Two-dimensional magnet-based positioning system and method for performing magnet-based position determination

Abstract

Disclosed is a magnet-based positioning system comprising an axially magnetized magnet (110), wherein two opposing magnetic poles (112, 113) are arranged along a common z-axis (111), and a magnetic sensor arrangement which is axially spaced from the magnet (110) and is configured to determine magnetic field vectors (141, 142) in an xy-plane (130) perpendicular to the common z-axis (111).The magnetic sensor arrangement is configured to determine a first magnetic field vector (141) at a first, as yet unknown, position (x1 | y1) in the xy-plane (130), and to determine a second magnetic field vector (142) at another, second, as yet unknown position (x2 | y2) in the xy-plane (130), and to determine an actual xy-position of the magnetic sensor arrangement relative to the magnet (110) based on the first and second magnetic field vectors (141, 142) and based on a known relative spatial distance (dx | dy) between the first, as yet unknown position (x1 | y1) and the second, as yet unknown position (x2 | y2).

Description

[0001] Embodiments of the present disclosure relate to a magnet-based positioning system and a method for magnet-based position determination. The innovative concept uses a two-dimensional approach, determining magnetic field vectors in a two-dimensional xy plane. Technical background

[0002] In some applications, it is useful to determine the precise position of a magnet relative to a magnetic sensor. For example, wireless charging of autonomous robots may require the robots to position themselves toward a wireless charging module at an optimal position for the highest charging efficiency. Accordingly, autonomous robots that need to be charged need to know where to go and how to position themselves within the charging bay.

[0003] Magnetic solutions are already known, where the robots incorporate a magnetic sensor array to locate a magnet installed at the loading location. However, these concepts employ a time- and energy-consuming iterative approach, requiring a robot to move step by step closer to the magnet. Other magnet-based positioning systems require initial calibration and further periodic on-site calibrations, as these can be temperature-dependent or dependent on the absolute magnetic field strength.

[0004] It would therefore be desirable to improve existing magnetic-based positioning systems so that they do not require on-site calibration, enable high-precision positioning, and are energy- and cost-efficient.

[0005] This object is achieved by the magnet-based positioning system disclosed herein and the corresponding method for performing magnet-based position determination according to the independent claims. Further embodiments and advantageous aspects are proposed in the dependent claims.

[0006] The innovative magnet-based positioning system comprises an axially magnetized magnet, with two opposing magnetic poles arranged along a common z-axis, and a magnetic sensor array axially spaced from the magnet. The magnetic sensor array is configured to determine magnetic field vectors in an xy-plane perpendicular to the common z-axis, wherein the magnetic field vectors represent the direction of radiated magnetic field lines in the xy-plane. The magnetic sensor array is configured to determine a first magnetic field vector at a first, yet unknown position (e.g., specified by first xy-coordinates (x1 | y1)) in the xy-plane and to determine a second magnetic field vector at another, second, yet unknown position (e.g., specified by second xy-coordinates (x2 | y2)) in the xy-plane.The magnetic sensor assembly is further configured to determine an actual xy position of the magnetic sensor assembly relative to the magnet based on the first and second magnetic field vectors and based on a known relative spatial distance between the first yet unknown position and the second yet unknown position.

[0007] The corresponding innovative method for performing magnet-based position determination comprises a step of providing an axially magnetized magnet, wherein two opposing magnetic poles are arranged along a common z-axis, and a step of providing a magnetic sensor arrangement that is axially spaced from the magnet and configured to determine magnetic field vectors in an xy-plane perpendicular to the common z-axis, wherein the magnetic field vectors represent the direction of radiated magnetic field lines in the xy-plane. The method further comprises a step of determining a first magnetic field vector at a first, yet unknown position (e.g., specified by first xy-coordinates (x1 | y1)) in the xy-plane and determining a second magnetic field vector at another, second, yet unknown position (e.g., specified by second xy-coordinates (x2 | y2)) in the xy-plane.The method further comprises a step of determining an actual xy position of the magnetic sensor arrangement relative to the magnet based on the first and second magnetic field vectors and based on a known relative spatial distance between the first yet unknown position and the second yet unknown position.

[0008] Accordingly, although the two positions of the magnetic sensor array are still unknown, the magnetic sensor array can accurately calculate its own position relative to the magnet by only having knowledge of the spatial distance between the two still unknown positions and by combining both magnetic field vectors in a suitable manner.

[0009] According to a further aspect, computer programs are provided, wherein each of the computer programs is configured to implement the method described above when executed on a computer or signal processor, such that the method described above is implemented by one of the computer programs.

[0010] In the following, embodiments of the present disclosure are described in more detail with reference to the figures. They show: Fig. 1A is a schematic perspective view of a well-known axially magnetized permanent magnet, Fig. 1B is a schematic perspective view of a well-known diametrically magnetized permanent magnet, Fig. 2A shows an embodiment of a magnet-based positioning system having an axially magnetized magnet and an axially spaced xy sensor plane perpendicular to the magnetization axis of the magnet, wherein radiated magnetic field lines are schematically illustrated, Fig. 2B is a schematic representation of magnetic field lines emitted by the magnet, seen from the xy sensor plane, Fig. 3A an example of an axially magnetized magnet, but with an xz sensor plane parallel to the magnetization axis of the magnet, with radiated magnetic field lines shown schematically, Fig. 3B is a schematic representation of magnetic field lines emitted by the magnet, seen from the xy sensor plane, Fig. 4 a schematic representation of magnetic field lines and magnetic field vectors in the xy plane with a magnetic sensor arrangement comprising two magnetic sensor elements, according to an embodiment, Fig. 5 another schematic representation of the magnetic field lines and magnetic field vectors of Fig. 4 according to an embodiment, Fig. 6 a schematic representation of magnetic field lines and magnetic field vectors in the xy plane with a magnetic sensor arrangement comprising a single magnetic sensor element, according to an embodiment, Fig. 7 is a schematic representation of magnetic field lines and magnetic field vectors in the xy plane with a magnetic sensor arrangement configured to solve ambiguity problems caused by two identical magnetic field angles, according to one embodiment, and Fig. 8 a schematic block diagram of an innovative method according to an embodiment. Description of the characters

