Actuator device and method

Abstract

The invention relates to an actuator device (1), in particular a pneumatic rotary actuator or a pneumatic gripper, for industrial automation, comprising a magnetic field sensor device (2) and a drive arrangement for performing a drive movement (3), wherein the drive arrangement has a rotary motion part (4) comprising a first magnetic element (5) and which, during the drive movement (3), changes its rotational position relative to the magnetic field sensor device (2) over a rotational position angular range of more than one revolution, wherein the drive arrangement further comprises a linear motion part (6) coupled to the rotary motion part (4), which has a second magnetic element (7) and performs a linear movement relative to the magnetic field sensor device (2) during the drive movement, wherein the magnetic field sensor device (2) is configuredto detect the magnetic fields of the first magnetic element (5) and the second magnetic element (7) and the actuator device (1) further comprises an evaluation unit (14) which is configured to determine, on the basis of the detected magnetic fields, a unique rotational position of the rotary motion part (4) with respect to the rotational position angular range.

Description

[0001] The invention relates to an actuator device for industrial automation, in particular a pneumatic rotary actuator or a pneumatic gripper, comprising a magnetic field sensor device and a drive arrangement for carrying out a drive movement, wherein the drive arrangement has a rotary motion part comprising a first magnetic element and, within the scope of the drive movement, changes its rotational position relative to the magnetic field sensor device over a rotational position angular range of more than one revolution, wherein the drive arrangement further comprises a linear motion part coupled to the rotary motion part.

[0002] For example, the linear motion component is a pneumatically actuated piston assembly which, together with the rotary motion component, forms a rack and pinion drive, in particular a pinion drive. An actuator device with a rotary position angle range of more than one revolution can also be referred to as a multi-turn actuator device.

[0003] One object of the invention is to determine a unique rotational position of the rotary motion part with respect to the rotational position angle range - i.e., with respect to an angular range that includes more than one revolution, i.e., more than 360 degrees.

[0004] The problem is solved by an actuator device according to claim 1. The actuator device has a second magnetic element which performs a linear movement relative to the magnetic field sensor device during the drive movement, wherein the magnetic field sensor device is configured to detect the magnetic fields of the first magnetic element and the second magnetic element, and the actuator device further comprises an evaluation unit configured to determine a unique rotational position of the rotary motion part with respect to the rotational position angle range based on the detected magnetic fields.

[0005] The statement that the magnetic field sensor device detects the magnetic fields of the first magnetic element and the second magnetic element means in particular that the magnetic field of the first magnetic element and the magnetic field of the second magnetic element are incorporated into the magnetic field detection carried out by the magnetic field sensor device, i.e., for example, that the magnetic field sensor device detects a total magnetic field that results from a superposition of the magnetic field of the first magnetic element and the magnetic field of the second magnetic element.

[0006] The linear movement of the second magnetic element relative to the magnetic field sensor causes a change in the magnetic field of the second magnetic element detected at the location of the magnetic field sensor. Since the rotary and linear motion components are coupled, and the linear movement of the linear motion component is therefore related to the rotary motion of the rotary motion component, the rotational position of the rotary motion component can be determined based on the detected magnetic field of the second magnetic element. Consequently, a unique rotational position of the rotary motion component can be determined with respect to its angular range.

[0007] Preferably, the first magnetic element rotates and the second magnetic element moves linearly with it, whereby the magnetic fields of the two magnetic elements superimpose and are detected in particular by a single sensor element, so that a unique assignment between a sensor signal of the sensor element and a system state of the drive arrangement is enabled over the entire range of motion - i.e. in particular the entire rotational position angle range.

[0008] In the manner described above, the evaluation unit can preferably determine the unique rotational position directly when the actuator device is switched on - thus enabling a true power-on for a multi-turn actuator device.

[0009] Advantageous further training is the subject of the sub-claims.

