eddy current sensor

Abstract

The application discloses a kind of eddy current sensors (33), for detecting relative position (32) in moving direction, comprising: first eddy current sensor fitting piece (34,37) and second eddy current sensor fitting piece (37,34), second eddy current sensor fitting piece (37,34) can be positioned relative to first eddy current sensor fitting in the relative position (32) to be detected;Evaluation circuit (36) is configured to determine relative position (32) based on electromagnetic measurement field, wherein the eddy current sensor fitting piece that generates electromagnetic induction field has smaller range than the eddy current sensor fitting piece that generates electromagnetic measurement field in transverse direction perpendicular to moving direction and perpendicular to the distance between eddy current sensor fitting piece;And correction fitting piece (40) is arranged at fixed position with predetermined distance relative to first eddy current sensor fitting, for generating electromagnetic correction field, to correct transverse displacement between eddy current sensor fitting transverse to moving direction (31).

Description

Technical Field

[0001] The present invention relates to an eddy current sensor according to the preamble of claim 1, a lever sensor including an eddy current sensor, and a method for detecting relative position according to the preamble of claim 9. Background Technology

[0002] An eddy current sensor according to the preamble of claim 1 is known from DE19631438A1.

[0003] As is known from DE102022114508A1, the measurement signal in an eddy current sensor can be increased by adding a target. Summary of the Invention

[0004] The purpose of this invention is to improve upon known systems.

[0005] Starting with an eddy current sensor for detecting relative position in a direction of movement, the eddy current sensor includes a first eddy current sensor mating member and a second eddy current sensor mating member, the second eddy current sensor mating member being positioned relative to the first eddy current sensor mating member at the relative position to be detected. The eddy current sensor mating members are configured to generate an electromagnetic measurement field based on the relative position and include an evaluation circuit configured to determine the relative position based on the electromagnetic measurement field. One of the eddy current sensor mating members is configured to generate the electromagnetic measurement field, and the other eddy current sensor mating member is configured to generate an electromagnetic induction field based on the electromagnetic measurement field. The eddy current sensor mating member generating the electromagnetic induction field has a smaller lateral range in a lateral direction perpendicular to the direction of movement and perpendicular to the distance between the eddy current sensor mating members than the eddy current sensor mating member generating the electromagnetic measurement field. The present invention provides a correction mating member disposed at a fixed position at a predetermined distance relative to the first eddy current sensor mating member to generate an electromagnetic correction field to correct lateral displacement between the eddy current sensor mating members in the direction of movement.

[0006] The eddy current sensor mentioned at the beginning is based on the consideration that lateral movement, such as that caused by mechanical tolerances, deformation, or bending of components like tie rods (also known as steering rods), is not detected when assessing relative position only in the direction of movement. This lateral displacement asymmetrically affects the electromagnetic measurement field and leads to distorted measurement results because they are difficult to distinguish from the actual relative movement of interest. In particular, this can result in unacceptable measurement errors in highly dynamic applications or where mechanical degrees of freedom are limited.

[0007] The aforementioned eddy current sensor solves this problem by arranging a correction fitting at a predetermined distance from one of the two eddy current sensor fittings. The correction fitting has a known geometric relationship with one of the eddy current sensor fittings and is integrated into the eddy current sensor in such a way that additional information can be obtained through this distance, allowing for the consideration or correction of lateral displacement between the eddy current sensor fittings in the direction of movement. Since the distance between the two eddy current sensor fittings is affected differently in the case of lateral displacement, the known geometric relationship between the correction fitting and the associated eddy current sensor fitting can distinguish between relative movement in the direction of movement and displacement in the direction of movement.

[0008] In this way, lateral displacement between the mating components of the eddy current sensor can be suppressed from the outset, identified for error detection, or compensated for to improve the reliability of the detected relative position, thereby enabling more robust and reliable detection of relative position in the direction of movement. This invention is particularly suitable for applications where the eddy current sensor mating components form part of a mechanically compliant or flexible structure, in which positional changes do not occur solely along an idealized direction of movement. A typical example is detecting wheel steering angle through the position of a tie rod in a vehicle, where bending effects due to vehicle weight or assembly tolerances can cause lateral displacement, which would result in significant measurement errors without the correction capabilities according to the invention.

[0009] Eddy current sensors are known, which consist of multiple eddy current sensor components working together, including several field-influencing elements, for example, to increase signal strength. In this arrangement, the field-influencing elements typically have a larger lateral range than the field-generating elements, causing them to act over a substantially uniform region of the electromagnetic measurement field and contribute to the measured quantity in the same direction. This, in particular, leads to the additional superposition of signal components.

[0010] In contrast, this invention is based on the discovery that different operational behaviors can be achieved when the lateral range of the eddy current sensor assembly that generates the electromagnetic induction field is selected to be smaller than the corresponding range of the eddy current sensor assembly that generates the electromagnetic measurement field in a direction orthogonal to the direction of movement and the connection direction between the eddy current sensor assemblies. In this arrangement, the eddy current sensor assemblies are not located in a substantially uniform field region, but rather in regions of varying field strengths, such that relative displacement laterally to the direction of movement causes changes in the electromagnetic coupling of the eddy current sensor assemblies that cancel each other out. As a result, lateral movement of the disturbance does not cause a unidirectional change in the signal, but is at least partially compensated for, thereby significantly improving the robustness of position determination.

