Rotation angle measurement method and rotation angle measurement circuit

Abstract

Rotation angle measurement methods, wherein - a rotary angle measuring system with a shaft rotatably mounted about a rotary axis, a sensor generating or changing a magnetic field, a first sensor system with at least one magnetic field sensor of a first type and a second sensor system with at least one magnetic field sensor of a second type is provided, - the first sensor system detects a first magnetic field component Bz and the second sensor system detects a second and a third magnetic field component Bx and By, wherein the first, the second and the third magnetic field components Bz, Bx, By are each perpendicular to each other, - each rotation angle value (Φ1) determined for a rotation angle of the shaft by the first sensor system has a known constant angular offset (ΔΦ) to the rotation angle value (Φ2) determined for the same rotation angle of the shaft by the second sensor system, - at a first time t1, at least one first measurement value (S1) is determined with the first sensor system and at least one second measurement value (T1) is determined with the second sensor system, - for which at least one first measured value (S1) is determined a first rotation angle value (Φ1) and for which at least one second measured value (T1) a second rotation angle value (Φ2) is determined, - from the first rotation angle value (Φ1) and the angular offset (ΔΦ) a first output rotation angle value (ΦA1) is determined as a reference value for the second sensor system, - a deviation (D1) of the second rotation angle value (Φ2) from the first output rotation angle value (ΦA1) is determined and - the deviation (D1) is minimized by changing at least one second measurement value (T1) and recalculating the second rotation angle value (Φ2), and a new second rotation angle value (Φ2) obtained by minimizing or the at least one changed second measurement value (T1) is output as a final output value (ΦE).

Description

[0001] The invention relates to a rotary angle measurement method and a rotary angle measurement circuit.

[0002] Integrated rotation angle determination sensor units are particularly well-known from applications in the automotive sector. Here, for example, the position of a shaft is determined by measuring the magnetic flux using magnetic field sensors.

[0003] Rotation angle determination unit with a combination of axial and perpendicular angle sensor are known, for example, from DE 10 20115 101 635 A1 or EP 3 147 631 B1.

[0004] Safety requirements are particularly high in this area. These requirements are defined by industry standards, such as ISO 26262. This ISO standard defines, for example, safety levels A to D, known as Automotive Safety Integrity Levels (ASIL), where ASIL A represents the lowest safety level and ASIL D the highest, with each safety level defining different requirements.

[0005] Requirements include, for example, a certain degree of redundancy with regard to the measurement methods and the hardware.

[0006] Against this background, the object of the invention is to specify a rotary angle measurement method for a rotary angle measurement system and a rotary angle measurement circuit that further develops the state of the art and in particular provides a particularly reliable, yet simple and cost-effective solution.

[0007] The problem is solved by a rotation angle measurement method with the features of claim 1 and by a rotation angle measurement circuit according to claim 8. Advantageous embodiments of the invention are the subject of dependent claims.

[0008] According to the first subject matter of the invention, a rotary angle measuring method is proposed, wherein a rotary angle measuring system is provided with a shaft rotatably mounted about a rotational axis, an encoder generating or changing a magnetic field, a first sensor system with at least one magnetic field sensor of a first type and a second sensor system with at least one magnetic field sensor of a second type.

[0009] The first sensor system detects a first magnetic field component, and the second sensor system detects a second and a third magnetic field component, with the first, second, and third magnetic field components each being perpendicular to each other.

[0010] Each rotation angle value determined for a rotation angle of the shaft by the first sensor system also exhibits a known constant angular offset for the same rotation angle of the shaft determined by the second sensor system.

[0011] At a first point in time, at least one first measurement value is determined with the first sensor system and at least one second measurement value is determined with the second sensor system; a first rotation angle value is determined for the at least one first measurement value and a second rotation angle value is determined for the at least one second measurement value.

[0012] From the first rotation angle value and the angle offset, a first output rotation angle value is determined as a reference value for the second sensor system, and a deviation of the second rotation angle value from the first output rotation angle value is determined.

[0013] Either the deviation is minimized by changing at least one second measured value and recalculating the second rotation angle value, and a new second rotation angle value obtained by minimizing, or the at least one changed measured value, is output as a final output value, or the deviation is compared with a threshold value and the first output rotation angle value is output as a final output value.

