Inductive position measurement system for determining movement along a curved track

Abstract

Inductive position measuring system (100), comprising: a flexible substrate (110) with a first excitation coil (111) and a first receiving coil arrangement (120), wherein the first excitation coil (111) and the first receiving coil arrangement (120) each run in a straight line along the substrate (110), a second excitation coil (211) and a second receiving coil arrangement (220), wherein the second excitation coil (211) and the second receiving coil arrangement (220) each run in a straight line, a metallic target (150) spaced apart from the substrate (110), which is configured to provide inductive coupling between the first excitation coil (111) and the first receiving coil arrangement (120) and between the second excitation coil (211) and the second receiving coil arrangement (220), wherein the actual position of the target (150) can be determined based on this inductive coupling, wherein the target (150) can be attached to a component (170) that is movable relative to the substrate (110), the position of which is to be determined, wherein the movable component (170) together with the target (150) can be deflected along a curved path along a first and a different second coordinate line (151, 152), and wherein the substrate (110) is curved, such that the straight first excitation coil (111) and the straight first receiving coil arrangement (120) are also curved and extend parallel to the first coordinate line (151), and wherein the straight second excitation coil (211) and the straight second receiving coil arrangement (220) are each curved and extend along the second coordinate line (152).

Description

[0001] The innovative concept described herein concerns a device for determining the current position of an object moving along a curved path. Position determination is achieved using inductive sensors.

[0002] In many applications, precise determination of the actual position of a moving object is desirable. Various measurement principles can be used for this purpose. For example, magnetic position measurements are known, where magnetic field sensors detect the magnetic field emanating from a magnetic component, and the current position of the magnetic component is determined based on this magnetic field information. However, magnetic field measurements have only limited accuracy. Furthermore, magnetic field sensors are susceptible to external interference.

[0003] Potentiometric position measurements are also well-known. These measuring principles also have limited accuracy. Furthermore, they are relatively susceptible to mechanical wear.

[0004] Optical sensors are also frequently used to determine the position of an object. However, these measurement principles are typically subject to the usual optical limitations. For example, optical measurements can usually only be carried out in sufficiently clear visibility conditions. In addition, the required measuring devices are usually relatively bulky.

[0005] Due to the limitations mentioned above, inductive measurement principles are increasingly being used today for the precise determination of the actual position of a moving object. No magnetic components are required, so the measurements are not affected by external influences from stray magnetic fields. Inductive measurement systems can also be manufactured on a very small scale and can be used even under challenging external conditions.

[0006] Inductive measuring devices can measure movements within a flat surface, i.e., in two-dimensional space. These are generally simple translational movements within the flat surface, as well as simple rotations within the flat surface. For example, DE 10 2004 056 049 A1 describes an inductive rotation sensor. Here, a rotor element mounted on a shaft rotates within a ring-shaped stator element. The position of the rotor element relative to the stator element is determined by means of inductive coils, which are printed as conductive traces on a flexible PCB.

[0007] However, determining the position during movement on a curved surface, especially movements in three-dimensional space, can only be accomplished with a high level of equipment complexity.

[0008] This applies, for example, to determining the position of components mounted on a multidimensional joint, as can be the case in joysticks or robot arms. An example of such a multidimensional joint would be a universal joint, also known as a cardan joint or universal joint. Such a universal joint allows rotational movements in two degrees of freedom, enabling a component attached to it to move along a spherical segment. This is therefore a multidimensional movement on a curved surface. As mentioned earlier, induction-based position determination in the case of multidimensional movements is only possible with a high level of equipment complexity. For example, several inductive measuring devices must be provided, each measuring in a different spatial direction.However, this leads to increased demands on the complexity of the overall system, accompanied by larger dimensions and directly associated increased production costs.

[0009] It would therefore be desirable to improve inductive position measurement systems in such a way that uncomplicated and cost-effective devices can be used to determine the actual position of a moving object in three-dimensional space, which can also be installed in the respective application in a space-saving manner.

[0010] This is achieved with an inductive position measuring system according to claim 1. The inductive position measuring system comprises a flexible substrate with a first and second excitation coil and a first and second receiving coil arrangement, wherein the first and second excitation coils and the first and second receiving coil arrangements each extend in a straight line along the substrate. The inductive position measuring system also comprises a metallic target spaced apart from the substrate, which is configured to provide inductive coupling between the first excitation coil and the first receiving coil arrangement, and between the second excitation coil and the second receiving coil arrangement, wherein the actual position of the target can be determined based on this inductive coupling.The target can be attached to a component that is movable relative to the substrate, the position of which is to be determined. The movable component, together with the target, can be deflected along a curved path along a first and second coordinate line. According to the innovative concept presented herein, the substrate is curved such that the first excitation coil and the first receiver coil assembly, both located on the substrate and extending along the first coordinate line, are also curved and extend along this first coordinate line. Similarly, the second excitation coil and the second receiver coil assembly, both located on the substrate and extending along the second coordinate line, are also curved and extend along the second coordinate line.

[0011] Further embodiments and advantageous aspects of this inductive position measuring system are mentioned in the respective dependent patent claims.

