Method for detecting an angle measurement value by means of a magnetic angle sensor

Abstract

In order to detect an angle measurement value, an angle sensor is provided which has at least three magnetic field sensors which lie on a circular line arranged concentrically in relation to a geometric axis of rotation. The angle sensor has a reference magnet which is rotatably mounted relative to the magnetic field sensors with respect to the axis of rotation. A respective measurement value for the magnetic field of the reference magnet is detected by means of the magnetic field sensors for an angular position of the reference magnet relative to the magnetic field sensors. The measurement values are transformed into a sine / cosine vector by means of the sine / cosine transformation, said vector having an α-component and a β-component. An angle measurement value is determined, corresponding to the arctangent of the ratio between the a- and β-component. For each of the measurement values detected for the angular position, a respective test value is provided in such a way that a vector formed from the test values corresponds to the inverse sine / cosine transformation of the sine / cosine vector. The test values are compared with the measurement values. If at least one measurement value is outside a tolerance band, an error is detected.

Description

[0001] PC 26014 H

[0002] 1

[0003] Method for recording an angle measurement value using a magnetic angle sensor

[0004] The invention relates to a method for detecting an angle measurement value using 5 of a magnetic angle sensor,

[0005] a) where an angle sensor is provided which

[0006] has at least three magnetic field sensors offset from each other in the circumferential direction with respect to a geometric axis of rotation, and

[0007] to generate a magnetic field, it has a reference magnet that is rotatably mounted with respect to the axis of rotation relative to the magnetic field sensors,

[0008] b) wherein, for each angular position of the reference magnet relative to the magnetic field sensors, a measurement value for the magnetic field of the reference magnet is recorded,

[0009] c) wherein the measured values ​​of the magnetic field sensors are transformed by means of a sine / cosine transformation into a transformation vector having a cr component and a -component, and

[0010] d) where an angle measurement is determined which corresponds to the arctangent of the ratio between the cr component and the -component.

[0011] From DE 102014 109693 A1, a method of the type mentioned above is known, in which a magnetic device and a sensor device are provided, which are rotatably mounted about a geometric axis of rotation relative to each other. The sensor device has three magnetic field sensors which are offset from each other by an angle of rotation relative to the axis of rotation such that the magnetic field sensors detect magnetic field measurement signals which are phase-shifted by 120 degrees. From the three magnetic field measurement signals, one measured value is sampled and transformed by means of a Clarke transformation into a transformation vector which has an α-component and a β-component as coordinates in an orthogonal coordinate system. In the case of a continuously rotating magnetic device, the output signals result in two harmonic oscillations (sin, cos) which are phase-shifted by 90 degrees relative to each other. From these two signals, respectively, aFrom their instantaneous values, an angle measurement for the angular position of the reference magnet relative to the magnetic field sensors is then directly calculated in an evaluation unit using the arctangent function. The method is not limited to three magnetic field sensors and primarily serves to compensate for external magnetic interference fields, which occur when the method is used in a motor vehicle, particularly in the automotive electronics application environment. Using more than three sensors increases the accuracy of the angle measurement.

[0012] As the number of sensors increases, the probability of at least one magnetic field sensor failing also rises along with the achievable precision. A failure does not necessarily result in a completely missing signal from the magnetic field sensor, but can also cause a continuous deviation in the measurement signal of the affected sensor. This disturbance can affect the magnetic field sensor signal erroneously, either with a constant magnitude or as an unstable, dynamic value.

[0013] The magnetic field sensors used can be of different types. In addition to magnetoresistive sensors such as AMR, GMR, or TMR sensors, which are characterized by high sensitivity, Hall sensors are frequently used due to their good monolithic integrability in CMOS process technologies.

[0014] Especially with magnetoresistive sensors, particularly TMR sensors, it is known that overdriving—that is, exposure to a magnetic field whose strength exceeds a certain threshold—can remagnetize the functional layers of the TMR sensor, thus causing hysteresis. Hysteresis corresponds to the described error pattern of a constant deviation in the output signal of the magnetic field sensor in question.

[0015] Besides defects in the electronic circuits themselves, malfunctions can also be caused by continuously acting external electromagnetic interference fields. These external interference fields manifest as either homogeneous or gradient static magnetic fields, or as transient or periodic alternating fields. The latter, in particular, can lead to malfunctions in the electronic circuits, while the former tend to distort the reference magnetic field provided by the reference magnet.