[0010] The invention further relates to a method for operating the actuator device, comprising the steps: - Performing the drive movement, - Detecting the magnetic fields of the first magnetic element and the second magnetic element with the magnetic field sensor device, and - Determining the unique rotational position based on the detected magnetic fields using the evaluation unit.

[0011] Further exemplary details and embodiments are explained below with reference to the figures. Fig. 1 a schematic representation of an actuator device, Fig. 2. A diagram showing the curves of a first magnetic field value and a second magnetic field value. Fig. 3 another diagram showing the curves of a first magnetic field value and a second magnetic field value, and Fig. 4 another diagram showing the curves of a first magnetic field value and a second magnetic field value.

[0012] The Fig. Figure 1 shows an exemplary design of an actuator device 1 for industrial automation. For illustrative purposes only, the actuator device 1 is designed as a pneumatic actuator device.

[0013] The actuator device 1 comprises a drive arrangement for performing a drive movement 3. The drive arrangement includes a rotary motion element 4 and at least one linear motion element 6 coupled to the rotary motion element 4. The linear motion element 6 is coupled to the rotary motion element 4 such that the rotary motion element 4 performs a rotary movement when the linear motion element 6 performs a linear movement. The drive movement 3 is, by way of example, the linear movement of the linear motion element 6. Alternatively, the drive movement can be the rotary movement of the rotary motion element 4, or another movement.

[0014] Linear movement is demonstrated along an x-direction. Rotational movement is demonstrated around an axis of rotation, which is oriented primarily in the z-direction. The z-direction is perpendicular to the plane of the drawing. A y-direction will also be considered in the following discussion. The x-direction, y-direction, and z-direction are orthogonal to each other.

[0015] The drive arrangement is exemplified as a rack and pinion drive, in particular a pinion drive. The rotary motion part 4 comprises a gear 17 and the linear motion part 6 comprises a rack 8 meshing with the gear 17.

[0016] Preferably, the drive arrangement is designed as a pneumatic drive arrangement. The linear motion element 6 is exemplified as a piston arrangement. The actuator device 1 comprises at least one pressure chamber 9, which acts pneumatically on the linear motion element 6 and whose pneumatic actuation can effect the drive movement – ​​and thus the linear and / or rotary movement. Exemplarily, the actuator device 1 has two pressure chambers 9, which act pneumatically on the linear motion element 6.

[0017] By way of example, the drive arrangement has a further linear motion element 10, which is also expediently designed as a piston arrangement and has a further rack 11 that engages with the gear 17. The further linear motion element 10 can be driven by means of at least one further pressure chamber 12, in particular by means of two further pressure chambers 12.

[0018] For example, the actuator device 1 has one or more wall structures 13 by means of which the one or more pressure chambers 9, 12 are delimited.

[0019] The actuator device 1 comprises a magnetic field sensor device 2, which is located in the Fig. Figure 1 is shown with dashed lines. The magnetic field sensor device is preferably designed as a magnetic field sensor element, in particular as a 3D Hall sensor. The magnetic field sensor device 2 is arranged in (or on) the actuator device 1 such that it is stationary with respect to the rotary motion part 4 and / or the linear motion part 6. The magnetic field sensor device 2 therefore does not move with the rotary motion part 4 or the linear motion part 6.

[0020] The rotary motion element 4 comprises a first magnetic element 5, which is exemplified as a ring magnet. The first magnetic element 5 is a permanent magnet. The ring magnet is, in particular, aligned coaxially with the axis of rotation of the rotary motion element 4. The first magnetic element 5 is, in particular, diametrically magnetized. By way of example, the magnetization direction of the first magnetic element 5 is perpendicular to the axis of rotation of the rotary motion element 4, and thus lies, in particular, in an xy-plane.