[0012] Some exemplary embodiments are shown in the drawing and are explained below. They show: Fig. 1 a schematic perspective view of a universal joint with two degrees of freedom, Fig. 2 a schematic view of a cut sphere to describe polar coordinates, Fig. 3 A schematic side view of an inductive position measuring system for measuring the position of a moving target with exactly one degree of freedom according to an example, Fig. 4 A schematic top view of an inductive position measuring system for measuring the position of a moving target with exactly one degree of freedom according to an example, Fig. 5 A schematic top view of an inductive position measuring system with additional coil arrangements for determining a relative position of the target according to an example, Fig. 6 A schematic top view of an inductive position measuring system according to an example in a simplified representation, Fig. 7 A schematic top view of an inductive position measuring system for measuring the position of a moving target with exactly one degree of freedom according to an example, Fig. 8 a schematic side view of an inductive position measuring system for measuring the position of a movable target with exactly two degrees of freedom according to an embodiment of the invention, Fig. 9 a schematic top view of an inductive position measuring system for measuring the position of a movable target with exactly two degrees of freedom according to an embodiment of the invention, Fig. 10 a schematic top view of an inductive position measuring system for measuring the position of a movable target with exactly two degrees of freedom according to a further embodiment of the invention, Fig. 11 a schematic top view of an inductive position measuring system for measuring the position of a movable target with exactly two degrees of freedom according to a further embodiment of the invention, Fig. 12 a schematic top view of an inductive position measuring system for measuring the position of a movable multi-part target with exactly two degrees of freedom according to a further embodiment of the invention, Fig. 13 a schematic top view of an inductive position measuring system for measuring the position of a movable multi-part target with exactly two degrees of freedom according to a further embodiment of the invention, Fig. 14 a schematic top view of an inductive position measuring system for measuring the position of a movable target designed in the form of a geometric hollow body with exactly two degrees of freedom according to a further embodiment of the invention, and Fig. 15 a schematic top view of an inductive position measuring system for measuring the position of a movable target designed in the form of a geometric hollow body with exactly two degrees of freedom according to a further embodiment according to the invention.

[0013] The following are examples of embodiments described in more detail with reference to the figures, whereby elements with the same or similar function are provided with the same reference numerals.

[0014] Process steps depicted or described in this disclosure may also be carried out in a different order than depicted or described. Furthermore, process steps relating to a specific feature of a device are interchangeable with that very feature of the device, and vice versa.

[0015] The introduction shows Fig. Figure 1 shows a perspective view of a universal joint 10, also known as a cardan joint or universal joint. The universal joint 10 rotatably connects two shafts 11 and 12. Each shaft 11 and 12 has an axis of rotation 21 and 22. The two axes of rotation 21 and 22 are offset from each other by 90° and extend through the universal joint 10. This allows each shaft 11 to move relative to the other shaft 12 in two degrees of freedom 31 and 32. These degrees of freedom are also referred to as DOF ​​(degrees of freedom).

[0016] Assuming that one of the two shafts 11, 12 is rigidly clamped, the freely movable shaft can perform a movement on a spherical segment. The freely movable shaft thus moves three-dimensionally in space in two independent degrees of freedom 31, 32.

[0017] Fig. Figure 2 shows the motion of a point P in three-dimensional spherical space. The position of point P can be defined using spherical or polar coordinates, where r represents the distance from the origin O, and thus the radius of motion, where the angle θ describes the so-called polar distance angle, and where the angle φ denotes the so-called azimuth angle. In the case of the previously described universal joint, the vector shown would correspond to V⇀ of the freely movable shaft. Since the length of the freely movable shaft is fixed by design, the radius of movement r is also fixed.

[0018] Point P would correspond to the axial end of the wave, which can therefore only move in two degrees of freedom: along the azimuth angle φ and along the polar distance angle θ. Thus, point P, i.e., the end of the wave, can move across the entire surface of the sphere with radius r shown in the example diagram.

[0019] If, however, one of these two degrees of freedom were restricted, then point P, i.e., the wave end, would only extend along a coordinate line running along the surface of the sphere. For example, if the polar distance angle θ were restricted, then the vector V⇀ For example, it is fixed in the xy-plane and could only move along the coordinate line 141. If, however, the azimuth angle φ were restricted, the vector would be V⇀ For example, it is fixed in the yz-plane and could only move along the coordinate line 142. If the vector is fixed... V⇀ In the xz-plane, for example, it could only move along the coordinate line 143.

[0020] Within the present disclosure, the term "coordinate line" is therefore used in its original sense, i.e., a coordinate line in a coordinate system denotes a curve on which all coordinates except one are constant.

[0021] If, for example, a wave has only one of the depicted degrees of freedom θ or φ, then the end of the wave, i.e., point P, moves exactly along a single coordinate line 141, 142, 143. This corresponds to a pendulum-like motion with one degree of freedom. If, on the other hand, the wave has both depicted degrees of freedom θ and φ, then the end of the wave, i.e., point P, can move along several coordinate lines 141, 142, 143 simultaneously, and thus across the entire surface of the sphere. This, in turn, corresponds to a pivoting motion with two degrees of freedom, with the resulting space of motion being segment-shaped.

[0022] After defining the degrees of freedom of a mechanical joint and the resulting possibilities of movement in spherical space, and the concept of the coordinate line, the innovative inductive position measurement system presented herein will be described in more detail below.

[0023] Fig. Figure 3 shows an inductive position measuring system 100 as merely an example. The inductive position measuring system 100 has a flexible substrate 110 which is in Fig. 4 is shown in a top view.

[0024] The flexible substrate 110 has a first excitation coil 111 and a first receiving coil assembly 120. As explained below, the receiving coil assembly 120 has several individual windings 131, 132, 133, 134, which run in an approximately wave-like pattern. The entire receiving coil assembly 120, like the first excitation coil 111, runs in a straight line along the flexible substrate 110. As shown here by way of example, the flexible substrate 110 can be in a strip shape.

[0025] However, it would also be conceivable that the flexible substrate has 110 other geometric shapes.

[0026] The inductive position measuring system 100 further comprises a metallic target 150 spaced apart from the substrate 110. The metallic target 150 is configured to provide inductive coupling between the first excitation coil 111 and the first receiving coil arrangement 120, whereby the actual position of the target 150 can be determined based on this inductive coupling. For a more detailed explanation, see below. Fig. 4 referred.

[0027] As in Fig. As shown in Figure 4, the excitation coil 111 can, for example, be designed in the form of a simple conductor loop. This can, for instance, be arranged completely around the receiving coil assembly 120. The excitation coil 111 can be supplied with a current or voltage signal, thereby generating an induction field. This induction field reaches the metallic target 150, in which an induced current is generated, which in turn generates a counter-induction field. This counter-induction field can then be received by the first receiving coil assembly 120. The receiving coil assembly 120 can therefore also be referred to, in the common terminology of this field, as a pickup coil assembly.

