DE102010003201A1 - Angle-measuring method for determining an angle of tilt/swiveling angle uses an angle-measuring unit and first and second measuring signals - Google Patents

Abstract

A first measuring signal (SX) represents a first parameter/characteristic for an angle of tilt/swiveling angle (alpha ) along a first axis (x). A second measuring signal (SY) represents a second parameter/characteristic for an angle of tilt/swiveling angle along a second axis (y). The first and second axes comprise an angle that deviates from 90[deg] by a known loss angle (F). A correcting value (c) is determined by relying on the first measuring signal and the loss angle. An independent claim is also included for a device for determining an angle of tilt/swiveling angle.

Description

The The invention relates to a method and a device for determination a rotation angle with an angle measuring unit that is formed to generate a first measurement signal and a second measurement signal.

In The automotive industry is increasing the demand for high-precision and at the same time robust angle measuring systems constantly. Angle measuring systems For example, in the field of vehicle dynamics control and in electrically assisted Steering systems used.

magnetic sensors are due to their non-contact and robust measuring principle especially well suited for use in the vehicle area. For measuring angles often sensor elements, For example, resolver, Hall sensors, AMR or GMR sensors (Anisotropic Magneto Resistance, Giant Magneto Resistance). The angle measuring systems For example, have two sensor units, which are formed are each to detect a directional component of a magnetic field. A GMR bridge includes, for example, a measuring bridge element that is formed is to detect a component of a first direction of the magnetic field and another measuring bridge element, which is formed, a second component of a second direction to capture the magnetic field. Under ideal conditions this will follow first measurement signal is a cosine signal and the second measurement signal delayed by 90 ° and follows a sinusoidal signal.

The Problem underlying the invention is to provide a method and to provide a device for determining a rotation angle, the one or the other contributes to a precise determination the angle of rotation.

The Task is solved by the characteristics of the independent Claims. Advantageous embodiments are characterized in the subclaims.

The Invention is characterized by a method and an apparatus for determining a rotation angle with an angle measuring unit. The angle measuring unit is formed, a first measurement signal representative of a first Angle of rotation characteristic along a first axis, and a second measurement signal representative is for a second rotation angle characteristic along a second axis, output. The first axis and the second axis shut down an angle that deviates by a known error angle of 90 °. A correction value is determined as a function of the first measurement signal and the wrong angle. Furthermore, it becomes a corrected measured value determined, dependent from the second measurement signal and the correction value. Depending on the first measurement signal and the corrected measurement becomes the rotation angle determined.

By the correction of the measurement signals can be an angle error in the determination the angle of rotation can be reduced. Advantageously, the correction value and the corrected measured value can be determined very easily. There are only a few, simple arithmetic operations required. Sizes that are required to determine the corrected value are directly from the measurement signals available and / or are provided by a storage device. This makes possible, an orthogonality error between the first measurement signal and the second measurement signal below Compensate real-time conditions.

According to one advantageous embodiment of the invention is the correction value determined depending on the product of the first measurement signal and the sinusoidal function value of the error angle and the corrected measured value are determined as a function of the sum of the second measured value and the correction value. The wrong angle can for example be determined in a final alignment in a production and the sine function value of the error angle can be stored in a memory unit, can be accessed on the fly, stored become. To determine the corrected measured value are thus only two Arithmetic operations, one multiplication and one addition, required.

According to one Another advantageous embodiment of the invention is the angle of rotation determined depending from an arctangent of the quotient of the corrected reading and the first measurement signal. By replacing the second measured value by the corrected measured value in the calculation of the arctan function value The angle of rotation can be determined very accurately. The arctangent function values can For example, using a CORDIC algorithm (Coordinate Rotation Digital Computer), for example, as a computer program in one Calculation unit is implemented, can be calculated very quickly.

embodiments The invention are explained in more detail below with reference to the schematic drawings.

It demonstrate:

1 a block diagram of an angle measuring device 10 .

2 a graphical representation for determining a correction value c,

3 a first diagram for displaying angle errors Δα and

4 a second diagram for the representation of the angular error Δα in the correction of a second measured value SY.

1 shows an angle measuring device 10 for determining a rotation angle α. The angle measuring device 10 has an angle measuring unit 50 with a sensor unit 20 and a facility 30 for signal processing and a device 40 for determining the rotation angle α.

The sensor unit 20 may be formed, for example, as a magnetic field sensor. The sensor unit 20 generates, for example, a first sensor measurement signal MX and a second sensor measurement signal MY. Under ideal conditions, the first sensor measurement signal MX follows a cosine signal and the second sensor measurement signal MY is delayed by 90 ° and follows a sine signal. However, the measuring signals of magnetic field sensors are frequently associated with equal components offset _x , offset _y . The constant components offset _x , offset _y can occur in particular when the sensors are used at high temperatures. Furthermore or as an alternative, the sensor elements can have a different sensitivity, for example due to temperature, aging and / or production tolerances, as a result of which the sensor measurement signals MX, MY have different amplitudes A _x , A _y . Due to manufacturing tolerances and / or assembly errors may additionally or alternatively occur deviations in the orthogonality of the sensor measurement signals MX, MY.