[0011] The same or equivalent elements or elements with the same or equivalent functionality are designated by the same or equivalent reference numerals in the following description.

[0012] Although some aspects are described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, with a block or device corresponding to a method step or a feature of a method step. Similarly, aspects described in connection with a method step also represent a description of a corresponding block, element, or feature of a corresponding device.

[0013] Method steps illustrated by means of a block diagram and described with reference to the block diagram may also be performed in an order that differs from the illustrated and / or described order. Furthermore, method steps relating to a specific feature of a device may be interchangeable with the feature of the device, and vice versa.

[0014] Furthermore, an xyz coordinate system is shown to facilitate understanding of the following description. The z-axis shown corresponds to the magnetization axis of the axially magnetized magnet. Accordingly, the terms z-axis and magnetization axis can be used interchangeably in the following description.

[0015] Some applications require precise position adjustment of two devices relative to each other. For example, high-precision positioning applications require the precise positioning of fixtures or the like in machines for industrial or medical applications. Another application area includes active motion compensation, where readjustment may be necessary due to environmental disturbances in optical applications. Furthermore, quick and accurate adjustments in the workflow / production may be required, e.g., by readjusting a tool head in food production or on an assembly line. Even further, near-field navigation may require precise position adjustment, e.g., autonomous robots navigating to an optimal wireless charging position.

[0016] For such positioning tasks, magnetic solutions are known that combine a magnet and a magnetic sensor. Conventional magnetic positioning systems use the magnet's magnetic field strength to adjust the relative position between the sensor and the magnet—that is, the higher the field strength, the closer the distance between the magnet and the sensor. However, such magnet-based positioning systems require initial calibration and further periodic on-site calibrations, as these calibrations can be temperature-dependent or dependent on the absolute magnetic field strength.

[0017] Instead, this innovative concept is independent of the magnetic field strength. It uses an angular calculation of at least two magnetic field vectors. Thus, it is independent of temperature and absolute magnetic field strength, making it calibration-free. Furthermore, xMR sensors (e.g., TMR, AMR, GMR, etc.) can be used for this innovative concept, with the sensors requiring only low power and featuring intrinsic, low-noise behavior.

[0018] For a brief introduction, Fig. 1A shows an axially magnetized cylindrical magnet 110, characterized in that its north pole 112 and south pole 113 are arranged along a vertical axis 111 extending through the magnet 110 along its height h, i.e., perpendicular to its diameter d. In other words, the north pole 112 and south pole 113 of the magnet are arranged at the top and bottom of the magnet 110, respectively. The vertical axis 111 can also be referred to as a vertical magnetization axis.

[0019] Fig. Figure 1B, in turn, shows a diametrically magnetized cylindrical magnet 210, characterized in that its north pole 212 and south pole 213 are arranged along a diametrical axis 211 extending along the diameter d of the magnet 210, i.e., perpendicular to its height h. In other words, the north pole 212 and south pole 213 of the magnet are arranged on the left and right sides of the magnet 210. The diametrical axis 211 can also be referred to as a diametrical magnetization axis.

[0020] Fig. Figure 2A shows an embodiment of an innovative magnet-based positioning system 100. It comprises an axially magnetized magnet 110. The axially magnetized magnet 110 may have a symmetrical cylindrical or ring shape, although other geometric shapes are also possible. Two opposing magnetic poles 112, 113 of the magnet 110 are arranged along a common z-axis 111, which corresponds to the magnetization axis of the magnet 110 described above. A coordinate system 150, which is Fig. 2A, shows the orientation of the z-axis 110. In this example, the z-axis 111 extends vertically through the magnet 110 along its height h (see Fig. 1A).

[0021] As can be seen, a plurality of magnetic field lines 140 radiate from the magnet 110 in a manner known in the art. As can also be seen, Fig. 2A illustrates an xy-plane 130, wherein the xy-plane is spanned such that it extends perpendicular to the aforementioned z-axis 111 (magnetization axis). Specifically, each of an x-axis and a y-axis of the xy-plane 130 is perpendicular to the z-axis 111 (magnetization axis). Accordingly, the xy-plane 130 is perpendicular to the magnetization axis 111 of the magnet 110.

[0022] The xy-plane 130 is spaced axially, i.e., along the z-axis 111 (magnetization axis), from the magnet 110. In this non-limiting example, the xy-plane 130 is located above the magnet 110. However, it may also be possible for the xy-plane 130 to be located below the magnet 110.

[0023] The xy-plane 130 represents a sensor plane, i.e., a plane in which an innovative magnetic sensor array (not shown here) is arranged. Accordingly, the innovative magnet-based positioning system 100 comprises a magnetic sensor array axially spaced from the magnet 110. It can be said that the magnet 110 and the magnetic sensor array are arranged in two different, spaced-apart xy-planes.