[0028] In response to the received counter-induction field, the receiving coil arrangement 120 generates an output signal that can be processed, for example, by a control unit 160, e.g., in the form of an ASIC (Application Specific Integrated Circuit). This output signal depends on the position of the target 150 relative to the receiving coil arrangement 120, so that the control unit 160 can derive a unique actual position of the target 150 from it.

[0029] To generate a unique signal over the entire path length, and thus determine a unique actual position, the receiving coil arrangement 120 can have a first receiving coil 121 and a second receiving coil 122. Due to their special geometry and their relative arrangement to each other, the receiving coils 121 and 122 are also referred to as the sine coil 121 and the cosine coil 122. The sine coil 121 and the cosine coil 122 are arranged with a 90° phase shift relative to each other.

[0030] Both the sine coil 121 and the cosine coil 122 can be configured as astatically. The sine coil 121 has two individual coil windings 131, 132 that are phase-shifted by 180°. Similarly, the cosine coil 122 has two individual coil windings 133, 134 that are phase-shifted by 180°. Due to this winding arrangement, a differential output signal can be generated in both the sine coil 121 and the cosine coil 122, which can be used to compensate for homogeneous external stray fields. Therefore, the receiving coils 121, 122 are also referred to as astatic receiving coils.

[0031] As in Fig. As shown in Figure 3, the target 150 can be attached to a component 170 that is movable relative to the substrate 110. The position of this component 170 is to be determined using the inductive position measuring system 100. For this purpose, the target 150 is attached to the component 170. The movable component 170, together with the target 150 attached to it, can be deflected along a first coordinate line 151. This first coordinate line 151 is a curved polar coordinate line, as previously described with reference to the one in [reference missing]. Fig. The polar coordinate lines 141, 142, and 143 shown in the illustrations describe the following: Target 150 moves on a segment of a circular path defined by polar coordinate line 151, i.e., on a segment or section of a circular path. Target 150 can therefore be deflected along a curved path. This deflection is symbolized by arrows 180.

[0032] The deflection 180 essentially corresponds to a previously described pendulum motion with one degree of freedom; that is, the component 170 with the target 150 attached to it can move back and forth along exactly one curved coordinate line 151. This pendulum-like motion 180 can result, for example, from the fact that the movable component 170 has only a single degree of freedom, which results, for example, from the clamping or support of the component 170. As in Fig. As indicated by example in Figure 3, the component 170 can, for instance, be mounted on a fixed bearing 190 with exactly one axis of rotation 191. Other embodiments, which will be explained in more detail with reference to the following figures, provide that the component 170 can have two degrees of freedom, so that the component 170, together with the target 150 attached to it, can move in a pivoting motion on a spherical segment.

[0033] Component 170 could, for example, be a specially clamped or mounted joystick axis. Similarly mounted robot axes, e.g., in robot arms, would also be conceivable. Since component 170 typically has a fixed length, its range of motion is also fixed. This results in the following: Fig. 3 schematically drawn curved coordinate line 151, along which the component 170 can move back and forth.

[0034] As it is in Fig. As shown in Figure 3 as an example, the target 150 can preferably be attached to an axial end of the component 170, which is directly opposite the flexible substrate 110. This allows for a very short distance between the target 150 and the flexible substrate 110, which increases the signal strength and thus the signal quality.

[0035] According to the innovative concept presented herein, the flexible substrate 110 is curved, such that the straight first excitation coil 111 and the straight first receiving coil arrangement 120 mounted on it are also curved and extend parallel to, i.e., at a constant distance from, the first coordinate line 151. The excitation coil 111 and the receiving coil arrangement 120 not only run parallel to the coordinate line 151 but also in the same direction as the coordinate line 151.

[0036] Due to this design, the straight first excitation coil 111 and the straight first receiving coil arrangement 120 each extend along the movement trajectory of the target 150 when the target 150 moves along the first coordinate line 151. The target 150, which moves along with the component 170, can thus always be positioned opposite the substrate 110 and the coils 111 and 120 arranged on it during the execution of movements.

[0037] The curvature of the substrate 110 can essentially always correspond to the curvature of the coordinate line 151; that is, the curvature of the substrate 110 can essentially correspond to the trajectory or curved path along which the target 150 moves. This allows the distance between the target 150 and the substrate 110 to remain essentially constant over the entire path of the target 150's movement. In other words, the target 150 can move with an essentially constant air gap relative to the first excitation coil 111 and the first receiving coil assembly 120. A constant air gap is desirable to maintain consistent signal quality. The air gap should be kept as small as possible to maximize signal strength.

[0038] With reference to the following figures, further advantages of the innovative inductive position measuring system 100 are explained. However, since these figures are simplified for the sake of clarity, we will first refer to the Fig. 5 and Fig. Reference is made to Figure 6, which explains these simplifications. However, in the figures, features with the same or similar function are referenced using the same reference symbols.

[0039] Fig. 5 shows essentially the same arrangement as Fig. 4, i.e., a flexible substrate 110 on which a previously discussed first excitation coil 111, as well as an astatic sine coil 121 and an astatic cosine coil 122, are arranged. Additionally, in the Fig. In the example shown in Figure 5, an optional additional coil arrangement 500 is arranged on the substrate 110. This optional additional coil arrangement 500 has two astatic receiving coils 135, 136, which are arranged with a phase shift of 90° to each other. The first receiving coil 135 has two windings 135A, 135B, which are phase shifted by 180° to each other. The second receiving coil 136 also has two windings 136A, 136B, which are phase shifted by 180° to each other.

[0040] The coils 135 and 136 of the additional coil arrangement 500 can have the same amplitude and elongation as the sine coil 121 and the cosine coil 122. However, the number of oscillations (periods) completed by the individual coils 135 and 136 of the additional coil arrangement 500 is significantly greater than the number of oscillations completed by the sine coil 121 and the cosine coil 122 over the same path length. The ratio of oscillations completed can be, for example, 5:1 or greater, meaning that the coils 135 and 136 of the additional coil arrangement 500 can have at least five times more oscillations completed than the sine coil 121 and the cosine coil 122 arranged over the same path length.

