DE102017128395A1 - Angle of rotation sensor unit and method for determining a rotation angle - Google Patents

Abstract

The present invention initially relates to a method for determining a rotation angle. In one step of the method, a first two-channel measuring signal is determined by measuring a magnetic field with respect to a first magnetic multipole terminal (03) having the rotational angle to be determined. The first dual-channel measurement signal comprises a first channel and a second channel which have a phase difference from one another. The first magnetic multiple pole (03) has a first number of magnetic poles (02). In a further step, a second two-channel measurement signal is determined by measuring a magnetic field with respect to a second magnetic multiple pole (08) having the rotational angle to be determined. The second dual-channel measurement signal comprises a first channel and a second channel which have a phase difference from one another. The second magnetic multipole (08) has a second number of magnetic poles (09) different from the first number. According to the invention, the rotational angle to be determined is calculated by applying at least one of the two two-channel measuring signals to a predetermined function of the rotational angle of the respective two-channel measuring signal. The invention further relates to a rotation angle sensor unit for determining a rotation angle.

Description

The present invention initially relates to a method for determining a rotation angle using two magnetic poles having different numbers of magnetic poles. The invention further relates to a rotation angle sensor unit for determining a rotation angle.

The US 8,319,493 B2 shows a sensor device for measuring a rotation angle. The sensor device comprises a plurality of coaxially arranged magnetic encoders each having a plurality of magnetic poles, the magnetic encoders having different numbers of the magnetic poles. The sensor device further comprises a plurality of magnetic field sensors which measure the magnetic field of the magnetic encoders. A phase difference detector serves to determine the phase differences between the signals of the magnetic field sensors. The angle of rotation is determined on the basis of the determined phase difference.

The object of the present invention is based on the prior art to increase the accuracy in determining a rotation angle using two magnetic poles.

Said object is achieved by a method according to the appended claim 1. The said object is further achieved by a rotation angle sensor unit according to the attached independent claim 7.

The inventive method is used to determine a rotation angle, which in particular has a first machine element relative to a second machine element. The first machine element and the second machine element are rotatable relative to each other. The first machine element is preferably a rotatable shaft. The method according to the invention is preferably used for determining a rotation angle on a rotary bearing, in particular on a roller bearing, which rotatably supports the first machine element relative to the second machine element.

In one step of the method according to the invention, a first two-channel measuring signal is determined by measuring a magnetic field with respect to a first magnetic multipole pole having the angle of rotation to be measured. Thus, the magnetic field of the first magnetic multipole is measured. The first two-channel measurement signal comprises at least a first channel and a second channel. The first channel and the second channel each represent a single measurement signal. The first channel and the second channel have a phase difference from one another. The phase difference is preferably (90 ± 5) °, more preferably (90 ± 1) °, and more preferably 90 °. The first two-channel measurement signal is preferably a sin / cos signal or an AB signal.

For measuring the first two-channel measuring signal, a first magnetic field sensor is preferably used. The first magnetic field sensor preferably comprises two magnetic field sensor elements that have a different angle of rotation with respect to the first magnetic multiple pole. Alternatively preferably, the first magnetic field sensor is designed to measure different directional components of the magnetic field of the first magnetic multipole, which have the described phase difference to each other.

The first magnetic multiple pole has the rotational angle to be measured, since it is preferably connected in a rotationally fixed manner to the first machine element. The first magnetic multipole has a first number of magnetic poles that alternate tangentially to the rotation. In particular, these are alternating magnetic north and south poles. The first number is preferably u. a. depends on a diameter of the first magnetic multiple pole and is preferably at least ten. The first magnetic multiple pole is preferably designed as an annular multipole encoder. The annular multipole encoder is preferably arranged coaxially with the axis of rotation. The alternating magnetic poles preferably extend completely circumferentially around the annular multipole encoder.

In a further step of the method according to the invention, a second two-channel measuring signal is determined by measuring a magnetic field with respect to a second magnetic multipole pole having the angle of rotation to be measured. Thus, the magnetic field of the second magnetic multipole is measured. The second dual-channel measurement signal comprises at least a first channel and a second channel. The first channel and the second channel each represent a single measurement signal. The first channel and the second channel have a phase difference from one another. The phase difference is preferred (90 ± 5) °, more preferably (90 ± 1) °, and more preferably 90 °. The second two-channel measurement signal is preferably a sin / cos signal or an AB signal.