[0024] As described further below, some embodiments may provide a magnetic sensor arrangement comprising a single magnetic sensor element, or exactly two magnetic sensor elements, or exactly three magnetic sensor elements. More than three magnetic sensor elements may also be possible.

[0025] The innovative magnetic sensor arrangement is configured to determine magnetic field vectors in the xy-plane 130, wherein the magnetic field vectors represent the direction of the emitted magnetic field lines 140 in the xy-plane 130. The magnetic field lines 140 themselves have a magnitude and a direction. Thus, they can also be referred to as magnetic field vectors, and the magnetic field can be referred to as a magnetic field vector field. The innovative magnetic sensor arrangement can be configured to measure the direction and optionally also the magnitude of the magnetic field vectors 140.

[0026] Fig. Figure 2B shows a top view of the magnet 110 from the xy-plane 130. Since the xy-plane 130 is perfectly orthogonal to the z-axis 111, the magnetic field vectors 140 are perfectly symmetrical, namely perfectly radial with respect to the center 114 of the magnet 110. In other words, the magnetic field vectors 140 of the axially magnetized magnet 110 always point toward or away from the center 114 of the magnet 110. This is also what the magnetic sensor array sees. A major advantage of this configuration is the fact that the symmetry of the magnetic field vectors 140 does not depend on the magnetic field strength, i.e., the magnetic sensor array always sees the same radial pattern of the magnetic field vectors 140, regardless of the magnetic field strength of the magnet 110.

[0027] Fig. 3A and Fig. 3B show a scenario in which a sensor array is arranged in an xz-plane 131. In contrast to Fig. 2A and Fig. 2B, the xz-plane 130 is not perpendicular but parallel to the magnetization axis 111 of the magnet 110. The same applies to a yz-plane (not shown).

[0028] In such parallel planes, the magnetic field vectors 140 are not perfectly radial, but instead are curved, with the curves pointing toward or away from the magnet 110. The same applies to a yz-plane. The curved pattern of the magnetic field vectors 140 depends strongly on the magnetic field strength. Without calibration, it is nearly impossible to accurately determine the position of the magnet 110 using a magnetic sensor arranged in a plane 131 aligned parallel to the magnetic axis 111 of the magnet 110.

[0029] Fig. Figure 4 shows a view from the xy plane 130, as previously described with reference to the Fig. 2A and Fig. 2B. As an example, an autonomous robot may be equipped with the magnetic sensor assembly, while a charging location may be equipped with the magnet 110, or vice versa. The illustrated xy-plane 130 in which the magnetic sensor assembly is arranged is perpendicular to the magnetic axis 111 of the axially magnetized magnet 110. Accordingly, the magnetic sensor assembly provided on the robot sees the magnetic field vectors 140, as exemplified in Fig. 4. With the innovative concept discussed here, the robot can precisely determine its position and / or orientation and / or position relative to the magnet 110 provided at the charging location. Thus, the robot can move to an optimal charging position relative to the magnet 110.

[0030] In the Fig. In the embodiment shown in Figure 4, the sensor arrangement can comprise a first magnetic sensor element 151 and a second magnetic sensor element 152. The first magnetic sensor element 151 is located at a first, as yet unknown position, which is indicated by way of example with a first xy coordinate (x1 | y1) in the xy plane 130. The second magnetic sensor element 152 is located at another, second, as yet unknown position, which is indicated by way of example with a second xy coordinate (x2 | y2) in the xy plane 130. The positions (x1 | y1) and (x2 | y2) of the magnetic sensor elements 151, 152 are unknown with respect to the position of the magnet 110, i.e., the relative position between the magnetic sensor arrangement and the magnet 110 is still unknown.

[0031] The first and second magnetic sensor elements 151, 152 are spaced apart from each other, with a known spatial distance (dx | dy) between the first and second magnetic sensor elements 151, 152 of the magnetic sensor array. Accordingly, the spatial distance between the first magnetic sensor element 151 and the second magnetic sensor element 152 defines a known relative distance (dx | dy) between the first, yet unknown, position (x1 | y1) and the second, yet unknown position (x2 | y2).

[0032] The magnetic sensor arrangement is configured to determine a first magnetic field vector 141 at the first, still unknown position (x1 | y1) in the xy-plane 130, e.g., by means of the first magnetic sensor element 151. The magnetic sensor arrangement is further configured to determine a second magnetic field vector 142 at the other, second, still unknown position (x2 | y2) in the xy-plane 130, e.g., by means of the second magnetic sensor element 152. Other embodiments with only a single magnetic sensor element or with three different magnetic sensor elements are discussed further below.

[0033] According to the innovative concept, the magnetic sensor arrangement is configured to determine an actual xy position of the magnetic sensor arrangement relative to the magnet 110 based on the aforementioned first and second magnetic field vectors 141, 142 and based on the aforementioned known relative spatial distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2).

[0034] For example, the magnetic sensor array may be configured to determine its actual xy position based on a two-dimensional triangulation using the first and second magnetic field vectors 141, 142. The triangulation may be performed using the aforementioned known relative spatial distance (dx | dy) between the first, yet unknown, position (x1 | y1) and the second, yet unknown position (x2 | y2) in combination with two angles.