[0041] The coils 135 and 136 of the additional coil arrangement 500, as well as the sine coil 121 and the cosine coil 122, receive the induction field emanating from the target 150. Due to their greater number of periods, coils 135 and 136 also generate an output signal more frequently when the target 150 sweeps over them. These output signals from coils 135 and 136 can be transmitted to the control unit 160 on a separate channel. By appropriately combining the output signals of coils 135 and 136 with the output signals of the sine coil 121 and the cosine coil 122, the accuracy of the position determination can be significantly increased. This essentially corresponds to the application of a vernier scale principle. For example, the absolute position of the target 150 can be determined using the sine coil 121 and the cosine coil 122, and a relative position of the target 150 can be determined using the coils 135, 136.

[0042] As mentioned at the beginning, the following figures are simplified for the sake of clarity. Such a simplification is in Fig. Figure 6 illustrates this. Here, only one of the two astatic receiving coils 121, 122 of the receiving coil arrangement 120 is shown, for example, only the sine coil 121. Similarly, only one of each of the two astatic coils 135, 136 of the additional coil arrangement 500 is shown, for example, the astatic coil 135. However, it is self-evident in the description of the following figures that both receiving coils 121, 122 of the receiving coil arrangement 120, i.e., both the sine coil 121 and the cosine coil 122, are always the subject of discussion. Likewise, it is understood that both receiving coils 135, 136 of the additional receiving coil arrangement 500 are always the subject of discussion. The excitation coil 111 can also be omitted for the sake of clarity, although it is of course present.

[0043] Under this premise, let us first consider the following: Fig. The 7 illustrated example is referenced. Here again, features with the same or similar function are referenced with the same reference symbols as in the other figures.

[0044] Fig. Figure 7 shows a top view of the purely exemplary inductive measuring system 100. Due to the top view, the previously discussed curvature of the substrate 110 is not visible here. However, this arrangement essentially corresponds to the one described previously with reference to the Fig. 3 and Fig. Example 4, in which target 150 moves with exactly one degree of freedom along a circular path segment, is again symbolized by arrow 180. The coordinate line 151, along which target 150 moves, is also shown.

[0045] The flexible substrate 110 can optionally be applied to a larger substrate 310, for example, in the form of a flex PCB (printed circuit board). The larger substrate 310 could also be a pre-formed structure, such as a bowl-shaped hollow hemisphere. This structure 310 can be made of various materials, such as plastic composites. Alternatively, the optional larger substrate 310 could be omitted, and the flexible substrate 110 could instead have the shape of the larger substrate 310 shown here as an example. In other words, the entire substrate 310 shown here would correspond to the flexible substrate 110.

[0046] Furthermore, as can be seen, the Target 150 has a different geometric shape than the one in Fig. 4. Example shown. In principle, the target 150 can have any geometric shape. Advantageously, however, the target 150 should be dimensioned such that its circumference at least partially surrounds the first excitation coil 111 and the first receiving coil arrangement 120 in a top view when the target 150 moves along the first coordinate line 151.

[0047] This means that the target 150 always surrounds a portion of the first excitation coil 111 and the first receiving coil assembly 120 when the target 150 moves. This ensures that the induction field and the counter-induction field are correctly established along the entire path of the target 150, in order to guarantee the previously described inductive measurement principle for determining the position of the target 150.

[0048] The Fig. 8 and Fig. Figure 9 shows exemplary embodiments of the inductive position measuring system 100 according to the invention. The in Fig. The embodiment shown in section 8 essentially corresponds to the one described above with reference to Fig. 3 discussed examples. However, one difference lies in the type of bearing of the moving component 170. In the example in Fig. In the embodiment shown in Figure 8, the bearing 190 has exactly two degrees of freedom according to the invention. This could, for example, be a bearing with reference to Fig. 1, discussed cross joint 10 act.

[0049] Due to the mounting of component 170 with a bearing that has two degrees of freedom, component 170 also has two degrees of freedom and can therefore move both in the same direction of extension as the polar coordinate line 151 (see deflection direction 180) and orthogonally to it (see deflection direction 181). All directions in between are also possible. The same applies to the target 150 attached to component 170.

[0050] This means that, according to the invention, the target 150 can move either along the first polar coordinate line 151 or along a second polar coordinate line 152 that is orthogonal to it. Due to the two degrees of freedom, the target 150 can also move along both the first polar coordinate line 151 and the second polar coordinate line 152 simultaneously. In this case, the target 150 can move in all spatial directions that lie between the two polar coordinate lines 151 and 152. In other words, a curved surface or plane can be defined between the two curved polar coordinate lines 151 and 152, within which the target 150 can move freely in all directions.

[0051] As in the Fig. As can be seen more clearly in the top view shown in Figure 9, the Target 150 can thus move in all directions across the curved surface. This is symbolically represented by the multi-headed arrow symbol 183. If one considers this top view on the surface shown in Figure 9, the Target 150 can move in all directions across the curved surface. Fig. If the Target 150 transmits a discernible curvature, then it can perform a movement along a spherical segment.

[0052] Embodiments therefore provide that the movable component 170 together with the target 150 can be deflected along both the first coordinate line 151 and simultaneously along the second coordinate line 152 on curved paths, so that the target 150 performs a pivoting movement in two degrees of freedom, the resulting movement space of the target 150 being spherical segment-shaped.

[0053] Although the target 150 is movable in all directions across the curved surface, it may be sufficient to provide a second straight and curved excitation coil 211 and a second straight and curved receiving coil arrangement 220 to determine the current actual position of the target 150.

[0054] As in Fig. As shown in Figure 9, the inductive position measuring system 100 can, for example, have a second excitation coil 211, which is essentially identical in design to the first excitation coil 111 described above. Furthermore, the position measuring system 100 can have a second receiving coil arrangement 220, which is also essentially identical in design to the first receiving coil arrangement 120 described above. That is, the second receiving coil arrangement 220 can also have one astatic sine coil and one astatic cosine coil.

