ROTATION ANGLE CAPTURE WITH A 3-D SENSOR AND AN AXIS OF ROTATION PARALLEL TO A PRINTED CIRCUIT BOARD

Abstract

In a sensor arrangement for determining a rotation angle of a magnet about an axis of rotation, with a sensor for capturing a radial component and a tangential component of the measuring field of the magnet and for determining the rotation angle on the basis of an atan function, the sensor is mounted, at a radial distance from the axis of rotation, on a printed circuit board parallel to the axis of rotation and is offset by an axial distance. In a design method, an initial axial distance and radial distance are selected, the profile is determined, and the axial distance and/or the radial distance is/are iteratively optimized. A selector lever is coupled in terms of movement to the magnet of the sensor arrangement. The sensor arrangement is optimized and installed with the selector lever, and a compensation arrangement is adjusted.

Claims

1. A sensor arrangement for determining a rotation angle of a magnet about an axis of rotation relative to a base carrier, the sensor arrangement comprising: the base carrier; the magnet configured to rotate relative to the base carrier about the axis of rotation to generate a magnetic measuring field; a sensor positionally fixed relative to the base carrier and configured to: capture a radial component and a tangential component of the measuring field with respect to the axis of rotation; and determine the rotation angle from the captured radial component and the captured tangential component on the basis of an arctangent function, wherein the sensor is mounted and electrically contact-connected next to the axis of rotation, with a radial distance from the axis of rotation, on a printed circuit board which is positionally fixed with respect to the base carrier, wherein a surface of the sensor runs parallel and tangentially with respect to the axis of rotation, and wherein the sensor is arranged offset with respect to a central plane, lying transversely with respect to the axis of rotation, of the magnet in the axial direction of the axis of rotation by an axial distance which is different from zero.

2. The sensor arrangement of claim 1, wherein: the axial distance and the radial distance are selected in such a way that a profile of the determined rotation angle, plotted against the actual rotation angle, is optimized in terms of its linearity to an error metric between the determined rotation angle and the actual rotation angle, wherein the error metric corresponds to a maximum error of 10° with respect to one full rotation of the magnet through 360°.

3. The sensor arrangement of claim 2, wherein: the profile is optimized to the effect that a compromise between its linearity and a modulation of the sensor is optimized.

4. The sensor arrangement of claim 2, wherein: the profile of the captured rotation angle is optimized on the basis of a finite element method (FEM) analysis of the measuring field at least at the location of the sensor.

5. The sensor arrangement of claim 4, wherein: the optimization is carried out in such a way that, of axial distances and radial distances which can be predefined on the basis of a rasterized FEM analysis, ones are selected which supply a comparatively optimum linearity of the profile.

6. The sensor arrangement of claim 1, wherein: the magnet is connected in a co-rotational fashion to a shaft which runs along the axis of rotation.

7. The sensor arrangement of claim 1, wherein: the sensor is an SMD sensor which is mounted and electrically contact-connected on a surface of the printed circuit board.

8. The sensor arrangement of claim 1, wherein: the sensor is a 3-D sensor.

9. The sensor arrangement of claim 2, wherein: at least one of a material of the magnet or a volume of the magnet is selected in such a way that the profile is optimized.

10. The sensor arrangement of claim 1, wherein: the sensor arrangement contains an adjustable compensation arrangement for compensating a residual error in the determined rotation angle with respect to the actual rotation angle.

11. A method for a sensor arrangement, the method comprising: rotating a magnet relative to the base carrier about an axis of rotation relative to a base carrier to generate a magnetic measuring field; capturing, with a sensor positionally fixed relative to the base carrier, a radial component and a tangential component of the measuring field with respect to the axis of rotation, wherein the sensor is mounted next to the axis of rotation with a radial distance from the axis of rotation, and is arranged offset with respect to a central plane, lying transversely with respect to the axis of rotation, of the magnet in the axial direction of the axis of rotation by an axial distance which is different from zero; determining a rotation angle from the captured radial component and the captured tangential component on the basis of an arctangent function; selecting an initial axial distance and radial distance; determining a profile; and iteratively varying at least one of the axial distance or the radial distance in order to optimize the profile.

12. The method of claim 11, wherein: the design method is carried out using a finite element method (FEM) analysis of the measuring field for the respective current axial distance and radial distance.

13. A selector lever arrangement for a vehicle, comprising: a selector lever which can be moved between at least two positions in order to select a vehicle function; and the sensor arrangement of claim 10, wherein the selector lever is kinetically coupled to the magnet, and the at least two positions can be differentiated by means of the determined rotation angle.