[0014] It is understood that the first type and the second type differ, for example with regard to the underlying measurement principle, with both sensor systems comprising one or more than one sensor of the respective type.

[0015] Furthermore, each sensor system is designed to provide one or more measured values, for example analog ones, as a basis for determining the angle of rotation. Accordingly, according to the inventive method, a rotation angle value is determined for the same position of the shaft using differently operating sensors.

[0016] However, the arrangement of the sensor systems or the individual sensors results in a constant angular offset between the sensor systems or the angular values ​​determined by the sensor systems for the same angle of rotation.

[0017] The angular offset is therefore constant, especially in an integrated design of the two sensor systems in one unit, since the relative arrangement of the sensor systems to each other does not change.

[0018] The angular offset can be determined, for example, preferably at the end of the manufacturing process as part of a calibration.

[0019] The angular offset describes the relationship or relative course of the characteristic curves of the two sensor systems to each other.

[0020] The angular offset between the values ​​determined using the first sensor system and the values ​​determined using the second sensor system is preferably stored as a constant angular value.

[0021] Alternatively, a table, a so-called look-up table, can be used to store the size, i.e., the value of the angle offset, for each angle value as a function of the determined angle.

[0022] In other words, each value of the characteristic curve of the first sensor system is assigned a value of the characteristic curve of the second sensor system that takes the angular offset into account.

[0023] It should also be understood that the aforementioned procedural steps do not all have to be carried out in the stated order.

[0024] It is essential that the measured values ​​from the first sensor system and the second sensor system are recorded at the same time, i.e., within the shortest possible time interval.

[0025] Determining the second rotation angle value, however, does not have to occur simultaneously with or directly after determining the first rotation angle value. Rather, according to one embodiment, the second rotation angle value is determined only after the first output rotation angle value has been determined.

[0026] The first output rotation angle value is determined, for example, by adding the angular offset or by using a table / look-up table.

[0027] The first output rotation angle value therefore represents, in effect, an expected rotation angle value for the second sensor system.

[0028] The first output rotation angle value preferably serves as a reference value for the second sensor system, whereby, due to different properties of the different types of sensors of the two sensor systems, differences may arise between the reference value determined by the first sensor system and the rotation angle value determined by the second sensor system.

[0029] Preferably, a first magnetic field component Bz is detected by the first sensor system and a second magnetic field component Bx and a third magnetic field component By are detected by the second sensor system.

[0030] The magnetic field components Bx, By and Bz are orthogonal to each other.

[0031] The two types of sensors differ, for example, in sensitivity, stray field dependencies, temperature dependencies, lifetime drift, and angular noise. If, for instance, the first sensor system is independent of stray fields and the second sensor system exhibits a significant stray field dependency in its measured values, then the difference between the first output rotation angle value and the second rotation angle value corresponds to the stray field influence.

[0032] According to the procedure, this difference is determined as the deviation of the second rotation angle value from the first output rotation angle value.

[0033] Either the deviation, according to the first alternative embodiment, is used to correct the second rotation angle value before it is output as the final output value, i.e., as the result or current rotation angle value. Alternatively, according to the second alternative embodiment, the deviation is used as a control value, with the first output rotation angle value, based on the first rotation angle value, being output as the final output value.

[0034] It goes without saying that the deviation can also be stored as a control value, allowing the long-term behavior of both sensor systems to be monitored.

[0035] The correction of the second rotation angle value, i.e., the minimization of the deviation, is achieved, for example, by modifying the existing second measurement and subsequently recalculating the second rotation angle value based on the modified measurement. According to a further development, the minimization process is terminated once the newly determined deviation falls below a certain threshold.

[0036] The process meets a high safety standard because two sensor systems with different sensors are used to determine the angle of rotation. Furthermore, according to additional training, the sensor systems and / or the sensors within the sensor systems are configured redundantly to increase safety, for example in a master-slave configuration.

[0037] Using the second measurement to minimize the deviation has the advantage that the change can be easily implemented in an analog component. In particular, this results in modified analog measurements that can be easily integrated into existing systems as the final output value.