[0035] As in Fig. As can be seen in Figure 4, due to the perfect symmetry of the magnetic field lines 140 discussed above, each magnetic field vector 141, 142 can have a unique magnetic field angle α1, α2. The first magnetic field angle α1 describes an angle of the first magnetic field vector 141 that extends between the first, still unknown position (x1 | y1) and the common z-axis 111. The second magnetic field angle α2 describes an angle of the second magnetic field vector 142 that extends between the second, still unknown position (x2 | y2) and the common z-axis 111.

[0036] Since each magnetic field angle α always points to the center of the magnet 110, which is represented by the common z-axis 111, each magnetic field angle α can be calculated by the following equation: α=atan 2(yx)

[0037] However, distance information, i.e., a distance between the magnetic sensor array and the magnet 110, may still be missing. However, this can be resolved by measuring at multiple positions. In other words, by measuring the magnetic field angle α in the xy plane 130 at two or more locations, the exact position of the magnet 110 relative to the sensor array can be calculated using triangulation, as described below.

[0038] Fig. Figure 5 shows an embodiment of an innovative magnet-based positioning system 100 for calculating the missing distance information, i.e., the missing spatial distance between the magnetic sensor array and the magnet 110, where the missing distance information is exemplified by Δx and Δy. As mentioned above, the first position (x1 | y1) and the second position (x2 | y2) are both still unknown. Only the relative distance (dx | dy) between the first, still unknown position (x1 | y1) and the second, still unknown position (x2 | y2) is known to the magnetic sensor array.

[0039] Optionally, the first unknown position (x1 | y1) can be set as a zero point (0 | 0) in the xy-plane 130. Then, the second unknown position (x2 | y2) can be defined as (dx | dy), which specifies the known relative distance (dx | dy) between the first unknown position (x1 | y1) and the second unknown position (x2 | y2).

[0040] The missing distance information, ie the still unknown spatial distance between the magnetic sensor arrangement and the magnet 110, can now be determined by calculating a spatial distance Δx, Δy between the first magnetic sensor arrangement 151 and the common z-axis 111 (= magnetization axis), as shown by way of example in Fig. 5, and / or by calculating a spatial distance between the second magnetic sensor arrangement 152 and the common z-axis 111 (= magnetization axis). As mentioned above, alternative embodiments with only a single magnetic sensor element or with three different magnetic sensor elements are discussed below.

[0041] Accordingly, while the spatial distance between the first magnetic sensor arrangement 151 and the common z-axis 111 (= magnetization axis) can be defined as Δx, Δy, the spatial distance between the second magnetic sensor arrangement 152 and the common z-axis 111 (= magnetization axis) can be defined as Δx + dx, Δy + dy.

[0042] These coordinates can now be inserted into equation 1 above, where α1 defines the first magnetic field angle corresponding to the first magnetic field vector 141, and α2 defines the second magnetic field angle corresponding to the second magnetic field vector 142: tan(α1)=ΔxΔy tan(α2)=Δx+dxΔy+dy

[0043] As can be seen, the above equations have two unknowns, namely Δx and Δy. Thus, equations 2 and 3 for Δx and Δy can be solved by substitution according to the following equations: Δx=Δy⋅tan(α1) tan(α2)=Δy⋅tan(α1)+dxΔy+dy Δy⋅tan(α2)+dy⋅tan(α2)=Δy⋅tan(α1)+dx Δy⋅(tan(α2)−tan(α1))=dx−dy⋅tan(α2) Δy=dx−dy⋅tan(α2)tan(α2)−tan(α1) Δx=Δy⋅tan(α1)

[0044] Accordingly, the magnetic sensor arrangement can determine its actual xy position relative to the magnet 110 by calculating the spatial distance Δx, Δy between at least one of the first and second still unknown positions (x1 | y1), (x2 | y2) and the common z-axis 111 (= magnetization axis) based on the first and second magnetic field angles α1, α2 and based on the known relative distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2).

[0045] However, the above equations can only be solved if tan(α2) = tan(α1). Physically, this means that the first magnetic sensor element 151 and the second magnetic sensor element 152 must not be in a common line with the magnet 110. In other words, the first magnetic sensor element 151 and the second magnetic sensor element 152 should not lie on the same magnetic field line 140.

[0046] Fig. 6 shows an alternative embodiment in which only a single sensor element 151 is used to determine the actual xy position of the magnetic sensor arrangement relative to the magnet 110.

[0047] In this embodiment, the magnetic-based positioning system 100 can move the single magnetic sensor element 151 from the first, yet unknown position (x1 | y1) to the second, yet unknown position (x2 | y2) along a predetermined movement distance x = dx, y = dy. The predetermined movement distance x = dx, y = dy defines the aforementioned known relative distance (dx | dy) between the first, yet unknown position (x1 | y1) and the second, yet unknown position (x2 | y2).

[0048] As in Fig. 6, the individual magnetic sensor element located at the first still unknown position (x1 | y1) is designated by the reference numeral 151, while the individual magnetic sensor element located at the second still unknown position (x2 | y2) is designated by way of example by the reference numeral 151'.