[0011] The term "eddy current sensor assemblies" refers to complementary functional units of an eddy current sensor that collectively participate in the generation of the electromagnetic source field and its field-related effects. One eddy current sensor assembly should be understood as an excitation element, i.e., an excitation coil, used to generate the electromagnetic source field, while the other should be understood as a reflector element configured to generate an induced field based on the electromagnetic source field, the induced field being opposite in direction to the electromagnetic source field and forming at least a portion of the electromagnetic measurement field. The assignment of roles is explicit: if one eddy current sensor assembly is understood as an excitation element, then the other must be understood as a reflector element, and vice versa.

[0012] Determining the relative position of a target from an electromagnetic measurement field, including an electromagnetic induction field, can generally be done in two ways. On one hand, the relative position can be determined based on changes in the electrical characteristics of the excitation coil itself caused by the electromagnetic measurement field. These changes can be determined by analyzing the impedance of the excitation coil, particularly its alternating current (AC) resistance, inductance, and / or the phase relationship between current and voltage. This so-called damping principle is based on the fact that the electromagnetic source field generated by the excitation coil induces eddy currents in the reflector, which in turn generate an electromagnetic induction field in the form of a reverse field, thus affecting the current consumption and impedance of the excitation coil. In this variation, the relative position is determined by evaluating the resulting impedance changes. On the other hand, the relative position can be determined based on the so-called transformer principle. In this case, in addition to the excitation coil, at least one receiving coil is provided, in which a voltage is induced by the electromagnetic induction field originating from the reflector. This voltage depends in a specific way on the spatial relationship between the excitation coil, the reflector, and the receiving coil. The relative position can then be determined based on the amplitude, phase, or frequency dependence of the induced voltage.

[0013] In further development of the specified eddy current sensor, a first eddy current sensor assembly includes a reflector, and a second eddy current sensor assembly includes an excitation coil for generating an electromagnetic source field, wherein the reflector is configured to generate an electromagnetic induction field contained within the electromagnetic measurement field based on the electromagnetic source field. Thus, when the calibration assembly is arranged in a fixed position relative to the reflector, a direct geometric relationship can be established between the two elements. This allows for a clear interpretation of changes in the distance between the reflector-calibration assembly system and the excitation coil caused by lateral displacement by comparing the electromagnetic induction field and the electromagnetic calibration field. This enables a robust distinction between relative movement in the measurement direction and lateral movement, the latter affecting the corresponding measurement quantity in a peculiar way due to the fixed internal geometry of the reflector and calibration assembly.

[0014] In a specific embodiment of the transformer principle described above, multiple receiving coils with periodic geometries (particularly sine and cosine geometries) are used, arranged in a phase-shifted manner relative to each other. The signals received by these coils can be correlated, enabling fine detection of relative positions through phase-based interpolation. This method, in a manner similar to vernier or interpolation principles, significantly improves position determination within a geometrical grid, thereby contributing to enhanced sensor measurement accuracy and resolution.

[0015] In the further development of the specified eddy current sensor, the correction mating element is a reflector and is configured to generate an electromagnetically induced magnetic field opposite in direction to the electromagnetic induction field of the first eddy current sensor mating element. In this way, the correction mating element can be integrated into existing sensor systems without additional electrical actuation or signal processing, thereby reducing space requirements, especially in applications with limited installation space or integration constraints. Since no dedicated power supply lines or signal connections are required, a compact and mechanically robust sensor unit can be achieved, where the lateral displacement correction function is implemented entirely through structural means.

[0016] In a preferred further development of the specified eddy current sensor, the excitation coil is designed as a flat coil extending within a coil plane defined by the direction of movement. This achieves high sensitivity to distance changes perpendicular to the coil plane, thereby enabling, in particular, high-resolution detection of the reflector's relative movement laterally to the direction of movement. Furthermore, the flat design allows for space-saving integration within a compact sensor arrangement. Moreover, the two-dimensional structure of the flat coil allows for easy scaling to multi-channel systems, for example, by arranging multiple flat coils adjacent to each other or in a differential configuration, thereby further improving the detection and compensation of lateral displacement.

[0017] In a further development of a particularly preferred eddy current sensor, the coil plane is oriented perpendicular to the imaginary connecting line between the first eddy current sensor mating component and the correction mating component. This achieves a clear geometric separation between the sensor's primary detection direction and the relative position of the field-effect elements, allowing for the unique differentiation of lateral displacements and enabling structural correction. Furthermore, mutual interference between fields is minimized, improving signal quality and simplifying evaluation. This orthogonal arrangement also supports compact and calibrable integration of all sensor components, offering high measurement accuracy and stability, particularly in mechanically demanding environments.