[0016] The robustness of such arrangements and the associated phenomena are generally summarized under the umbrella term of electromagnetic compatibility (EMC). The calculation of the arctangent function from the two orthogonal signals (α-component, β-component) then leads to an incorrect result for the angular position, even though the EMC-induced interference is already compensated for in the useful and measurement signals by means of a distortion of the reference magnetic field using methods known in the prior art.

[0017] The task is therefore to specify a method of the type mentioned above that makes it possible to detect errors occurring in angle measurement.

[0018] This task is solved in a procedure of the type mentioned above by:

[0019] e) that for each of the measured values ​​recorded for the angular position a test value is provided such that a vector formed from the test values ​​corresponds to the inverse sine / cosine transformation of the transformation vector,

[0020] f) that for each individual magnetic field sensor the deviations between the measured value and the test value assigned to it are determined, g) and that in the event that at least one of the deviations lies outside a predetermined tolerance band, an error in the angle measurement is detected.

[0021] From the calculated angular position, test values ​​are determined using reverse calculation and compared with the measured values ​​of the magnetic field sensors, taking a tolerance band into account. If the measured values ​​are error-free, i.e., if they correspond to the projections of a vector arranged radially to the axis of rotation in the plane spanned by the magnetic field sensors onto radial lines that each pass through the axis of rotation and the measuring point of the respective magnetic field sensor, the test values ​​match the measured values ​​exactly. Otherwise, at least for some measured values, a deviation occurs between the measured value and the corresponding test value. If the deviation lies outside the tolerance band assigned to the respective test value, a fault is detected.

[0022] The test values ​​can, for example,

[0023] by inverse sine-cosine transformation of the transformation vector or - if the angle measurement refers to the angle between the sine-cosine vector and the axis of the orthogonal coordinate system underlying the sine-cosine transformation that is assigned to the a-component - by calculating the cosine from the angle measurement

[0024] or - if the angle measurement refers to the angle between the sine-cosine vector and the axis of the orthogonal coordinate system assigned to the -component - by calculating the sine from the angle measurement

[0025] The test values ​​can be determined directly. However, it is also possible to extract the test values ​​from a look-up table, in which a predetermined number of test values ​​corresponding to the number of magnetic field sensors is stored for each angle measurement. This has the advantage that only minimal computing power is required to perform the procedure. If no corresponding test values ​​are stored in the look-up table for an angle measurement obtained during the measurement, the test values ​​can be determined for the angle stored in the look-up table that most closely approximates the angle measurement. If necessary, the test values ​​can also be determined by interpolating two or more test values ​​entered in the look-up table to improve accuracy.

[0026] The sine / cosine transform can be any sine-cosine transform, the most well-known being the Clarke aka Alpha-Beta transform.

[0027] The term "magnetic field sensors offset from each other in the circumferential direction with respect to a geometric axis of rotation" refers to magnetic field sensors that are offset from each other in the circumferential direction of a cylindrical surface arranged concentrically to the geometric axis of rotation or on a circular line arranged concentrically to the geometric axis of rotation.

[0028] In a preferred embodiment of the invention, it is provided that the method according to claim 1 is first carried out for a first angular position that the reference magnet has relative to the magnetic field sensors, and that in the event that an error in the angle measurement is detected at the first angular position,

[0029] i) the reference magnet is brought into a second angular position relative to the magnetic field sensors, which differs in magnitude from the first angular position by more than 60° and less than 120°, in particular by more than 70° and less than 110° and preferably by more than 80° and less than 100°,

[0030] ii) steps b) to g) from claim 1 are carried out for the second angular position, and

[0031] iii) From the deviations determined for the first and second angular positions, the deviation with the largest magnitude is identified, and the magnetic field sensor to which the deviation with the largest magnitude is assigned is identified as faulty. If the measured value of a single magnetic field sensor is faulty and the measured and test values ​​are recorded for only a single angular position, it may occur at certain angular positions that the deviation between the faulty measured value and the test value assigned to it is smaller in magnitude than the corresponding deviation that occurs between the measured value and the test value of at least one other magnetic field sensor. In this case, it is not readily possible to determine from the deviations which magnetic field sensor output the faulty measured value.However, if, according to claim 2, the measured values ​​and deviations are determined for at least two angular positions, the magnetic field sensor for which the deviation is greatest is also the one that has output an erroneous measured value.