For measuring the second two-channel measuring signal, a second magnetic field sensor is preferably used. The second magnetic field sensor preferably comprises two magnetic field sensor elements that have a different angle of rotation with respect to the second magnetic multiple pole. Alternatively preferably, the second magnetic field sensor is designed to measure different directional components of the magnetic field of the second magnetic multipole having the described phase difference to each other.

The second magnetic multiple pole has the rotational angle to be measured, since it is preferably connected in a rotationally fixed manner to the first machine element. The second magnetic multipole has a second number of magnetic poles that alternate tangentially to the rotation. In particular, these are alternating magnetic north and south poles. The second number is preferably u. a. is dependent on a diameter of the second magnetic multiple pole and is preferably at least ten. The second magnetic multipole is preferably formed as an annular multipole encoder. The annular multipole encoder is preferably arranged coaxially with the axis of rotation. The alternating magnetic poles preferably extend completely circumferentially around the annular multipole encoder.

The first number of magnetic poles of the first magnetic multipole differs from the second number of magnetic poles of the second magnetic multipole. Preferably, the first number of the magnetic poles of the first magnetic multipole differs by two from the second number of the magnetic poles of the second magnetic multipole, so that the number of pairs of the magnetic poles of the first magnetic multipole is one by the number of pairs of the magnetic poles of the second magnetic multipole differs.

The two magnetic poles preferably have a common axis of rotation and are preferably arranged axially adjacent. The two magnetic poles preferably have a same ring diameter, wherein the two magnetic poles can also have different ring diameters. The two two-channel measuring signals can be detected in the radial direction or in the axial direction. If the two two-channel measuring signals are detected in the radial direction, they can be detected at an inner diameter or at an outer diameter of the respective multipole.

According to the invention, the rotational angle to be measured is calculated by applying at least one of the two two-channel measuring signals to a predetermined function which quantitatively describes the dependence of the rotational angle to be measured on the respective two-channel measuring signal.

The function is preferably stored in the form of an assignment table. One column of the allocation table comprises discretized values of the relevant two-channel measurement signal, comprising in each case a value for the first channel and a value for the second channel. An optionally existing further column of the allocation table comprises discretized values of the respective other two-channel measurement signal, comprising in each case a value for the first channel and a value for the second channel. In addition, the allocation table has a further column, which comprises discretized values of the rotation angle to be measured.

Alternatively preferably, the predetermined function is described analytically.

A particular advantage of the method according to the invention is that the use of the previously determined function, for example in the form of an assignment table, permits a low-cost and accurate determination of the angle of rotation starting from at least one of the two two-channel measuring signals. By using the predetermined function, irregularities of the magnetic poles, such as irregular magnetizations or irregular widths of the poles, do not affect the determination of the rotation angle.

The method according to the invention preferably comprises a step in which the function of the angle of rotation is determined quantitatively by the respective two or two two-channel measuring signals. This step represents a calibration. The function is preferably determined beforehand in that the rotation angle is changed, while at the same time the rotation angle is determined by a reference measurement and the respective or both two-channel measurement signals is determined. Preferably, the angle of rotation and both of the two two-channel measuring signals are determined simultaneously. The angle of rotation is preferably over at least one Rotation changed, so that the range of rotation angle at least 0 ° to 360 °. For reference measurement is preferably an additional rotation angle sensor, which preferably measures with high precision and high resolution.

Both of the two two-channel measuring signals are preferably used to calculate the angle of rotation to be measured, wherein at least one of the two two-channel measuring signals is applied to the predetermined function, while the other of the two two-channel measuring signals can be used in different ways to calculate the angle of rotation to be measured.

In a first preferred embodiment of the method according to the invention, the angle of rotation to be measured is calculated by applying the first two-channel measuring signal and the second two-channel measuring signal to the predetermined function. The function describes the dependence of the angle of rotation on the first two-channel measuring signal and on the second two-channel measuring signal.

