INDUCTIVE POSITION DETERMINATION SYSTEM WITH VARIING COIL GEOMETRY AND CORRESPONDING METHOD FOR POSITION DETERMINATION

Abstract

The present disclosure relates to an inductive position determination system (100) with a planar excitation coil (130) and a first and second planar receiving coil arrangement (110, 120) arranged within the planar excitation coil (130), and a target (140) movable relative to the first and second planar receiving coil arrangement (110, 120), wherein the first receiving coil arrangement (110) and the second receiving coil arrangement (120) each generate a first and second output signal dependent on the position of the target (140), and wherein the lateral width extent (180) of the first and second planar receiving coil arrangement (110, 120) each varies along the movement path of the target (140).

Description

[0001] The innovative concept described here concerns inductively measuring linear position and rotation angle sensors.

[0002] In many modern applications, it is necessary to detect the absolute position of a linearly or rotationally moving object. While small motion ranges can be covered by magnetic sensor systems consisting, for example, of a linear Hall sensor and a simple dipole permanent magnet, larger motion ranges can only be achieved using encoder tracks (multipole strip magnets), which leads to a significant increase in cost.

[0003] A typical automotive application requiring a large range of motion is steering and rack position detection. Typical motion ranges here are up to 300 mm. Inductive sensors are particularly suitable for this.

[0004] Conventional position or angle detection systems based on inductive sensors are implemented according to the vernier principle (two tracks with N and N+1 periods, and two sensors). Each sensor provides a relative angle with N or N+1 periods. The absolute angle or position is determined by subtracting the two angles.

[0005] The detectable linear range is high, but the system is complex, requiring at least one excitation coil and four receiver coils (sin / cos with N and N+1 periods), plus (typically) two sensors. In the layout, the four receiver coils cannot simply be distributed across two layers. Instead, they must be arranged side by side, which significantly increases the required board space. Alternatively, a four-layer PCB can be used instead of a two-layer PCB. In this case, the two receiver coil traces are implemented on separate layers, resulting in a smaller package. Both variants (side-by-side or four-layer PCB) increase costs.

[0006] Alternatively, a solution with only one receive coil signal period can be used. However, this solution has significantly lower accuracy due to high signal deviations caused by edge effects of the receive coils.

[0007] It would therefore be desirable to improve existing inductive positioning systems so that they can be manufactured in a space-saving and cost-effective manner, while at the same time providing high resolution and accuracy.

[0008] This goal is achieved with an inductive positioning system and a corresponding method for determining a position using such an inductive positioning system according to the independent claims. Further embodiments and advantageous aspects of the positioning system and the corresponding method are recited in the respective dependent claims.

[0009] The inductive positioning system described herein includes, among other things, a planar excitation coil and a first and second planar receiving coil arrangement arranged within the planar excitation coil. The positioning system further includes a target movable relative to the first and second planar receiving coil arrangements. The first receiving coil arrangement and the second receiving coil arrangement each generate a first and second output signal dependent on the position of the target. According to the innovative concept presented here, the lateral extent of the first and second planar receiving coil arrangements varies along the movement path of the target.

[0010] The innovative method for position determination presented here using such an inductive positioning system provides, among other things, that a first and a second planar receiving coil arrangement and a target movable relative to the first and second planar receiving coil arrangement are provided. The innovative concept provides that the lateral extent of the first and second planar receiving coil arrangements each vary along a movement path of the target. The method also includes detecting a first and a second output signal, which the first and second receiving coil arrangements each generate depending on the position of the target.The method further includes combining the first and second output signals to obtain a vector, wherein the rotation angle of the vector provides an ambiguous position indication of the target, and wherein the length of the vector describes the signal amplitude of the two combined output signals, which is dependent on the actual position of the target. Finally, an unambiguous position of the target is determined based on the rotation angle and the length of the vector.

[0011] Some exemplary embodiments are shown in the drawing and explained below. They show: Fig. 1 a schematic plan view of a conventional inductive linear position sensor to explain the general operating principle, Fig. 2 a schematic plan view of an inductive single-track positioning system according to an embodiment, Fig. 3A is a schematic diagram showing the output signals associated with the positioning system of Fig. 2 can be generated, Fig. 3B is a schematic diagram showing the signal generated from the two output signals from Fig. 3A calculated relative angle including the corresponding vector length, Fig. 3C is a schematic diagram showing Fig. 3B in polar coordinates, and Fig. 3D schematic diagram showing the angular error of the positioning system.