The first MX and second sensor measurement signal MY can be represented as follows: MX = Offset x + A x · Cos (α) (1) MY = offset y + A y · Sin (β) (2)

The device 30 for signal processing, for example, is designed to determine the DC offset _x , offset _y in the respective operating state and to compensate. Additionally or alternatively, the device 30 designed for signal processing in the respective operating state perform an amplitude compensation. The device 30 for signal processing is thus designed to output the first measurement signal SX, which is representative of a first rotational angle characteristic along a first axis x, and the second measurement signal SY, which is representative of a second rotational angle parameter along a second axis y. The respective rotational angle characteristic is, for example, a magnetic field strength. The first axis x and the second axis y include, for example, an angle that deviates by a known error angle F of 90 °. The error angle F can be determined, for example, during a final adjustment in production and stored in a memory unit that can be accessed during operation. The first and second measurement signals SX, SY can be represented as follows: SX = A · cos (α) (3) SY = A · sin (β) (4)

Taking into account the known error angle F results in: SY = A · sin (α-F) (5)

The device 30 for signal conditioning is electrically coupled to the device 40 for determining the angle of rotation α. The device 40 for determining the rotary wine angle α is designed, for example, as a computing unit and has a correction unit 42 and a calculation unit 45 on. The correction unit 42 has, for example, a memory unit in which the error angle F and / or the sinusoidal function values of the error angle F are stored.

The correction unit 42 For example, it is configured to determine a correction value c depending on the product of the first measurement signal SX and the sinusoidal function value of the error angle F and to determine a corrected measurement value KY depending on the sum of the second measurement value SY and the correction value c.

The correction value c and the corrected measured value KY can be represented as follows: c = SX * sin (F) (6) KY = SY + c (7)

The correction unit 42 is coupled with the calculation unit 45 , The calculation unit 45 is configured to determine the rotation angle α depending on an Argus tangent of the quotient of the corrected measured value KY and the first measurement signal SX.

The rotation angle α can be represented as follows: α = arctane (KY / SX) (8)

The replacement of the second measured value SY by the corrected measured value KY makes it possible to reduce an angle error Δα. The determination of the corrected measured value KY is in 2 shown graphically. The first measurement signal SX is along the ers th axis x is plotted and the second measurement signal SY is plotted along the second axis y. Relative to a rectangular coordinate system, which is spanned by a first reference axis x0 and a second reference axis y0, the first axis and the second axis have a false angle F. In the embodiment shown, the error angle F is greater than zero. In order to be able to determine the rotation angle α as accurately as possible with the aid of the arctangent function, the second measured value SY is replaced by a corrected measured value KY, which approximately corresponds to a Y setpoint value Ysoll. For small error angles F, the cosine function value of the error angle F can be approximated as follows. cos (F) ≈ 1 (9)

As a result, taking into account Equations (6) and (7): Ysoll ≈ KY = SY + c = SY + SX * sin (F) (10)

3 shows the course of the angle error Δα without corrective measures. If the first axis x and the second axis y have an angle which deviates by 90 ° from the known error angle F, this orthogonality error is converted into the angular error Δα in the determination of the angle of rotation α.

has the error angle, for example, a value of 2 °, the angle error Δα depends on the angle of rotation α to be determined, a cosinusoid Course up with a fluctuation range of 0 ° to 2 °.

By replacing the second measured value SY with the corrected measured value KY, the angular error Δα is drastically reduced. If the error angle F has, for example, a value of 2 °, the angle error Δα depends on the angle of rotation α to be determined, a maximum angle error Δα of ± 0.009 ° ( 4 ).

10

Angle measuring device

20

sensor unit

30

Facility for signal conditioning

40

contraption for determining a rotation angle

50

Angle measuring unit

50

Angle measuring unit

A _x , A _y , A

amplitude

α

angle of rotation

β

angle

c

correction value

Δα

angle error

F

Skew

KY

corrected reading

Offset _x , offset _y

DC component

MX

first Sensor measuring signal

MY

second Sensor measuring signal

SX

first measuring signal

SY

second measuring signal

X

first axis

Y

second axis

Claims (4)

Method for determining a rotation angle (α) with a Angle measuring unit which is formed a first measurement signal (SX), the representative is for one first rotational angle characteristic along a first axis (x), and a second measurement signal (SY) representative is for a second rotation angle characteristic along a second axis (y), the first axis (x) and the second axis (y) includes an angle that is about a known Error angle (F) deviates from 90 ° and at the - one Correction value (c) is determined depending on the first measurement signal (SX) and the error angle (F), - a corrected measured value (KY) is determined from the second measurement signal (SY) and the correction value (c) and - the angle of rotation (α) determined becomes dependent from the first measurement signal (SX) and the corrected measurement value (KY). The method of claim 1 wherein the correction value (c) is determined depending of the product of the first measurement signal (SX) and the sinusoidal function value of the incorrect angle (F) and the corrected measured value (KY) becomes dependent from the sum of the second measured value (SY) and the correction value (C). The method of claim 1 and 2 wherein the angle of rotation (α) determined becomes dependent from an arctangent of the quotient of the corrected reading (KY) and the first measurement signal (SX). An apparatus for determining an angle of rotation (α) with an angle measuring unit, which is designed, a first measuring signal (SX), which is representative of a first rotational angle characteristic along a first axis (x), and a second measuring signal (SY), which is representative of output a second rotational angle characteristic along a second axis (y), wherein the first axis (x) and the second axis (y) enclose an angle that deviates by a known error angle (F) of 90 ° and the device is formed Correction value (c) to be determined as a function of the second measurement signal (SY) and the error angle (F), - to determine a corrected measurement value (KY) as a function of the first measurement signal (SX) and the correction value (c) and - the rotation angle (α ) depending on the first measurement signal (SX) and the corrected measurement value (KY).