[0038] According to a first embodiment, each sensor system has at least two sensors of the respective type and / or the rotary angle measuring system has two first sensor systems and two second sensor systems.

[0039] In another embodiment, the first magnetic field component runs parallel to the axis of rotation at an angle of at most 1° or at most 0.1°.

[0040] According to another embodiment, the first type comprises a Hall sensor and the first sensor system comprises at least two sensors. Using at least two Hall sensors enables stray field independence, where the Hall sensors are, for example, horizontal Hall sensors, also known as Hall plates or Z-plates. However, the resolution of Hall sensors is typically no better than 0.1°.

[0041] In another advanced training, the second type is a magnetoresistive sensor, for example, an anisotropic magnetic resistive (AMR) sensor, a giant magnetic resistive (GMR) sensor, or a tunnel magnetic resistive (TMR) sensor. TMR sensors, in particular, enable a resolution of 0.01° over 360°. It is understood that magnetoresistive sensors typically have four magnetoresistive elements arranged as a Wheatstone bridge, specifically as a full bridge or a half bridge.

[0042] According to another embodiment, the deviation is minimized by adjusting the second angle value in one or more steps, i.e., the second rotation angle value is changed only once or several times to minimize the deviation. This minimization takes place, for example, within a control loop (tracking loop), where the loop includes, for example, the steps of changing the second measured value, recalculating the second rotation angle value, and determining the deviation.

[0043] The loop essentially represents a type of phase-locked loop (PLL). Using this loop, fundamental shortcomings of the second sensor system, such as a high dependence of the measured values ​​on stray fields, are compensated for or corrected by relying on the first sensor system, which does not exhibit this shortcoming or only to a lesser extent. For example, the influence of a stray field can be compensated for in this way.

[0044] According to a further aspect of the invention, a rotary angle measuring circuit comprises a first measurement processing unit, a second measurement processing unit and an evaluation unit.

[0045] The first measurement processing unit has at least one input terminal for receiving at least one measurement value from a first sensor system, a first rotation angle determination unit for determining a first rotation angle from the at least one measurement value of the first sensor system, an output value determination unit for determining a first output rotation angle value based on the first rotation angle and a known constant angular offset between the first and the second sensor system, and an output terminal for outputting the first output rotation angle value.

[0046] The second measurement processing unit has at least one input connection for receiving at least one measurement value from a second sensor system, a first signal processing unit for processing the at least one measurement value, and two output connections for outputting the two processed measurement values ​​from the second sensor system.

[0047] The evaluation unit has at least two input connections for receiving the first output rotation angle value from the first measurement processing unit and the at least one processed measurement value from the second sensor system from the second measurement processing unit, at least one output connection, a rotation angle determination unit, a comparison unit and a second signal processing unit.

[0048] The second signal processing unit is designed to modify or retain at least one processed measurement value from the second sensor system, taking into account a deviation, and to pass it on to the rotation angle determination unit as at least one further processed measurement value.

[0049] The rotation angle determination unit is designed to determine a second rotation angle value from at least one further processed measured value of the second sensor system, and the comparison unit is designed to determine a deviation between the first output rotation angle value and the second rotation angle value and to pass the deviation on to the second signal processing unit.

[0050] The evaluation unit's at least one output port is designed to output the second rotation angle value or the at least one further processed measurement value from the second sensor system as a final output value. Alternatively, the first measurement processing unit has a further output port for outputting the first output rotation angle value as a final output value, and the evaluation unit's output port is designed to output the deviation or a control value determined by comparing the deviation with a threshold value.

[0051] It is understood that the type and number of measured values ​​received by the first and second measurement processing units depend on the sensor(s) of the respective sensor system. The measurement processing units have a corresponding number of input connections.

[0052] A measured value is, for example, a voltage output by a sensor, i.e., a voltage applied to the input terminal. In addition to a signal component dependent on the rotation angle or prevailing magnetic field, the measured value can also contain other components, such as an offset.

[0053] A wide variety of sensor systems and many variations of sensor arrangements for determining rotation angles are known, each with its own advantages and disadvantages.

