motor vehicle having an electromechanical steering system

Abstract

Electromechanical steering system (20) comprising a steering linkage (22), a steering device (24), in particular a steering wheel (25), a steering pinion (26), an electric motor (28), an axle to be steered (30) and an angle sensor (32), wherein the angle sensor (32) is designed and configured to determine a driver steering angle, wherein a steering pinion angle of the steering pinion (26) on the axle to be steered (30) is calculated based on a rotor position angle of the electric motor (28), wherein the steering linkage (22) is approximated as a torsion bar and a driver hand torque is estimated based on the rotor position angle, the steering pinion angle and a stiffness of the approximated torsion bar, and wherein a friction torque is estimated based on the driver hand torque and a detected torsion bar torque.

Description

[0001] The disclosure relates to an electromechanical steering system. The disclosure relates to a method, in particular a computer-implemented method. The disclosure relates to a motor vehicle.

[0002] Electromechanical steering systems are known in the prior art. Prior art electromechanical steering systems use the torque measured at a torsion bar to calculate the basic assist force that can be provided by a servo motor.

[0003] CN 116 678 532 A deals with a method for friction testing of a steering column, in which frictional torques of several friction pairs are measured.

[0004] DE 10 2017 203 735 A1 relates to a device and a method for detecting a driver's hand movement of a steering wheel, wherein a steering wheel torque and an angular velocity of a steering column are measured.

[0005] DE 10 2012 204 870 B4 relates to an electric power steering system for a vehicle, in which a torque sensor is modeled as a torsion bar with a linear spring and a damping effect.

[0006] Frictional influences on the steering system, such as those caused by the steering shaft, steering column, connecting joints, and input shaft including the seal, are perceived by the driver in terms of steering behavior, particularly during power transmission from the driver to the road. However, due to their upstream position in the torque flow, these frictional influences cannot be detected by the torsion bar and therefore cannot be directly compensated for. The same applies to the feedback path from the road to the driver. The known electromechanical steering systems are perceived as unsatisfactory.

[0007] The purpose of the invention is to improve electromechanical steering systems.

[0008] The problem is solved in particular by an electromechanical steering system with the features of claim 1. The problem is solved in particular by a method, especially a computer-implemented method, with the features of claim 8. The problem is solved in particular by a motor vehicle with the features of claim 9. Further features and details of the invention will become apparent from the dependent claims, the description, and the drawings. Features and details described in connection with the electromechanical steering system according to the invention naturally also apply in connection with the method and the motor vehicle according to the invention. The reverse is also true, so that the disclosure of the individual aspects of the invention always includes, or can include, reciprocal references.

[0009] According to one aspect, the problem is solved in particular by an electromechanical steering system with the features of claim 1.

[0010] An electromechanical steering system can be configured, comprising at least one of the following: a steering linkage, a steering device (in particular a steering wheel), a steering pinion, an electric motor, an axle to be steered, and an angle sensor. The angle sensor is specifically designed and configured to determine the driver's steering angle. Based on the rotor position angle of an electric motor, the steering pinion angle on the axle to be steered can be calculated. The steering linkage can be approximated as a torsion bar. Based on the rotor position angle, the steering pinion angle, and the stiffness of the approximated torsion bar, a driver's hand torque can be estimated. Based on the driver's hand torque and a detected torsion bar torque, a friction torque can be estimated.

[0011] An electromechanical steering system is designed in particular to include at least one of the following components: A steering system, in particular, comprises a series of joints and links that receive the driver's steering angle and translate it into a movement capable of steering the vehicle. The steering system can be approximated as a torsion bar, as described elsewhere herein.

[0012] A steering device comprises, in particular, various components that are available to the driver to operate the steering system. This includes, for example, a steering wheel.

[0013] A steering pinion is, in particular, a part of the steering system that transmits the driver's steering angle to the axle being steered. The steering pinion can, for example, be associated with a steering shaft of a steering system. It may be mounted on a torsion bar, in which case the torque on the torsion bar can be measured by a torque sensor.