[0049] According to the innovative concept, the magnetic sensor arrangement can determine the first magnetic field angle α1 when the single magnetic sensor element 151 is located at the first yet unknown position (x1 | y1), according to the following equation: α1=atan2(yx)

[0050] After moving the single magnetic sensor element 151 from the first unknown position (x1 | y1) to the second unknown position (x2 | y2), the magnetic sensor arrangement can determine the second magnetic field angle α2 according to the following equation: α2=atan2(yx)

[0051] When the individual magnetic sensor element 151 is moved from the first, still unknown position (x1 | y1) to the second, still unknown position (x2 | y2) by the known distance (dx | dy), the individual magnetic sensor element 151 should not be moved in one direction (forward / backward) along the current magnetic field line 140, since then the magnetic field angles α1, α2 would be identical. In other words, the magnet-based positioning system 100 can move the individual magnetic sensor element 151 in a direction that differs from the first magnetic field angle α1 (forward along the magnetic field line 140) and from the first magnetic field angle α1 plus / minus 180° (backward along the magnetic field line 140).

[0052] For example, the magnet-based positioning system 100 may move the single magnetic sensor element 151 in a direction perpendicular to the first magnetic field angle α1, as exemplified in Fig. 6 shown.

[0053] After calculating the first magnetic field angle α1 for the first magnetic field vector 141 according to equation 10 and the second magnetic field angle α2 for the second magnetic field vector 142 according to equation 11, the missing distance information Δx, Δy can be determined in the same way as in the above embodiment ( Fig. 4) can be calculated according to equations 2 to 7, which leads to the same following results as above: Δy=dx−dy⋅tan(α2)tan(α2)−tan(α1) Δx=Δy⋅tan(α1)

[0054] As mentioned above, the single magnetic sensor element 151 should not be moved in one direction (forward / backward) along the current magnetic field line 140, otherwise the first and second magnetic field angles α1, α2 would be identical, resulting in the above equations not being able to be solved. The same problem may occur if, in the above embodiment, two magnetic sensor elements 151, 152 ( Fig. 4) both magnetic sensor elements 151, 152 would be located on the same magnetic field line 140.

[0055] To solve such ambiguity problems, the two magnetic sensor elements 151, 152 ( Fig. 4) or the single magnetic sensor element 151 ( Fig. 6) be moved to a third still unknown position (x3 | y3) and the above calculations can be repeated using the third still unknown position (x3 | y3) instead of one of the first and second still unknown positions (x1 | y1) and (x2 | y2).

[0056] Accordingly, if the magnetic sensor assembly can determine that the first magnetic field angle α1 and the second magnetic field angle α2 are identical (or shifted by ± 180°), the magnet-based positioning system 100 can move the magnetic sensor assembly (with a single sensor element 151 or two sensor elements 151, 152) relative to the magnet 110 and can determine a new second magnetic field angle α2 at a third, yet unknown position (x3 | y3).

[0057] Of course, it may also be advantageous in this case to move the magnetic sensor arrangement in a direction that differs from the first or the second magnetic field angle α1, α2 (forward along the magnetic field line 140) and differs from the first or the second magnetic field angle α1, α2 ± 180° (backward along the magnetic field line 140).

[0058] Again, it may be advantageous to move the magnetic sensor arrangement (with a single sensor element 151 or two sensor elements 151, 152) in a direction perpendicular to the first or second magnetic field angle α1, α2.

[0059] Fig. Figure 7 shows another embodiment for resolving such ambiguity problems. In this embodiment, the magnetic-based positioning system 100 may further include a third magnetic sensor element 153 located at a third, yet unknown position (x3 | y3).

[0060] The third magnetic sensor element 153 can be placed on a different axis than the first and second magnetic sensor elements 151, 152, so that all three magnetic sensor elements 151, 152, 153 can have the shape of a triangle. This way, further ambiguities can be avoided.

[0061] The magnetic sensor arrangement with three magnetic sensor elements 151, 152, 153 can be configured to determine a third magnetic field vector 143 at the third, still unknown position (x3 | y3) in the xy plane 130. The magnetic sensor arrangement can also be configured to determine a third magnetic field angle a3, which describes the angle of the third magnetic field vector 143 extending between the third, still unknown position (x3 | y3) and the common z-axis 111 (= magnetization axis).

[0062] Thus, if the magnetic sensor assembly determines that the first and second magnetic sensor elements 151, 152 are arranged along a common magnetic field line 140, i.e., if the first magnetic field angle α1 and the second magnetic field angle α2 are identical (or shifted by ± 180°), then the magnetic sensor assembly can use the determined third magnetic field angle α3 instead of one of the first and second magnetic field angles α1, α2 and use the determined third magnetic field vector 143 instead of one of the first and second magnetic field vectors 141, 142. In this case, the determination of the actual xy position of the magnetic sensor assembly relative to the magnet 110 is based on a combination of one of the first and second magnetic field vectors 141, 142 and the third magnetic field vector 143.