[0054] A sensor system is defined here as a unit which includes at least one sensor and typically a control unit and outputs a signal quantity comprising at least one typically analog signal, wherein the signal quantity is sufficient to determine a rotation angle of a shaft.

[0055] For example, the first sensor system comprises three horizontal Hall sensors arranged in fixed angular positions on a circle around the axis of rotation of the shaft, with each Hall sensor detecting a first magnetic field component running parallel to the axis of rotation.

[0056] For example, a control unit of the sensor unit outputs two voltages as measured values, with each voltage being derived from two of the three Hall voltages of the three sensors. The first sensor system would therefore provide two measured values ​​suitable as a basis for determining the rotation angle of the shaft and would be independent of stray fields.

[0057] The second sensor system comprises, for example, two magnetoresistive sensors, e.g., two AMR sensors or two TMR sensors or two GMR sensors, wherein the two sensors are arranged, for example, on a circle around the axis of rotation of the shaft at opposite positions and one sensor detects a second magnetic field component perpendicular to the axis of rotation, while the other sensor detects a third magnetic field component orthogonal to the second component and to the axis of rotation.

[0058] A control unit of the second sensor system accordingly provides two voltages, which correspond to the second and third magnetic field components and are suitable as a basis for determining a rotation angle.

[0059] The processing of the measured values ​​by the signal processing units includes, for example, digitizing and / or calculating the offset of, for example, an operating voltage, a phase, etc.

[0060] Furthermore, it is understood that the rotation angle measurement method according to the invention can be carried out using the rotation angle measurement circuit.

[0061] The components of the evaluation unit form a loop, comparable to a phase-locked loop (PLL), which essentially allows the second set of measurements to be controlled based on the first set. The operation performed when the measured values ​​change is essentially a rotation by an angle determined as a deviation.

[0062] The individual components or units are implemented analogously, i.e., using analog components, and / or digitally, i.e., using software, e.g., on a (not further specified) microcontroller (µC) and / or as an application-specific integrated circuit (ASIC). High speed can be achieved particularly through hardware solutions.

[0063] It goes without saying that in a digital implementation, the typically analog measured values ​​of the sensor systems must first be converted using analog-to-digital converters, or the circuit must have corresponding converters.

[0064] Preferably, at least the two rotation angle determination units, the output angle determination unit and the comparison unit are designed as software and / or ASIC.

[0065] The first and second signal processing units are preferably either both analog or both designed as software and / or ASIC.

[0066] In other words, the evaluation unit in particular, i.e. the control loop, has both analog and digital components.

[0067] It is further noted that the evaluation unit preferably has additional output connections to output further values, e.g., the at least one further processed measured value from the second sensor unit and / or the deviation.

[0068] According to a first embodiment, the first measurement processing unit has an analog-to-digital converter between each input terminal and the first rotation angle determination unit for converting the at least one measurement value of the first sensor system into digital signals, wherein the first rotation angle determination unit and the output value determination unit are designed to process digital signals.

[0069] In another embodiment, the second measurement processing unit has an analog-to-digital converter between each input terminal and the first signal processing unit for converting the at least one measurement value of the second sensor system into digital signals, wherein the second signal processing unit of the evaluation unit is designed to process digital signals.

[0070] According to an alternative embodiment, the evaluation unit has at least one analog-to-digital converter between the second signal processing unit and the second angle determination unit for digitizing the at least one further processed measured value, and a digital-to-analog converter between the comparison unit and the second signal processing unit for converting the deviation into an analog signal, wherein the second angle determination unit and the comparison unit as well as the first measured value processing unit are designed to process digital signals and the second signal processing unit as well as the first measured value processing unit are designed to process analog signals.

[0071] In this embodiment, the signal path from the second sensor unit or the corresponding input terminals of the circuit remains completely analogous up to the second rotation angle determination unit of the evaluation unit.