[0012] In the following, embodiments are described in more detail with reference to the figures, wherein elements with the same or similar function are provided with the same reference numerals.

[0013] Method steps depicted or described within the scope of the present disclosure may also be performed in a different order than that depicted or described. Furthermore, method steps relating to a specific feature of a device are interchangeable with that same feature of the device, and the same applies vice versa.

[0014] The inductive positioning system described here is described below using a linear displacement sensor as an example. However, the principles also apply to rotation angle sensors for determining a rotation angle.

[0015] In addition, exemplary embodiments are described below in which the positioning system has two receiving coil arrangements that are phase-shifted (e.g., by 90°) from one another. These examples are 2-phase systems. However, 3-phase systems are also conceivable, in which three receiving coil arrangements that are phase-shifted (e.g., by 60° each) would be provided.

[0016] Fig. 1 first shows a conventional inductive positioning system 10, on the basis of which the general functional principle of inductive positioning will be explained in general terms in advance, before the details of the present innovative concept are discussed in more detail.

[0017] The Fig. The position-determining system 10 shown in Figure 1 comprises a planar excitation coil 11 and two planar receiving coil arrangements 12, 13. An inductive target 14 moves along the extension direction of the coils 11, 12, 13. The actual position of the target 14 is to be determined by means of the position-determining system 10.

[0018] For this purpose, the excitation coil 11 is first applied with an alternating current signal, which induces an induced current in the target 14. The target 14, in turn, generates an induced current in the receiving coil assemblies 12, 13, which then each generate a corresponding output signal. The first receiving coil assembly 11 generates a first output signal, and the second receiving coil assembly 12 generates a second output signal. The amplitude of the respective output signal depends on the actual position of the target 14 relative to the two receiving coils 12, 13.

[0019] The two receiving coils 11, 12 are designed to be sinusoidal and cosinusoidal, respectively, resulting in a sinusoidal and cosinusoidal signal waveform for the corresponding output signals. The two output signals are combined, e.g., using an arctangent calculation, to obtain a unique value that represents the actual position of the target 14.

[0020] This unique value results from the fact that the receiving coil arrangements 12, 13 exhibit exactly one period, i.e., one full oscillation, over the entire travel path of the target 14. Thus, at each actual position of the target 14, exactly one unique combined signal value, e.g., an arctangent value, results.

[0021] However, the Fig. The positioning system 10 shown in Figure 1 has a very coarse resolution and thus very low accuracy due to the single period. Due to edge effects, a very large signal offset also occurs, which further degrades the signal quality.

[0022] However, many modern technical applications require high to very high resolution or accuracy in position determination. This is achieved, among other things, by increasing the number of periods of the receiving coil arrangements 12, 13. This allows the determined actual position to be determined with higher resolution, i.e., in smaller steps.

[0023] However, increasing the number of periods inevitably leads to ambiguities, since the individual periods each deliver the same signal values ​​at the corresponding points. This means that after each pass of a full period, the signal values ​​repeat with the pass of the following period.

[0024] Several approaches are conceivable for resolving these ambiguities. For example, the so-called vernier principle, which is also known from mechanical calipers, can be applied. However, this would require two additional receiving coil arrangements with a different number of periods (than the previous two receiving coil arrangements) as well as two sensors, which in turn complicates the design of the position determination system 10 and thus increases production costs. For a three-phase system, a total of six receiving coil arrangements would be required.

[0025] The innovative concept described herein provides a solution to the aforementioned problems. It proposes a positioning system that requires only two (for a 2-phase system) or three (for a 3-phase system) receiving coil arrangements and a single sensor. This allows for cost-effective production. At the same time, an innovative method for resolving the aforementioned ambiguities is proposed, thereby increasing the resolution and accuracy of positioning.

[0026] Fig. 2 shows a conceivable embodiment of an innovative positioning system 100. The positioning system 100 has a planar excitation coil 130. The positioning system 100 also has a first planar receiving coil arrangement 110 arranged within the planar excitation coil 130 and a second planar receiving coil arrangement 120 arranged within the planar excitation coil 130.