[0021] During the drive movement 3, the rotary motion element 4 – and thus also the first magnetic element 5 – changes its rotational position relative to the magnetic field sensor device 2 over a rotational angular range of more than one revolution. This rotational angular range extends from 0 to more than 360 degrees, for example, from 0 to 720 degrees, or even more. Successive sub-ranges of the rotational angular range, each extending over exactly 360 degrees, are also referred to as revolutions and are referenced with consecutive revolution numbers, with the first sub-range – i.e., the range from 0 to 360 degrees – being assigned the revolution number "0". The last sub-range can also have less than 360 degrees, particularly if the rotational angular range is not an integer multiple of 360 degrees.

[0022] The linear motion element 6 has a second magnetic element 7. The second magnetic element 7 is a permanent magnet. During the drive movement, the linear motion element 6 – and thus also the second magnetic element 7 – performs the linear movement relative to the magnetic field sensor device 2. The second magnetic element 7 can, for example, be designed as a ring magnet and is preferably aligned with its ring axis in the axial direction of the linear movement. Preferably, the second magnetic element 7 is axially magnetized. In particular, the magnetization direction of the second magnetic element 7 is in the x-direction. Preferably, the magnetization direction of the second magnetic element 7 is orthogonal to the magnetization direction of the first magnetic element 4.

[0023] As mentioned above, the actuator 1 can be designed, for example, as a pneumatic rotary actuator or as a pneumatic gripper. In a pneumatic rotary actuator configuration, a shaft is advantageously driven by means of the rotary motion element 4, or the rotary motion element 4 is designed as the driven shaft. The pneumatic rotary actuator serves, for example, to actuate a valve, in particular a process valve. Preferably, an arrangement is provided that includes a valve and the actuator 1, wherein the actuator 1 serves to actuate the valve with the drive movement. In a pneumatic gripper configuration, a gripping section, in particular a gripping finger, is arranged on the linear motion element 6, which can be set into a gripping motion by the drive movement.

[0024] The magnetic field sensor device 2 is configured to detect the magnetic fields of the first magnetic element 5 and the second magnetic element 7. The magnetic field of the first magnetic element 5 shall also be referred to as the first magnetic field, and the magnetic field of the second magnetic element 7 as the second magnetic field. The two magnetic fields superimpose within the magnetic field sensor device 2, particularly within the magnetic field sensor element. Preferably, the magnetic field sensor element is configured to measure the magnetic field strength of the superimposed magnetic fields of the first magnetic element 5 and the second magnetic element 7, particularly in several spatial directions, for example, in three spatial directions, preferably orthogonal to each other. In this way, the magnetic fields of the magnetic elements 5 and 6 can be detected.

[0025] The actuator device includes an evaluation unit 14, which is implemented, for example, as a computer unit, in particular as a microcontroller. The evaluation unit 14 is communicatively connected to the magnetic field sensor device 2 and receives one or more magnetic field sensor signals from the magnetic field sensor device 2. According to an alternative embodiment, the evaluation unit can be integrated into the magnetic field sensor device, or the magnetic field sensor device can be integrated into the evaluation unit.

[0026] The evaluation unit 14 is designed to determine, based on the detected magnetic fields, a unique rotational position of the rotary motion element 4 with respect to the rotational position angular range. A unique rotational position is defined as one that corresponds to only a single angle within the rotational position angular range. As mentioned above, the rotational position angular range extends over more than one revolution, i.e., over more than 360 degrees. The unique rotational position can also be referred to as the absolute rotation angle.

[0027] The evaluation unit 14 conveniently provides rotation position information containing the determined unique rotation position, for example as a numerical value. Optionally, the evaluation unit 14 outputs the rotation position information, for example as an output signal.

[0028] The term "rotational orientation" refers to the angle of rotation of the rotary motion element 4 within one revolution—that is, the angle of rotation within a range of 0 to 360 degrees. For each revolution, the rotational orientation begins at 0 degrees and ends at 360 degrees. The rotational orientation is not unique with respect to the (multiple revolutions) range of rotational position angles, as the same rotational orientation can occur in different revolutions.