[0063] In summary, the innovative concept proposes three possible solutions to resolve the ambiguities discussed above caused by identical first and second magnetic field angles α1, α2. 1. Using a third magnetic sensor element 153 and placing it in a different axis than the first and second magnetic sensor elements 151, 152, so that all three magnetic sensor elements 151, 152, 153 form a triangle: With an innovative magnetic sensor arrangement comprising three magnetic sensor elements 151, 152, 153, it is always possible to immediately determine the relative position between the magnetic sensor arrangement and the magnet 110 in the innovative manner described here. However, the use of three magnetic sensor elements 151, 152, 153 may be more expensive than the embodiments discussed above, which have only two magnetic sensor elements 151, 152 or even just a single magnetic sensor element 151. 2. Using two magnetic sensor elements 151, 152 and moving at least one of the first and second magnetic sensor elements 151, 152 out of the common magnetic field line 140: For positioning purposes, either the magnet 110 or the magnetic sensor assembly can be movable. Thus, if the first and second magnetic field angles α1, α2 measured by the first and second magnetic sensor elements 151, 152 are equal, a movement can be initiated to determine the relative position between the magnet 110 and the magnetic sensor assembly. An accurate position calculation is possible with only two magnetic sensor elements 151, 152, but not always immediately. 3. Using only a single magnetic sensor element 151 and moving it sequentially to different positions: According to this embodiment, the individual sensor element 151 can determine a first magnetic field angle α1 at a first position (x1 | y1). Then, the sensor element 151 can be moved, e.g., perpendicular to the first magnetic field vector 141 to a second position (x2 | y2), where a second magnetic field angle α2 can be determined. To avoid further ambiguities, the individual sensor element 151 should not be moved in the direction of (or away from) the first magnetic field angle α1. This embodiment can use only a single sensor element 151 and a magnet 110, whereby the relative position between the magnetic sensor array and the magnet 110 is not immediately known, but is always known after two measurements (with the movement in between) of the two magnetic field angles α1, α2. Furthermore, the moving distance must be known.

[0064] Fig.Figure 8 shows a schematic block diagram of a corresponding method for performing a magnet-based position determination according to the innovative concept discussed above.

[0065] At block 801, an axially magnetized magnet 110 is provided, with two opposing magnetic poles 112, 113 arranged along a common z-axis 111.

[0066] At block 802, a magnetic sensor assembly is provided, wherein the magnetic sensor assembly is axially spaced from the magnet 110 and configured to determine magnetic field vectors 141, 142 in an xy-plane 130 perpendicular to the common z-axis 111. The magnetic field vectors 141, 142 represent a direction of radiated magnetic field lines 140 in the xy-plane 130.

[0067] At block 803, a first magnetic field vector 141 is determined at a first, yet unknown position (x1 | y1) in the xy-plane 130 and a second magnetic field vector 142 is determined at another, second, yet unknown position (x2 | y2) in the xy-plane 130.

[0068] At block 804, an actual xy position of the magnetic sensor array relative to the magnet 110 is determined based on the first and second magnetic field vectors 141, 142 and based on a known relative spatial distance (dx | dy) between the first yet unknown position (x1 | y1) and the second yet unknown position (x2 | y2).

[0069] A further embodiment relates to a computer-readable storage medium having a computer program stored thereon for carrying out the method described herein when executed on a computer or signal processor.

[0070] Some or all of the method steps may be performed by (or using) a hardware device, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, some or more of the key method steps may be performed by such a device.

[0071] Depending on specific implementation requirements, embodiments of the invention may be implemented in hardware or software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-ray Disc, a CD, a ROM, a PROM, an EPROM, an EEPROM, or a FLASH memory, a hard disk, or other magnetic or optical storage device storing electronically readable control signals that can interact or cooperate with a programmable computer system to perform the respective method. Therefore, the digital storage medium may be computer-readable.

[0072] Some embodiments according to the invention thus comprise a data carrier having electronically readable control signals capable of interacting with a programmable computer system such that one of the methods described herein is carried out.

[0073] In general, embodiments of the present invention can be implemented as a computer program product with a program code, wherein the program code is effective to perform one of the methods when the computer program product is run on a computer. The program code can also be stored, for example, on a machine-readable medium.

[0074] Other embodiments include the computer program for performing one of the methods described herein, wherein the computer program is stored on a machine-readable carrier.

[0075] In other words, an embodiment of the method according to the invention is thus a computer program which has a program code for carrying out one of the methods described herein when the computer program runs on a computer.

[0076] A further embodiment of the method according to the invention is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program for performing one of the methods described herein is recorded. The data carrier, the digital storage medium, or the recorded medium is typically tangible and / or non-transitory.

[0077] A further embodiment of the method according to the invention is thus a data stream or a sequence of signals that represents the computer program for carrying out one of the methods described herein. The data stream or the sequence of signals can be configured, for example, to be transmitted via a data communication connection, for example, via the Internet.

[0078] A further embodiment comprises a processing device, for example a computer or a programmable logic device, which is configured or adapted to carry out one of the methods described herein.

[0079] A further embodiment comprises a computer on which the computer program for performing one of the methods described herein is installed.

[0080] A further embodiment according to the invention comprises a device or system configured to transmit a computer program for performing at least one of the methods described herein to a recipient (e.g., electronically or optically). The recipient may, for example, be a computer, a mobile device, a storage device, or a similar device. The device or system may, for example, comprise a file server for transmitting the computer program to the recipient.

[0081] In some embodiments, a programmable logic device (e.g., a field-programmable gate array, an FPGA) may be used to perform some or all of the functionality of the methods described herein. In some embodiments, a field-programmable gate array may interact with a microprocessor to perform any of the methods described herein. In general, the methods are preferably performed by any hardware device.

[0082] The devices described herein may be implemented, for example, using a hardware device, or using a computer, or using a combination of a hardware device and a computer.

[0083] The methods described herein may be implemented, for example, using a hardware device, or using a computer, or using a combination of a hardware device and a computer.

[0084] Although this disclosure has been described with reference to illustrative embodiments, this description is not to be viewed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of this disclosure, will become apparent to those skilled in the art upon reference to the description. Therefore, the appended claims are intended to encompass all such modifications or embodiments.