[0027] Planar means that the respective coils 110, 120, 130 are flat and arranged within a plane. Fig. This is illustrated schematically in Figure 2 using a two-dimensional coordinate system with an x-axis and a y-axis. The coils 110, 120, 130 can be arranged in one and the same plane. However, the coils 110, 120, 130 can also be arranged in different planes parallel to one another. For example, the respective coils 110, 120, 130 can be arranged in different layers of a multilayer (e.g., a two-layer) substrate.

[0028] For example, the respective receiving coil assemblies 110, 120 can have vias 160, 260 at suitable locations, wherein the vias 160, 260 connect two superimposed substrate layers to one another. At these vias 160, 260, the respective receiving coil assemblies 110, 120 can thus change substrate layers. This means that a receiving coil assemblies 110, 120 can, for example, initially run in a first substrate layer and change to the second substrate layer by means of the via 160, 260. Thus, the receiving coil assemblies 110, 120 can be arranged alternately in different substrate layers, so that the receiving coil assemblies 110, 120 can be interwoven with one another in a multilayer substrate.

[0029] Each planar receiving coil arrangement 110, 120 has a planar winding 110W, 120W with multiple turns 111. A planar winding 110W can extend from a starting point 151 to an end point 152 and can have multiple turns 111. The planar receiving coil arrangements 110, 120 can, for example, have a sinusoidal shape running in the plane, with one winding 110W, 120W describing the entire sinusoidal curve between the starting point 151 and the end point 152, and with each turn 111 corresponding to a half-wave. Two consecutive half-waves or turns 111 would thus correspond to one period.

[0030] The two receiving coil arrangements 110, 120 can have the same periodicity, i.e., both receiving coil arrangements 110, 120 have the same number of periods. In the non-limiting embodiment shown here, both receiving coil arrangements 110, 120 have a periodicity of '6', i.e., both receiving coil arrangements 110, 120 have six full periods or twelve half-waves or turns 111.

[0031] In the Fig. In the exemplary embodiment illustrated in Figure 2, the two receiving coil arrangements 110, 120 are each configured as so-called astatic coils. This will be explained using the example of the first receiving coil arrangement 110, but this also applies to the second receiving coil arrangement 120. In an astatic receiving coil arrangement 110, its (e.g., sinusoidal) winding 110W can initially run from a starting point 151 in a first direction (here, e.g., from left to right) along the longitudinal extension direction (e.g., in the y-direction) of the first receiving coil arrangement 110. At one end 152 of the astatic receiving coil arrangement 110, the winding 110W can then be reversed and returned to the starting point 151 (e.g., from right to left), whereby the individual turns 111 of the oppositely running winding 110W are 180° out of phase with each other. This results in the double sine curves per receiving coil arrangement 110, 120, as seen here.Homogeneous stray fields can be compensated by means of an astatic receiving coil arrangement 110, 120.

[0032] The receiving coil arrangements 110, 120 have a longitudinal extension direction 170 and a lateral width extension 180 running perpendicular thereto. In the Fig. In the embodiment illustrated in FIG. 2, the aforementioned longitudinal extension direction 170 can, for example, run along the indicated y-axis, and the lateral width extension 180 can be dimensioned perpendicular thereto, i.e., for example, along the indicated x-axis. This means that the lateral width extension 180 of the first and second planar receiving coil arrangements 110, 120 is each dimensioned perpendicular (e.g., in the x-direction) to their longitudinal extension direction 170 (e.g., the y-direction).

[0033] As previously mentioned, the two receiving coil arrangements 110, 120 can each be sinusoidally shaped and have several, e.g., two or more, consecutive periods. This means that each planar receiving coil arrangement 110, 120 can have the geometric shape of a sinusoidal oscillation.

[0034] If the receiving coil arrangements 110, 120 are sinusoidal, the lateral width extension 180 with the amplitude A x (see e.g. A1, A2) of the respective sinusoidal shape, and the period duration (ie two consecutive half-waves 111) of the respective planar receiving coil arrangement 110, 120 is measured in its longitudinal direction 170.

[0035] In the 2-phase system illustrated here as an example, the two receiving coil arrangements 110, 120 can each be offset by 90° from each other, so that the geometries of the two receiving coil arrangements 110, 120 correspond to a sine and a cosine oscillation. In a 3-phase system, however, another sinusoidal receiving coil arrangement (not illustrated here) could be provided, whereby all three receiving coil arrangements can then each be offset by 60° from each other. The respective offset refers to an offset along the longitudinal direction 170 or along the direction of movement of the target 140.