[0072] The invention is explained in more detail below with reference to the drawings. Similar parts are labelled with identical designations. The illustrated embodiments are highly schematic; that is, the distances as well as the lateral and vertical extents are not to scale and, unless otherwise indicated, do not exhibit any derivable geometric relationships to one another. In these drawings, the Fig. 1 a schematic diagram of a first embodiment of a rotation angle measuring method according to the invention, Fig. 2 a schematic diagram of a second embodiment of a rotation angle measuring method according to the invention, Fig. 3 a view of a first embodiment of a rotary angle measuring circuit according to the invention.

[0073] The illustration of Fig. Figure 1 shows a process of a rotation angle measurement method according to a first embodiment of the invention, in order to determine the rotation angle of a shaft rotatably mounted about a rotation axis by means of a sensor, a first sensor system with at least one magnetic field sensor of a first type and a second sensor system with at least one magnetic field sensor of the second type.

[0074] At a first time t1, a first measurement S1 is determined using a first sensor system and a second measurement T1 is determined using a second sensor system, wherein the first sensor system detects a first magnetic field component Bz, the second sensor system detects a second magnetic field component Bx and a third magnetic field component By and the magnetic field components Bx, By and Bz are orthogonal to each other.

[0075] A constant angular offset Δϕ between rotation angle values ​​determined for the same shaft position using the two sensor systems, due to the arrangement of the two sensor systems, is known.

[0076] A first rotation angle value ϕ1 is determined from the first measured value S1. Subsequently, based on the first rotation angle value ϕ1 and the angular offset Δϕ, a first output rotation angle value ϕA1 is determined as a reference / comparison value for the second sensor system.

[0077] Furthermore, a second rotation angle value ϕ2 is determined before, during or after determining the first rotation angle value ϕ1 and / or determining the first output rotation angle value ϕA1 from the second measured value T1 of the second sensor system.

[0078] The following process determines the deviation D1 of the second rotation angle value ϕ2 from the first output rotation angle value ϕA1. In a loop L1 that is executed at least once, the deviation D1 is minimized. Within the loop L1, based on the deviation D1, the second rotation angle value ϕ2 is changed either directly or by modifying the existing second measured value T1 and recalculating the second rotation angle value ϕ2. The deviation D1 of the now modified second rotation angle value ϕ2 from the first output rotation angle value ϕA1 is then determined again.

[0079] For example, loop L1 will continue to run until the deviation value D1 falls below a threshold.

[0080] Furthermore, the second rotation angle value ϕ2 is output as the final output value ϕE.

[0081] In the illustration of the Fig. Figure 2 shows a second embodiment of the rotation angle measurement method according to the invention. The following only highlights the differences compared to the embodiment shown in Figure 2. Fig. 1. Explained in the embodiment shown.

[0082] The final output value ϕE is the first output rotation angle value ϕA1. The deviation D1 is determined, but not used in a loop to correct / optimize the second rotation angle value ϕ2. Instead, it is only used to monitor the two sensor systems and compared to a threshold value. Any threshold exceedance is output or displayed using an error value ER.

[0083] In the illustration of the Fig. Figure 3 shows a first embodiment of a rotary angle measuring circuit SCH according to the invention.

[0084] The rotary angle measuring circuit SCH has a first measurement processing unit M1, a second measurement processing unit M2 and an evaluation unit AE.

[0085] In the illustrated embodiment, the first measurement processing unit M1 has two input connections, a rotation angle determination unit W1, an output value determination unit AU and an output connection.

[0086] The input terminals are designed to be connected to a first sensor unit (not shown) in order to receive two initial measurement signals S1 and S2 from the first measuring unit. Using the first rotation angle determination unit W1, a first rotation angle value ϕ1 can be determined from the two initial measurement signals S1 and S2 received via the input terminals from the first sensor unit.

[0087] The output determination unit AU is designed to receive the first rotation angle value ϕ1 and, based on this first rotation angle value ϕ1 and a known constant angular offset Δϕ between the first and second sensor systems, to determine a first output rotation angle value ϕA1. For this purpose, the angular offset Δϕ or a lookup table containing correspondingly converted angle values ​​is stored in the output determination unit AU. The output terminal is designed to output the first output rotation angle value ϕA1.

[0088] In the illustrated embodiment, the second measurement processing unit M2 has two input connections for receiving two measured values ​​T1 and T2 from a second sensor system, a first signal processing unit SV1, and an output connection. The first signal processing unit SV1 is designed to process the two measured values ​​T1 and T2 and output them as processed measured values ​​T1' and T2' via the output connection.