[0018] In further development of the specified eddy current sensor, the second eddy current sensor assembly divides the space into a first half-space and a second half-space opposite to the first half-space, wherein the first eddy current sensor assembly is disposed in the first half-space and the calibration assembly is disposed in the second half-space. In this way, a symmetrical sensor architecture is constructed, in which the second eddy current sensor assembly serves as a central reference point, while field influencing elements are arranged on either side of it in a defined geometry. This design enables differential evaluation, where the relative movement of the first eddy current sensor assembly and the calibration assembly has opposite effects on the measured quantity, thereby particularly enabling the detection or compensation of lateral deviations or asymmetric effects. This improvement is particularly effective when the second eddy current sensor assembly is an excitation coil extending in a coil plane defined by the direction of movement and arranged perpendicular to the connecting line between the first eddy current sensor assembly and the calibration assembly, both of which are formed as reflectors. In this configuration, the attenuation effect of the calibration assembly cancels out the asymmetry of the field coupling of the first eddy current sensor assembly caused by lateral displacement, thereby structurally suppressing lateral errors without requiring evaluation by an evaluation circuit.

[0019] In a further development of the specified eddy current sensor, the first eddy current sensor mating element is arranged in a first half-space, and the correction mating element is arranged in the same position relative to the direction of movement. This increases the symmetry of the field-influencing elements relative to the direction of movement, thereby further reducing the influence of lateral displacement on the electromagnetic measurement field. Since the reflector and correction mating element are aligned along the direction of movement, lateral deviations affect their respective field couplings in approximately opposite ways, allowing lateral errors to be identified more clearly and their effects reduced through proper evaluation. Therefore, this development represents an improvement on the concept of structural lateral displacement compensation and enhances the robustness of position evaluation with respect to lateral tolerances or bending effects.

[0020] In the further development of the specified eddy current sensor, the first eddy current sensor mating component and the correction mating component in the first half-space have the same design. In this way, the field symmetry is further improved at the structural level, allowing lateral displacement to be largely or completely eliminated from the sensor signal through appropriate arrangement, particularly by utilizing the symmetrical distances of the two mating components from the excitation coil. The identical design results in lateral movement producing interference effects of opposite direction and equal magnitude on the field effect, thus canceling each other out in differential evaluation. Therefore, even in systems with significant mechanical compliance or high thermal loads, the relative position in the direction of movement can be detected with particularly high accuracy and robust anti-interference capabilities.

[0021] According to another aspect of the invention, a tie rod sensor for detecting the position of a vehicle's tie rod in a lateral direction perpendicular to the direction of travel includes one designated eddy current sensor, wherein one eddy current sensor assembly is fixedly connected to the vehicle's chassis, and the other eddy current sensor assembly is fixedly connected to the vehicle's tie rod.

[0022] The specified tie rod sensor is based on the consideration that direct position measurement at the tie rod is particularly sensitive to tolerances and dynamic deformation, such as deformation caused by bending loads during vehicle steering. This lateral deformation causes undesirable changes in the distance between the sensor mating parts, which can lead to a significant loss of accuracy in traditional sensor systems based on a single target. Furthermore, known solutions typically require integrating space-consuming sensor units (“sensor towers”) onto the tie rod or indirectly determining the steering angle via other components such as the steering wheel, which increases cost and complexity.

[0023] The specified tie rod sensor addresses this problem by using two eddy current sensor mating components with a defined geometric relationship, between which the excitation element is centrally located. Due to this symmetrical arrangement, the lateral displacement of the tie rod caused by bending affects the two field-influencing elements in the same direction but in opposite ways, allowing interference effects to compensate for each other with proper evaluation. The sensor configuration according to the invention is designed to robustly and reliably detect the relative lateral position of the tie rod even in the presence of mechanical deformation in the system.

[0024] This approach allows for direct detection of wheel steering angle at the tie rod, eliminating the need for complex or expensive steering angle sensor systems on the steering wheel. Integration with the chassis and / or tie rods can be achieved in a space-saving manner, and no movable cable connections are required. This, in addition to reducing manufacturing costs, improves robustness against environmental influences such as vibration, temperature, or contamination. Omitting separate sensor components elsewhere in the vehicle simplifies the system architecture and opens up new possibilities for modular steering systems, particularly in applications employing steer-by-wire technology.

[0025] In the further development of the specified lever sensor, the electromagnetic source field has a magnetic flux density, and its equivalent current direction vector is set in a plane radially oriented relative to the direction of movement.

[0026] According to another aspect of the present invention, a method for detecting relative position in a direction of movement by means of one of a specified eddy current sensors includes the following steps: generating an electromagnetic source field using one of the eddy current sensor mating components; generating an electromagnetic measurement field, the electromagnetic measurement field including an electromagnetic induction field generated by another eddy current sensor mating component based on the electromagnetic source field; generating an electromagnetic correction field using a correction mating component for correcting lateral displacement between the eddy current sensor mating components in the direction of travel transverse to the direction of movement; and determining the relative position based on the electromagnetic measurement field and the electromagnetic correction field.