[0014] An electric motor is, in particular, a component that serves as an amplifying drive for the steering system, specifically by translating the movement of the electric motor into the movement of an axle that can be moved laterally by the steering pinion. In this process, a rotor angle of the electric motor can be transmitted to the axle to be steered as a lateral movement.

[0015] The axle to be steered is, in particular, the axle of the vehicle through which the steering system acts and which can be used to steer the vehicle. For example, a rack and pinion system may be used. The axle, especially the rack and pinion, may be a different axle than the one that holds the wheels and through which drive is transmitted.

[0016] An angle sensor is, in particular, a component that can determine the driver's steering angle. It can be located in various parts of the steering system, such as in the steering wheel and / or the steering column.

[0017] These components enable, in particular, an electromechanical steering system that translates the driver's steering angle to the axle being steered, thus steering the vehicle. The steering linkage can be approximated as a torsion bar to estimate the driver's hand torque, which is then used to calculate the frictional torque. The angle sensor helps determine the driver's steering angle, and the electric motor transmits the rotor position angle to the axle.

[0018] To compensate for potential variations in steering system friction, the friction of the steering system during driving is determined using a hybrid approach combining measurement technology and modeling, particularly with the presented methodology. The corresponding steps of a procedure described elsewhere herein can be executed on a computing device, such as a control unit, by running a computer program that can be read by a storage device. Instructions stored in the computer program, which can be read by the computing device, can then instruct it to control an electromechanical steering system (or a motor vehicle described elsewhere herein) and perform the corresponding steps.

[0019] The friction coefficient identified in this way can be used for various applications. It allows for the implementation of an analysis of the friction behavior within the steering system. An (axle-parallel) steering system enables the implementation of such an analysis. The steering system, which transmits the driver's steering angle to the axle, consists of various components such as the steering shaft, connecting joints, and seals. These components can cause initial frictional forces due to wear or damage, which can negatively affect the performance of the steering system.

[0020] Analyzing the friction behavior within the steering system allows verification of whether all steering system components are functioning correctly and exhibiting the expected frictional forces. The lubrication damage model can also be used to assess whether a steering system component is worn or not.

[0021] Furthermore, analyzing the friction behavior in the steering system allows for a prediction of its service life, thus enabling planned maintenance. This increases efficiency and reduces unplanned downtime, as the system can be inspected and serviced early.

[0022] It allows for the analysis of defects based on EPS-internal or vehicle bus-based measurements. The electromechanical steering system, particularly through a computer-implemented method, allows for the analysis of defects based on internal measurements from the electric power steering (EPS) or the vehicle bus. These measurements can provide information about the condition of various parts of the steering system and the system's behavior under different conditions.

[0023] The analysis can, for example, examine friction in the steering system, the power output of the drive motor, or the system's current consumption. By using measurements from the vehicle's data bus, information about driver demands and vehicle handling in relation to the steering system can also be gathered.

[0024] Implementing this analysis allows for a more precise diagnosis of potential problems in the system and facilitates the maintenance and servicing of the electromechanical steering system. It can also contribute to improving vehicle safety and comfort by identifying problems early and meeting driver information requirements.

[0025] It allows for an analysis of friction behavior over the lifetime of the electromechanical steering system. A key function of the electromechanical steering system is to analyze friction behavior throughout its entire lifespan. This enables continuous monitoring and diagnostics of the system component during its operational life.

[0026] By using internal or external sensors, such as the angle sensor, the torque sensor, and / or the vehicle bus measurements, the system can monitor friction behavior in real time and over extended periods. This can help implement or activate early warning systems or suggest maintenance work to prevent or mitigate potential problems.

[0027] It enables functional integration within the EPS control system and optimization of steering feel. The electromechanical steering system, in particular, offers the possibility of functional integration within the EPS (Electric Power Steering) control system and optimization of steering feel. Through the use of sensors and actuators, the system can acquire real-time information about the vehicle's condition and driver requirements and then incorporate this information into the control settings.