[0029] Preferably, the evaluation unit 14 is configured to provide, and in particular determine, a first magnetic field value and a second magnetic field value using the magnetic field sensor device 2. The first magnetic field value depends on the rotational orientation of the first magnetic element 5. For example, the first magnetic field value indicates the rotational orientation of the first magnetic element 5. In particular, the magnetic field sensor device 2 measures a magnetic field strength in the x-direction and a magnetic field strength in the y-direction, and the evaluation unit 14 calculates the rotational orientation of the first magnetic element 5 (about the axis of rotation extending in the z-direction) based on these magnetic field strengths.

[0030] The second magnetic field value depends on the distance between the second magnetic element 7 and the magnetic field sensor device 2. Optionally, the second magnetic field value indicates the distance of the second magnetic element 7 from the magnetic field sensor device 2. For example, the second magnetic field value is a magnetic field strength, particularly in the z-direction.

[0031] Preferably, the first magnetic field value is based (particularly exclusively) on a first magnetic field component (measured by the magnetic field sensor device 2), for example, the magnetic field strength in the x-direction, and a second magnetic field component (measured by the magnetic field sensor device 2), for example, the magnetic field strength in the y-direction. Preferably, the second magnetic field value is based (particularly exclusively) on a third magnetic field component (measured by the magnetic field sensor device 2), for example, the magnetic field strength in the z-direction. The first, second, and third magnetic field components are preferably orthogonal to each other. This means, in particular, that the spatial directions in which these magnetic field components are measured are orthogonal to each other.Preferably, the first magnetic field component and the second magnetic field component are aligned orthogonally to the axis of rotation of the rotary motion part 4 - i.e., for example, orthogonally to the z-direction - and / or the third magnetic field component is aligned in the axial direction of the axis of rotation of the rotary motion part - i.e., for example, in the z-direction.

[0032] Preferably, the evaluation unit 14 is designed to determine the unique rotational position of the rotary motion part 4 based on the first magnetic field value and the second magnetic field value.

[0033] For example, the evaluation unit 14 is configured to provide (in particular, to determine) the rotational orientation of the rotary motion part 4 based on the detected first magnetic field value and to determine the number of revolutions of the rotary motion part 4 based on the detected second magnetic field value. The number of revolutions indicates within which revolution of the rotational position angular range the rotary motion part 4 is located. The evaluation unit 14 is configured to determine the unique rotational position based on the rotational orientation and the number of revolutions.

[0034] With reference to the in the Fig. The diagram shown in Figure 2 is intended to illustrate an exemplary procedure for determining the unambiguous rotational position.

[0035] The horizontal axis shows the rotational angular range, which by way of example comprises approximately 2.5 revolutions: a first revolution U0, a second revolution U1, and a third revolution U2. The vertical axis shows a first curve 15 of the first magnetic field value (exemplarily representing the rotational orientation) and a second curve 16 of the second magnetic field value. The first curve 15 repeats periodically for each (full) revolution, in particular from 0 degrees to 360 degrees. The second curve 16 increases monotonically over the entire rotational angular range. Advantageously, the second magnetic field value primarily represents the magnetic field strength provided by the second magnetic element 7. By way of example, the second magnetic element 7 moves towards the magnetic field sensor device 2 with increasing rotational position of the rotary motion element 4 (in particular monotonically), preferably over the entire rotational angular range.

[0036] The evaluation unit 14 expediently has for each transition from one revolution to the next revolution a respective transition threshold value S1, S2, which corresponds to the respective second magnetic field value at which this transition takes place.

[0037] A transition from one revolution to the next revolution should also be referred to as a revolution transition.

[0038] The evaluation unit 14 compares the second magnetic field value with one (or more) transition threshold values ​​S1, S2 to determine the rotation stage of the rotary motion part 4 and to provide the corresponding number of revolutions. If the second magnetic field value is less than the first transition threshold value S1, the evaluation unit 14 provides the number of revolutions "0". If the second magnetic field value is greater than the first transition threshold value S1 and less than the second transition threshold value S2, the evaluation unit 14 provides the number of revolutions "1". If the second magnetic field value is greater than the second transition threshold value S2, the evaluation unit 14 provides the number of revolutions "2".