[0027] The specified method is based on the consideration that the evaluation of electromagnetic measurement fields formed solely by electromagnetic induction (common in traditional eddy current sensor methods with only one reflector) is particularly susceptible to interference caused by lateral movement, temperature fluctuations, and mechanical deformation. Especially in mechanically flexible structures, such as those created by the weight of a vehicle at the vehicle's tie rod, changes in position perpendicular to the actual measurement direction can significantly affect sensor accuracy and lead to erroneous position signals.

[0028] The specified method addresses this problem by generating an additional correction field that can be specifically used to differentiate between relative position and lateral displacement. The correction field is generated by a correction mating element arranged in a defined geometric relationship with one of the mating elements of the eddy current sensor, enabling the generation of a measurement signal that exhibits a characteristic response to lateral deviations. Through joint evaluation of the damping excitation field and the correction field, the relative position in the direction of movement can be determined with greater accuracy because the disturbance effects acting laterally in the direction of movement can be systematically suppressed and clearly identified and compensated for.

[0029] In this way, a robust, adaptive, and evaluable measurement method is obtained, which can also be used under harsh environmental conditions. Integrating the correction field into the method logic also enables evaluation using a simplified physical model, as the structural redundancy is used to make undesirable effects geometrically and technically separable. Therefore, this method is particularly suitable for safety-related applications requiring high accuracy, fault tolerance, and compact design.

[0030] According to another aspect of the invention, the control device is configured to perform one of the specified methods.

[0031] In further development of the specified device, the specified device includes memory and a processor. The specified method is stored in memory as a computer program, and the processor is configured to execute the method when the computer program is loaded from memory into the processor.

[0032] According to another aspect of the invention, a computer program includes program code means for performing all steps of a specified method when the computer program is executed on one of the electronic devices or specified devices.

[0033] According to another aspect of the present invention, a computer program product includes program code stored on a computer-readable medium, which, when executed on a data processing device, performs a specified method. Attached Figure Description

[0034] The features, characteristics, advantages, and implementations of the present invention described above become more apparent from the following description of exemplary embodiments, which are explained in more detail with reference to the accompanying drawings. The drawings show: Figure 1 A schematic diagram of the vehicle dynamics control system is shown. Figure 2 It shows Figure 1 A perspective view of the vehicle in the middle; Figure 3a It shows Figure 2 A schematic diagram of a conventional eddy current sensor at the tie rod of the vehicle shown. Figure 3b This illustrates a first-person view of the eddy current sensor according to the invention. Figure 2 A schematic diagram of the tie rod of the vehicle shown; and Figure 3c Showing a second-person perspective Figure 3a and 3b A schematic diagram of an eddy current sensor.

[0035] In the accompanying drawings, the same technical elements have the same reference numerals and are described only once. These drawings are purely schematic and do not represent actual geometric scales in particular. Detailed Implementation

[0036] Reference Figure 1 A schematic diagram of vehicle 2 with a basically known vehicle dynamics control system is shown. Details of this vehicle dynamics control system can be found in DE102011080789 A1.

[0037] Vehicle 2 is movable in the direction of travel 3 and includes a chassis 4, also known as a frame, which is movably supported in the direction of travel 3 by two front wheels 5 and two rear wheels 6. Each wheel 5, 6 can be braked by a brake (explained later) which is fixedly mounted on the chassis 4 to slow the movement of vehicle 2 on a road not shown in the figure.

[0038] The direction of travel 3 of vehicle 2 during its movement can be determined by the driver of vehicle 2 by turning the steering wheel 7 (at...). Figure 1(Symbolically shown in the image) The steering wheel 7 is turned to the steering angle 8 for control. The steering wheel 7 then controls the steering gear 9 based on the steering angle 8, which sets the wheel steering angle 10 of the front wheels 5 according to the steering angle 8. Based on the time-varying steering angle 8, the vehicle 2 travels along a road trajectory defined by the driver.

[0039] During the movement of vehicle 2, wheels 5 and 6 may detach from the road and deviate from the trajectory specified by the driver in a manner known to those skilled in the art. To avoid this behavior, vehicle 2 is equipped with the vehicle dynamics control system mentioned in the opening section.

[0040] The vehicle dynamics control system includes the aforementioned brakes at points 5 and 6 on each wheel (in Figure 1 (Referring to the figure 11) and wheel speed sensor 12. Wheel speed sensor 12 measures the wheel speed 13 of each wheel and transmits it to control unit 14. Control unit 14 also receives inertial data 16 from inertial sensor 18, such as the yaw rate of vehicle 2, and calculates the actual driving direction from it. Then, control unit 14 checks whether the determined driving direction corresponds to the steering angle 8 specified by the driver or to the wheel steering angle 10. In case of deviation, control unit 14 outputs control signal 20 to actuator 22, actuator 22 individually actuates brake 11 using appropriate actuator signal 24 to correct the vehicle's driving direction 3.