In a second preferred embodiment of the method according to the invention, the calculation of the angle of rotation to be determined comprises several substeps. In a sub-step, a coarse value of the rotation angle to be determined is calculated on the basis of the first two-channel measurement signal and the two-channel measurement signal. For this purpose, it is preferably assumed that the channels of the two two-channel measuring signals are ideal sine and cosine signals. In a further sub-step, starting from the coarse value of the rotation angle to be determined, those poles of the first magnetic multipole are determined which cause the first two-channel measurement signal. These are those poles which come closest to the location of the measurement of the first two-channel measurement signal at the given rotation angle. Preferably, that period of the first magnetic multipole determined by the detected poles of the first magnetic multipole is determined. In a further sub-step, the angle of rotation to be determined is calculated by applying the first two-channel measuring signal and taking into account the previously determined poles of the first magnetic multipole to a predetermined function. The function describes the dependence of the angle of rotation on the first two-channel measuring signal and the poles of the first magnetic multi-pole respectively effecting the first two-channel measuring signal for this angle of rotation. This calculation process is used to calculate an accurate value of the rotation angle. The designations given as the first and second magnetic poles or as first and second two-channel measurement signal are interchangeable, d. H. Alternatively, the second dual-channel measurement signal can be used to calculate the exact value of the rotation angle.

The rotation angle sensor unit according to the invention is used to determine a rotation angle and comprises a first magnetic multiple pole and a second magnetic multiple pole. The two poles together have the angle of rotation to be determined. The first magnetic multipole has a first number of magnetic poles. The second magnetic multipole has a second number of magnetic poles different from the first number.

The inventive rotation angle sensor unit further comprises a first magnetic field sensor for measuring a first two-channel measurement signal. The first magnetic field sensor is arranged opposite to the first magnetic multiple pole. The first dual-channel measurement signal comprises a first channel and a second channel which have a phase difference from one another.

The rotation angle sensor unit according to the invention further comprises a second magnetic field sensor for measuring a second two-channel measurement signal. The second magnetic field sensor is arranged opposite to the second magnetic multiple pole. The second dual-channel measurement signal comprises a first channel and a second channel which have a phase difference from one another.

The rotation angle sensor unit according to the invention further comprises a measurement signal processing unit which is configured to calculate the rotation angle to be determined by applying at least one of the two two-channel measurement signals to a predetermined function. The function describes the dependence of the angle of rotation on the respective two-channel measuring signal. The function is preferably stored in a data memory of the measurement signal processing unit. The function is preferably stored in the form of an allocation table in the data memory of the measurement signal processing unit.

The rotation angle sensor unit according to the invention is preferably formed in a rotary bearing, in particular in a rolling bearing. The bearing comprises two mutually rotatable rings; in particular an outer ring and an inner ring. The two magnetic field sensors sit on one of the two rings, while the two magnetic poles are at least rotatably connected to the other of the two rings.

The rotation angle sensor unit according to the invention preferably also has features that are specified for the method according to the invention and its preferred embodiments. In particular, the measurement signal processing unit is preferably designed for carrying out one of the described preferred embodiments of the method according to the invention.

• 1 ein erfindungsgemäß zu bestimmendes zweikanaliges Messsignal;
• 2 zwei erfindungsgemäß zu verwendende magnetische Mehrfachpole;
• 3 eine Veranschaulichung eines Phasenfehlers zwischen den in 2 gezeigten magnetischen Mehrfachpolen;
• 4 eine Veranschaulichung eines Amplitudenfehlers bei dem in 1 gezeigten zweikanaligen Messsignal; und
• 5 eine Veranschaulichung eines zeitlichen Fehlers bei dem in 1 gezeigten zweikanaligen Messsignal.

Further details, advantages and developments of the invention will become apparent from the following description of a preferred embodiment of the invention, with reference to the drawing. Show it:

• 1 a two-channel measuring signal to be determined according to the invention;
• 2 two magnetic poles to be used according to the invention;
• 3 an illustration of a phase error between the in 2 shown magnetic poles;
• 4 an illustration of an amplitude error in the in 1 shown two-channel measurement signal; and
• 5 an illustration of a timing error in the 1 shown two-channel measurement signal.

1 shows a two-channel measurement signal to be determined according to the invention 01 in terms of magnetic poles 02 a first magnetic multipole 03 , The magnetic poles 02 include north poles N and south poles S , The two-channel measuring signal 01 is measured with two magnetic field sensor elements (not shown) opposite to the magnetic multipole 03 are arranged. Therefore, the two-channel measurement signal includes 01 a first channel 04 , which also as a channel A or sin channel, and a second channel 06 , which also as a channel B or Cos channel can be called. The two-channel measuring signal 01 thus stops FROM Signal. The first magnetic multipole 03 is in this representation only by its magnetic poles 02 shown. The first magnetic multipole 03 is technically designed as an annular Multipolencoder.

