular the wheel actuator, can adversely affect the reliability and comfort of the steer-by-wire steering system used.Furthermore, these requirements require a particularly powerful wheel actuator, which is usually accompanied by increased weight and increased costs.

[0006] US 2019 / 0 233 005 A1 relates to a steering control device that controls a steering for a vehicle with a steering system.

[0007] US 2018 / 0208 235 A1 relates to a steer-by-wire control method for a steer-by-wire steering system in a vehicle equipped with a motor and a battery. DE 102018 115 329 A1 relates to a steer-by-wire steering system and a feedback actuator for such a steer-by-wire steering system.

[0008] The technical problem is to create a method for steering a motor vehicle using a steer-by-wire steering system and a steer-by-wire steering system that offer increased reliability and improved comfort. In particular, the weight and cost requirements of the steer-by-wire steering system are to be reduced.

[0009] The solution to the technical problem is achieved by the subject matter having the features of the independent claims. Further advantageous embodiments of the invention are set forth in the subclaims.

[0010] A method for steering a motor vehicle by means of a steer-by-wire steering system is proposed, the method comprising the steps of:

[0011] Detecting at least one state variable of the motor vehicle and / or at least one component of the motor vehicle by means of at least one detection device,

[0012] Determining at least one performance characteristic based on the at least one detected state variable by means of a control device,

[0013] Determining at least one steering parameter based on the determined performance characteristic by means of the control device,

[0014] Setting the specified at least one steering parameter by means of the control device.

[0015] Further proposed is a steer-by-wire steering system for steering a motor vehicle, comprising: at least one detection device for detecting at least one state variable of the motor vehicle and / or at least one component of the motor vehicle, a control device, wherein the control device is configured to determine at least one performance characteristic and to establish and set at least one steering parameter, wherein the steer-by-wire steering system is configured to carry out a method according to an embodiment described in this disclosure. Further proposed is, in particular, a motor vehicle having a steer-by-wire steering system according to an embodiment described in this disclosure. The motor vehicle is, in particular, a passenger vehicle that can be steered by a driver.

[0016] The steer-by-wire steering system may comprise or incorporate one, several, or all of the components of the motor vehicle described in this disclosure. In particular, the steer-by-wire steering system comprises, in a manner known per se, as components a wheel actuator for generating a wheel steering force, a force feedback actuator for generating a steering resistance force on the steering handle and / or for limiting a maximum range of motion of the steering handle, and / or at least one voltage source for supplying voltage to the steer-by-wire steering system.

[0017] In particular, the same technical effects and advantages as described with reference to the method in this disclosure apply to the proposed steer-by-wire steering system and the proposed motor vehicle.

[0018] A conflict of objectives when steering the motor vehicle using the steer-by-wire steering system is that the steer-by-wire steering system should not be overloaded when steering, while a steering behavior that is comfortable for the driver can usually only be achieved by placing a large load on the steer-by-wire steering system, in particular on the wheel actuator.

[0019] A fundamental idea of ​​the invention is to resolve this conflict of objectives by determining at least one current performance characteristic of the steer-by-wire steering system and adjusting the steering behavior in such a way that the steer-by-wire steering system is loaded within the framework of its current performance capability. This offers the driver the best possible comfort when steering without overloading the steer-by-wire steering system. In particular, the invention results in components of the steer-by-wire steering system, such as the wheel actuator, being able to be made smaller because the steering behavior can be adjusted in such a way that, as a result of the adapted steering behavior, the power requirement of the wheel actuator, for example, is not so high. This reduces the weight and costs of the steer-by-wire steering system.

[0020] The at least one performance characteristic serves in particular as a measure of the current performance of the steer-by-wire steering system. In particular, the at least one performance characteristic can serve as a measure of a power supply and / or a power requirement for operating the steer-by-wire steering system. The power supply can, for example, be an electrical power available for operating the steer-by-wire steering system. The power requirement can, for example, be an electrical power required for operating the steer-by-wire steering system. The at least one performance characteristic is determined based on one or more detected state variables.

[0021] The at least one state variable can, in particular, also be a current parameter value of the steering parameter. Based on the current steering parameter and / or parameter value, the performance characteristic can be determined, for example, as a measure of the current power requirement of the steer-by-wire steering system.