[0055] The second excitation coil 211 and the second receiving coil arrangement 220 are again shown here only in a simplified form. However, they essentially correspond to the exemplary arrangement as shown in Fig. 5 is shown.

[0056] Furthermore, an additional coil arrangement 600 can optionally be provided here as well, which essentially corresponds to the previously described optional additional coil arrangement 500 in order to obtain a finer subdivision in the position determination.

[0057] While the first excitation coil 111 and the first receiving coil assembly 120 are arranged to extend along the first curved polar coordinate line 151, the second excitation coil 211 and the second receiving coil assembly 220 can be arranged to extend along the second curved polar coordinate line 152.

[0058] The first curved polar coordinate line 151 runs orthogonally to the second curved polar coordinate line 151. Accordingly, the second excitation coil 211 and the second receiving coil arrangement 220 can also be positioned orthogonally to the first excitation coil 111 and the first receiving coil arrangement 120. This results in a cross-shaped arrangement, as exemplified in Fig. 9 is shown.

[0059] Thus, the position measuring system 100 according to the invention can determine the current actual position of the target 150 along the first coordinate line 151 by means of the first excitation coil 111 and the associated first receiving coil arrangement 120. Additionally, the position measuring system 100 can determine the current actual position of the target 150 along the second coordinate line 152, which runs orthogonally to it, by means of the second excitation coil 211 and the associated second receiving coil arrangement 220.

[0060] The inductive position measuring system 100 can be designed to combine the output signals of the first receiving coil arrangement 120 and the output signals of the second receiving coil arrangement 220 in order to derive coordinates (e.g. polar coordinates in spherical space) that indicate the current actual position of the target 150 on the curved surface.

[0061] This would correspond to a two-dimensional position determination (e.g., in the x and y directions) within a plane. According to such an embodiment, which has a second excitation coil 211 and an associated second receiving coil arrangement 220, the current actual position of the target 150 can be determined over the entire curved surface.

[0062] The second excitation coil 210 and the second receiving coil arrangement 220 can also be arranged on the flexible substrate 110. The flexible substrate 110 can, for example, be configured in a cross shape, with the respective coils 111, 120, 211, 220 each being arranged on the four arms of the cross.

[0063] The second excitation coil 210 and the second receiving coil arrangement 220 could also be arranged on a second flexible substrate (not explicitly shown here), whereby the first and the second flexible substrate could cross each other, as shown.

[0064] The flexible substrate 110 and, if present, the optional second flexible substrate, could each be arranged on the larger substrate 310. However, it would also be conceivable that the flexible substrate 110 has the shape of the larger substrate 310 shown here as an example. That is, the entire substrate 310 shown here would correspond to the flexible substrate 110 described herein. Thus, the first excitation coil 111, the first receiving coil assembly 120, the second excitation coil 211, and the second receiving coil assembly 220 would again be arranged on the flexible substrate 110.

[0065] The second excitation coil 211 and the second receiving coil assembly 220 can be coupled to the previously described control unit 160 (e.g., ASIC) for signal processing purposes. As shown in Fig. As shown in Figure 9 as an example, it would also be conceivable that a second control unit 161 could be provided, which could be coupled to the second excitation coil 211 and the second receiving coil arrangement 220 for the purpose of signal processing.

[0066] In the case of the second excitation coil 211 and the second receiving coil arrangement 220, the target 150 should also be advantageously dimensioned such that its circumference surrounds the second excitation coil 211 and the second receiving coil arrangement 220 at least partially in a top view when the target 150 moves along the second coordinate line 152.

[0067] This means that the target 150 always surrounds a portion of the second excitation coil 211 and the second receiving coil arrangement 220 when the target 150 moves. This ensures that the induction field and the counter-induction field are correctly established along the entire path of the target 150, in order to guarantee the previously described inductive measurement principle for determining the position of the target 150.

[0068] As previously mentioned, the target 150 can move along both the first coordinate line 151 and the second coordinate line 152 simultaneously. This allows the target 150 to move in all directions across the curved surface. The current position of the target 150 can be determined by processing the output signals of both the first receiving coil arrangement 120 and the second receiving coil arrangement 220 to calculate the coordinates that represent the target 150's current position (comparable to x and y values ​​in a plane).

[0069] Therefore, it is advantageous if the target 150 is dimensioned such that its circumference always surrounds both the first excitation coil 111 and the first receiving coil arrangement 120, as well as the second excitation coil 211 and the second receiving coil arrangement 220, even when the target 150 moves along the first coordinate line 151 and simultaneously along the second coordinate line 152. Thus, output signals from the first and second receiving coil arrangements 120 and 220 can be received along the entire path of movement of the target 150 in order to determine the coordinates of the target 150, and therefore its current position on the curved surface.

[0070] Even if the target 150 is deflected along the first coordinate line 151 up to a certain point (e.g. maximum), the target 150 should still (at least partially) cover the second excitation coil 211 and the associated second receiving coil arrangement 220 in order to obtain an output signal from the second receiving coil arrangement 220 for calculating the coordinates of the target 150.

[0071] The same applies to a deflection of the target 150 along the second coordinate line 152. That is, even if the target 150 is deflected along the second coordinate line 152 up to a certain point (e.g., maximum), the target 150 should still (at least partially) cover the first excitation coil 111 and the associated first receiving coil arrangement 120 in order to obtain an output signal from the first receiving coil arrangement 120 for calculating the coordinates of the target 150.

[0072] Exemplary embodiments therefore provide that the target 150 is dimensioned such that its circumference at least partially surrounds the first excitation coil 111 and the first receiving coil arrangement 120 in a top view, even when the target 150 moves along the second coordinate line 152 to a predetermined (e.g., maximum) displacement. Alternatively or additionally, the target 150 can be dimensioned such that its circumference at least partially surrounds the second excitation coil 211 and the second receiving coil arrangement 220 in a top view, even when the target 150 moves along the first coordinate line 151 to a predetermined (e.g., maximum) displacement.