[0028] By adjusting the control settings, various aspects of the steering feel can be optimized, such as lubrication, power transmission functionality, and adaptation to different driving conditions. This can contribute to a better steering feel and improved driving safety.

[0029] It can be used to compensate for variations in steering system friction during production. The electromechanical steering system is designed to automatically compensate for different friction coefficients in the steering system. During production, these differences can arise from variations in the manufacturing process or the assembled parts, and can impair the vehicle's steering.

[0030] By measuring the frictional forces acting on the steering system, it can automatically take corrective action (via the electric motor that assists the steering through the pinion gear) to ensure the vehicle remains consistently steerable and offers optimal steering feel. This is particularly valuable after manufacturing, as it ensures that vehicles sold to end consumers have a pleasant and consistent steering feel.

[0031] It can be used to compensate for aging effects. The electromechanical steering system, in particular, has a function that allows it to compensate for aging effects in the steering linkage. Over time, the steering linkage can suffer from frictional losses due to wear and tear of the material. This can affect the steering feel and the performance of the steering system.

[0032] By detecting and compensating for aging effects, the system can maintain its effectiveness and safety over a longer period. It enables continuous monitoring of steering linkage friction and can automatically make adjustments to ensure optimal steering feel.

[0033] It can be used for optimization through general knowledge of steering system friction. The electromechanical steering system, in particular, has a function that allows for the optimization of steering system friction based on general knowledge. This means, specifically, that the system is able to automatically adjust the friction in the steering system, thereby ensuring better steering feel and greater efficiency. This function is based primarily on the analysis of measurements from the electric power steering (EPS) system or the vehicle's bus, as well as on general knowledge of the friction behavior in the steering system.

[0034] This functionality allows the system to automatically adjust for optimal performance. It also provides better control over steering feel, thus improving safety and driving comfort.

[0035] It allows the measured driver hand torque to be used directly within the EPS control system. The electromechanical steering system has the functionality to use the measured driver hand torque directly in the EPS control system. This enables more precise control of the steering system and allows the system to better respond to the driver's needs. This can improve the steering feel.

[0036] It enables its use for the comparison threshold in hands-on / off detection. Specifically, the electromechanical steering system offers a functionality that allows the measured driver hand torque to be used to define a comparison threshold for hands-on / off detection. By using the measured driver hand torque, a threshold can be defined that indicates whether the action is a human action or simulated by the system. This allows for more precise control of the system and improves the safety and reliability of the steering system.

[0037] The focus is in particular on an electromechanical steering system (Electric Power Steering - EPS), especially for use as a passenger car steering system, further in particular in connection with steering shaft and / or steering column and in particular combination steering column module.

[0038] In one embodiment, an axle-parallel (APA) steering system can be implemented, although the approach can be applied to all types of EPS. An axle-parallel (APA) steering system is a type of steering system in which the steering axis is located directly at the front of the steering system and lies in the same plane as the vehicle's wheels. In such a system, the steering shaft and the steering device (steering wheel) are located on the same side, and the axle is controlled by a single steering shaft.

[0039] This means that the axle runs directly into the vehicle frame and not, as with an adjustable (AV) steering system, onto a bearing on the side of the frame. An AP steering system is therefore simpler in design and is often used in lighter or smaller vehicles. However, it offers limited performance under heavy loads or in large vehicles with large turning radii.

[0040] The subject of this disclosure is therefore a method for identifying steering system friction (consisting of steering shaft, steering column, connecting joints, and input shaft including seal) during driving operation and a corresponding system for carrying out such a method (also to be described as a process). The steering system is considered in particular as a torsion bar, and the information from the steering pinion and the steering wheel angle can be used in the combined steering column module to detect the angle of rotation, in particular to approximate the driver's hand torque.

[0041] This approach and the derived driver hand torque can be used for anomaly analysis and functional development within the EPS.

[0042] This allows for the identification of a steering system friction coefficient under system load, such as by a hand torque.

[0043] This allows for a more realistic and / or vehicle-specific friction coefficient analysis compared to standard empty-wheel steering tests.