According to the invention, a rotation angle φ to measure, having a machine element. The first magnetic multipole 03 is rotatably connected to this machine element, so he also the rotation angle φ having. Accordingly, the first magnetic multiple pole 03 rotated relative to the magnetic field sensor elements (not shown).

2 first illustrates the already in 1 shown first magnetic multiple pole 03 , According to the invention, a second magnetic Mehrfachpol 08 with magnetic poles 09 used, which as well as the first magnetic poles 03 is formed as an annular Multipolencoder and the angle of rotation φ at a measuring position 10 having. However, the number of magnetic poles differs 02 of the first magnetic multipole 03 from the number of magnetic poles 09 of the second magnetic multipole 08 , The number of pairs of magnetic poles 09 of the second magnetic multipole 08 is one greater than the number of pairs of magnetic poles 02 of the first magnetic multipole 03 , In that regard, the invention uses the vernier principle.

According to the invention, a second two-channel measuring signal (not shown) is determined with two further magnetic field sensor elements (not shown), which are opposite to the second magnetic multipole 08 are arranged. The first channel 04 of the first two-channel measurement signal 01 will be referred to as A ₁ designated. The second channel 06 of the first two-channel measurement signal 01 will be referred to as B ₁ designated. Using the first two-channel measurement signal 01 becomes a first rotation angle auxiliary value φ ₁ certainly. The first channel of the second two-channel measurement signal is hereinafter referred to as A ₂ designated. The second channel of the second two-channel measurement signal is hereinafter referred to as B ₂ designated. The second two-channel measurement signal is used to generate a second auxiliary angle measurement φ ₂ certainly. According to the invention, the angle of rotation φ as a function of the first rotation angle auxiliary value φ ₁ and the second rotational angle auxiliary measured value φ ₂ certainly: $$\phi =f\left({\phi }_1.{\phi }_2\right)$$

$${\phi }_2=f\left(A_2,B_2\right)+\mathrm{\Delta }\phi$$

3 illustrates a phase error 11 between the two in 2 shown magnetic poles 03 . 08 which due to a limited exact alignment of the two magnetic Multiple poles 03 . 08 occurs to each other. The phase error 11 is hereinafter referred to as Δφ and is inventively determined based on the following relationships: $${\phi }_1=f\left(A_1.B_1\right)$$

$${\phi }_2=f\left(A_2.B_2\right)+\mathrm{\Delta }\phi$$

4 illustrates an amplitude error in FIG 1 shown first two-channel measurement signal 01 , The amplitude of the first channel 04 of the first two-channel measurement signal 01 deviates in this example from the amplitude of an ideal measurement signal 13 from.

5 illustrates a timing error in the 1 shown first two-channel measurement signal 01 , The time course of the first channel 04 of the first two-channel measurement signal 01 deviates in this example from the zeiltichen course of the ideal measurement signal 13 from.

According to a preferred embodiment, a mapping table in the form of a look-up table is determined in advance. For this purpose, a reference measurement is performed with a high-precision rotation angle sensor. The angle of rotation is changed and the first and second two-channel measuring signal 01 are measured. Below is an example of such a mapping table: angle of rotation A ₁ B1 A2 B2 0 ° A ₁ (0) B ₁ (0) A ₂ (0) B ₂ (0) 1 ° A ₁ (1) B ₁ (1) A ₂ (1) B ₂ (1) 2 ° A ₁ (2) B ₁ (2) A ₂ (2) B ₂ (2) ⋮ ⋮ ⋮ ⋮ ⋮

According to a first preferred embodiment, the measured values are determined to determine an unknown angle of rotation A ₁ . B ₁ . A ₂ and B _{2 of} the two two-channel measuring signals 01 looked up in the allocation table.

According to a second preferred embodiment, first a coarse value of the unknown rotation angle is obtained from the auxiliary rotation angle measurement values φ ₁ and φ ₂ certainly. By the coarse value is known which poles 02 of the first magnetic multipole 03 the currently measured values A ₁ and B ₁ of the first two-channel measurement signal 01 have effected; ie in which period of the first magnetic poles 03 is measured at the set angle of rotation. In a further partial step, the measured values A ₁ and B ₁ of the first two-channel measurement signal 01 in the allocation table for the previously determined period of the first magnetic multipole 03 looked up to determine an accurate value of the rotation angle.