[0022] The detection device can comprise and / or form one or more sensors for detecting the at least one state variable. The detection device can additionally or alternatively record the at least one state variable in a vehicle-internal and / or vehicle-external database. The at least one detection device can be configured to detect a plurality of state variables, in particular simultaneously. The detection device forwards the detected state variable to the control device for further processing.

[0023] The control device can comprise and / or form one or more control modules. A control module can be designed, for example, to determine the at least one performance characteristic and / or to specify the at least one steering parameter and / or to set the at least one steering parameter. The control device can comprise at least one computing unit and a memory. It is also possible for the control device to be at least partially or completely integrated into a central or multiple decentralized control unit(s) of the motor vehicle. For example, the control device can be integrated into a steering control unit of the steer-by-wire steering system. The control device is further configured to receive the at least one detected state variable.

[0024] The at least one steering parameter serves, in particular, as a specification for the steering behavior of the steer-by-wire steering system. The at least one steering parameter can be, for example, a steering resistance force, a maximum range of motion of the steering handle, or a maximum generable wheel steering force. This will be explained in more detail below.

[0025] In particular, the at least one steering parameter can comprise a parameter value or parameter value range. The control device can set the at least one steering parameter based on the performance characteristic such that the current power available for operating the steer-by-wire steering system is fully utilized. This makes it possible to set the most comfortable steering behavior within the scope of the power available. The at least one steering parameter can in particular be set such that the power requirement for operating the steer-by-wire steering system corresponds to the determined power supply for operating the steer-by-wire steering system. For example, a difference, in particular a negative difference (power supply less than power requirement), between a certain power supply and a certain power requirement can be reduced by reducing a steering resistance force to a lower value than a currently set value.For example, by reducing the steering resistance force, the power required to operate the steer-by-wire steering system can be reduced and brought into line with the currently available power supply. Furthermore, for example, a difference, in particular a positive difference (power supply greater than power demand), between a certain power supply and a certain power demand can be reduced by increasing the steering resistance force to a value higher than a currently set value. For example, by increasing the steering resistance force, the power required to operate the steer-by-wire steering system, in particular the force feedback actuator, can be increased and brought into line with the currently available power supply. This increases the comfort when steering using the steer-by-wire steering system.In other words, an increase in the steering resistance force on the steering wheel leads in particular to a reduction in the steering wheel rotation speed specified by the driver and thus to a reduction in the power requirement.

[0026] The power requirement of the steer-by-wire steering system is adjusted indirectly by specifying and adjusting at least one steering parameter.

[0027] In particular, based on the determined performance characteristic, a parameter value and / or parameter value range can be specified from a plurality of possible parameter values ​​and / or parameter value ranges. In particular, the specification can include selecting the at least one steering parameter based on the determined at least one performance characteristic from a plurality of possible, predefined steering parameters, which are provided, for example, in a lookup table.

[0028] Using the described method, the load on the steer-by-wire steering system can be kept as low as possible, while maintaining the highest possible level of comfort for the driver when steering the vehicle within the current performance capability of the steer-by-wire steering system. In particular, overloading of the steer-by-wire steering system can be avoided. This increases the reliability and safety when steering the vehicle using the steer-by-wire steering system. Furthermore, the described method allows the steer-by-wire steering system to be dimensioned in such a way that, for example, a smaller and more cost-effective wheel actuator is sufficient to meet the performance and comfort requirements.

[0029] Further advantages, features, and aspects of the invention will become apparent from the following description. The features mentioned in the claims and in the description can, in principle, be combined with one another in any desired manner.

[0030] In one embodiment, the at least one steering parameter is an adjustable steering resistance force on a steering handle of the motor vehicle and / or the at least one steering parameter is an adjustable maximum movement range of the steering handle and / or the at least one steering parameter is an adjustable maximum wheel steering force that can be generated to deflect the wheels. This allows a

[0031] The power requirement for operating the steer-by-wire steering system can be specifically increased or reduced. Using these steering parameters, the power requirement for operating the steer-by-wire steering system can be adjusted and / or the available power for operating the steer-by-wire steering system can be fully utilized, as explained in more detail below.