[0036] The position determination system 100 also includes a target 140 that is movable relative to the first and second planar receiving coil arrangements 110, 120. The target 140 can be configured, for example, in the form of a metal plate. The movable target 140 can move linearly, ie, along a linear path. As shown in Fig. As can be seen in Figure 2, the target 140 can move, for example, along the longitudinal extension direction 170 of the planar receiving coil assemblies 110, 120. The target 140 can therefore, for example, have a movement path that runs from a starting point 151 in the longitudinal extension direction 170 of the two receiving coil assemblies 110, 120.

[0037] In the Fig. 2, the planar receiving coil arrangements 110, 120 extend essentially in a straight line along their longitudinal direction 170. However, it would also be conceivable for the planar receiving coil arrangements 110, 120 to extend in a curved manner, e.g., in a wave-like or annular manner. For example, the planar receiving coil arrangements 110, 120 could be arranged in a circle. In this case, the target 140, which is movable along the longitudinal direction 170 of the receiving coil arrangements 110, 120, could move on a corresponding circular path, so that instead of the Fig. 2 linear position sensor shown as an example, a rotation angle sensor could be provided.

[0038] In any case, the first receiving coil arrangement 110 and the second receiving coil arrangement 120 can each generate a first and second output signal dependent on the actual position of the target 140. That is, the first receiving coil arrangement 110 can generate a first output signal, and the second receiving coil arrangement 120 can generate a different second output signal.

[0039] The signal shape of the output signals can be based on the geometry of the respective receiving coil arrangement 110, 120. For example, a sinusoidal receiving coil arrangement 110, 120 can generate a sinusoidal signal waveform. This will be explained below with reference to Fig. 3A discussed in more detail.

[0040] In any case, the innovative concept described herein provides that the lateral width extension 180 (e.g., in the x-direction) of the first and second planar receiving coil arrangements 110, 120 varies along the movement path of the target 140, or across the longitudinal extension direction 170 of the receiving coil arrangements 110, 120. In other words, the physical amplitude A x of the respective receiving coil arrangement 110, 120 over their longitudinal extension direction 170, which is illustrated purely by way of example using a first physical amplitude A1 and a larger second physical amplitude A2.

[0041] In the Fig. 2, the lateral width extension 180 or the physical amplitude A xof the respective receiving coil arrangement 110, 120 along the movement path of the target 140 (here: from left to right). For example, the lateral width extension 180 or the physical amplitude A x of the respective receiving coil arrangement 110, 120 along the movement path of the target 140 (here: from left to right) continuously, e.g. linearly. For example, the Fig. 2, the lateral width dimension 180 or physical amplitude A1 is smaller than the lateral width dimension 181 or physical amplitude A2. This gives the planar receiving coil arrangements 110, 120 a funnel shape, as shown in the Fig. 2 shown top view can be clearly seen.

[0042] However, it would also be conceivable that the lateral width extension 180 or the physical amplitude A xof the respective receiving coil arrangement 110, 120 along the movement path of the target 140 (here: from left to right) becomes smaller and smaller. For example, the lateral extent 180 or the physical amplitude A x the respective receiving coil arrangement 110, 120 along the movement path of the target 140 (here: from left to right) continuously, e.g. linearly.

[0043] The lateral extension 180 or the physical amplitude A x However, the respective receiving coil arrangement 110, 120 may also change non-continuously along the movement path of the target 140 (here: from left to right). It should be noted that between the starting point 151 and the reversal or end point 152, there are no equal lateral width extensions 180 or physical amplitudes A. x The lateral widths 180 or physical amplitudes A xare therefore all different or unique across the entire movement path of the target 140, ie there is no amplitude value that occurs twice or more. This can avoid ambiguities in signal evaluation or position determination (see also the following discussion with reference to Fig. 3A).