LIST OF REFERENCE NUMBERS

01

first two-channel measuring signal

02

magnetic poles

03

first magnetic multipole

04

first channel

05

-

06

second channel

07

-

08

second magnetic multipole

09

magnetic poles

10

measuring position

11

phase error

12

-

13

ideal measuring signal

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 8319493 B2 [0002]

Claims (10)

Method for determining a rotation angle; comprising the following steps: Determining a first two-channel measuring signal (01) by measuring a magnetic field with respect to a first magnetic multipole (03) having the angle of rotation to be determined, the first two-channel measuring signal (01) comprising a first channel (04) and a second channel (06), having a phase difference with each other, and wherein the first magnetic multipole (03) has a first number of magnetic poles (02); Determining a second two-channel measuring signal by measuring a magnetic field with respect to a second magnetic multipole (08) having the rotational angle to be determined, the second two-channel measuring signal comprising a first channel and a second channel having a phase difference to one another, the second magnetic multipole ( 08) has a second number of magnetic poles (09) different from the first number; and - Calculating the rotation angle to be determined by applying at least one of the two two-channel measurement signals (01) to a predetermined function of the rotation angle of the respective two-channel measurement signal (01). Method according to Claim 1 , characterized in that the predetermined function of the rotation angle of the respective two-channel measurement signal (01) is stored in the form of an assignment table. Method according to Claim 1 or 2 , characterized in that the function of the rotation angle of the respective two-channel measurement signal (01) is thereby determined in advance that the rotation angle is changed, while the rotation angle is determined by a reference measurement and the respective two-channel measurement signal (01) is determined. Method according to one of Claims 1 to 3 , characterized in that the calculation of the rotation angle to be measured by applying the first two-channel measurement signal (01) and the second two-channel measurement signal to the predetermined function of the rotation angle of the first two-channel measurement signal (01) and the second two-channel measurement signal. Method according to one of Claims 1 to 3 , characterized in that the calculation of the rotation angle to be determined comprises the following sub-steps: - calculating a coarse value of the rotation angle to be determined, starting from the first two-channel measurement signal (01) and the second two-channel measurement signal; - Determining the first two-channel measuring signal causing pole (09) of the first magnetic multipole (08) on the basis of the coarse value of the rotation angle; and - calculating the angle of rotation to be determined by applying the first two-channel measuring signal and the determined poles (09) of the first magnetic multipole (08) to a predetermined function of the angle of rotation of the first two-channel measuring signal and the respective two-channel measuring signal causing poles (09 ) of the first magnetic multipole (08). Method according to one of Claims 1 to 5 , characterized in that the first channel (04) and the second channel (06) of the first two-channel measuring signal (01) have a phase difference of (90 ± 5) ° to each other and that the first channel and the second channel of the second two-channel measuring signal a Phase difference of (90 ± 5) ° to each other. A rotation angle sensor unit for determining a rotation angle, comprising: a first magnetic multiple pole (03) and a second magnetic multiple pole (08), which together have the rotational angle to be determined, wherein the first magnetic multiple pole (03) has a first number of magnetic poles (02) and the second magnetic multiple pole (08 ) has a second number of magnetic poles (09) different from the first number; a first magnetic field sensor arranged opposite the first magnetic multipole (03) for measuring a first two-channel measuring signal (01), wherein the first two-channel measuring signal (01) comprises a first channel (04) and a second channel (06) having a phase difference from one another exhibit; - A second magnetic field sensor arranged opposite the second magnetic multipole pole (08) for measuring a second two-channel measuring signal, wherein the second two-channel measuring signal comprises a first channel and a second channel, which have a phase difference from each other; and a measurement signal processing unit configured to calculate the rotation angle to be measured by applying at least one of the two two-channel measurement signals (01) to a predetermined function of the rotation angle of the respective two-channel measurement signal (01). Angle of rotation sensor unit after Claim 7 , characterized in that the two magnetic poles (03, 08) are each formed as an annular multipole encoder. Angle of rotation sensor unit after Claim 7 or 8th , characterized in that the two magnetic poles (03, 08) have a common axis of rotation and are arranged axially adjacent. Rotation angle sensor unit according to one of Claims 7 to 9 characterized in that the first number of the magnetic poles (02) of the first magnetic multipole (03) differs by two from the second number of the magnetic poles (09) of the second magnetic multipole (08).

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