[0032] The steering resistance force can be generated, for example, by means of the force feedback actuator and can be perceived by the driver as a counterforce on the steering handle.

[0033] Steering resistance force particularly influences how quickly or slowly the steering handle can be moved by the driver. Reducing the steering resistance force can in particular be a measure to relieve the steer-by-wire steering system, e.g. the force feedback actuator, if the power available to operate the steer-by-wire steering system is not sufficient to generate a currently set steering resistance force, e.g. by means of the force feedback actuator. Alternatively, increasing the steering resistance force can also be a suitable measure to indirectly relieve the wheel actuator if, for example, the driver can no longer turn the steering handle so quickly due to the increased steering resistance force that the wheel actuator is overloaded by the driver's rapid steering movement and the resulting increased wheel steering force.Which of the measures is more suitable for relieving the load on the steer-by-wire steering system can be determined, in particular, using the performance parameter. The respective measure can be implemented by specifying and adjusting the steering parameter.

[0034] The maximum range of motion can be specified, for example, using the force feedback actuator. The maximum range of motion specifies, in particular, how many revolutions of the steering handle are necessary to fully turn the vehicle's wheels. In other words, the maximum range of motion is, in particular, a permitted angle of rotation by which the steering handle can be rotated in both steering directions. By adjusting the maximum range of motion, a transmission ratio between steering movements and wheel movements can be influenced. In particular, reducing the maximum range of motion can increase the power required to operate the steer-by-wire steering system due to a larger transmission ratio, while increasing the maximum range of motion can reduce the power required due to a smaller transmission ratio.Increasing the maximum range of motion is particularly useful for relieving the load on the steer-by-wire steering system, for example, when the power available to operate the steer-by-wire steering system is insufficient to cover the current power requirement. This is due, among other things, to the fact that with a larger maximum range of motion, a steering movement of the steering handle, particularly due to the smaller gear ratio, leads to a smaller movement of the wheel actuator, in particular to a lower rack speed. This in turn requires less power to generate the necessary wheel steering force, thus reducing the power requirement.

[0035] The maximum wheel steering force that can be generated is, in particular, an adjustable value which limits the maximum power requirement of the wheel actuator. In other words, the maximum power consumption of the wheel actuator can be limited by the maximum wheel steering force that can be generated. The maximum wheel steering force that can be generated specifies, in particular, the maximum force with which the wheels can be moved. In particular, increasing the maximum wheel steering force that can be generated can increase the power requirement, while reducing the maximum wheel steering force that can be generated can reduce the power requirement. Reducing the maximum wheel steering force that can be generated is, in particular, a measure to relieve the load on the steer-by-wire steering system, for example if the power supplied to operate the steer-by-wire steering system is not sufficient to cover the current power requirement for operating the steer-by-wire steering system.For example, it can be provided to define a steering resistance force and / or a maximum range of motion of the steering handle and / or a maximum generable wheel steering force as the at least one steering parameter in order to reduce a difference between the power supply and the power requirement. The defined steering parameter can be set, e.g. to reduce a negative difference, such that the steering resistance force and / or the maximum generable wheel steering force is / are reduced and / or the maximum range of motion of the steering handle is / are increased in order to reduce the power requirement and relieve the load on the steer-by-wire steering system. Furthermore, the defined steering parameter can be set, e.g. to reduce a positive difference, such that the steering resistance force and / or the maximum generable wheel steering force is / are increased and / or the maximum range of motion of the steering handle is / are reduced in order to increase the power requirement and, e.g.to improve steering comfort within the current performance of the steer-by-wire steering system.

[0036] In one embodiment, determining the at least one performance characteristic comprises selecting at least one characteristic value of the at least one performance characteristic based on at least one predetermined determination rule, wherein the at least one determination rule specifies an assignment of the at least one performance characteristic to the at least one state variable. This allows the at least one characteristic value to be determined particularly accurately and reliably.