[0089] The evaluation unit AE is designed to receive the two processed measured values ​​T1' and T2' from the second measured value processing unit M2 via two input connections and to modify or leave them as they are by means of a second signal processing unit SV2, taking into account a deviation D1, and to pass them on as further processed measured values ​​T1" and T2" to a second rotation angle determination unit W2 of the evaluation unit AE.

[0090] The second rotation angle determination unit W2 is designed to determine a second rotation angle value ϕ2 from the two further processed measured values ​​T1" and T2" of the second sensor unit and to pass the second rotation angle value ϕ2 to a comparison unit VE of the evaluation unit AE.

[0091] The comparison unit VE is designed to receive the first rotation angle value ϕ1 from the first measurement processing unit M1 via a further input connection of the evaluation unit AE, to receive the second rotation angle value ϕ2 from the second rotation angle determination unit W2, to determine the deviation of the second rotation angle value ϕ2 from the first rotation angle value ϕ1 and to pass the deviation on to the second signal processing unit SV2.

[0092] Furthermore, the evaluation unit AE has an output connection for outputting the second rotation angle value ϕ2 as the final output value ϕE.

[0093] Alternatively (shown with dashed lines), the first measurement processing unit M1 has a further output connection for outputting the first output rotation angle ϕA1 or the first rotation angle value ϕ1, wherein the output connection of the evaluation unit AE is suitable, for example, to output the deviation D1.

[0094] In another alternative (shown in dashed lines), the evaluation unit AU has two output connections, the output connections being designed to each output one of the two further processed measured values ​​T1" or T2" from the second sensor unit.

[0095] According to a first embodiment, all components of the rotation angle determination circuit SCH arranged above the dotted line L are analog, and those arranged below the line are digital. Alternatively, for example, all components of the rotation angle determination circuit SCH are digital. It is understood that the rotation angle determination circuit SCH may, if necessary, particularly if the measurement signals S1, S2 and / or T1, T2 are analog and / or between digital and analog components, include appropriate converters.