[0039] The evaluation unit 14 multiplies the provided number of revolutions by 360 degrees and adds the rotational orientation (in degrees) to the result in order to calculate the unique rotational position.

[0040] According to a preferred embodiment, the third magnetic field component is smaller, in particular significantly smaller, than the first and second magnetic field components. This reduces the potentially interfering influence of the second magnetic element 7 on the measurement of the rotational orientation. However, if the third magnetic field component is smaller, noise may occur in the detected third magnetic field component. The following discussion will focus on the Fig. 2. An approach will be explained which serves in particular to avoid this noise distorting the determination of the unambiguous rotational position.

[0041] Preferably, the evaluation unit 14 is configured to determine the number of revolutions taking into account the first magnetic field value. For example, the evaluation unit 14 is configured to identify two consecutive candidates for the number of revolutions based on the detected second magnetic field value and to select one of the two candidates as the number of revolutions based on the detected first magnetic field value.

[0042] For example, in the evaluation unit 14, one or more transition regions B1, B2 are defined for the second magnetic field value, with each transition region B1, B2 containing a respective second magnetic field value at which a transition from one revolution to the next occurs. For example, the first transition region B1 contains the second magnetic field value at which the transition from the first revolution U0 to the second revolution U1 occurs, and the second transition region B2 contains the second magnetic field value at which the transition from the second revolution U1 to the third revolution U2 occurs.

[0043] Each transition region B1, B2 comprises a respective continuous interval of values. The transition regions B1, B2 are spaced apart from each other. For example, each transition region B1, B2 encompasses the values ​​that a noisy second magnetic field value can assume during the respective transition from one revolution to the next.

[0044] In response to the fact that a second magnetic field value is located below the first transition region B1, evaluation unit 14 concludes that the number of revolutions is 0. Evaluation unit 14 multiplies the number of revolutions by 360 degrees and adds the rotation orientation to the result to calculate the unique rotational position.

[0045] In response to the detection of a second magnetic field value within the first transition region B1, evaluation unit 14 identifies the numbers "0" and "1" as possible rotational speed candidates. Evaluation unit 14 then checks the rotational orientation to determine which of the two candidates is correct. For example, evaluation unit 14 compares the rotational orientation to a rotational orientation threshold value, specifically 180 degrees. If the rotational orientation is greater than the rotational orientation threshold value, evaluation unit 14 selects the smaller of the two rotational speed candidates as the rotational speed, in this example, "0". If the rotational orientation is less than the rotational orientation threshold value, evaluation unit 14 selects the larger of the two rotational speed candidates as the rotational speed, in this example, "1".The evaluation unit 14 multiplies the selected number of revolutions by 360 degrees and adds the rotational orientation to the result to calculate the unique rotational position.

[0046] The evaluation unit 14 handles the other possible cases analogously. If the second magnetic field value is located between the transition zones B1 and B2, the evaluation unit 14 concludes that the number of revolutions is "1". If the second magnetic field value is located within the second transition zone B2, the evaluation unit 14 determines whether the number of revolutions is "1" or "2" based on the rotational orientation. If the second magnetic field value is located above the second transition zone B2, the evaluation unit 14 concludes that the number of revolutions is "2". In each of these cases, the evaluation unit 14 multiplies the determined number of revolutions by 360 degrees and adds the rotational orientation to the result to calculate the unique rotational position.

[0047] With reference to the Fig. Section 3 below discusses an embodiment in which the second magnetic element 7 can move past the magnetic field sensor device 2. In this case, a change of sign of the third magnetic field component or the second magnetic field value can occur.

[0048] In the diagram of Fig. Figure 3 shows the rotation angle range on the horizontal axis, which here comprises two revolutions U0, U1. The first curve 15 of the first magnetic field value and the second curve 16 of the second magnetic field value are shown on the vertical axis.