[0037] The characteristic value can, for example, be a value of the current power supply and / or power requirement for operating the steer-by-wire steering system. For example, the characteristic value can be a value of the electrical power available and / or required to operate the force feedback actuator. The predefined determination rule can, for example, comprise a determination function, a determination characteristic curve, a machine-learned determination model and / or a determination table, or can be designed as such. The control device can keep the determination rule in the memory and access the determination rule for determination. For example, the determination rule can be configured such that a state variable detected as a voltage, for example, is multiplied by a predefined value of a current flowing through the steer-by-wire steering system in order to obtain an electrical power as the characteristic value. The determination rule can, for example,determined and / or specified based on physical calculations, simulations, empirical test series, a machine learning model, and / or empirical values. In particular, determining the at least one performance characteristic comprises selecting at least one characteristic value of the at least one performance characteristic based on at least one predetermined determination rule, wherein the at least one determination rule specifies an assignment of the at least one performance characteristic to a plurality of recorded state variables.

[0038] In one embodiment, the setting of the at least one steering parameter comprises selecting at least one parameter value and / or a parameter value range of the at least one steering parameter based on at least one predetermined setting rule, wherein the at least one setting rule specifies an assignment of the at least one steering parameter to the at least one performance characteristic. As a result, the at least one parameter value and / or a parameter value range is set particularly precisely and reliably. The setting rule can, for example, comprise a setting function, a setting characteristic curve, a machine-learned setting model and / or a setting table or be designed as such. The control device can keep the setting rule in the memory and access the setting rule for setting purposes. The setting rule can, for example,determined and / or specified based on physical calculations, simulations, empirical test series, a machine learning model and / or empirical values.

[0039] In particular, the parameter value and / or the parameter value range can be set in such a way that a power requirement for operating the steer-by-wire steering system is or will be adapted to a power supply for operating the steer-by-wire steering system.

[0040] In particular, the setting of the at least one steering parameter comprises selecting at least one parameter value and / or a parameter value range of the at least one steering parameter based on at least one setting rule, wherein the at least one setting rule specifies an assignment of the at least one steering parameter to a plurality of specific performance parameters.

[0041] In one embodiment, the at least one steering parameter is determined taking into account a user specification. This increases user-friendliness. A user specification can, for example, be a steering profile specified by a user, such as a sporty or comfortable steering profile. When determining the at least one steering parameter, the user specification can be taken into account, for example, such that a parameter value and / or parameter value range to be set corresponds to the parameter value and / or parameter value range specified by the user for the at least one performance characteristic.

[0042] In one embodiment, a voltage of at least one voltage source for supplying power to the motor vehicle and / or the at least one component of the motor vehicle is recorded as a state variable. By recording the voltage as a state variable, the at least one performance characteristic can be determined particularly precisely. Based on the voltage, the performance characteristic can be determined, for example, as a measure of the current power available for operating the steer-by-wire steering system. The higher the voltage of the voltage source, the greater the power available for operating the steer-by-wire steering system can be, for example. The at least one voltage source can in particular be a 12-volt voltage source. The at least one voltage source can in particular be a voltage source of the wheel actuator and / or the force feedback actuator.

[0043] In one embodiment, a temperature of the motor vehicle and / or of the at least one component of the motor vehicle and / or a temperature of the ambient air and / or a speed of the motor vehicle is recorded as a state variable. Based on one or more of the aforementioned state variables, the at least one performance characteristic can be determined particularly accurately and reliably. The performance of the steer-by-wire steering system can be influenced by the temperature of the components of the motor vehicle and / or the temperature of the ambient air and / or the speed of the motor vehicle. The performance of the steer-by-wire steering system can, in particular, be temperature-dependent. For example, the performance of the wheel actuator and / or force feedback actuator can be reduced at particularly high or particularly low temperatures.The lower the speed of the motor vehicle, the greater the power requirement of the steer-by-wire steering system may be, e.g., due to increased frictional force when steering the wheels. This can be taken into account when determining the at least one performance characteristic and / or when specifying the at least one steering parameter.

[0044] The at least one state variable can further be a current flowing through a component of the motor vehicle, an electrical line resistance, and / or a friction coefficient of the wheels in contact with a ground surface. For example, the flowing current can be detected using a current sensor. Furthermore, for example, a line resistance of a line supplying power to the wheel actuator and / or force feedback actuator can be recorded in a database. Furthermore, for example, the friction coefficient of the wheels in contact with a ground surface can be recorded in a database or estimated based on vehicle condition data.