[0044] As in Fig. 2 is shown as an example, the lateral width extension 180 or the physical amplitudes A x of the first and second planar receiving coil arrangements 110, 120 change in equal proportions along their longitudinal extension direction 170. This means that the lateral width extension 180 or physical amplitude A x of the first receiving coil arrangement 110 changes to the same extent as the lateral extent 180 or physical amplitude A xthe second receiving coil arrangement 120. Thus, if one receiving coil arrangement becomes larger / smaller, the other receiving coil arrangement becomes larger / smaller proportionally by the same amount or factor.

[0045] The period length, however, can remain unchanged. As in Fig. 2, the lateral width extension 180 or physical amplitude A x of the respective receiving coil arrangement 110, 120. Their respective period duration, i.e., the length of a period to be measured in the longitudinal direction 170, remains unchanged. This has the advantage that the output signals generated by the respective receiving coil arrangement 110, 120 also have a substantially constant period duration, resulting in a continuous signal profile, which in turn facilitates signal evaluation.

[0046] As already mentioned at the beginning, the signal shape of the output signals of the receiving coil arrangements 110, 120 can correlate with their geometric shape. For example, sinusoidal receiving coil arrangements 110, 120 can each generate a sinusoidal output signal.

[0047] Fig. Figure 3A shows a diagram in which the output signals of the two Fig. 2, are plotted as a function of the actual position of the target 140. In this example, the output signals are the voltages induced in the receiving coil arrangements 110, 120. To create the Fig. In the diagram shown in Figure 3A, the excitation coil 130 was excited with an alternating voltage of 2.4 V at a frequency of 3.5 MHz. The external dimensions of the excitation coil 130 were 15.7 mm x 83 mm. The period length of the two receiving coil assemblies 110, 120 was 10 mm each. The lateral width 180 of the two receiving coil assemblies 110, 120 increased continuously from 2.5 mm to 12.5 mm between the starting point 151 and the end point 152. The air gap was 1 mm, and the dimensions of the target 140 were (length x width x thickness) 20 mm x 5 mm x 0.5 mm. The numerical values ​​given here are purely exemplary and therefore should not be interpreted as limiting.

[0048] Graph 310 shows the output signal curve of the first receiving coil arrangement 110. Graph 320 shows the output signal curve of the second receiving coil arrangement 120. Both signal curves are also sinusoidal and exhibit an offset in the x-direction. The vertical offset in the y-direction shown here can be ignored for the following discussion. The vertical offset can also be compensated, if necessary, using common methods, for example, by reducing the air gap (the air gap between the target 140 and the receiving coil arrangements 110, 120).

[0049] As in Fig. 3A, the signal amplitude 380 of the respective output signal 310, 320 increases continuously along the movement path of the target 140, ie with increasing y-value. Accordingly, the receiving coil arrangements 110, 120 generate with increasing lateral width 180 ( Fig. 2) an output signal with a correspondingly increasing signal amplitude of 380. This also applies in the other direction, ie with decreasing lateral width 180 ( Fig. 2) the signal amplitude 380 of the output signal of the respective receiving coil arrangement 110, 120 also decreases.

[0050] Fig. Figure 3B shows another diagram in which the two output signals 310 and 320 were combined, for example, using the arctangent function. Here, too, the numerical values ​​given are purely exemplary and should therefore be interpreted as non-limiting.

[0051] As can be seen, by applying the arctangent function, an angle between -180° and +180° is obtained for each full period, which encodes the actual position (y-axis) of the target. However, the diagram shows six consecutive runs 351, ..., 356 with angles from -180° to +180° each, which leads to ambiguities in determining the actual position of the target 140. This is because in the Fig. 2, the two receiving coil arrangements 110, 120 each have six periods, which is why the output signals 310, 320 ( Fig. 3A) also have six periods, and accordingly, applying the arctangent function results in six equal passes 351, ..., 356, each from -180° to +180°. The angle of rotation, taken on its own, therefore initially provides an ambiguous position indication of target 140.

[0052] To resolve these ambiguities, the innovative concept provides that the signal amplitudes 380 ( Fig. 3A) to determine the position of the target 140. This becomes somewhat clearer when one looks at Fig. 3C. Here, the combined output signals of the receiving coil arrangements 110, 120 are given in polar coordinates. The vector 330 corresponds to the angle signal obtained using the arctangent function from Fig. 3B. The angle of rotation Φ of the vector 330 describes the Fig. 3B shown angle (y-axis) between -180° and +180° per period or pass 351, ..., 356, and the length r of the vector 330 describes the magnitude of the signal amplitude 380.