[0073] A non-limiting exemplary implementation of Target 150 is described in the Fig. 10 and Fig. 11 shown. As in Fig. As can be seen in Figure 10, the target 150 can be designed as a single piece, wherein the target 150 is positioned in an undisplaced rest position opposite a crossing point where the first excitation coil 111 and the first receiving coil arrangement 120 cross with the second excitation coil 211 and the second receiving coil arrangement 220.

[0074] The target 150 can, for example, have such a large area that the circumference of the target 150 always covers both the first excitation coil 111 and the first receiving coil arrangement 120 as well as the second excitation coil 211 and the second receiving coil arrangement 220.

[0075] In Fig. Figure 11 shows the target 150 at its maximum displacement along the first coordinate line 151 and along the second coordinate line 152. The maximum displacement along the first coordinate line 151 is indicated by the marker line shown in dashed lines. 151The maximum deflection along the second coordinate line 152 is marked with the marker line max, which is also shown in dashed lines. 152 marked.

[0076] The area of ​​the target 150 is sufficiently large that its circumference still covers part of the second excitation coil 211 and the second receiving coil assembly 220, even when the target 150 is deflected maximally along the first coordinate line 151. Furthermore, the area of ​​the target 150 is sufficiently large that its circumference still covers part of the first excitation coil 111 and the first receiving coil assembly 120, even when the target 150 is deflected maximally along the second coordinate line 152.

[0077] However, it may be that the target 150 cannot be dimensioned that large, for example due to installation space limitations, or due to limited space for mounting it on the moving component 170 itself. In this case, it may be advantageous to use a multi-part target 150.

[0078] Fig. Figure 12 shows a non-limiting example of a multi-part target 150 in an undisplaced rest position. The target 150 has a first target section 101 positioned opposite a crossing point where the first excitation coil 111 and the first receiving coil assembly 120 intersect with the second excitation coil 211 and the second receiving coil assembly 220.

[0079] The target 150 further comprises a second target section 102, which is positioned on a diagonal 230 running through the intersection and through the first target section 101. The second target section 102 can be mechanically connected to the first target section 101. The second target section 102 can be directly adjacent to the first target section 101, as shown by way of example in Fig. Figure 12 shows that the second target section 102 can also be arranged at a distance from the first target section 101, as exemplified in Figure 12. Fig. 13 is shown.

[0080] The target 150 further comprises a third target section 103, which is also positioned on this diagonal 230, but is arranged opposite the second target section 102 when viewed from the first target section 101. The third target section 103 can also be mechanically connected to the first target section 101. The third target section 103 can be directly adjacent to the first target section 101, as shown by way of example in Fig. Figure 12 shows that the third target section 103 can also be arranged away from the first target section 101, as exemplified in Figure 103. Fig. 13 is shown.

[0081] This arrangement of the individual target sections 101, 102, 103 results in a multi-part target 150 with a geometric shape approximately resembling a double figure eight. This yields a stronger output signal at the respective receiving coil arrangements 120, 220.

[0082] Furthermore, the area or overall size of the target can be 150 compared to that in Fig. The size of the target 150 can be significantly reduced in the embodiment shown in Figure 11. Nevertheless, this special geometry of the target 150 ensures that the circumference of the target 150 still covers part of the second excitation coil 211 and the second receiving coil arrangement 220, even when the target 150 is deflected maximally along the first coordinate line 151.

[0083] For example, the second target section 102 can cover the lower part of the second excitation coil 211 and the second receiving coil assembly 220, even if the target 150 were deflected maximally to the left (along the first coordinate line 151). Conversely, the third target section 103 can cover the upper part of the second excitation coil 211 and the second receiving coil assembly 220, even if the target 150 were deflected maximally to the right (along the first coordinate line 151).

[0084] Furthermore, this special geometry of the target 150 ensures that the circumference of the target 150 still covers part of the first excitation coil 111 and the first receiving coil arrangement 120, even when the target 150 is deflected maximally along the second coordinate line 152.

[0085] For example, the third target section 103 can cover the left part of the first excitation coil 111 and the first receiving coil assembly 120, even if the target 150 were deflected maximally downwards (along the second coordinate line 152). Conversely, the second target section 102 can cover the right part of the first excitation coil 111 and the first receiving coil assembly 120, even if the target 150 were deflected maximally upwards (along the second coordinate line 152).

[0086] It is also conceivable to have embodiments in which the multi-part target 150 has only two of the three target sections 101, 102, 103 shown here as examples. Likewise, embodiments in which the multi-part target 150 has more than the three target sections 101, 102, 103 shown here as examples would be conceivable.

[0087] In the embodiments discussed so far, the target 150 was designed as a solid, full-surface part. However, in all embodiments discussed herein, it would also be conceivable for the target 150 to be designed in the form of a ring-shaped geometric hollow body. Ring-shaped means that the body is closed in itself. The outer contour of the ring-shaped body can be arbitrary.

[0088] Thus, it could be, for example, a hollow rectangle, a hollow cylinder, and the like. For instance, the Target 150 could be designed in the form of a flat rectangle that is hollow inside, so that essentially only the outer contours of the rectangle consist of solid material. This can be achieved, for example, by stamping it out of a sheet-like material, such as a sheet of metal.

[0089] Fig. Figure 14 shows a non-limiting embodiment in which the target 150 is configured as a circular, annular hollow body. The circular hollow body can be flat, so that it has approximately the shape of a circular, annular plate. Alternatively, the circular hollow body can have a longitudinal extent, so that it essentially has the shape of a hollow cylinder.

[0090] Fig. Figure 15 shows another non-limiting embodiment. Here, the target 150 is designed in the form of a rectangular hollow body. The rectangular hollow body can be flat, so that it has approximately the shape of a rectangular ring-shaped plate. Alternatively, the rectangular hollow body can have a longitudinal extension, so that it essentially has the shape of a hollow cuboid.

[0091] In all embodiments, it is advantageous if the target 150 comprises metal or consists of metal. For example, the target 150 can be designed in the form of a metal plate or in the form of a metallization arranged on a support substrate.