[0041] In such control systems, the steering angle 8 is typically used as a measure of the driver-specified driving direction 3. However, in modern vehicle systems with active steering systems, variable steering ratios, or mechanical compliance in the steering system, significant deviations may occur between the steering angle 8 and the actual wheel steering angle 10 set on the wheels 5. Therefore, in safety-critical or highly automated applications, it is necessary to directly detect the wheel steering angle 10 and incorporate it as a relevant control variable into the vehicle dynamics control system. Only in this way can it be ensured that the actual response of the vehicle 2 conforms to the driver's intention or system commands, and that targeted corrections can be made when deviations occur.

[0042] Reference Figure 2 The diagram illustrates the steering mechanism in vehicle 2. To avoid unnecessarily complicating the following explanation, many technical components, such as active steering elements, have been omitted. For detailed information on understanding the steering mechanism, please refer to, for example, DE102005007307A1.

[0043] When the driver turns the steering wheel 7 to the steering angle 8, the steering wheel 7 causes the steering column 26 to rotate around the rotation axis 28, which in turn moves the tie rod 30 to steer the front wheels. The rotation angle of the steering column 26 around the rotation axis 28 corresponds to the steering angle 8, so the steering angle 8 of the steering wheel 7 can be determined by measuring the rotation angle of the steering column 26.

[0044] The tie rod 30 is mechanically connected to the front wheel 5 and converts the rotational motion of the steering column 26 into translational motion, thereby changing the wheel steering angle 10 of the front wheel 5. Therefore, the actual steering angle 10 of the front wheel 5 directly depends on the instantaneous position of the tie rod 30 relative to the chassis 4 of the vehicle 2. This position describes the lateral displacement of the tie rod 30 in the lateral direction 31 perpendicular to the direction of travel 3, and has a fixed geometric relationship with the wheel steering angle 10.

[0045] Based on this relationship, the wheel steering angle 10 can be determined by detecting the relative position 32 of the tie rod 30 relative to the chassis 4. For this purpose, a position sensor 33 is used, which will be discussed in more detail later. Given the known kinematics of the components of the steering system of vehicle 2, the currently applied wheel steering angle 10 can be calculated precisely or derived directly from the relative position 32. This method enables highly accurate and direct detection of the wheel steering angle 10, independent of mechanical tolerances, clearances, or variable steering ratios. A prerequisite for achieving this goal is that the detection of the wheel steering angle 10 must be highly accurate.

[0046] To detect the relative position 32 mentioned above, a position sensor 33 in the form of an eddy current sensor is typically used. These conventional eddy current sensors, such as… Figure 3a As shown, and to distinguish examples of eddy current sensors according to the invention, they are indicated by reference numeral 33′.

[0047] Traditional eddy current sensors include a first eddy current sensor assembly in the form of an excitation coil 34, which will be referred to later. Figure 3a To discuss this in more detail, the excitation coil 34 is arranged on a printed circuit board 35. The printed circuit board 35 is typically fixedly mounted on the vehicle chassis 4, and in addition to the excitation coil 34, it also includes necessary evaluation circuitry 36 to convert the sensor signal (described later) into a relative position 32 to be determined. Furthermore, the conventional eddy current sensor 33' includes a second eddy current sensor mating element, which is movably arranged relative to the excitation coil 34 and thus relative to the evaluation circuitry 36 on the pull rod 30 in the form of a conductive measuring reflector 37, also referred to in technical terms as a target, such that the measuring reflector 37 can be positioned relative to the excitation coil on the printed circuit board 35 at the relative position 32 to be detected.

[0048] During operation, the excitation coil 34 on the printed circuit board 35 is supplied with high-frequency alternating current by the evaluation circuit 36, thereby generating an electromagnetic source field 38. This electromagnetic source field 38 extends over the space into which the measuring reflector 37 enters. If the measuring reflector 37 is within the range of this electromagnetic source field 38, eddy currents are induced therein due to its conductivity. These eddy currents then generate an electromagnetic induction field (not further mentioned in FIG. 3a), which is opposite to the electromagnetic source field 38. This electromagnetic induction field carries information about the relative position 32 to be determined, which can be extracted from the electromagnetic induction field in various ways.

[0049] One extraction method is to directly detect the feedback effect of the measuring reflector 37 on the excitation coil 34. This measurement principle is called the damping principle. In this case, the feedback effect, dependent on the relative position, causes the electromagnetic source field 38 to be weakened by the electromagnetic induction field in the region of the excitation coil 34, thereby manifesting the relative position 32 as a change in the electrical characteristics of the excitation coil. Therefore, the relative position 32 can be detected, for example, based on changes in the impedance, alternating current (AC) resistance, or phase of the excitation coil 34. In the damping principle, the electromagnetic source field 38 and the electromagnetic measurement field cannot be observed separately; the electromagnetic measurement field carries information about the relative position 32 to be determined based on the electromagnetic induction field.