[0049] During the drive movement 3, the second magnetic element 7 moves past the magnetic field sensor device 2 within a transition section A of the rotational position angle range. Within the transition section A, a transition 18 occurs from one revolution U0 of the rotary motion part 4 to the next revolution U1.

[0050] The evaluation unit 14 is designed to determine the number of revolutions within the transition section A, taking into account the first magnetic field value.

[0051] For example, in the evaluation unit 14, a transition range B is defined for the second magnetic field value. The transition range B contains the second magnetic field value at which the transition 18 from revolution U0 to the next revolution U1 occurs. In particular, the transition range B includes those values ​​that a noisy second magnetic field value can assume during the transition 18 from revolution U0 to the next revolution U1.

[0052] In response to the fact that a second detected magnetic field value is outside the transition region B and is negative, the evaluation unit 14 concludes that the number of revolutions is 0. The evaluation unit 14 determines the rotational orientation as the unique rotational position.

[0053] In response to the detection of a second magnetic field value within transition region B, evaluation unit 14 identifies the numbers "0" and "1" as possible rotation values. Evaluation unit 14 then checks the rotation orientation to determine which of the two rotation value candidates is correct. For example, evaluation unit 14 compares the rotation orientation to a rotation orientation threshold value, specifically 180 degrees. If the rotation orientation is greater than the rotation orientation threshold value, evaluation unit 14 selects the smaller of the two rotation value candidates as the rotation value, in this example, "0". If the rotation orientation is less than the rotation orientation threshold value, evaluation unit 14 selects the larger of the two rotation value candidates as the rotation value, in this example, "1".The evaluation unit 14 multiplies the selected number of revolutions by 360 degrees and adds the rotational orientation to the result to calculate the unique rotational position.

[0054] Responding to the fact that a second detected magnetic field value is outside the transition region B and is positive, the evaluation unit 14 concludes that the number of revolutions is equal to 1. The evaluation unit 14 adds the rotation orientation to 360 degrees to calculate the unique rotational position.

[0055] Optionally, the evaluation unit 14 is designed to perform linearization and / or temperature compensation of the first magnetic field value and / or the second magnetic field value.

[0056] The following will refer to the Fig. 4. Another approach will be explained, which can be used particularly when the rotation angle range exceeds two revolutions.

[0057] In the diagram of Fig. Figure 4 shows the rotation angle range on the horizontal axis, which here comprises three rotations U0, U1, U2. The first curve 15 of the first magnetic field value and the second curve 16 of the second magnetic field value are shown on the vertical axis.

[0058] Preferably, the evaluation unit 14 has a look-up table comprising a plurality of value pairs consisting of a first magnetic field value and a second magnetic field value, as well as a plurality of rotational position values, each value pair being assigned to a specific rotational position value. Each rotational position value corresponds to a unique rotational position. The evaluation unit 14 is configured to determine the unique rotational position using the look-up table.

[0059] The pairs of values ​​stored in the look-up table, namely first magnetic field values ​​and second magnetic field values, shall also be referred to as "stored pairs of values", "stored first magnetic field values", and "stored second magnetic field values". The pairs of values ​​(consisting of first magnetic field value and second magnetic field value) detected by the magnetic sensor device 2, namely first magnetic field values ​​and second magnetic field values, shall also be referred to as "detected pairs of values", "detected first magnetic field values", and "detected second magnetic field values".

[0060] The look-up table is created, for example, by calculation or simulation, or by iteratively approaching reference points and taking corresponding measurements.

[0061] Preferably, the look-up table has a finer gradation (especially with regard to the rotation position values) in areas where there is a jump in the course of the first magnetic field value - i.e., especially at transitions from one revolution to the next revolution - than in other areas.

[0062] The look-up table is stored, for example, in a memory of evaluation unit 14.

[0063] The second magnetic field value is expediently temperature compensated.