[0044] The frictional torque of the steering system M Reibung,LS is particularly idealized as the difference between driver hand torque M Fahrer and the torsion bar torque M DS to assume. MRefrigerant,LS=MDriver−MDS

[0045] The torsion bar torque can be measured, while the driver's hand torque cannot. The torsion bar torque can be determined, in particular, at a torsion bar of a steering system, especially using a torque sensor.

[0046] An angle sensor is available on the steering wheel, particularly in the combination steering column module, which measures the driver's steering angle φ. LRW can determine.

[0047] The EPS is determined using the measured rotor angle φ. Rotorthe calculated steering angle at the pinion φ berechneter LRW (including translations).

[0048] This offers in particular an approach to real-time determination of steering column friction by sensors on the combined steering column module (if one is present) and the electromechanical power steering during driving.

[0049] In this methodology, the steering system is approximated as a torsion bar. Its relative rotation can be determined using the calculated steering angle and the driver's steering angle.

[0050] From the knowledge of the stiffness of the series connection consisting of torsion bar, steering shaft, steering column and connecting joint c ges The driver's hand torque can be estimated.

[0051] In the procedure, or by the system, the driver torque can be calculated according to formula (2), where M Fahrer The driver torque is, where the driver steering angle is φ. LRWand the calculated steering pinion angle φ berechneter LRW is: MFahrer=(φLRW−φcalculated LRW)⋅cges

[0052] Furthermore, in particular, the measured torque (on a torsion bar) M can be used to determine DS and accordingly, a frictional torque of the steering system can be determined using formula (1).

[0053] By subtracting the torque on the torsion bar in suitable situations (reversal point, slow steering and similar) the steering string friction can be determined, as shown in equation (1).

[0054] This can lead to gimbal effects (variable translation) and angular drifts between φ. LRW and φ berechneter LRW be taken into account.

[0055] The driver hand torque M determined in this way Fahrer In addition to determining steering system friction, it can also be directly incorporated as input into the EPS functionality to improve response (further optimization of steering feel).

[0056] Furthermore, this approach can also be applied in reverse. This allows an excitation to be transmitted from the road surface to the driver.

[0057] From one perspective, the angle sensor can be located in a combined steering column module.

[0058] A combined steering column module is, in particular, a combination of a steering column and a steering column, which can be arranged in a single component. It allows the driver to move the steering wheel and thus steer the vehicle. The module can also include additional functions, such as transmitting steering angle information to the electromechanical steering system.

[0059] From one perspective, the steering system can have at least one selected from a torsion bar, a steering shaft, a steering column or at least one connecting joint.

[0060] A torsion bar is, in particular, a mechanical structure used primarily to transmit and / or monitor rotational movements. It has, in particular, a rod-shaped section (with a diameter) that may be connected at least at one end to at least one joint. By rotating the rod-shaped section around an axis, the at least one joint can be moved, thus transmitting and / or monitoring the rotational movement.

[0061] A steering shaft is, in particular, a part of the steering system that establishes the mechanical connection between the steering device, especially the steering wheel, and the steering column. Its primary function is to enable the steering's rotational movement.

[0062] The steering column is, in particular, a component of the steering column, especially the combined steering column module, which connects the steering device, especially the steering wheel, to the steering shaft. It can also be considered the axis of rotation of the steering system.

[0063] Connecting joints are components that connect different parts of the steering column, particularly the combined steering column module. In steering systems, connecting joints can link the steering shaft to the steering column or other system components such as the steering linkage or the angle sensor. They provide a movable connection to transmit rotational movements and forces.

[0064] According to one approach, the steering system friction can be determined by subtracting a torque from the torsion bar in suitable situations, particularly at a turning point or during slow steering. In particular, a difference can be calculated.

[0065] According to one aspect, at least one of gimbal effects (variable translation) or angular drift between φ can occur. LRW and φ berechneter LRW be taken into account.