[0053] In Fig. 3C it is clearly visible that with increasing angle of rotation Φ of vector 330, the amplitude, ie the length r of vector 330, also increases. The continuously increasing vector length r is due to the continuously increasing lateral width extension 180 of the two receiving coil arrangements 110, 120 ( Fig. 2). As mentioned above, the signal amplitude 380 of the first and second output signals 310, 320 each changes proportionally to the changing lateral width extension 180 of the first and second planar receiving coil arrangements 110, 210. Thus, as the lateral width extension 180 increases / decreases, the signal amplitude 380 also increases / decreases proportionally.

[0054] In Fig. 3C it is clearly visible that by means of the length r of the vector 330 in combination with the angle of rotation Φ, each point in the polar coordinate system can be assigned exactly one unique actual position of the target, such as P1 = f(r, Φ).

[0055] If you now look again Fig. 3B, one also sees the vector length 340, which increases continuously throughout the entire movement path of the target 140 and always has a unique value. If a specific rotation angle Φ is combined with the value of the vector length 340 prevailing at this point for each pass 351, ..., 356, this results in exactly one unique combination of rotation angle Φ and signal amplitude 380 for each actual position throughout the entire movement path of the target 140. This allows the previously mentioned ambiguities to be resolved, and the current actual position of the target 140 can be determined with high resolution and unambiguously.

[0056] Fig. 3D illustrates this using the angular error in mm. Here, too, the numerical values ​​given are purely exemplary and therefore not to be interpreted as limiting. As can be seen, the innovative positioning system 100 has an angular error that is almost zero. This is illustrated by graph 360. The initial deflection at the beginning of the actual position of the target is merely due to edge effects and can be compensated. In comparison to graph 360, which has almost no angular error, the second graph 370 depicts the angular error of a reference system with receiving coil arrangements that have only a single period ( Fig. 1). Here, it can be seen that there are significant deviations (angular errors) in determining the actual position of the target, which is due to the low resolution (only a single period).

[0057] One advantage of the innovative concept described herein is, among other things, that despite the provision of only two receiving coil arrangements 110, 120, a very high degree of accuracy in determining the position of the target 140 can be achieved. Embodiments provide that in a 2-phase system, exactly two receiving coil arrangements 110, 120 with the same periodicity are sufficient, wherein these two receiving coil arrangements 110, 120 are offset from one another by 90° in the longitudinal direction. Further embodiments provide that in a 3-phase system, exactly three receiving coil arrangements with the same periodicity are sufficient, wherein these three receiving coil arrangements are offset from one another by 60° in the longitudinal direction. Furthermore, exactly one target 140 is sufficient in both a 2-phase system and a 3-phase system. Two or more receiving coil arrangements with the same periodicity are also called single-track.

[0058] Conventional inductive positioning systems, which use a vernier scale principle, require significantly more components to achieve comparable resolution and accuracy in positioning. A 2-phase system requires two receiving coil arrays with the same periodicity, as well as two additional receiving coil arrays with the same periodicity. The periodicity of the first coil pair must differ from the periodicity of the second coil pair. Two different targets are also required. Receiving coil arrays with different periodicities are also referred to as dual-track or multi-track. A 3-phase system using the vernier scale principle requires a total of six receiving coil arrays and two targets. To integrate the individual coils into a multi-layer substrate, a single metal layer is required for each receiving coil array.Thus, a dual-track system requires a substrate with at least four metal layers. Furthermore, a multi-track positioning system requires a multi-RX input chip.

[0059] For the innovative single-track positioning system 100 presented herein, however, only exactly two or exactly three receiving coil arrangements, each with the same periodicity, are sufficient. The receiving coil arrangements can be arranged in exactly two planes or layers. For example, in both a 2-phase system and a 3-phase system, a two-layer substrate, i.e., a substrate with exactly two integrated metal layers, is sufficient. In both a 2-phase system and a 3-phase system, the individual receiving coil arrangements, as initially described with reference to Fig. 2, distributed across the individual layers or interwoven into each other.