[0032] In another advantageous embodiment of the invention, it is provided that the method according to claim 1 is carried out for a first angular position that the reference magnet has relative to the magnetic field sensors, and that in the event that an error in the angle measurement is detected at the first angular position,

[0033] i) the reference magnet is moved to a further angular position relative to the magnetic field sensors and steps b) to g) from claim 1 are carried out for the further angular position,

[0034] ii) Step i) is repeated until an angular position is reached which differs from the first angular position by at least 180° and preferably by at least 360°,

[0035] iii) that from the deviations determined for the first and subsequent angular positions, the deviation with the largest magnitude is identified, and that the magnetic field sensor (5, 6, 7) to which the deviation with the largest magnitude is assigned is identified as faulty. These measures allow for a more reliable identification of the magnetic field sensor that issued the faulty measurement. The measurement values ​​for the subsequent angular positions can be acquired at constant time intervals. It is also possible for the subsequent angular positions to be offset from each other at constant angular intervals. If the subsequent angular positions are offset from each other at different angular intervals, it is advantageous if these angular intervals do not exceed a predetermined maximum value. This ensures that during the 180° or 180° intervals, the measurement values ​​are not exceeded.A sufficiently large number of measurements are taken during a 360° rotation, and the angular positions of successive measurements are not too far apart.

[0036] In a further development of the method, after identifying the magnetic field sensor that issued the erroneous reading, the magnetic angle sensor continues to operate in an emergency mode. In this mode, the angle measurement is determined solely from the readings of the remaining magnetic field sensors that have not been identified as faulty. As soon as an erroneous reading is detected, the magnetic field sensor that issued the erroneous reading or signal is no longer used to determine the angle position. The angle position is then determined using the remaining undisturbed or less disturbed readings or signals.A significant advantage of this method is that the magnetic angle sensor can continue operating in emergency mode. In contrast, under current technology, a device utilizing the angle measurement provided by the angle sensor must enter a safe state upon detecting a fault, particularly in safety-critical applications. However, a safe state often necessitates halting the operation of the angle sensor, potentially leading to a failure or shutdown of the entire system, such as a vehicle. While redundant angle sensors are known in the art, allowing the device to continue operating in the event of a fault, these are relatively complex due to the multiple independent sensor arrays with magnetic field sensors.

[0037] The method according to the invention can also be applied in a redundant angle sensor comprising at least two independent sensor arrangements with magnetic field sensors. The method can be applied to each of these simple angle sensors. This significantly increases the safety integrity of the redundant angle sensor.

[0038] In a preferred embodiment of the invention, an emergency operation indicator is activated when the angle sensor is operated in emergency mode.

[0039] In an advantageous embodiment of the invention, the magnetic field sensors of the angle sensor are located on a circular line arranged concentrically to the geometric axis of rotation. The magnetic field sensors are arranged at the same distance from the axis of rotation.

[0040] Further details, features and advantages of the present invention will become apparent from the following description of an exemplary embodiment with reference to the drawing.

[0041] It shows:

[0042] Fig. 1 shows a schematic overview of an angle sensor,

[0043] Fig. 2 shows a block diagram of a device for carrying out the method according to the invention,

[0044] Fig. 3 is a graphical representation of an angular error resulting from the calculation of the angle between a magnetic field of a reference magnet and a magnetic field sensor arrangement with three magnetic field sensors arranged on a circular path at 120° intervals with respect to an axis of rotation. This error is derived from the arctangent of the ratio of the a- and α-components of a Clarke vector formed from the measured values ​​of the magnetic field sensors by Clarke transformation, when the measured value of one of the magnetic field sensors has an error of 5%, with the angles given in degrees. Fig. 4 is a graphical representation of the deviations between the measured values ​​of the individual magnetic field sensors and their respective test values, which were determined from the Clarke vector by inverse Clarke transformation. The abscissa represents the angle between the magnetic field and the magnetic field sensor arrangement in degrees, and the ordinate represents the deviation in percent.

[0045] A measuring device 1, designated in its entirety by 1 in Figure 1, for determining an angle measurement value comprises a reference magnet 2 and a sensor arrangement 3, which are rotatably mounted relative to each other about an imaginary axis of rotation 4 by means of a bearing (not shown in detail in the drawing). The reference magnet 2 has a north pole N and a south pole S, which are offset from each other by 180° with respect to the axis of rotation 4.