[0045] In one embodiment, the at least one steering parameter is a maximum permissible deviation between an actual position of a wheel actuator and a target position of the wheel actuator specified by a steering handle. By specifying the deviation, the power requirement of the steer-by-wire steering system can be influenced in such a way that the conflict of objectives explained above is effectively resolved. The actual position can, for example, be an actual position of a rack deflected by the wheel actuator relative to a reference position. The target position can, for example, be a position of the rack relative to the reference position specified by a detected steering angle. The maximum permissible deviation specifies, in particular, a maximum permissible control difference when adjusting the actual position relative to the target position. The greater the specified maximum permissible deviation, the smaller the power requirement of the steer-by-wire steering system is usually.If, for example, the power requirement needs to be reduced, the specified maximum permissible deviation can be increased. If, for example, the power requirement needs to be increased, the specified maximum permissible deviation can be reduced.

[0046] In one embodiment, a part of a wheel actuator generates a part of a wheel steering force and / or a further part of the wheel actuator generates a further part of the wheel steering force, wherein the at least one steering parameter is a maximum part of the wheel steering force that can be generated and / or a maximum further part of the wheel steering force that can be generated. As a result, the power requirement for operating the wheel actuator can be specifically changed for a part of the wheel actuator. In particular, the maximum parts of the wheel steering force that can be generated can be separately specified and set as steering parameters. The part of the wheel actuator and / or the further part of the wheel actuator can, for example, each form part of a stator of the wheel actuator and / or part of a coil of the wheel actuator.

[0047] The invention is explained in more detail using exemplary embodiments. The figures show:

[0048] Fig. 1 is a schematic representation of an embodiment of the steer-by-wire steering system;

[0049] Fig. 2 is a schematic flow diagram of an embodiment of the method; Fig. 3 is a schematic flow diagram of a further embodiment of the method and

[0050] Fig. 4 is a schematic representation of another embodiment of the steer-by-wire steering system.

[0051] In the following, the same reference symbols refer to elements with the same technical features.

[0052] Fig. 1 shows a schematic representation of an embodiment of a steer-by-wire steering system 100. The steer-by-wire steering system 100 is part of a motor vehicle (not shown). In the embodiment shown, the steer-by-wire steering system 100 has a detection device 1 designed as a voltmeter, a further detection device 1-1 designed as a voltmeter, a control device 2 designed as a computing unit, a force feedback actuator 7 designed as an electric motor, a steering handle 3 designed as a steering wheel, two wheels 4 for steering the motor vehicle, a wheel actuator 8 designed as an electric motor, a voltage source 5 designed as a battery for supplying voltage to the force feedback actuator 7, and a further voltage source 5-1 designed as a battery for supplying voltage to the wheel actuator 8.

[0053] The voltage source 5 and the further voltage source 5-1 provide at least part of the electrical power available for operating the steer-by-wire steering system 100.

[0054] The voltage source 5 provides a voltage ui for operating the force feedback actuator 7. The detection device 1 detects a current voltage ui of the voltage source 5 as a state variable zi. The detected state variable zi is forwarded by the detection device 1 to the control device 2.

[0055] The additional voltage source 5-1 provides a voltage U2 for operating the wheel actuator 8. The additional detection device 1-1 detects a current voltage U2 of the additional voltage source 5-1 as a state variable Z2. The detected state variable Z2 is also forwarded by the additional detection device 1-1 to the control device 2.

[0056] The control device 2 receives the state variables zi, Z2. Based on the state variables zi, Z2, the control device 2 determines a power parameter PA and a power parameter pß. The power parameter PA serves, for example, as a measure of the available electrical power for operating the force feedback actuator 7. The determined power parameter PB serves, for example, as a measure of the available electrical power for operating the wheel actuator 8.

[0057] Based on the performance parameters PA, PB, the control device 2 defines at least one steering parameter Si, s2, S3. For example, it is possible that a parameter value of the performance parameter PA is greater than a parameter value of the performance parameter PB. The power available for operating the wheel actuator 8 may therefore be less than the power available for operating the force feedback actuator 7. This may influence the definition of at least one steering parameter Si, s2, s3.