[0050] Another feasible method for extracting the relative position 32 to be determined is to detect the feedback effect of the measuring reflector 37 by at least one receiving coil (not further shown in the figure). This measurement principle is known as the transformer principle. In this case, the electromagnetic induction field originating from the measuring reflector 37 and depending on the relative position 32 will induce a voltage in at least one receiving coil. The relative position 32 can then be determined based on the characteristic properties of the induced voltage, such as its amplitude, phase, or frequency response. When multiple receiving coils are used, these coils should be rationally arranged with a defined phase-shift geometry, such as a sine and cosine configuration relative to each other. By performing phase-based interpolation on the signals obtained from these phase-shift receiving coils, the relative position 32 can be determined at high resolution within the geometric grid according to the vernier principle, for example, by a vernier algorithm, which enables particularly accurate and fine detection of the relative position 32. Since, in the transformer principle, the electromagnetic source field 38 and the electromagnetic measurement field carrying information about the relative position 32 to be determined, based on the electromagnetic induction field, act at different locations in the sensor, these two fields can be observed separately.

[0051] In a manner known per se, the electromagnetic source field 38 can be described by its magnetic field lines B (not further mentioned in Figure 3a), or by curl. Described by ×B, this curl characterizes the local vortex structure, thus representing the distribution of the field in space. To describe the orientation and position of the excitation coil 34 independently of its specific geometric configuration (e.g., flat coil, rod coil, or other winding form), a so-called equivalent current direction vector is introduced. Figure 3a The equivalent current direction vector 39 is indicated by reference numeral 39 in the attached figure. This vector specifies the direction in which the current must flow in order to generate a locally present electromagnetic source field 38 through an ideal current-carrying winding. Formally, it is generated by the curl of the electromagnetic source field 38 according to Ampere's law, which states that... ×B is a measure of the local current density J that generates the electromagnetic source field 38. In the case shown, the equivalent current direction vector 39 corresponds to the direction of the excitation current flowing through the excitation coil 34 (not further mentioned). Although the electromagnetic source field 38 itself extends concentrically around this current flow, the equivalent current direction vector 39 indicates the potential current flow direction, thus enabling a systematic description of the position and orientation of the excitation coil 34 in space.

[0052] According to Figure 3a In the electromagnetic source field 38, the printed circuit board 35 is arranged such that the equivalent current direction vector 39 of the excitation coil 34 lies within a local tangential plane relative to the movement path of the pull rod 30. This plane is crossed by the line connecting the pivot points of the front wheels 5 in the mounted state of the vehicle 2, or in other words, by the longitudinal direction (i.e., the lateral direction 31 here) of the pull rod 30 and the circumferential direction of the line connecting the pivot points of the front wheels 5. Through this orientation of the equivalent current direction vector 39, Figure 3a The excitation coil 34 is positioned such that the electromagnetic source field 38 at the center of the excitation coil 34 is perpendicular to the pull rod 30.

[0053] The evaluation circuit on the printed circuit board 35 detects changes in impedance based on the aforementioned damping principle or transformer principle, and thereby determines the relative position 32 of the reflector 37 relative to the excitation coil 34. An evaluation circuit employing a vernier principle to implement the transformer principle can be found in DE102022117762A1. Due to this physical coupling, the relative movement of the pull rod 30 relative to the chassis 4, and the resulting wheel steering angle 10, can be detected by a conventional eddy current sensor 33′.

[0054] However, in practice, problems arise when using a conventional eddy current sensor 33' at the tie rod 30. Because the tie rod 30 is subjected to mechanical loads during operation—primarily due to loads from the chassis 4—it undergoes elastic deformation. This deformation particularly causes bending in the area between the support points of the tie rod 30, resulting in a slight offset in the position of the measuring reflector 37, but in a measurement-related manner, primarily in the lateral direction 31 and lateral to the driving direction 3, and not further mentioned in the height direction of the vehicle 2.

[0055] This lateral displacement of the measuring reflector 37 causes a change in the distance between the measuring reflector 37 and the excitation coil 34. This change is not due to the actual relative movement of the pull rod 30 in the lateral direction 31, but rather to the lateral displacement caused by the aforementioned bending. Therefore, the electromagnetic measuring field carrying the relative position 32 to be detected is affected asymmetrically, which may lead to impedance measurement distortion and thus measurement error in the determined relative position 32. As a result, the detected wheel steering angle 10 is incorrect, even though the pull rod 30 has not changed in the direction of movement.

[0056] This influence is in reference Figure 1 This is particularly critical in safety-related vehicle dynamics control systems, where even small measurement errors can lead to incorrect intervention or inaccurate vehicle guidance. Therefore, according to the position sensor 33 of the present invention, an eddy current sensor is proposed that can detect, correct, or prevent such lateral displacement in an electromagnetic measurement field. The following will refer to... Figure 3b and 3c This needs to be explained.

[0057] To avoid the aforementioned lateral displacement error, the position sensor 33 according to the invention includes an additional correction fitting, which is formed as another reflector, hereinafter referred to as the correction reflector 40. The correction reflector 40 is arranged on the pull rod 30 at a fixed position relative to the measuring reflector 37, and enters the electromagnetic source field 38 in the same manner as the measuring reflector 37 in the direction of movement 31, and generates a similar electromagnetic induction field opposite to that of the measuring reflector 37 through the same induced eddy currents.