[0046] The sensor device 3 comprises three magnetic field sensors 5, 6, 7 arranged on a semiconductor chip, which are angularly offset from each other by 120° with respect to the axis of rotation 4. The semiconductor chip is oriented with its plane of extension orthogonal to the axis of rotation 4. The magnetic field sensors 5, 6, 7 are located on a circular path 8 concentric with the axis of rotation 4. When the magnetic device 2 is rotated about the axis of rotation 4 relative to the sensor device 3, the magnetic field sensors 5, 6, 7 generate magnetic field measurement signals that are phase-shifted by 120° relative to each other.

[0047] Figure 2 shows a device for carrying out the method according to the invention. Each magnetic field sensor 5, 6, 7 has a signal output 9, 10, 11 for outputting its magnetic field measurements. The output magnetic field measurements serve as inputs to a sine-cosine transformation device 12 for transforming the magnetic field measurements into a transformation vector that has an α-component and a β-component in an orthogonal coordinate system. Each signal output 9, 10, 11 is connected to a corresponding input of the sine-cosine transformation device 12. The α-component of the transformation vectors is output at an α-component output 13 and the β-component at a β-component output 14 of the sine-cosine transformation device 12.

[0048] The sine-cosine transformation device 12 performs a calculation operation referred to in the literature as al-phaZbeta or Clarke transformation according to equation (1):

[0049] a rl -0.5 -0.5] [Ml'

[0050] M 3 3 (1

[0051]

[0052] =i0 M2 )

[0053] Here, M1 denotes a first measured value acquired by means of a first magnetic field sensor 5, M2 a second measured value acquired by means of a second magnetic field sensor 6, M3 a third measured value acquired by means of a third magnetic field sensor 7, a the a-component and ß the -component of the transformation vector.

[0054] The sine / cosine transformation device 12 comprises a signal conditioning device, not shown in detail in the drawing, which is known per se and serves to calibrate, amplify, and filter signals used for transforming the measured values ​​into the transformation vector. With the aid of the signal conditioning device, the measurement signals from the magnetic field sensors 5, 6, 7 are amplified such that they can be directly compared with test values, which will be described in more detail below.

[0055] The a-component output 13 is connected to an a-component input 15 and the -component output 14 to an -component input 16 of an arctangent calculation device 17. According to equation (2), the arctangent calculation device 17 calculates the arctangent function from the ratio of the -component to the a-component and outputs the result as an angle measurement cp at output 18. <P = arctan

[0056]

[0057] (2)

[0058] The angle measurement is fed to an input of a calculation unit 19, which is connected to the output 18 of the arctangent calculation unit 17. For each angle measurement output at output 18, the calculation unit 19 generates three test values, each of which is output at one of the outputs 20, 21, or 22 of the calculation unit 19. To determine a first test value, corresponding to the measured value of the first magnetic field sensor 5, the sine of the angle measurement is calculated. <p gebildet. Zum Bestimmen eines zweiten, dem Messwert des zweiten Magnetfeldsensors 6 zugeordneten Prüfwerts, wird der Sinus aus dem Winkel p + 120° gebildet, und zum Bestimmen eines dem Messwert des dritten Magnetfeldsensors 6 zugeordneten Prüfwerts wird der Sinus aus dem Winkel p + 240° gebildet.

[0059] In an alternative embodiment of the procedure, the test values ​​are determined by inverse sine / cosine transformation of the transformation vector according to equation (3):

[0060] PX 3

[0061] -0.5

[0062] P2 (3) _P3. 3

[0063]

[0064] Here, P1 denotes the first test value, P2 the second test value, P3 the third test value, a the a-component, and ß the -component of the transformation vector. However, determining the test values ​​from the angle measurement or the angle measurement shifted by 120° or 240° is preferred because this also incorporates errors that occurred during the calculation of the arctangent of the transformation vector in the arctangent calculation device 17.

[0065] The test values ​​are fed to a comparator 23, which determines the deviations between the measured values ​​of the magnetic field sensors 5, 6, 7 and their respective assigned test values. One deviation is determined by calculating the difference between the measured value of the first magnetic field sensor 5 and the test value of the first magnetic field sensor 5, another deviation by calculating the difference between the measured value of the second magnetic field sensor 6 and the test value of the second magnetic field sensor 6, and a further deviation by calculating the difference between the measured value of the third magnetic field sensor 7 and the test value of the third magnetic field sensor 7. The deviations are each output at their respective outputs 24, 25, 26 of the comparator 23.

[0066] If at least one of the three deviations lies outside a tolerance band, an error in the angle measurement is detected, and the magnetic field sensor 5, 6, 7 whose measurement signal caused the error is identified. It is assumed that only the measured value of one of the three magnetic field sensors 5, 6, 7 caused the error.