[0058] The at least one steering parameter Si can, for example, be an adjustable steering resistance force on a steering handle 3 of the motor vehicle. The steering resistance force can be generated, for example, by means of the force feedback actuator 7. The greater the steering resistance force, the more power is generally required to operate the force feedback actuator 7.

[0059] The at least one steering parameter s2 can alternatively or additionally be, for example, an adjustable maximum range of motion of the steering handle 3. The maximum range of motion of the steering handle 3 can be limited, for example, by means of the force feedback actuator 7. In particular, with a small maximum range of motion, more power is required to operate the wheel actuator 8 than with a larger maximum range of motion.

[0060] The at least one steering parameter s3 can alternatively or additionally be, for example, an adjustable maximum wheel steering force that can be generated to deflect the wheels 4 of the motor vehicle. The greater the wheel steering force, the more power is required to operate the wheel actuator 8.

[0061] Furthermore, the control device 2 sets the specified steering parameter Si, s2, s3. For example, setting 40 the specified steering parameter Si, s2, s3 can comprise a change in parameter values ​​and / or parameter value ranges in a control and / or regulation routine. In particular, the control device 2 can regulate and / or control the specified steering parameter Si, s2, s3 such that a parameter value of the steering parameter Si, s2, s3 lies within a parameter value range of the steering parameter Si, s2, s3.

[0062] Fig. 2 shows a schematic flow diagram of an embodiment of the method.

[0063] The method can be carried out, for example, by means of a steer-by-wire steering system 100 according to the embodiment shown in Fig. 1.

[0064] In a step 10, at least one state variable of a motor vehicle and / or at least one component of the motor vehicle is detected by means of at least one detection device.

[0065] For example, a voltage of at least one voltage source for supplying power to the motor vehicle and / or the at least one component of the motor vehicle can be detected as a state variable. Alternatively or additionally, a temperature of the motor vehicle and / or the at least one component of the motor vehicle and / or an ambient temperature and / or a speed of the motor vehicle can be detected as a state variable.

[0066] In a step 20, at least one performance characteristic is determined based on the at least one detected state variable by means of a control device.

[0067] The determination of the at least one performance characteristic may in particular comprise that at least one characteristic value of the at least one performance characteristic is selected on the basis of at least one predetermined determination rule, wherein the at least one determination rule specifies an assignment of the at least one performance characteristic to the at least one state variable.

[0068] In a step 30, at least one steering parameter is determined by means of the control device based on the at least one specific performance characteristic.

[0069] The determination of the at least one steering parameter can, in particular, comprise selecting at least one parameter value and / or parameter range of the at least one steering parameter based on at least one determination rule, wherein the at least one determination rule specifies an assignment of the at least one steering parameter to the at least one performance characteristic. Alternatively or additionally, the determination of the at least one steering parameter can be carried out taking into account a user specification.

[0070] In a step 40, the specified at least one steering parameter is adjusted, for example by adjusting a steering control and / or regulation.

[0071] Fig. 3 shows a schematic flow diagram of another embodiment of the method.

[0072] In a step 10, a currently set steering parameter a, a temperature t of a component of a steer-by-wire steering system 100, a voltage u of at least one voltage source 5, 5-1 (Fig. 1) and a speed v of a motor vehicle are detected as state variables zi,..., z4 by means of a detection device 1, 1-1 (cf. Figs. 1 and 4).

[0073] In a step 20, starting from the state variables zi ,... , z4, the performance parameters p A , PB, where, for example, a parameter value (not shown) of a performance parameter p A and a characteristic value (not shown) of a

[0074] Performance parameter PB can be selected based on the determination rule B. The determination rule B gives in particular a relationship between the state variables zi ,... , z4 and the performance parameters p A , PB. The value of the performance parameter p Acan be, for example, a value of a current power supply of the steer-by-wire steering system 100. The characteristic value of the power characteristic PB can be, for example, a value of a current power requirement for operating the steer-by-wire steering system 100. There can be a difference between the power supply and the power requirement, which can be reduced by setting the at least one steering parameter Si, S2, S3.