[0064] Advantageously, the evaluation unit 14 performs an interpolation (e.g. linear or spline) if a recorded pair of values ​​consisting of the first magnetic field value and the second magnetic field value lies between two pairs of values ​​stored in the look-up table.

[0065] Preferably, the evaluation unit 14 searches the look-up table using the least squares method to find a suitable pair of values ​​in order to determine the unique rotation position.

[0066] As mentioned above, the first magnetic field value is, by way of example, the rotational orientation of the rotary motion element 4 and the second magnetic field value is, by way of example, the detected z-magnetic field component.

[0067] For example, for a detected first magnetic field value and a detected second magnetic field value, the evaluation unit 14 selects the stored value pair where the deviation between the detected first magnetic field value and the stored first magnetic field value, and the deviation between the detected second magnetic field value and the stored second magnetic field value, is smallest. Based on this selected stored value pair and a directly adjacent value pair, the evaluation unit 14 then performs an interpolation of the rotational position values ​​assigned to these value pairs in order to calculate the unique rotational position.

[0068] The following section will discuss a case in which, at the transition from one rotation to the next—that is, where the rotational orientation jumps from 360 degrees to 0 degrees—an intermediate value, specifically a value less than 360 degrees (preferably less than 350 degrees) and greater than 0 degrees (preferably greater than 10 degrees), is erroneously detected as the first magnetic field value—that is, as the rotational orientation. This case will be referred to as the intermediate value case. Such an intermediate value can occur, in particular, when an analog sensor element is used as the magnetic field sensor device 2, whose detected signal (representing the rotational orientation) can only rise or fall at a finite rate.

[0069] The evaluation unit 14 is designed to detect this intermediate value case, in which an intermediate value is (erroneously) recorded for the first magnetic field value during a rotation transition, by the fact that the recorded pair of values ​​consisting of the first and second magnetic field values ​​does not match any stored pair of values. For this purpose, the evaluation unit 14 is designed, for example, to check whether a deviation between a recorded pair of values ​​and stored pairs of values ​​(in particular, all stored pairs of values ​​or a selection of stored pairs of values) exceeds a predetermined limit.For example, evaluation unit 14 checks for each stored pair of values ​​whose first magnetic field value is equal to the detected first magnetic field value (or lies within a tolerance range of the detected first magnetic field value) whether a deviation between the detected second magnetic field value and the stored second magnetic field value exceeds a predetermined limit. If the deviation exceeds the limit, evaluation unit 14 concludes that the intermediate value case has occurred.

[0070] In response to the detected intermediate value case, the evaluation unit 14 identifies, based on the second magnetic field value, the rotation transition that best matches the detected second magnetic field value, for example, using the look-up table. Specifically, the evaluation unit 14 identifies the rotation transition whose assigned (stored) second magnetic field value is closest to the detected second magnetic field value. Rotation transitions are defined as those entries in the look-up table whose rotation value is 360 degrees or an integer multiple of 360 degrees.

[0071] The evaluation unit 14 is designed to provide the rotational position value of this identified rotational transition as the unique rotational position.

[0072] Optionally, the evaluation unit 14 is configured to correct the detected rotational orientation to 0 degrees if the intermediate value is less than 180 degrees and to select the larger of the two rotational numbers associated with the identified rotational transition to determine the unique rotational position. Furthermore, the evaluation unit 14 is configured to correct the detected rotational orientation to 360 degrees if the intermediate value is greater than 180 degrees and to select the smaller of the two rotational numbers associated with the identified rotational transition to determine the unique rotational position. The evaluation unit 14 then multiplies the selected rotational number by 360 degrees and adds the corrected rotational orientation to the result.