[0066] The electromechanical steering system is designed so that at least one gimbal effect (variable ratio) or angular drift occurs between the driver's steering angle (φ). LRW ) and the calculated steering pinion angle (φ berechneter LRW ) is taken into account.

[0067] A gimbal effect occurs when a rack with variable gearing is used, resulting in a change in rotational speed as the rack is moved from one end to the other. In this case, the rotational speed at the input (e.g., steering wheel) cannot directly correlate with the rotational speed at the output (e.g., axle).

[0068] Cardan effects refer specifically to changes in the angular velocity of a rack due to variable gear ratio (also known as bevel gear ratio). These effects are particularly noticeable when a rack with a variable gear ratio is used, such as in a steering system. The changes can be both positive and negative cardan effects and primarily affect the speed at which the rack rotates, depending on its position within the system. Cardan effects are especially important to consider when analyzing and optimizing the behavior of mechanical systems.

[0069] Angle drift occurs when there is an undesirable difference between the actual and the ideal angular position of an axis. This can be caused by inaccurate or worn parts of the steering column or by other factors.

[0070] Angle drift refers specifically to the unwanted difference between the actual and ideal angular profile of an axle. This can occur due to wear or mechanical fluctuations. In the context of an electromechanical steering system, angle drift can distort steering feel and impair performance. Therefore, it can be important to monitor and, if necessary, compensate for this angle drift to ensure optimal steering feel and high system reliability.

[0071] By taking these effects into account, the electromechanical steering system can offer a better and more precise steering feel and help to identify and compensate for potential sources of error.

[0072] According to one aspect, the determined driver hand torque M FahrerIn addition to determining steering string friction, the data can be directly incorporated as input into the EPS functionality to improve response.

[0073] The electromechanical steering system is designed to allow the measured driver hand torque (M_driver) to be used not only to determine steering linkage friction but also as an input for the EPS functionality. This means the system can directly use the driver hand torque as input for its control logic, thereby achieving a better adaptation of the steering feel to the individual needs of the driver. In this way, the system can improve performance by optimizing the efficiency of power transmission.

[0074] From one perspective, the electromechanical steering system can be designed and configured to transmit a stimulus from the road surface to the driver.

[0075] The electromechanical steering system is specifically designed to transmit feedback from the road surface to the driver. This enables greater precision and safety while driving, as the system can relay information about the road surface's condition. The road surface can then influence the steering, particularly with less of a reduction in effect than without the system. This allows for the transmission of road surface information to the driver.

[0076] By using the sensors described herein, the system can detect the friction of the steering system in order to at least partially compensate for it, thus transmitting information about the road surface as accurately as possible. This allows the driver to make corresponding adjustments via the steering system, ensuring better control of the vehicle. This can be particularly advantageous in critical situations such as on wet or icy roads.

[0077] From an independent perspective, a computer-implemented procedure may be provided.

[0078] The procedure includes, in particular, the step of determining the driver's steering angle.

[0079] The method includes, in particular, the step of calculating a steering pinion angle based on a rotor position angle of an electric motor of a steering pinion on an axle to be steered.

[0080] The method includes, in particular, the step of approximating a steering system as a torsion bar.

[0081] The method includes, in particular, the step of estimating a driver's hand torque based on the rotor position angle, the steering pinion angle and a stiffness of the approximated torsion bar.

[0082] The procedure includes, in particular, the step of estimating a frictional torque based on the driver's hand torque and a recorded torsion bar torque.

[0083] The method, particularly the computer-implemented one, can be described by the features, properties, and advantages of the motor vehicle and the electromechanical steering system. This also applies across the category boundaries of method, device, and system. Thus, the motor vehicle and the electromechanical steering system can also be described by the features, properties, and advantages of the method, particularly the computer-implemented one. For the sake of readability and conciseness, a repetition of all these features, properties, and advantages is omitted.

[0084] In the procedure, or by the system, the driver torque can be calculated according to formula (2), where M Fahrer The driver torque is, where the driver steering angle is φ. LRW and the calculated steering pinion angle φ berechneter LRW is: MFahrer=(φLRW−φcalculated LRW)⋅cges

[0085] Furthermore, in particular, the measured torque (on a torsion bar) M can be used to determine DS and accordingly, a frictional torque of the steering system can be determined using formula (1).