[0075] In a step 30, based on the at least one performance characteristic p A , PB the steering parameters Si, S2, S3 are determined, whereby at least one parameter value (not shown) of the steering parameters Si, S2, S3 is selected based on the specification rule F. The specification rule F specifies in particular a relationship between the performance parameters p A, PB and the steering parameters Si, S2, S3. The respective parameter value of the steering parameters Si, S2, S3 can be selected such that the difference between the power supply and the power demand can be reduced or eliminated. In a step 40, the specified steering parameters Si, S2, S3 are adjusted and in this way, for example, the power supply is brought into line with the power demand for operating the steer-by-wire steering system 100.

[0076] Fig. 4 shows a further embodiment of the steer-by-wire steering system 100. In the embodiment shown, the steer-by-wire steering system 100 has a detection device 1 designed as a voltmeter, a further detection device 1-1 designed as a voltmeter, a control device 2 designed as a computing unit, a voltage source 5 designed as a battery, a further voltage source 5-1 designed as a battery, and a wheel actuator 8 designed as a two-part electric motor. One part 8-1 of the wheel actuator 8 can generate part of a wheel steering force. Another part 8-2 of the wheel actuator 8 can generate another part of the wheel steering force.

[0077] In particular, the parts 8-1, 8-2 can be subjected to respective voltages ui, U2. This ensures that the wheel actuator 8 can at least partially generate the wheel steering force even if, for example, one of the voltage sources 5, 5-1 does not provide any voltage ui, u2 or provides too low a voltage.

[0078] The voltage source 5 provides a voltage ui for operating part 8-1 of the wheel actuator 8. The detection device 1 detects a current voltage ui of the voltage source 5 as a state variable zi. The detected state variable zi is forwarded from the detection device 1 to the control device 2. The further voltage source 5-1 provides a voltage u2 for operating the further part 8-2 of the wheel actuator 8. The detection device 1-1 detects a current voltage U2 of the further voltage source 5-1 as a state variable Z2.

[0079] Additionally, a state variable Z3 can be recorded, which serves, for example, as a measure of a currently set maximum portion of the wheel steering force that can be generated by part 8-1. Furthermore, a state variable Z4 can be recorded, which serves, for example, as a measure of a currently set maximum portion of the wheel steering force that can be generated by the further part 8-2.

[0080] Based on the state variables zi, Z2, Z3, Z4, a power parameter PA (Fig. 3) and a power parameter PB (Fig. 3) can be determined. For example, the power parameter PA can serve as a measure of the current power supply for operating both parts 8-1, 8-2 of the wheel actuator 8. Furthermore, for example, the power parameter PB can serve as a measure of the current power requirement for operating the wheel actuator 8 to generate maximum wheel force.

[0081] Based on a difference between the performance parameters PA, PB, a maximum part of the wheel steering force that can be generated by part 8-1 of the wheel actuator 8 can be calculated as

[0082] Steering parameter Si and a further maximum part of the wheel steering force that can be generated by means of the further part 8-2 of the wheel actuator 8 are determined and set as steering parameter S2, so that the current power requirement is covered by the current power supply.

[0083] For example, the steering parameters Si, S2 together can specify a maximum wheel steering force that can be generated that is smaller than the currently set maximum wheel steering force that can be generated.

[0084] In this way, the power requirement, for example, for one part 8-1, 8-2 of the wheel actuator 8 or for both parts 8-1, 8-2 of the wheel actuator 8 can be reduced. As a result, the power available for operating part 8-1 and / or the power available for operating the further part 8-2 can be sufficient to generate the set maximum wheel steering force that can be generated by means of part 8-1 and / or the further part 8-2 of the wheel actuator 8. This increases the reliability and safety of the steer-by-wire steering system 100.