Claims

[1] Actuator device (1), in particular a pneumatic rotary actuator or pneumatic gripper, for industrial automation, comprising a magnetic field sensor device (2) and a drive arrangement for performing a drive movement (3), wherein the drive arrangement has a rotary motion part (4) comprising a first magnetic element (5) and which, during the drive movement (3), changes its rotational position relative to the magnetic field sensor device (2) over a rotational position angular range of more than one revolution, wherein the drive arrangement further comprises a linear motion part (6) coupled to the rotary motion part (4), which has a second magnetic element (7) and performs a linear movement relative to the magnetic field sensor device (2) during the drive movement, wherein the magnetic field sensor device (2) is designedto detect the magnetic fields of the first magnetic element (5) and the second magnetic element (7) and the actuator device (1) further comprises an evaluation unit (14) which is configured to determine, on the basis of the detected magnetic fields, a unique rotational position of the rotary motion part (4) with respect to the rotational position angular range. [2] Actuator device (1) according to claim 1, wherein the evaluation unit (14) is configured to provide a first magnetic field value and a second magnetic field value using the magnetic field sensor device (2), wherein the first magnetic field value depends on a rotational orientation of the first magnetic element (5) and the second magnetic field value depends on a distance of the second magnetic element (7) to the magnetic field sensor device (2), and to determine the unique rotational position on the basis of the first magnetic field value and the second magnetic field value. [3] Actuator device (1) according to claim 2, wherein the evaluation unit (14) is configured to provide the rotational orientation of the rotary motion part (4) based on the detected first magnetic field value and to determine a number of revolutions of the rotary motion part (4) based on the detected second magnetic field value, wherein the number of revolutions indicates within which revolution (U0, U1, U2) of the rotation position angle range the rotary motion part (4) is located, and the evaluation unit (14) is configured to determine the unique rotation position based on the rotational orientation and the number of revolutions. [4] Actuator device (1) according to claim 3, wherein the evaluation unit (14) is configured to determine the number of revolutions taking into account the first magnetic field value. [5] Actuator device (1) according to claim 4, wherein the evaluation unit (14) is configured to determine two successive number of revolutions based on the detected second magnetic field value and to select one of the two number of revolutions as the number of revolutions based on the detected first magnetic field value. [6] Actuator device (1) according to one of claims 3 to 5, wherein the second magnetic element (7) is movable past the magnetic field sensor device during the drive movement (3) within a transition section (A) of the rotation position angle range, wherein within the transition section (A) there is a transition (18) from one revolution (U0) of the rotary motion part (4) to the next revolution (U1), and the evaluation unit (14) is configured to determine the number of revolutions within the transition section (A) taking into account the first magnetic field value. [7] Actuator device (1) according to one of claims 2 to 6, wherein the evaluation unit has a look-up table comprising a plurality of value pairs consisting of a respective first magnetic field value and a respective second magnetic field value, as well as a plurality of rotation position values, wherein each value pair is assigned to a respective rotation position value, and wherein the evaluation unit (14) is configured to determine the unique rotation position using the look-up table. [8] Actuator device (1) according to a preceding claim, wherein the first magnetic field value is based on a first magnetic field component and a second magnetic field component, and the second magnetic field value is based on a third magnetic field component, wherein the first magnetic field component, the second magnetic field component and the third magnetic field component are orthogonally aligned to each other. [9] Actuator device (1) according to claim 8, wherein the first magnetic field component and the second magnetic field component are aligned orthogonally to an axis of rotation of the rotary motion part (4) and / or the third magnetic field component is aligned in the axial direction of the axis of rotation of the rotary motion part (4). [10] Actuator device (1) according to a preceding claim, wherein the magnetic field sensor device is designed as a magnetic field sensor element, in particular as a 3D Hall sensor. [11] Actuator device (1) according to a preceding claim, wherein the drive arrangement is designed as a rack and pinion drive, the rotary motion part (4) comprises a gear (17) and the linear motion part (6) comprises a rack (8) engaging with the gear (17). [12] Method for operating an actuator device according to any of the preceding claims, comprising the steps: - Performing the drive movement, - Detecting the magnetic fields of the first magnetic element and the second magnetic element with the magnetic field sensor device, and - Determining the unique rotational position based on the detected magnetic fields using the evaluation unit.

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