14. The selector lever arrangement of claim 13, wherein: the compensation arrangement is set during its fabrication within the scope of an end-of-line setting with respect to the selector lever arrangement.

15. The method of claim 11, further comprising: installing the sensor arrangement with a selector lever arrangement that can be moved between at least two positions in order to select a vehicle function, wherein the selector lever is kinetically coupled to the magnet and the at least two positions can be differentiated by means of the determined rotation angle; and setting the compensation arrangement within the scope of an end-of-line setting with respect to the selector lever arrangement.

16. A selector lever arrangement for a vehicle, comprising: a selector lever which can be moved between at least two positions in order to select a vehicle function; and the sensor arrangement of claim 1, wherein the selector lever is kinetically coupled to the magnet, and the at least two positions can be differentiated by means of the determined rotation angle.

17. The sensor arrangement of claim 3, wherein: the profile of the captured rotation angle and the profile of the modulation is optimized on the basis of a finite element method (FEM) analysis of the measuring field at least at the location of the sensor.

18. The sensor arrangement of claim 17, wherein: the optimization is carried out in such a way that, of axial distances and radial distances which can be predefined on the basis of a rasterized FEM analysis, ones are selected which supply a comparatively optimum linearity of the profile.

Description

[0041] Further features, effects and advantages of the invention can be found in the following description of a preferred exemplary embodiment of the invention and the appended figures. In this context, in each case in a schematic basic diagram:

[0042] FIG. 1 shows a selector lever arrangement according to the invention with a sensor arrangement in a side view,

[0043] FIG. 2 shows the sensor arrangement from FIG. 1 in a front view,

[0044] FIG. 3 shows a diagram with a determined rotation angle, plotted against an actual rotation angle,

[0045] FIG. 4 shows a rotation angle sensor system according to the prior art,

[0046] FIG. 5 shows a diagram of determined rotation angles plotted against an actual rotation angle for various sensor positions, and

[0047] FIG. 6 shows the sensor positions for the determinations according to FIG. 5.

[0048] FIG. 1 shows a selector lever arrangement 2 for a vehicle (not illustrated in more detail), here an automobile, with a selector lever 4. The selector lever 4 can be moved between two positions P1,2, as indicated by arrows. A transmission stage (forward, reverse, parking, gear speed selection) in the automobile can be selected as a vehicle function by means of the selector lever 4 in a manner which is not explained in more detail. The current position of the selector lever 4 is to be detected, in order to be able to correspondingly actuate the transmission. For this purpose, the selector lever 4 is kinetically coupled to a magnet 6.

[0049] The kinetic coupling is carried out by mounting the magnet 6 in a co-rotational fashion on a shaft 10, wherein the selector lever 4 is in turn kinetically coupled to the shaft 10 in a manner which is not explained in more detail. The magnet 6 and shaft 10 can be rotated here about an axis of rotation 12 or rotated into a specific rotation angle WT depending on the position P1,2. In order to detect the positions P1,2, the actual rotation angle WT of the shaft 10 and therefore of the magnet 6 is to be determined. The magnet 6 is part of a sensor arrangement 8.

[0050] FIG. 2 shows once more the sensor arrangement 8 from FIG. 1 in a viewing direction of the arrow II from FIG. 1; FIG. 1 shows the viewing direction I from FIG. 2. The sensor arrangement 8 serves to determine a (determined) rotation angle WE which would correspond to the actual rotation angle WT in an ideal sensor arrangement.

[0051] The sensor arrangement 8 has a base carrier 14. The magnet 6 and shaft 10 can be rotated relative to the base carrier 14 about the axis of rotation 12. The magnet 6 is magnetized diametrically with respect to the axis of rotation 12 (indicated by the north pole N and south pole S). The magnet 6 is here a permanent magnet and generates a magnetic measuring field 16 which is coupled in a co-rotational fashion to the magnet 6 and is illustrated in the figures only by a small number of field lines.

[0052] The sensor arrangement 8 also contains a sensor 18, here a 3-D Hall sensor, which is mounted in a positionally fixed fashion with respect to the base carrier 14. The sensor 18 is configured to capture a radial component KR and a tangential component KT of the measuring field 16. The corresponding radial direction and tangential direction relate to the axis of rotation 12. The sensor 18 is configured to determine the rotation angle WE from the captured radial component KR and the captured tangential component KT on the basis of an arctangent (atan) function.

[0053] The sensor 18 is positioned at a radial distance AR from the axis of rotation 12. For this purpose, it is mounted and electrically contact-connected next to the axis of rotation 12, that is to say at a distance therefrom, on a printed circuit board 20. A surface 22 of the printed circuit board 20 is oriented parallel and tangentially with respect to the axis of rotation 12. In the example, the sensor 18 is an SMD component.