[0085] List of reference symbols

[0086] 1 recording device

[0087] 1-1 additional recording device

[0088] 2 Control device

[0089] 3 Steering handle

[0090] 4 wheels

[0091] 5 Voltage source

[0092] 5-1 additional voltage source

[0093] 7 Force feedback actuator

[0094] 8 Wheel actuator

[0095] 8-1 Part of the wheel actuator

[0096] 8-2 further part of the wheel actuator

[0097] 10 steps of recording

[0098] 20 steps of determining

[0099] 30 Step of setting

[0100] 40 steps of setting

[0101] 100 Steer- By- Wire- Steering system a currently set steering parameter

[0102] B Determination regulation

[0103] F Determination rule

[0104] PA , PB performance characteristic

[0105] SI , S2, S3 Steering parameters t temperature

[0106] U1 voltage

[0107] U2 further voltage

[0108] V speed

[0109] Z1 , . . . , Z4 State variable

Claims

Patent claims 1. A method for steering a motor vehicle by means of a steer-by-wire steering system (100), the method comprising the steps of: detecting (10) at least one state variable (zi,..., Z4) of the motor vehicle and / or at least one component of the motor vehicle by means of at least one detecting device (1, 1-1), Determining (20) at least one performance characteristic (p A , PB) based on the at least one detected state variable (zi Z4) by means of a control device (2), Determining (30) at least one steering parameter (si, s2, s3) based on the at least one specific performance parameter (p A , PB) by means of the control device (2), Setting (40) the specified at least one steering parameter (si, s2, s3) by means of the control device (2).

2. Method according to claim 1, characterized in that the at least one steering parameter (si, s2, s3) is an adjustable steering resistance force (si) on a steering handle (3) of the motor vehicle and / or that the at least one steering parameter (si, s2, s3) is an adjustable maximum range of movement (s2) of the steering handle (3) and / or that the at least one steering parameter (si, s2, s3) is an adjustable maximum wheel steering force (s3) that can be generated to deflect the wheels (4).

3. Method according to one of the preceding claims, characterized in that the determination (20) of the at least one performance characteristic (p A , PB) includes that at least one parameter value of the at least one performance parameter (p A , PB) is selected based on at least one predetermined determination rule (B), wherein the at least one determination rule (B) includes an assignment of the at least one performance characteristic (p A, PB) ZU which specifies at least one state variable (zi ,... , Z4).

4. Method according to one of the preceding claims, characterized in that the setting (30) of the at least one steering parameter (si, s2, s3) comprises that at least one parameter value and / or parameter range of the at least one steering parameter (si, s2, s3) is selected on the basis of at least one predetermined setting rule (F), wherein the at least one setting rule (F) specifies an assignment of the at least one steering parameter (si, S2, S3) to the at least one performance characteristic (PA, PB).

5. Method according to one of the preceding claims, characterized in that the setting (30) of the at least one steering parameter (si, S2, S3) takes place taking into account a user specification.

6. Method according to one of the preceding claims, characterized in that a voltage (u) of at least one voltage source (5, 5-1) for supplying voltage to the motor vehicle and / or to the at least one component of the motor vehicle is detected as the state variable (zi,..., Z4).

7. Method according to one of the preceding claims, characterized in that a temperature (t) of the motor vehicle and / or of the at least one component of the motor vehicle and / or a temperature of the environment and / or a speed (v) of the motor vehicle is detected as the state variable (zi,..., Z4).

8. Method according to one of the preceding claims, characterized in that the at least one steering parameter (si, S2, S3) is a maximum producible deviation between an actual position of a wheel actuator (8) and a desired position of the wheel actuator (8) predetermined by a steering handle (3).

9. Method according to one of the preceding claims, characterized in that a part (8-1) of a wheel actuator (8) generates a part of a wheel steering force and / or that a further part (8-2) of the wheel actuator (8) generates a further part of the wheel steering force, wherein the at least one steering parameter (s1, S2, S3) is a maximum producible part of the wheel steering force and / or a maximum producible further part of the wheel steering force.

10. Steer-by-wire steering system (100) for steering a motor vehicle, comprising: at least one detection device (1, 1-1) for detecting at least one state variable (zi,..., Z4) of the motor vehicle and / or at least one component of the motor vehicle, a control device (2), wherein the control device (2) is configured to determine at least one performance parameter (PA, PB) ZU and to specify and set at least one steering parameter (si, S2, S3), wherein the steer-by-wire steering system (100) is configured to carry out a method according to one of claims 1 to 9.

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