[0060] The accuracy of position determination can be further increased with the present position determination system 100. As already mentioned, the air gap, i.e., the vertical distance between the target 140 and the receiving coil assemblies 110, 120, can be changed, for example, to correct an offset. For this purpose, for example, a third planar receiving coil assembly can be provided, which is configured to generate a third output signal, wherein this third output signal describes the air gap, i.e., the distance of the target 140 from the third receiving coil assembly. Thus, the distance or air gap can be determined, and a measurement error in the position determination induced by distance fluctuations can thereby be compensated.

[0061] In summary, the innovative concept described herein proposes an inductive single-track sensor system 100 for absolute position detection. Advantageously, in 2-phase systems, only a single excitation coil 130 and exactly two receiver coil arrangements 110, 120 (e.g., sin / cos), as well as a single sensor and a single target 140, are required.

[0062] The planar coils 110, 120, 130 can be arranged on a substrate, such as a PCB (Printed Circuit Board). The corresponding PCB layout includes the two receiving coil assemblies 110, 120, which have their physical amplitude A xThe lateral width extension 180 changes depending on the movement position or direction of the target 140. The voltage amplitudes 380 induced in the receiving coil assemblies 110, 120 depend on the actual position of the target 140. The vector length 340 is calculated from the falling / rising sine signal, and in combination with the arctangent function, the absolute angle or position can be measured.

[0063] By evaluating the vector length 340 in combination with the arc tangent, a unique actual position of the target 140 can be determined. Fig. Figure 3A shows an example simulation result for the Fig. 2 illustrated positioning system 100.

[0064] The positioning system 100 can be implemented on a two-layer circuit board, resulting in reduced costs. Accuracy is also significantly increased compared to conventional designs.

[0065] The innovative concept described here is suitable for many industrial and automotive applications. It is conceivable for any application requiring absolute position or angle detection, especially with large detectable motion ranges. Absolute linear position detection of a rack in a steering gear would be a typical application in the automotive sector.

[0066] The inductive positioning system 100 described herein has, among other advantages: • Stray field immunity through inductive scanning principle, • Increased accuracy (compared to standard layouts that suffer from edge effects), • Smaller installation space / smaller area / requires only 2-layer PCB, • Requires only a single sensor • Lower system costs, since absolute position / angle detection is realized by a set of exactly one excitation coil 130 and exactly two receiver coil assemblies 110, 120 on a 2-layer circuit board. (The vernier principle requires at least a 4-layer circuit board or a larger circuit board area.) • The concept is applicable to linear position and rotary encoders, • The positioning system 100 can also be used for indexing.

[0067] The above-described embodiments merely illustrate the principles of the innovative concept described herein. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the concept described herein be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein.

[0068] Although some aspects have been described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device.