[0054] The sensor 18 is also arranged offset by an axial distance AA with respect to a central plane 24, here a plane of symmetry, lying transversely with respect to the axis of rotation 12, of the magnet 6.

[0055] FIG. 3 shows a profile 26 of the determined rotation angle WE (in degrees), plotted against the actual rotation angle WT (in degrees). In the sensor arrangement 8, the axial distance AA and the radial distance AR are selected in such a way that the profile 26 of the determined rotation angle WE plotted against the actual rotation angle WT is optimized with respect to its linearity. In the example, a quadratic error metric of a respective error F, i.e. of a deviation (indicated by a line) of the rotation angle WE perpendicularly from the profile of the rotation angle WT is minimized for realistically possible axial distances AA and radial distances AR.

[0056] The corresponding optimization or minimization has been carried out in the present case by means of a theoretical or modeled FEM analysis of the ratios for various axial distances AA and radial distances AR, until a comparatively optimum linearity, here the smallest possible error metric, was reached as illustrated in FIG. 3. Intermediate results for alternative values of the distances AA, AR are represented by dashed lines with errors F of different magnitudes.

[0057] In this context, variations of the material of the magnet and the volume of the magnet 6 have also been taken into account in the present case, and the error metric has correspondingly also been minimized with respect to these parameters. After the minimization, the optimized profile 26 which is illustrated by a solid line is obtained.

[0058] However, the respective optimization also takes into account the respective modulation of the sensor 18 by means of the measuring field 16 with possible axial distances AA and radial distances AR and magnetic parameters. An optimum compromise is selected in the present case between modulation and the most linear possible profile 26, and corresponding parameters (AA, AR, magnetic parameters) are found.

[0059] The sensor arrangement 8 also contains an adjustable compensation arrangement 28 in order to compensate the residual error FR between the rotation angle WE and the actual rotation angle WT to eliminate it completely here. According to one mapping function (not described here in more detail), the profile of the rotation angle WE is therefore optimized further and mapped onto respective values of a corrected rotation angle WK. The course of the rotation angle WK plotted against the rotation angle WT is also shown in FIG. 3 and is identical thereto, and therefore ideal.

[0060] In a design method for the sensor arrangement 8, initial values for the distances AA, AR and the magnet parameters are therefore firstly selected and these are varied with the abovementioned iteration method using a respective FEM analysis of a respective selection, which gives rise to the dashed curves in FIG. 3 with different error metrics. At the end of the iteration method, when there is a minimal error metric the solid-line profile 26 with the residual error FR is obtained.

[0061] The setting of the compensation arrangement 28 therefore takes place only after the optimization of the sensor arrangement 8 and its installation in the selector lever arrangement 2 within the scope of an EOL setting during the manufacture or fabrication of the selector lever arrangement 2.

[0062] FIG. 5 shows dashed-line alternative profiles 26 of determined rotation angles WE (in degrees, sensor signal), plotted against the actual (mechanical) rotation angle WT (solid line, in degrees). In this context, according to FIG. 6 axial distances AA and radial distances AR (variation indicated by arrows) are varied in the sensor arrangement 8. The illustrated curves in FIG. 5 correspond to some of the sensor positions indicated by dots. If the position of the sensor 18 underneath the magnet 6 is correctly selected (profile 26 with minimum deviation), the signal error with respect to adjacent positions (other profiles 26) can be minimized to a great enough extent that the raw (non-linearized) sensor signal has an error F down to virtually zero. In this example, the sensor positions are 0.5 mm away from one another, and the error F for the optimized position 30 is at <4° with respect to the ideal sensor straight line (WT). For relatively small distances of 0.25 mm, e.g. optimized profiles 26 (not illustrated) with a maximum error F of less than 0.5° are obtained.

LIST OF REFERENCE SYMBOLS

[0063] 2 Selector lever arrangement [0064] 4 Selector lever [0065] 6 Magnet [0066] 8 Sensor arrangement [0067] 10 Shaft [0068] 12 Axis of rotation [0069] 14 Base carrier [0070] 16 Measuring field [0071] 18 Sensor [0072] 20 Printed circuit board [0073] 22 Surface [0074] 24 Central plane [0075] 26 Profile [0076] 28 Compensation arrangement [0077] 30 Optimized position [0078] P1,2 Position [0079] WT Rotation angle (actual) [0080] WE Rotation angle (determined) [0081] WK Rotation angle (corrected) [0082] N North pole [0083] S South pole [0084] KT Tangential component [0085] KR Radial component [0086] AA Axial distance [0087] AR Radial distance [0088] F Error [0089] FR Residual error [0090] Bx,y Field component