[0092] The innovative concept described herein will be summarized below. The inductive position measuring system 100 according to the invention enables the measurement of two-dimensional movement based on inductive measurement technology. This can be achieved by means of two sets of PCB coils 111, 120, 211, 220 arranged perpendicular to each other, flexible PCBs 110, and metallic targets 150 in a hollow ring or rectangular shape.

[0093] The two-dimensional motion just mentioned is a movement along an x- and y-axis in a two-dimensional coordinate system. Due to the bending or curvature of the x- and y-axes of the linear motion system, the movement of a joint in a spatial coordinate system can be calculated, provided that the constant bending radius of the curved substrate 110 is known.

[0094] When a diagonal movement is performed, all axes may be involved, and different embodiments may be required to achieve accurate position determination using the inductive position measuring system 100.

[0095] An inductive position sensor according to the invention can comprise a first and second transmitter coil Tx (excitation coil 111, 211) as well as two receiver coil arrangements 120, 220, each with two receiver coils Rx, Ry 121, 122; 221, 222 and a metallic target 150, which covers at least the Rx, Ry coil amplitudes. The Rx, Ry receiver coils 121, 122; 221, 222 can be sinusoidal (Rx) or cosine (Ry) coils.

[0096] To determine an absolute position, one period of the sinusoidal and cosinusoidal receiving coils 121, 122; 221, 222 should pass through the line of motion (trajectory) of the joint (featuring the metallic target 150).

[0097] In the Fig. As shown in the example 6, it is possible to increase the accuracy for two-dimensional movements with one or more channels, using a vernier principle, or by means of a multitude of sensor periods over the entire linear range.

[0098] To utilize the advantages of the inductive measuring principle for this type of two-dimensional movement, the innovative concept described herein provides that the substrate 110, e.g., in the form of a flexible PCB, is bent together with the coil system 111, 211, 120, 220 located on it. In some embodiments, thin laminate-based PCBs can be used. Advantageously, however, single-layer, double-layer, or multi-layer flexible PCBs can also be used. With such flexible boards, different shapes and cuts can be made to cover the circular range of motion below the joint, which in Fig.4 is symbolized by reference numerals 110 and 151. With such flexible PCBs, it is also possible to easily laminate the flexible PCB three-dimensionally onto a circular base, which can be made of various materials: plastic composites, etc. For example, a flexible PCB can be glued onto a plastic half-tube.

[0099] Another important aspect concerns the geometry of the target 150. In the present inductive position measuring system 100, circular or rectangular targets 150 can be used. In some embodiments, the target 150 is designed in the form of a metal rectangle, the width of which is determined depending on the linear range of motion and the required accuracy. Preferably, hollow rectangles and circles with a specific frame width can be used to cover the required area below the target 150. In this way, the induced current is enabled to induce an oppositely directed field in the receiving coil arrangements 120, 220, which allows for position determination.

[0100] The Target 150 can also be designed as a plastic part with a metallization layer. This metallization layer can consist of different metallic alloys to improve the sensor's properties: Ni-Au-Cu-Al alloys or combinations of one, two, or more elements are possible.

[0101] The innovative Position Measuring System 100 described herein has the potential to drastically reduce the costs of joint position determination in robots while simultaneously increasing position accuracy. Possible applications include robotics in virtually all sectors, as well as all conceivable joystick applications and any application where complex mechanical systems are currently required to translate movements to similar sensor concepts.

[0102] Thus, the innovative concept presented here enables the detection of two-dimensional movements using inductive sensors and the provision of linear encoding for these two-dimensional movements. The linear motion can then be translated into multidimensional signal processing.

[0103] The innovative inductive position measuring system 100 presented here can also be designed in the form of the following embodiments, which can be combined with all other embodiments described herein.

[0104] According to one embodiment, the substrate 110 can be strip-shaped, wherein the straight excitation coil 110 and the straight receiving coil arrangement 120 each extend in the same direction as the strip-shaped substrate 110.

[0105] According to another embodiment, the strip-shaped substrate 110 can be curved along its longitudinal direction.

[0106] According to another embodiment, the substrate 110 can be designed as a single-layer or multi-layer flexible film substrate.

[0107] According to another embodiment, the second excitation coil 211 and the second receiving coil arrangement 220 can be arranged on a second flexible and curved substrate.

[0108] According to another embodiment, the strip-shaped second substrate can be curved along its longitudinal direction.

[0109] According to a further embodiment, this second substrate can be strip-shaped, wherein the straight-running second excitation coil 211 and the straight-running second receiving coil arrangement 220 each extend in the same direction as the strip-shaped second substrate.

[0110] According to another embodiment, the second substrate can be designed as a single-layer or multi-layer flexible film substrate.

[0111] According to a further embodiment, the first receiving coil arrangement 120 can have at least a first receiving coil 121 (e.g., sine coil) and a second receiving coil 122 (e.g., cosine coil) arranged offset thereto, and / or the second receiving coil arrangement 220 can have at least a third receiving coil 221 (e.g., sine coil) and a fourth receiving coil 222 (e.g., cosine coil) arranged offset thereto.

[0112] According to a further embodiment, the excitation coil 111 can be configured to be supplied with an electrical signal in order to generate an induction field that causes an electric current flow in the metallic target 150, wherein the metallic target 150 can be configured to generate an induction field in response to the current flow, which couples into the first receiving coil arrangement 120, whereupon the first receiving coil 121 generates a first output signal and the second receiving coil 122 generates a second output signal, wherein the first and the second output signals depend on the position of the target 150 relative to the receiving coil arrangement 120, and wherein the inductive position measuring system 100 can further comprise a control unit 160 configured to combine the first and second output signals (e.g.,using the tan function) to determine the position of target 150 based on the result of this combination.