Claims

[1] Inductive positioning system (100), comprising: a planar excitation coil (130) and a first and second planar receiving coil arrangement (110, 120) arranged within the planar excitation coil (130), and a target (140) movable relative to the first and second planar receiving coil arrangement (110, 120), wherein the first receiving coil arrangement (110) and the second receiving coil arrangement (120) each generate a first and second output signal dependent on the position of the target (140), and wherein the lateral width extent (180) of the first and second planar receiving coil arrangements (110, 120) each varies along the movement path of the target (140). [2] Inductive positioning system (100) according to claim 1, wherein the target (140) is configured to move along the longitudinal direction (170) of the first and second receiving coil assemblies (110, 120). [3] Inductive position determination system (100) according to claim 1 or 2, wherein the lateral width extent (180) of the first and second planar receiving coil arrangements (110, 120) is each measured perpendicular to the longitudinal extension direction (170) of the first and second planar receiving coil arrangements (110, 120). [4] Inductive position determination system (100) according to one of the preceding claims, wherein the lateral width extent (180) of the first planar receiving coil arrangement (110) and the lateral width extent (180) of the second planar receiving coil arrangement (120) each change in equal proportions over their longitudinal extension direction (170). [5] Inductive positioning system (100) according to one of the preceding claims, wherein the lateral width extent (180) of the first and second planar receiving coil arrangements (110, 120) each continuously increases along the movement path of the target (140). [6] Inductive positioning system (100) according to one of the preceding claims, wherein the lateral width extent (180) of the first and second planar receiving coil arrangements (110, 120) each continuously decreases along the movement path of the target (140). [7] Inductive position determination system (100) according to one of the preceding claims, wherein the first planar receiving coil arrangement (110) is sinusoidal, wherein the lateral width extension (180) of the first planar receiving coil arrangement (110) of the amplitude A x corresponds to the sinusoidal shape, and wherein the period of the sinusoidal shape is measured in the longitudinal direction (170) of the first planar receiving coil arrangement (110). [8] Inductive position determination system (100) according to one of the preceding claims, wherein the second planar receiving coil arrangement (120) is sinusoidally designed and offset from the first planar receiving coil arrangement (110), wherein the lateral width extension (180) of the second planar receiving coil arrangement (120) of the amplitude A x corresponds to the sinusoidal shape, and wherein the period of the sinusoidal shape is measured in the longitudinal direction (170) of the second planar receiving coil arrangement (120). [9] Inductive position determination system (100) according to one of claims 7 or 8, wherein the sinusoidal first planar receiving coil arrangement (110) has a plurality of periods with constant period duration but different amplitudes A1, A2, and / or wherein the sinusoidal second planar receiving coil arrangement (120) has a plurality of periods with constant period duration but different amplitudes A1, A2. [10] Inductive positioning system (100) according to one of the preceding claims, wherein the signal strength (380) of the first and second output signals (310, 320) each changes proportionally to the varying lateral width extent (180) of the first and second planar receiving coil arrangements (110, 210), where as the lateral width (180) increases / decreases, the signal strength (380) also increases / decreases. [11] Inductive positioning system (100) according to one of the preceding claims, wherein the inductive positioning system (100) is designed to combine the first output signal (310) and the second output signal (320) to obtain a vector (330), wherein the angle of rotation (Φ) of the vector (330) provides an ambiguous position indication of the target (140), and wherein the length of the vector (330) describes the signal amplitude (380) of the two combined output signals (310, 320) dependent on the actual position of the target (140), and wherein the inductive position determination system (100) is designed to determine a unique position of the target (140) based on the angle of rotation (Φ) and the length of the vector (330). [12] Inductive positioning system (100) according to one of the preceding claims, wherein the inductive positioning system (100) has exactly two planar receiving coil arrangements (110, 120) and / or exactly one target (140). [13] Inductive positioning system (100) according to one of the preceding claims, further comprising a third planar receiving coil arrangement configured to generate a third output signal, said third output signal describing the distance of the target (140) to the third receiving coil arrangement, and wherein the inductive position determination system (100) is configured to compensate for a measurement error in the position determination induced by distance fluctuations based on the third output signal. [14] Inductive positioning system (100) according to one of the preceding claims, further comprising a two-layer substrate, wherein the first and second planar receiving coil arrangements (110, 120) are each distributed over the two layers of the two-layer substrate. [15] Inductive positioning system (100) according to one of the preceding claims, wherein the inductive position determination system (100) is designed in the form of a linear displacement sensor, wherein the first and second receiving coil arrangements (110, 120) each extend in a straight line, or wherein the inductive position determination system (100) is designed in the form of a rotation angle sensor, wherein the first and second receiving coil arrangements (110, 120) each extend in a ring shape. [16] Inductive positioning system (100) according to one of the preceding claims, further comprising a third planar receiving coil arrangement arranged within the planar excitation coil (130), wherein the first receiving coil arrangement (110), the second receiving coil arrangement (120) and the third receiving coil arrangement each generate a first, second and third output signal dependent on the position of the target (140), and wherein the lateral width extent (180) of the first, second and third planar receiving coil assemblies each varies along the path of movement of the target (140). [17] A method for determining position using an inductive positioning system (100), the method comprising the following steps: Providing a first and second planar receiving coil arrangement (110, 120), and a target (140) movable relative to the first and second planar receiving coil arrangement (110, 120), wherein the lateral width extent (180) of the first and second planar receiving coil arrangements (110, 120) each varies along a movement path of the target (140), detecting a first and a second output signal (310, 320) which the first and second receiving coil arrangements (110, 120) each generate as a function of the position of the target (140), Combining the first and second output signals (310, 320) to obtain a vector (330), wherein the angle of rotation (ϕ) of the vector (330) provides an ambiguous position indication of the target (140), and wherein the length of the vector (330) describes the signal amplitude (380) of the two combined output signals (310, 320) dependent on the actual position of the target (140), and Determining a unique position of the target (140) based on the angle of rotation (ϕ) and the length of the vector (330).

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