[0058] The fixed arrangement of the correction reflector 40 relative to the measuring reflector 37 creates a structural relationship that allows for the differentiation between lateral movement of the excitation coil 34 in the travel direction 3 and relative movement in the lateral direction 31. If the excitation coil 34 moves due to lateral displacement caused by bending, its distance from the reflectors 37 and 40 changes in a specific manner. Since the relative geometry of the reflectors relative to each other is constant, conclusions about the actual cause of the field change can be drawn from the different effects of the electromagnetic source field 38 on the two reflectors. In particular, it can be identified whether this change is due to expected movement in the lateral direction 31 or undesirable lateral movement in the travel direction 3. This leads to the separation of the measured variables, thus laying the foundation for reliable compensation or error detection.

[0059] This idea should not be understood as limited to providing two reflectors 37, 40. The key lies in integrating an additional correction fitting into the electromagnetic source field 38, which is positioned at a predetermined distance relative to one of the two eddy current sensor fittings 34, 37 (i.e., relative to the excitation coil 34 or the measuring reflector 37). This defined geometric coupling ensures that lateral displacement of the other eddy current sensor fitting 37, 34, particularly in the travel direction 3, results in specific changes in the field distribution, which can be detected and / or suppressed through appropriate evaluation.

[0060] The calibration mating element can be implemented as a calibration reflector 40, or as an additional excitation coil or any element with electromagnetic effects. The decisive factor is solely its fixed relationship with one of the eddy current sensor mating elements 34, 37, forming a structural reference based on which changes in the field effect caused by lateral movement can be clearly identified or compensated. Therefore, this invention makes the design of the eddy current sensor-type position sensor 33 universal and flexible, allowing for adjustments in mechanics and signal processing according to requirements and installation conditions.

[0061] In this embodiment, two reflectors 37 and 40 are positioned at the same location 41 on the pull rod 30 in the lateral direction 31. Unlike a conventional eddy current sensor 33', where the printed circuit board 35 with the excitation coil 34 is positioned in the tangential plane relative to the pull rod 30, the reflector 37 and 40 are positioned according to the eddy current sensor 33'. Figure 3bIn this embodiment, the printed circuit board 35 with the excitation coil is now positioned in a radial plane relative to the pull rod 30. The radial plane is the plane crossed by the line connecting the pivot points of the front wheels 5 in the mounted state of the vehicle 2, or in other words, the plane crossed by the longitudinal direction of the pull rod 30 (i.e., the lateral direction 31 here) and the radial direction away from the pivot point of the front wheels 5. In short, in a conventional eddy current sensor 33', the printed circuit board 35 with the excitation coil 34 is tangentially oriented to the pull rod 30, while in the position sensor 33 according to the invention, the printed circuit board 35 with the excitation coil 34 is radially oriented to the pull rod 30.

[0062] In the position sensor 33 according to the invention, the equivalent current direction vector 39 of the excitation coil 34 thus extends in the radial plane, meaning that the magnetic field line B at the center of the excitation coil 34 is now tangentially oriented with the pull rod 30. In this embodiment, two reflectors 37 and 40 are arranged on opposite sides of the printed circuit board 35 at equal reflector distances 42. They are substantially identical in material and geometry, and their symmetrical arrangement contributes to the symmetry of the field and the stability of the measurement.

[0063] When the pull rod 30 undergoes lateral displacement, for example due to the elastic bending under the driving load described above, the distance 42 between the two reflectors 37 and 40 and the excitation coil 34 will not change in the same direction, but in opposite directions. Since the reflectors 37 and 40 are arranged at the same position 41 in the lateral direction 31, have the same design, and are positioned on opposite sides of the printed circuit board 35 perpendicular to the pull rod 30 with equal reflector distance 42, the lateral movement of the pull rod 30 perpendicular to the lateral direction 31 affects the electromagnetic coupling of the reflectors 37 and 40 with the excitation coil 34 in an opposite manner.

[0064] If the measuring reflector 37 moves closer to the excitation coil 34 due to the deformation of the pull rod, the correcting reflector 40 will move away from the excitation coil 34 by the same amount, and vice versa. Both reflectors 37 and 40 generate electromagnetic induction fields according to their positions in the region of the source field 38, wherein the electromagnetic induction field generated by the correcting reflector 40 is in the opposite direction to the electromagnetic induction field generated by the measuring reflector 37.

[0065] Due to this relative arrangement, the following structured self-compensation is achieved: the change in the induced field caused by lateral movement acts on the formed electromagnetic measurement field in a mutually compensating manner. The electromagnetic measurement field corrected in this way can then be evaluated using one of the known eddy current measurement principles, either by detecting the impedance change of the excitation coil (damping principle) or by the voltage induced in the receiving coil by the electromagnetic measurement field (transformer principle), in order to determine the relative position in the lateral direction 31 for lateral displacement correction.

[0066] Therefore, no separate differential signal processing or further modification of the evaluation circuit 36 ​​of the conventional eddy current sensor 33' is required to achieve this purpose.