[0113] According to a further embodiment, the second excitation coil 211 can be configured to be supplied with an electrical signal in order to generate an induction field that causes an electric current flow in the metallic target 150, wherein the metallic target 150 can be configured to generate an induction field in response to the current flow, which couples into the second receiving coil arrangement 220, whereupon the third receiving coil 221 generates a third output signal and the fourth receiving coil 222 generates a fourth output signal, wherein the third and fourth output signals depend on the position of the target 150 relative to the receiving coil arrangement 220, and wherein the inductive position measuring system 100 can further comprise a control unit 161 configured to combine the third and fourth output signals (e.g.,using the tan function) to determine the position of target 150 based on the result of this combination.

[0114] The embodiments described above 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 obvious to other people skilled in the art. Therefore, it is intended that the concept described herein be limited only by the scope of protection set forth in the following patent claims and not by the specific details presented herein by way of description and explanation of the embodiments.

[0115] Although some aspects have been described in connection with a device, it is understood that these aspects also constitute a description of the corresponding process, so that a block or component of a device is also to be understood as a corresponding process step or as a feature of a process step. Similarly, aspects described in connection with or as a process step also constitute a description of a corresponding block, detail, or feature of a corresponding device.

Claims

[1] Inductive position measuring system (100), comprising: a flexible substrate (110) with a first excitation coil (111) and a first receiving coil arrangement (120), wherein the first excitation coil (111) and the first receiving coil arrangement (120) each run in a straight line along the substrate (110), a second excitation coil (211) and a second receiving coil arrangement (220), wherein the second excitation coil (211) and the second receiving coil arrangement (220) each run in a straight line, a metallic target (150) spaced apart from the substrate (110), which is configured to provide inductive coupling between the first excitation coil (111) and the first receiving coil arrangement (120) and between the second excitation coil (211) and the second receiving coil arrangement (220), wherein the actual position of the target (150) can be determined based on this inductive coupling, wherein the target (150) can be attached to a component (170) that is movable relative to the substrate (110), the position of which is to be determined, wherein the movable component (170) together with the target (150) can be deflected along a curved path along a first and a different second coordinate line (151, 152), and wherein the substrate (110) is curved, such that the straight first excitation coil (111) and the straight first receiving coil arrangement (120) are also curved and extend parallel to the first coordinate line (151), and wherein the straight second excitation coil (211) and the straight second receiving coil arrangement (220) are each curved and extend along the second coordinate line (152). [2] Inductive position measuring system (100) according to claim 1, wherein the straight-running first excitation coil (111) and the straight-running first receiving coil arrangement (120) each extend along the motion trajectory of the target (150) when the target (150) moves along the first coordinate line (151). [3] Inductive position measuring system (100) according to claim 1 or 2, wherein the curvature of the substrate (110) substantially corresponds to the curvature of the curved track (151) on which the target (150) moves, such that the target (150) moves with a substantially constant air gap relative to the first excitation coil (111) and the first receiving coil arrangement (120). [4] Inductive position measuring system (100) according to one of claims 1 to 3, wherein the first coordinate line (151) is a curved polar coordinate line, such that the target (150) which can be deflected along the first coordinate line (151) moves on a circular path segment. [5] Inductive position measuring system (100) according to one of claims 1 to 4, wherein the target (150) is dimensioned such that its circumference surrounds the first excitation coil (111) and the first receiving coil arrangement (120) at least partially in a top view when the target (150) moves along the first coordinate line (151). [6] Inductive position measuring system (100) according to one of the preceding claims, wherein the first coordinate line (151) and the second coordinate line (152) are orthogonal to each other, so that the first excitation coil (111) and the first receiving coil arrangement (120) are arranged orthogonally to the second excitation coil (211) and the second receiving coil arrangement (220). [7] Inductive position measuring system (100) according to one of the preceding claims, wherein the movable component (170) together with the target (150) can be deflected along both the first coordinate line (151) and the second coordinate line (152) on curved paths, so that the target (150) performs a pivoting movement in two degrees of freedom, wherein the resulting movement space of the target (150) is spherical segment-shaped. [8] Inductive position measuring system (100) according to one of the preceding claims, wherein the target (150) is dimensioned such that its circumference surrounds the second excitation coil (211) and the second receiving coil arrangement (220) at least partially in a top view when the target (150) moves along the second coordinate line (152). [9] Inductive position measuring system (100) according to one of the preceding claims, wherein the target (150) is dimensioned such that its circumference surrounds both the first excitation coil (111) and the first receiving coil arrangement (120) as well as the second excitation coil (211) and the second receiving coil arrangement (220) at least partially in a top view when the target (150) moves along the first and the second coordinate lines (151, 152). [10] Inductive position measuring system (100) according to one of claims 1 to 8, wherein the target (150) is dimensioned such that its circumference at least partially surrounds the first excitation coil (111) and the first receiving coil arrangement (120) in a top view, even when the target (150) moves up to a predetermined deflection along the second coordinate line (152), and / or wherein the target (150) is dimensioned such that its circumference surrounds the second excitation coil (211) and the second receiving coil arrangement (220) at least section by section in a top view, even when the target (150) moves along the first coordinate line (151) to a predetermined deflection. [11] Inductive position measuring system (100) according to one of the preceding claims, wherein the target (150) is designed in the form of a metal plate or in the form of a metallization arranged on a support substrate. [12] Inductive position measuring system (100) according to one of claims 1 to 10, wherein the target (150) is designed in the form of a geometric hollow body. [13] Inductive position measuring system (100) according to one of the preceding claims, wherein the target (150) is designed as a single piece, wherein the target (150) is positioned in an undisplaced rest position opposite a crossing point where the first excitation coil (111) and the first receiving coil arrangement (120) cross with the second excitation coil (211) and the second receiving coil arrangement (220). [14] Inductive position measuring system (100) according to one of claims 1 to 12, wherein the target (150) is designed in multiple parts, wherein in an undisplaced rest position of the target (150): • a first target section (101) is positioned opposite a crossing point where the first excitation coil (111) and the first receiving coil assembly (120) cross with the second excitation coil (211) and the second receiving coil assembly (220), and • a second target section (102) is positioned on a diagonal (230) running through the intersection point and through the first target section (101), and • a third target section (103) is also positioned on this diagonal (230), but is located opposite the second target section (102) when viewed from the first target section (101).

Images