Amplitude evaluation by means of a goertzel algorithm in a differential transformer displacement sensor

Patent metadata

Field	Value
Publication number	US-9243933-B2
Application number	US-201214342850-A
Country	US
Kind code	B2
Filing date	Sep 7, 2012
Priority date	Sep 9, 2011
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

Displacement sensor arrangement including at least one primary coil, at least a first and a second secondary coil and at least one magnetically soft coupling element, which magnetically couples the primary coil and the two secondary coils, the displacement sensor being designed so that a position and/or deflection depending on the magnetic coupling between the primary coil and at least the first and second secondary coil is detected, the displacement sensor arrangement having a signal processing unit, which is designed to perform digital signal processing of at least one electrical variable of the two secondary coils and determine the position and/or deflection, the signal processing unit having at least one Goertzel filter.

First claim

The invention claimed is:

1. A displacement sensor arrangement, comprising:
at least one primary coil, at least one first and one second secondary coil;
at least one soft magnetic coupling element, which magnetically couples the primary coil and the two secondary coils; and
a signal processing unit, connected to both of the two secondary coils, the signal processing unit configured to perform digital signal processing of at least one electrical variable to determine a position and/or a deflection depending on the magnetic coupling between the primary coil and at least the first and second secondary coils, by:
digitizing electrical signals of the two secondary coils to produce the at least one electrical variable,
windowing the electrical variable, and
filtering the windowed electrical variable with a Goertzel filter to determine a magnitude of the electrical variable which indicates the position and/or the deflection between the primary coil and at least the first and second secondary coils.

2. The displacement sensor arrangement as claimed in claim 1 , wherein the displacement sensor arrangement comprises at least one first displacement element, comprising at least one first position encoder magnet, wherein the first displacement element is disposed to be displaceable along a measurement direction (m → ) relative to the soft magnetic coupling element, and the primary coil and the secondary coils are magnetically coupled by the soft magnetic coupling element and wherein the magnetic field generated by the first position encoder magnet influences the coupling element at least locally such that the relative position between the first displacement element and the soft magnetic coupling element is detected directly or indirectly by at least one of the secondary coils.

3. The displacement sensor arrangement as claimed in claim 1 , wherein the displacement sensor is in the form of a differential transformer displacement sensor, especially of an LVDT, “Linear Variable Differential Transformer”, wherein the soft magnetic coupling element is in displaceable form and the position and/or deflection of said coupling element is recorded.

4. The displacement sensor arrangement as claimed in claim 1 , wherein the signal processing unit is designed such that the at least one electrical variable of the two secondary coils is assessed and/or analyzed with the at least one Goertzel filter depending on the electrical excitation signal of the primary coil, wherein especially the center frequency of the at least one Goertzel filter essentially corresponds to the frequency of the excitation voltage and/or of the excitation current on/through the primary coil.

5. The displacement sensor arrangement as claimed in claim 1 , wherein the signal processing unit comprises at least one Goertzel filter respectively for assessing and/or analyzing the at least one electrical variable of the first and the second secondary coils.

6. The displacement sensor arrangement as claimed in claim 1 , wherein the signal processing unit comprises at least one analog-to-digital converter, with which the at least one electrical variable of the two secondary coils is digitized as the first digital secondary coil signal and as the second digital secondary coil signal, wherein the signal processing unit comprises a window function, especially a Hanning window function, with which windowing of the first and second digital secondary coil signals respectively is carried out.

7. The displacement sensor arrangement as claimed in claim 6 , wherein the signal processing unit is designed such that following the windowing of the first and of the second digital secondary coil signals, at least said two signals are each filtered by a Goertzel filter, following which summation and differencing of the result of the Goertzel filter is carried out, after which the quotient of the difference signal divided by the summation signal is formed.

8. The displacement sensor arrangement as claimed in claim 1 , wherein the signal processing unit comprises a clock generator unit, wherein both the excitation voltage and/or the excitation current on/through the primary coil are generated depending on a clock signal of said clock generator unit, and also the center frequency of the at least one Goertzel filter are defined.

9. The displacement sensor arrangement as claimed in claim 1 , wherein the displacement sensor arrangement is of redundant design and comprises two first secondary coils and two second secondary coils, which are connected to the signal processing unit or each of which is connected to a signal processing unit.

10. The displacement sensor arrangement as claimed in claim 1 , wherein the at least one Goertzel filter is designed such that it filters with respect to a single frequency.

11. The displacement sensor arrangement as claimed in claim 1 , wherein the at least one Goertzel filter is designed such that it acts as a decimation bandpass filter.

12. A use of a displacement sensor arrangement in motor vehicles, the displacement sensor comprising:
at least one primary coil;
at least one first and one second secondary coil; and
at least one soft magnetic coupling element, which magnetically couples the primary coil and the two secondary coils; and
a signal processing unit, connected to both of the two secondary coils, the signal processing unit configured to perform digital signal processing of at least one electrical variable to determine a position and/or a deflection depending on the magnetic coupling between the primary coil and at least the first and second secondary coils, by:
digitizing electrical signals of the two secondary coils to produce the at least one electrical variable,
windowing the electrical variable, and
filtering the windowed electrical variable with a Goertzel filter to determine a magnitude of the electrical variable which indicates the position and/or the deflection between the primary coil and at least the first and second secondary coils.

Assignees

• Lehmann Sören
• Grunwald Frank
• Continental Teves Ag & Co Ohg

Inventors

• Lehmann Sören
• Grunwald Frank

Classifications

• G01P3/44

  for measuring angular speed (G01P3/56 takes precedence) · CPC title

• G01P15/00

  Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration · CPC title

• G01D5/20 Primary

  by varying inductance, e.g. by a movable armature · CPC title

• G01P3/00

  Measuring linear or angular speed; Measuring differences of linear or angular speeds (G01P5/00 - G01P11/00 take precedence; {direction and speed indication G01P13/045}; counting mechanisms G06M) · CPC title

• G01B21/045

  Correction of measurements (G01B9/02055 takes precedence) · CPC title