[0067] To identify the magnetic field sensor 5, 6, 7 whose measurement signal caused the error, the deviations determined for the angular position for which the error was detected are temporarily stored. This angular position is also referred to below as the "first angular position".

[0068] Now the reference magnet 2 is moved relative to the sensor device 3 into a second angular position, which differs in magnitude from the first angular position by more than 60° and less than 120°.

[0069] For the second angular position, a measurement of the magnetic field of the reference magnet 2 is recorded using the magnetic field sensors 5, 6, 7. The measured values ​​thus obtained are transformed according to equation (1) by means of a sine / cosine or Clarke transformation into a second transformation vector, which has a second α-component and a second β-component. By forming the arctangent of the quotient with the second β-component in the numerator and the second α-component in the denominator, a second angular measurement 2 is determined according to equation (2).

[0070] Subsequently, a second test value is provided for each of the measured values ​​recorded for the second angular position. A second test value assigned to the measured value of the first magnetic field sensor 5 is determined by sinusoidal calculation of the second angular measurement 2, an extended second test value assigned to the measured value of the second magnetic field sensor 6 is determined by sinusoidal calculation of the angle 2 + 120°, and a further second test value assigned to the measured value of the third magnetic field sensor 7 is determined by sinusoidal calculation of the angle 2 + 240°.

[0071] The second test values ​​are fed to the comparison device 23, which determines the deviations between the second measured values ​​of the magnetic field sensors 5, 6, 7 and the test values ​​assigned to them.

[0072] From the six deviations determined in this way for the first and second angular positions, the deviation with the largest magnitude is determined using a device connected to the comparator 23 for determining the maximum 27. The magnetic field sensor 5, 6, 7, which is associated with the deviation with the largest magnitude, is identified as faulty, and the measuring device 1 is subsequently operated in an emergency mode in which the measured values ​​of the faulty magnetic field sensor are no longer considered in the calculation. This requires an adjustment of the transformation matrix. By way of example, the measured values ​​M2 of the second magnetic field sensor 6 are assumed to be faulty below. After switching to emergency mode, the measured values ​​M2 are no longer considered. The transformation equations then change as follows:

[0073] 0 1 FM11

[0074] 2V3 M2 (4)

[0075]

[0076] 3 J LM3.

[0077] By comparing equation (1) with equation (4), it can be seen that the coefficients weighting the measured value M2 are set to zero in emergency mode, and the remaining coefficients are adjusted accordingly. Using the method described above, an error occurring during angle measurement, which is present only in the measured values ​​of one of the three magnetic field sensors 5, 6, 7, can be detected and unambiguously assigned to one of the three magnetic field sensors 5, 6, 7.

[0078] Figure 3 shows an error analysis in which the measurement signals of the magnetic field sensor 7 are subjected to a constant error of 5% deviation over one revolution. During the error analysis, the magnetic field sensor 5 is positioned at an angular position of 0 degrees, the magnetic field sensor 6 at a position of 120 degrees, and the magnetic field sensor 7 at a position of 240 degrees. The magnetic field sensor 5 provides the measured value M1, the magnetic field sensor 6 the measured value M2, and the magnetic field sensor 7 the measured value M3, as defined in Equation 1.

[0079] After calculating the angular position according to equations (2) and (3), the curve shown in Fig. 3 is obtained as the difference between an angular position calculated from error-free measured values ​​M1, M2, M3 and an angular position calculated from the error-free measured values ​​M1 and M3, as well as the error-prone measured values ​​M2.

[0080] The rotational angular position of the reference magnet 4, which is rotatably mounted relative to the sensor arrangement 3 comprising the magnetic field sensors 5, 6, 7, is plotted on the abscissa from -180 degrees to +180 degrees. The deviation from the error-free angular position value in degrees is shown on the ordinate. The five percent deviation of the measured value M2 results in a maximum deviation of 2.6 degrees in the determined angular measurement.

[0081] Figure 4 shows the progression of the individual deviations of the test values ​​determined according to the method described above from the corresponding measured values ​​of the magnetic field sensors. Over the course of a complete rotation from -180 to +180 degrees, the method according to the invention is able to identify a defective magnetic field sensor 5, 6, 8 by determining the maximum value of the deviation.