[0086] From an independent perspective, a motor vehicle may have an electromechanical steering system as described elsewhere herein, wherein the motor vehicle may be designed and equipped to carry out a procedure, in particular a computer-implemented procedure, as described elsewhere herein.

[0087] The motor vehicle can be described by the features, properties, and advantages of the method, the motor vehicle, and the electromechanical steering system. This also applies across the category boundaries of method, device, and system. Thus, the method and the electromechanical steering system can also be described by the features, properties, and advantages of the motor vehicle. For the sake of readability and conciseness, a repetition of all these features, properties, and advantages is omitted.

[0088] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination. The drawings schematically show: Fig. 1. a schematic representation of an exemplary embodiment of a motor vehicle, an exemplary embodiment of an electromechanical steering system; Fig. 2 a schematic representation of an exemplary embodiment of a method. Fig. Figure 1 shows a schematic representation of an exemplary embodiment of a motor vehicle 50 comprising an exemplary embodiment of an electromechanical steering system 20.

[0089] The electromechanical steering system 20 can comprise at least one selected from a steering linkage 22, a steering device 24, in particular in the form of a steering wheel 25, a steering pinion 26, an electric motor 28, an axle to be steered 30 and an angle sensor 32.

[0090] The steering pinion 26 can be arranged, in particular, on a steering axle 30 such that a movement of the steering pinion 26 can be converted into a lateral movement of the steering axle, wherein the movement of the axle 30 can be parallel to a rotational movement of the steering pinion 26. This allows for the steering of wheels (not shown). Bellows 33 can be arranged to provide spring-loaded mounting for the wheels (not shown).

[0091] The angle sensor 32 is specifically designed and configured to determine the driver's steering angle. The angle sensor 32 can be arranged in a combined steering column module 34.

[0092] Based on the rotor position angle of the electric motor 28, a steering pinion angle of the steering pinion 26 on the axis 30 to be steered can be calculated. In particular, a position of the steering pinion 26 can correspond to a position of the electric motor such that a rotor position angle can be calculated. The electric motor 28 can have a belt and / or ball screw drive 35, which is designed and arranged to enable the rotation of a pinion 29 that meshes with a corresponding counterpart 27 of the axis 30, in particular the rack 31.

[0093] The steering system 22 can be approximated as a torsion bar. In particular, it can be provided that a (digital) representation of the steering system 22 exists as a continuous torsion bar, to which a corresponding rotation and / or stiffness can be assigned. The steering system 22 has, in particular, at least one selected from a torsion bar 36, a steering shaft 38, a steering column 40, or at least one connecting joint 42.

[0094] Based on the rotor position angle, the steering pinion angle, and the stiffness of the approximate torsion bar, a driver's hand torque can be estimated. Based on the driver's hand torque and a torsion bar torque detected by torque sensor 39, a friction torque can be estimated.

[0095] By subtracting (mathematical difference calculation) a torque on the torsion bar 36, the steering string friction can be determined in suitable situations, in particular in one selected from a reversal point or a slow steering maneuver.

[0096] At least one of gimbal effects, corresponding to a variable translation, or angular drifts between driver steering angle φ LRW and calculated steering pinion angle φ berechneter LRW can be taken into account.

[0097] The determined driver hand torque M Fahrer In addition to determining steering string friction, it can be directly incorporated as input into the functionality of the electromechanical steering system (EPS functionality) to improve response.

[0098] The electromechanical steering system 20 can be designed and configured to transmit an impulse from the roadway to the driver.

[0099] Fig. Figure 2 shows a schematic representation of an exemplary embodiment of a method.

[0100] Method 100 is in particular designed to be computer-implemented, i.e. it can have a computer program product with machine-readable instructions that are processed by a computing device (not shown) of the motor vehicle 50 (see Fig. 1) can be read from a storage device (not shown) to control an electromechanical steering system 20 in a motor vehicle 50 in such a way as to perform at least one of the following steps.