Claims

[1] Angle of rotation measurement methods, wherein - a rotary angle measuring system with a shaft rotatably mounted about a rotary axis, a sensor generating or changing a magnetic field, a first sensor system with at least one magnetic field sensor of a first type and a second sensor system with at least one magnetic field sensor of a second type is provided, - the first sensor system detects a first magnetic field component Bz and the second sensor system detects a second and a third magnetic field component Bx and By, wherein the first, the second and the third magnetic field components Bz, Bx, By are each perpendicular to each other, - each rotation angle value (Φ1) determined for a rotation angle of the shaft by the first sensor system has a known constant angular offset (ΔΦ) to the rotation angle value (Φ2) determined for the same rotation angle of the shaft by the second sensor system, - at a first time t1, at least one first measurement value (S1) is determined with the first sensor system and at least one second measurement value (T1) is determined with the second sensor system, - for which at least one first measured value (S1) is determined a first rotation angle value (Φ1) and for which at least one second measured value (T1) a second rotation angle value (Φ2) is determined, - from the first rotation angle value (Φ1) and the angular offset (ΔΦ) a first output rotation angle value (ΦA1) is determined as a reference value for the second sensor system, - a deviation (D1) of the second rotation angle value (Φ2) from the first output rotation angle value (ΦA1) is determined and - the deviation (D1) is minimized by changing at least one second measurement value (T1) and recalculating the second rotation angle value (Φ2), and a new second rotation angle value (Φ2) obtained by minimizing or the at least one changed second measurement value (T1) is output as a final output value (ΦE). [2] Rotation angle measuring method according to claim 1, characterized by that each sensor system has at least two sensors of the respective type. [3] Angle of rotation measuring method according to claim 1 or 2, characterized by that the rotary angle measuring system has two first sensor systems and two second sensor systems. [4] Angle of rotation measuring method according to one of the preceding claims, characterized by that the first magnetic field component Bz runs parallel to the axis of rotation or at an angle to the axis of rotation of at most 1° or at most 0.1°. [5] Angle of rotation measuring method according to one of the preceding claims, characterized by that the first type is a Hall sensor and the first sensor system includes at least two sensors. [6] Angle of rotation measuring method according to one of the preceding claims, characterized by that the second type is a magnetoresistive sensor. [7] Angle of rotation measuring method according to one of the preceding claims, characterized by , that minimizing the deviation (D1) is achieved by adjusting the second rotation angle value (Φ2) in several steps. [8] Rotary angle measuring circuit (SCH) configured for carrying out a rotary angle measuring method according to any one of claims 1 to 7, comprising - a first measurement processing unit (M1), a second measurement processing unit (M2) and an evaluation unit (AE), - the second measurement processing unit (M2) has at least one input connection for receiving at least one measurement value (T1, T2) from a second sensor system, a first signal processing unit (SV1) for processing the at least one measurement value (T1, T2) and at least one output connection for outputting the at least one processed measurement value (T1', T2') from the second sensor system, - the first measurement processing unit (M1) has at least one input terminal for receiving at least one measurement value (S1, S2) from a first sensor system, a first rotation angle determination unit (W1) for determining a first rotation angle (Φ1) from the at least one measurement value (S1, S2) of the first sensor system, an output value determination unit (AU) for determining a first output rotation angle value (ΦA1) based on the first rotation angle (Φ1) and a known constant angular offset (ΔΦ) between the first and the second sensor system, and an output terminal for outputting the first output rotation angle value (ΦA1). - the evaluation unit (AE) has at least two input terminals for receiving the first output rotation angle value (ΦA1) from the first measurement processing unit (M1) and the at least one processed measurement value (T1', T2') of the second sensor system from the second measurement processing unit (M2), at least one output terminal, a second rotation angle determination unit (W2), a comparison unit (VE) and a second signal processing unit (SV2), wherein - the second signal processing unit (SV2) is designed to modify or retain at least one processed measured value (T1', T2') of the second sensor system, taking into account a deviation (D1), and to pass it on as at least one further processed measured value (T1'', T2'') to the second rotation angle determination unit (W2), - the second rotation angle determination unit (W2) is designed to determine a second rotation angle value (Φ2) from the at least one further processed measured values ​​(T1'', T2'') of the second sensor system and - the comparator unit (CU) is designed to determine the deviation (D1) between the first output rotation angle value (ΦA1) and the second rotation angle value (Φ2) and to pass the deviation (D1) to the first signal processing unit (SV1), wherein - the at least one output terminal of the evaluation unit (AE) is designed to output the second rotation angle value (Φ2) or the at least one further processed measured value (T1'', T2'') of the second sensor system as a final output value (ΦE). [9] Rotary angle measuring circuit (SCH) according to claim 8, characterized by, that the first measurement processing unit (M1) between each input terminal and the first rotation angle determination unit (W1) has an analog-to-digital converter for converting the at least one measurement value (S1, S2) of the first sensor system into digital signals, wherein the first rotation angle determination unit (W1) and the output value determination unit (AU) are designed to process digital signals. [10] Rotary angle measuring circuit (SCH) according to claim 8 or 9, characterized by , that the second measurement processing unit (M2) between each input terminal and the first signal processing unit (SV1) has an analog-to-digital converter for converting the at least one measurement value (T1, T2) of the second sensor system into digital signals, wherein the second signal processing unit (SV2) of the evaluation unit (AE) is designed to process digital signals. [11] Rotary angle measuring circuit (SCH) according to claim 8 or 9, characterized by , that - the evaluation unit (AE) between the second signal processing unit (SV2) and the second rotation angle determination unit (W2) includes at least one analog-to-digital converter for digitizing the at least one further processed measured value (T1'', T2'') and - has a digital-to-analog converter between the comparator unit (VE) and the second signal processing unit (SV2) for converting the deviation (D1) into an analog signal, wherein - the second rotation angle determination unit (W2) and the comparison unit (VE) as well as the first measurement processing unit (M1) are designed to process digital signals and - the second signal processing unit (SV2) and the first measurement processing unit (M2) are designed to process analog signals.

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