[0082] In the example diagram in Figure 4, magnetic field sensor 6 (deviation 120°) exhibits a maximum deviation of 5.4%, which exceeds the deviations measured for magnetic field sensor 5 (deviation 0°) and magnetic field sensor 7 (deviation 240°). If this maximum deviation also lies outside the tolerance band, angle sensor 1 continues to operate in emergency mode, as described above. The calculation of the angle measurement value <p, erfolgt ab diesem Zeitpunkt dann gemäß den Gleichungen (2) und (4).

[0083] It should also be mentioned that the threshold values ​​that limit the tolerance band are freely selectable and can be defined application-specifically.

Claims

Patent claims 1. Method for recording an angle measurement value using a magnetic angle sensor (1), a) wherein an angle sensor (1 ) is provided, which has at least three magnetic field sensors (5, 6, 7) offset from each other in the circumferential direction with respect to a geometric axis of rotation (4), and to generate a magnetic field, a reference magnet (2) rotatably mounted with respect to the axis of rotation (4) relative to the magnetic field sensors (5, 6, 7) b) wherein, for each angular position of the reference magnet (2) relative to the magnetic field sensors (5, 6, 7), a measurement value for the magnetic field of the reference magnet (2) is recorded by means of the magnetic field sensors (5, 6, 7), c) wherein the measured values ​​of the magnetic field sensors (5, 6, 7) are transformed by means of a sine / cosine transformation into a transformation vector having an a-component and an -component, and d) where an angle measurement is determined which corresponds to the arctangent of the ratio between the a-component and the -component, characterized by e) that for each of the measured values ​​recorded for the angular position a test value is provided such that a vector formed from the test values ​​corresponds to the inverse sine / cosine transformation of the transformation vector, f) that for each of the individual magnetic field sensors (5, 6, 7) the deviations between the measured value and the test value assigned to it are determined, g) and that if at least one of the deviations lies outside a predetermined tolerance band, an error in the angle measurement is detected.

2. Method according to claim 1, characterized in that the method according to claim 1 is carried out for a first angular position that the reference magnet (2) has relative to the magnetic field sensors (5, 6, 7), and that in the event that an error in the angle measurement is detected at the first angular position, i) the reference magnet (2) is brought into a second angular position relative to the magnetic field sensors (5, 6, 7), which differs in magnitude from the first angular position by more than 60° and less than 120°, in particular by more than 70° and less than 110° and preferably by more than 80° and less than 100°, ii) steps b) to f) of claim 1 are carried out for the second angular position, and iii) from the deviations determined for the first and second angular positions, the deviation with the largest amount is determined, and the magnetic field sensor (5, 6, 7) to which the deviation with the largest amount is assigned is identified as faulty.

3. Method according to claim 1, characterized in that the method according to claim 1 is carried out for a first angular position that the reference magnet (2) has relative to the magnetic field sensors (5, 6, 7), and that in the event that an error in the angle measurement is detected at the first angular position, i) the reference magnet (2) is moved to a further angular position relative to the magnetic field sensors (5, 6, 7) and steps b) to f) from claim 1 are carried out for the further angular position,18 ii) Step i) is repeated until an angular position is reached which differs from the first angular position by at least 180° and preferably by at least 360°, iii) from the deviations determined for the first and subsequent angular positions, the deviation with the largest amount is determined, and the magnetic field sensor (5, 6, 7) to which the deviation with the largest amount is assigned is identified as faulty.

4. Method according to claim 2 or 3, characterized in that the magnetic angle sensor (1) continues to operate in an emergency mode after the magnetic field sensor (5, 6, 7) that has output the faulty measurement has been identified, in which the angle measurement value is determined only from the measurement values ​​of the remaining magnetic field sensors (5, 6, 7) that have not been identified as faulty.

5. Method according to claim 4, characterized in that an emergency operation indicator is activated when the angle sensor (1) is operated in emergency mode.

6. Method according to one of claims 1 to 5, characterized in that the magnetic field sensors (5, 6, 7) of the angle sensor (1) are located on the circular line arranged concentrically to the geometric axis of rotation (4).

7. A method according to any one of claims 1 to 6, characterized in that the magnetic field sensors (5, 6, 7) are arranged and configured such that the measuring directions of successively adjacent magnetic field sensors (5, 6, 7) on the circular line each enclose an angle between them that deviates from 90°, and that this angle is in particular 120° or 60°.19 8. Method according to one of claims 4 to 7, characterized in that the sine-Z-cosine transformation is carried out using a matrix, and that the coefficients of the matrix are changed when the emergency mode is activated such that the sine-Z-cosine transformation is carried out only with the measured values ​​of the magnetic field sensors (5, 6, 7) that are not recognized as faulty.

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