[0101] In one step of a determination 110, a driver steering angle can be determined. This indicates, in particular, the position of a steering device 24, such as a steering wheel 25.

[0102] In one step of a calculation 120, a steering pinion angle can be calculated. This calculation 120 can be based on a rotor position angle of an electric motor 28, which corresponds to a steering pinion 26 on a steering axle 30, such as a rack 31 (see Fig. 1). The position and / or movement of the steering pinion 26 can be converted into a supporting movement to set the axis 30, in particular the rack 31, into a lateral movement in the direction of the movement of the pinion 26.

[0103] In one step of an approximation 130, a steering system 22 can be approximated as a torsion bar. In this process, the components of the steering system 22 that are at least partially movable relative to each other, such as the combined steering column module 34, in particular comprising at least one selected from a torsion bar 36, a steering shaft 38, a steering column 40 or at least one connecting joint 42, can be assumed to be fixed relative to each other.

[0104] In one step of an estimation 140, a driver hand torque can be estimated based on the rotor position angle, the steering pinion angle and a stiffness of the approximated torsion bar.

[0105] In one step of an estimation 150, a frictional torque can be estimated based on the driver's hand torque and a recorded torsion bar torque.

Claims

[1] Electromechanical steering system (20) comprising a steering linkage (22), a steering device (24), in particular a steering wheel (25), a steering pinion (26), an electric motor (28), an axle to be steered (30) and an angle sensor (32), wherein the angle sensor (32) is designed and configured to determine a driver steering angle, wherein a steering pinion angle of the steering pinion (26) on the axle to be steered (30), in particular a rack (31), is calculated based on a rotor position angle of the electric motor (28), wherein the steering linkage (22) is approximated as a torsion bar and a driver hand torque is estimated based on the rotor position angle, the steering pinion angle and a stiffness of the approximated torsion bar, and wherein a friction torque is estimated based on the driver hand torque and a detected torsion bar torque. [2] Electromechanical steering system (20) according to claim 1, characterized by , that the angle sensor (32) is arranged in a combination steering column module (34). [3] Electromechanical steering system (20) according to at least one of the preceding claims, characterized by , that the steering system (22) has at least one selected from a torsion bar (36), a steering shaft (38), a steering column (40) or at least one connecting joint (42). [4] Electromechanical steering system (20) according to at least one of the preceding claims, characterized by , that by subtracting a torque on the torsion bar (36) in suitable situations, in particular in one selected from a reversal point or a slow steering maneuver, the steering string friction is determined. [5] Electromechanical steering system (20) according to at least one of the preceding claims, characterized by , that at least one of gimbal effects (variable translation) or angular drifts between driver steering angle φ LRW and calculated steering pinion angle φ berechneter LRW be taken into account. [6] Electromechanical steering system (20) according to at least one of the preceding claims, characterized by , that the determined driver hand torque M Fahrer In addition to determining steering string friction, it is directly incorporated as input into the functionality of the electromechanical steering system (EPS functionality) to improve response. [7] Electromechanical steering system (20) according to at least one of the preceding claims, characterized by , that the electromechanical steering system (20) is designed and configured to transmit an excitation from the roadway to the driver. [8] Method (100), in particular computer-implemented, comprising the steps: - of determining (110) a driver's steering angle; - of a calculation (120) of a steering pinion angle based on a rotor position angle of an electric motor (28) of a steering pinion (26) on an axle to be steered; - an approximation (130) of a steering linkage (22) as a torsion bar; - an estimation (140) of a driver's hand torque based on the rotor position angle, a steering pinion angle and a stiffness of the approximate torsion bar; and - of an estimation (150) of a frictional torque based on the driver's hand torque and a detected torsion bar torque. [9] Motor vehicle (50) comprising at least one electromechanical steering system (20) according to at least one of claims 1 to 7, designed and configured to carry out a method (100) according to claim 8.

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