Claims

[1] A magnetic-based positioning system (100) having the following features: an axially magnetized magnet (110), wherein two opposite magnetic poles (112, 113) are arranged along a common z-axis (111), a magnetic sensor arrangement axially spaced from the magnet (110) and configured to determine magnetic field vectors (141, 142) in an xy-plane (130) perpendicular to the common z-axis (111), wherein the magnetic field vectors (141, 142) represent a direction of radiated magnetic field lines (140) in the xy-plane (130), wherein the magnetic sensor arrangement is configured to determine a first magnetic field vector (141) at a first still unknown position (x1 | y1) in the xy plane (130), and to determine a second magnetic field vector (142) at another second still unknown position (x2 | y2) in the xy plane (130), and to determine an actual xy position of the magnetic sensor arrangement relative to the magnet (110) based on the first and second magnetic field vectors (141, 142) and based on a known relative spatial distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2). [2] The magnetic-based positioning system (100) of claim 1, wherein the magnetic sensor array is configured to determine its actual xy position based on triangulation using the first and second magnetic field vectors (141, 142). [3] The magnetic-based positioning system (100) according to claim 1 or 2, wherein the magnetic sensor arrangement is configured to determine a first magnetic field angle α1, which describes an angle of the first magnetic field vector (141) extending between the first still unknown position (x1 | y1) and the common z-axis (111), and to determine a second magnetic field angle α2 which describes an angle of the second magnetic field vector (142) extending between the second still unknown position (x2 | y2) and the common z-axis (111). [4] The magnetic-based positioning system (100) according to claim 3, where the relative distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2) of the magnetic sensor arrangement is known, and wherein the magnetic sensor arrangement is configured to determine its actual xy position relative to the magnet (110) by Calculating a spatial distance (Δx, Δy) between at least one of the first and second still unknown positions (x1 | y1, x2 | y2) and the common z-axis (111) based on the first and second magnetic field angles α1, α2 and based on the known relative distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2). [5] The magnetic-based positioning system (100) according to claim 4, wherein the magnetic sensor arrangement comprises a first magnetic sensor element (151) located at the first still unknown position (x1 | y1) and another second magnetic sensor element (152) located at the second still unknown position (x2 | y2), wherein a spatial distance between the first magnetic sensor element (151) and the second magnetic sensor element (152) defines the known relative distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2). [6] The magnetic-based positioning system (100) according to claim 4, wherein the magnetic sensor arrangement comprises a single magnetic sensor element (151), and wherein the magnet-based positioning system is configured to move the single magnetic sensor element (151) from the first still unknown position (x1 | y1) to the second still unknown position (x2 | y2) along a predetermined movement distance (x = dx, y = dy), where the predetermined movement distance (x = dx, y = dy) defines the known relative distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2), and wherein the magnetic sensor arrangement is configured to to determine the first magnetic field angle α1 when the individual magnetic sensor element (151) is located at the first, still unknown, position (x1 | y1), and to determine the second magnetic field angle α2 when the individual magnetic sensor element (151') is located at the second, still unknown, position (x2 | y2). [7] The magnetic-based positioning system (100) according to claim 6, wherein after determining the first magnetic field angle α1, the magnetic-based positioning system (100) is configured to move the single magnetic sensor element (151) in a direction that is different from the first magnetic field angle α1 and different from the first magnetic field angle α1 ± 180°. [8] The magnetic-based positioning system (100) according to claim 6 or 7, wherein after determining the first magnetic field angle α1, the magnetic-based positioning system (100) is configured to move the single magnetic sensor element (151) in a direction perpendicular to the first magnetic field angle α1. [9] The magnetic-based positioning system (100) according to one of claims 3 to 8, wherein, if the magnetic sensor arrangement determines that the first magnetic field angle α1 and the second magnetic field angle α2 are identical or shifted by ± 180°, then the magnet-based positioning system (100) is configured to move the magnetic sensor arrangement relative to the magnet (110) and to determine the second magnetic field angle (α2) at a third, still unknown position (x3 | y3). [10] The magnet-based positioning system (100) according to claim 9, configured to move the magnetic sensor assembly relative to the magnet (110) in a direction that differs from the determined first or second magnetic field angle α1, α2 and differs from the first or second magnetic field angle α1, α2 ± 180°. [11] The magnetic-based positioning system (100) according to one of claims 1 to 5, which further comprises a third magnetic sensor element (153) located at a third, yet unknown position (x3 | y3), wherein the magnetic sensor arrangement is configured to determine a third magnetic field vector (143) at the third still unknown position (x3 | y3) in the xy plane (130), and to determine a third magnetic field angle α3 which describes an angle of the third magnetic field vector (143) extending between the third still unknown position (x3 | y3) and the common z-axis (111). [12] The magnetic-based positioning system (100) according to claim 11, wherein, if the magnetic sensor arrangement determines that the first magnetic field angle α1 and the second magnetic field angle α2 are identical or shifted by ± 180°, then the magnetic sensor arrangement is configured to use the determined third magnetic field angle α3 instead of the second magnetic field angle α2 and to use the determined third magnetic field vector (143) instead of the second magnetic field vector (142), and to determine the actual xy position of the magnetic sensor arrangement relative to the magnet (110) based on the first and third magnetic field vectors (141, 143). [13] The magnet-based positioning system (100) according to any one of the preceding claims, wherein the axially magnetized magnet (110) has a symmetrical cylindrical shape. [14] A method (800) for performing a magnet-based position determination, the