[0067] List of reference numerals 2 vehicles 3. Direction of travel 4. Chassis (frame) 5. Front wheels 6 rear wheels 7. Steering wheel 8. Steering angle 9. Steering gear 10 Wheel steering angle 11. Brake 12 Wheel speed sensors 13 Wheel speed 14 Control Unit 16 Inertial Data 18 Inertial Sensors 20 Control Signals 22 Actuators 24 Actuator Signals 26 Steering column 28. Rotation axis of the steering column 30 Tie rod (steering rod) 31 Lateral direction (perpendicular to the direction of travel) 32 Relative Position 33 Position sensor (eddy current sensor according to the present invention) 33′ Traditional eddy current sensor 34 Excitation Coils 35 Printed Circuit Boards 36 Evaluation Circuit 37 Measuring reflector 38 Electromagnetic Source Field 39. Equivalent current direction vector ( ×B) 40 Correcting the reflector 41. Position of the reflector in the lateral direction 42. Distance between the reflector and the excitation coil

Claims

1. An eddy current sensor (33) for detecting relative position (32) in a direction of movement, the eddy current sensor (33) comprising: - A first eddy current sensor mating part (34, 37) and a second eddy current sensor mating part (37, 34), the second eddy current sensor mating part (37, 34) being locating relative to the first eddy current sensor mating part at the relative position (32) to be detected. - Wherein, the eddy current sensor assembly is configured to generate an electromagnetic measurement field based on the relative position; and - Evaluation circuit (36), which is configured to determine the relative position (32) based on the electromagnetic measurement field. -In this configuration, one of the eddy current sensor fittings (34, 37) is configured to generate the electromagnetic measurement field, and the other eddy current sensor fitting (37, 34) is configured to generate an electromagnetic induction field based on the electromagnetic measurement field. - wherein the eddy current sensor assembly that generates the electromagnetic induction field has a smaller range in the lateral direction perpendicular to the direction of movement and perpendicular to the distance between the eddy current sensor assemblies than the eddy current sensor assembly that generates the electromagnetic measurement field. Its features are, - A correction fitting (40) is positioned at a fixed position at a predetermined distance relative to the first eddy current sensor fitting to generate an electromagnetic correction field to correct the lateral displacement between the eddy current sensor fittings in the direction of movement (31).

2. The eddy current sensor according to claim 1, wherein, The first eddy current sensor assembly includes a reflector (37), and the second eddy current sensor assembly includes an excitation coil (34) for generating an electromagnetic source field (38), wherein the reflector (37) is configured to generate an electromagnetic induction field contained in the electromagnetic measurement field based on the electromagnetic source field (38).

3. The eddy current sensor according to claim 2, wherein, The correction fitting is a reflector (40) and is configured to generate an electromagnetic induction magnetic field opposite in direction to the electromagnetic induction field of the first eddy current sensor fitting (37).

4. The eddy current sensor according to claim 2, wherein, The excitation coil (34) is designed as a flat coil extending in a coil plane defined by the direction of movement, wherein the coil plane is preferably perpendicular to the imaginary connecting line between the first eddy current sensor mating member (37) and the correction mating member (40).

5. The eddy current sensor according to claim 1, wherein, The second eddy current sensor assembly divides the space into a first half-space and a second half-space opposite to the first half-space, wherein the first eddy current sensor assembly (37) is disposed in the first half-space and the correction assembly (40) is disposed in the second half-space. Preferably, when viewed from the direction of movement or / or a direction transverse to the direction of movement, the first eddy current sensor assembly (37) and the correction assembly (40) are located at the same position (41).

6. The eddy current sensor according to claim 5, wherein, The first eddy current sensor fitting (37) and the correction fitting (40) in the first half-space have the same design.

7. A lever sensor for detecting the position of a lever (30) of a vehicle (2) in a lateral direction (31) perpendicular to the direction of travel (3), comprising an eddy current sensor (33) according to any one of claims 1 to 6, wherein, One eddy current sensor assembly can be fixedly connected to the chassis (4) of the vehicle (2), and the other eddy current sensor assembly can be fixedly connected to the tie rod (30) of the vehicle.

8. The lever sensor according to claim 7, wherein, The electromagnetic source field (38) has a magnetic flux density, and the equivalent current direction vector (39) of the magnetic flux density is arranged in a plane radially oriented relative to the moving direction (31).

9. A method for detecting relative position (32) in a direction of movement using an eddy current sensor (33) according to any one of claims 1 to 6, comprising: - An electromagnetic source field (38) is generated using one of the eddy current sensor fittings (34, 37). - Generate an electromagnetic measurement field, which includes an electromagnetic induction field generated based on the electromagnetic source field (38) using another eddy current sensor assembly (37, 34); Its features are, - An electromagnetic correction field is generated using the correction fitting (40) to correct the lateral displacement between the eddy current sensor fittings in the travel direction (3) transverse to the moving direction (31); and - Determine the relative position (32) based on the electromagnetic measurement field and the electromagnetic correction field.

10. A control device for performing the method according to claim 9.

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