method comprising the following steps: Providing an axially magnetized magnet (110), wherein two opposite magnetic poles (112, 113) are arranged along a common z-axis (111), Providing a magnetic sensor arrangement axially spaced from the magnet (110) and configured to determine magnetic field vectors (141, 142) in an xy-plane (130) perpendicular to the common z-axis (111), wherein the magnetic field vectors (141, 142) represent a direction of radiated magnetic field lines (140) in the xy-plane (130), Determining a first magnetic field vector (141) at a first still unknown position (x1 | y1) in the xy plane (130) and determining a second magnetic field vector (142) at another second still unknown position (x2 | y2) in the xy plane (130), and Determining an actual xy position of the magnetic sensor arrangement relative to the magnet (110) based on the first and second magnetic field vectors (141, 142) and based on a known relative spatial distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2). [15] The method (800) of claim 14, wherein the step of determining the actual xy position of the magnetic sensor array relative to the magnet (110) is based on triangulation using the first and second magnetic field vectors (141, 142). [16] The method (800) according to claim 14 or 15, which further comprises a step of determining a first magnetic field angle α1, which describes an angle of the first magnetic field vector (141) extending between the first still unknown position (x1 | y1) and the common z-axis (111), and a step of determining a second magnetic field angle a2 which describes an angle of the second magnetic field vector (142) extending between the second still unknown position (x2 | y2) and the common z-axis (111). [17] The method according to claim 16, where the relative distance (dx | dy) between the first unknown position (x1 | y1) and the second unknown position (x2 | y2) is known, and wherein the method comprises a further step of determining the actual xy position of the magnetic sensor arrangement relative to the magnet (110) by Calculating a spatial distance (Δx, Δy) between at least one of the first and second still unknown positions (x1 | y1, x2 | y2) and the common z-axis (111) based on the first and second magnetic field angles α1, α2 and based on the known relative distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2). [18] The method (800) according to claim 17, wherein the magnetic sensor arrangement comprises a first magnetic sensor element (151) located at the first still unknown position (x1 | y1) and another second magnetic sensor element (152) located at the second still unknown position (x2 | y2), wherein a spatial distance between the first magnetic sensor element (151) and the second magnetic sensor element (152) defines the known relative distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2). [19] The method (800) according to claim 17, wherein the magnetic sensor arrangement comprises a single magnetic sensor element (151), and wherein the method further comprises a step of moving the single magnetic sensor element (151) from the first still unknown position (x1 | y1) to the second still unknown position (x2 | y2) along a predetermined movement distance (x = dx, y = dy), where the predetermined movement distance (x = dx, y = dy) defines the known relative distance (dx | dy) between the first still unknown position (x1 | y1) and the second still unknown position (x2 | y2), and the method further comprising the following steps: Determining the first magnetic field angle α1 when the individual magnetic sensor element (151) is located at the first, yet unknown, position (x1 | y1), and Determining the second magnetic field angle α2 when the individual magnetic sensor element (151') is located at the second, still unknown, position (x2 | y2). [20] The method (800) according to claim 19, wherein the step of moving the single magnetic sensor element (151) from the first still unknown position (x1 | y1) to the second still unknown position (x2 | y2) along the predetermined moving distance (x = dx, y = dy) comprises the following step: Moving the single magnetic sensor element (151) in a direction different from the first magnetic field angle α1 and different from the first magnetic field angle α1 ± 180°. [21] The method (800) according to claim 19 or 20, wherein the step of moving the single magnetic sensor element (151) from the first still unknown position (x1 | y1) to the second still unknown position (x2 | y2) along the predetermined moving distance (x = dx, y = dy) comprises the following step: Moving the single magnetic sensor element (151) in a direction perpendicular to the first magnetic field angle α1. [22] The method (800) according to any one of claims 16 to 21, where, if it is determined that the first magnetic field angle α1 and the second magnetic field angle α2 are identical or shifted by ± 180°, then the method comprises at least the following steps: Moving the magnetic sensor assembly relative to the magnet (110) and Determine the second magnetic field angle α2 at a third unknown position (x3 | y3). [23] The method (800) of claim 22, wherein the step of moving the magnetic sensor assembly relative to the magnet (110) comprises the step of: Moving the magnetic sensor arrangement relative to the magnet (110) in a direction that differs from the determined first or second magnetic field angle α1, α2 and differs from the first or second magnetic field angle α1, α2 ± 180°. [24] The method (800) according to any one of claims 14 to 18, which further comprises a third magnetic sensor element (153) located at a third, yet unknown position (x3 | y3), the method further comprising the following steps: Determining a third magnetic field vector (143) at the third still unknown position (x3 | y3) in the xy-plane (130) and Determining a third magnetic field angle α3 which describes an angle of the third magnetic field vector (143) extending between the third still unknown position (x3 | y3) and the common z-axis (111). [25] The method (800) according to claim 24, where, if it is determined that the first magnetic field angle α1 and the second magnetic field angle α2 are identical or shifted by ± 180°, then the method comprises at least the following steps: Using the determined third magnetic field angle α3 instead of the second magnetic field angle α2 and using the determined third magnetic field vector (143) instead of the second magnetic field vector (142), and Determining the actual xy position of the magnetic sensor arrangement relative to the magnet (110) based on the first and third magnetic field vectors (141, 143). [26] A computer-readable storage medium having stored thereon a computer program for carrying out the method according to claims 14 to 25 when executed on a computer or signal processor.

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