EP1828723A1 - Procede pour determiner un point de commutation lors de l'analyse des signaux d'un ensemble capteur magnetique - Google Patents

Procede pour determiner un point de commutation lors de l'analyse des signaux d'un ensemble capteur magnetique

Info

Publication number
EP1828723A1
EP1828723A1 EP05801731A EP05801731A EP1828723A1 EP 1828723 A1 EP1828723 A1 EP 1828723A1 EP 05801731 A EP05801731 A EP 05801731A EP 05801731 A EP05801731 A EP 05801731A EP 1828723 A1 EP1828723 A1 EP 1828723A1
Authority
EP
European Patent Office
Prior art keywords
switching point
signal
slope
output signal
magnetic sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05801731A
Other languages
German (de)
English (en)
Inventor
Rasmus Rettig
Christelle Andriot
Ruediger Block
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1828723A1 publication Critical patent/EP1828723A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/24471—Error correction
    • G01D5/2448—Correction of gain, threshold, offset or phase control

Definitions

  • the invention relates to a method for determining a switching point in the evaluation of the signals of a magnetic sensor arrangement, according to the preamble of the main claim.
  • a magnetic input signal modulated by a magnetic field influencing donor element is converted into an electrical voltage by a suitable sensor, for example by the Hall effect or the so-called XMR effect.
  • The- This periodic signal is fed to a comparator, which converts it into a binary signal depending on whether the electrical signal is above or below a switching threshold.
  • EP 0 875 774 A2 magnetic sensors are equipped with so-called adaptive hysteresis, which set their hysteresis to a fixed percentage value as a function of the peak-peak amount of their output signal.
  • adaptive hysteresis which set their hysteresis to a fixed percentage value as a function of the peak-peak amount of their output signal.
  • Critical in this known arrangement in particular the behavior of the sensor in the occurrence of air gap impacts, ie abrupt changes in the air gap. If the air gap gets larger quickly, the magnetic input amplitude of the sensor decreases so fast that the hysteresis is not readjusted and the sensor can lose signal edges. The Therefore, the size of the hysteresis continues to determine the maximum distance between the sensor and a sensor wheel, which still generates correct output signals without missing edges, via the maximum permissible air gap.
  • the switching threshold of the sensor is at the height of the saddle point, then the sensor is not clearly defined and its output signal shows a significantly increased jitter, which makes the usability of the signal as a measured variable for determining e.g. the vehicle speed at a speed sensor greatly deteriorated.
  • a solution to the problem described above can be achieved by selecting a hysteresis in such a way that the resulting switching points are always more than 20% away from the offset-corrected zero point of the signal.
  • the disadvantage of such an approach is that that in the case of a sinusoidal excitation, the switching point is far away from the optimum switching point at zero and thus the jitter is increased. Furthermore, the increase in hysteresis degrades the behavior of the sensor in the case of air gap jumps, which generate short-term significantly reduced signal amplitudes. If these are below the set 20% of the original amplitude sensor signals are lost.
  • the output signal of the magnetic sensor arrangement analyzed in a given temporal window of the signal range and determines an optimal switching point with respect to the slope and / or the position in the region of the zero crossing of the oscillation of the output signal.
  • an optimal choice of switching points of a magnetic sensor while avoiding the disadvantages described above is possible, that is, a switching point is selected so that its deviation from the offset-corrected zero point is minimal and at the same time it is ensured that he is in a range of maximum slope the input signal and not on a saddle point.
  • a switching point is selected so that its deviation from the offset-corrected zero point is minimal and at the same time it is ensured that he is in a range of maximum slope the input signal and not on a saddle point.
  • a numerical derivative by time and the optimum switching point at the maximum slope of the derived signal can be selected.
  • An additional weighting in the selection of the switching point can be made to the effect that preferably a position of the switching point in the range of the zero crossing of the output signal is made. It is also advantageous if, when selecting the optimum switching point, a threshold value for the slope is predetermined, which must be minimally achieved.
  • the respective maximum and minimum can be determined and the mean value determined therefrom can be calculated.
  • An offset correction can be carried out by changing the hysteresis such that upon detection of a switching edge, the slope of the signal continuously calculated from leading and following values is checked, and in the event that the slope is smaller than a predetermined value, the hysteresis is increased until the switching point lies within a range of sufficient slope of the output signal of the magnetic sensor arrangement.
  • FIG. 1 shows a schematic view of a transmitter wheel with a tooth-gap contour and an opposite magnetic sensor according to the prior art, which detects the magnetic field changes caused by the tooth-gap contour during a rotation with a downstream evaluation device and generates switching edges therefrom;
  • 4a and 4b show the course of the electrical output signal of a magnetic differential field sensor with saddle points (4a) and the numerical derivative (4b) with switching points according to the invention for the output signal
  • FIG. 5 is a block diagram of the signal processing of Figures 4a and 4b and
  • FIG. 6 shows an example of the differentiation of the signal according to the block diagram of FIG. 5.
  • Figure 1 the principle of detection of magnetic field-influencing surface structures on a sensor wheel 1 is shown, in which case a tooth-gap contour Z, L is present, the one idealized when passing under a known from the in the introduction to the description of the prior art magnetic field sensor 2 here generated in block 3 sinusoidal waveform of the measurement signal.
  • a binary signal in the form of a rectangular signal is now generated with conventional circuit technology according to block 4, the switching edges of which ideally lie exactly in the zero crossing of the sinusoidal signal after the block 3.
  • the legal signal from block 4 can now be supplied to a control unit, not shown here.
  • FIG. 2 a shows in detail a profile 10 of the magnetic input signal over the full revolution of 360 ° of the encoder wheel according to the FIGURE, which generates this approximately sinusoidal profile, for example with the magnetic field-influencing teeth Z during one revolution.
  • FIG. 2b shows a binary output signal 12 whose switching points lie exactly at the zero crossing of the signal 1 (dot-dashed line) and a binary output signal 13 (solid line) which is connected to a comparator with fixed hysteresis between the regions +2 and -. 2 of the magnetic input signal 10 switches.
  • a differential field 14 of a difference field sensor is shown in FIG can be seen that has significant saddle 15 over time t in the region of the zero crossing of the waveform of the differential field 14.
  • Such known differential field sensors are generally based on the Hall sensors mentioned in the introduction as magnetic field sensitive sensors 2 according to the figure 1.
  • these magnetic fields for large pitches of encoder wheels as magnetic field influencing donor elements are no longer sinusoidal, but have overlaps saddle 15 , The position of the saddle 15 in the signal curve 14 is dependent on the position of the sensor 2 relative to the encoder wheel. 1
  • the output signal 16 which is likewise plotted over time t in FIG. 3, also switches here as a rectangular signal on the basis of a fixed hysteresis in the range between the values +10 and -10 of the magnetic signal of the differential field 14.
  • FIG. 4b shows the first derivative 111 over the time t of the signal curve 110 according to FIG. 4a, which can be determined, for example, using conventionally known numerical methods and can be implemented digitally with little effort, as shown in FIG. 5 and FIG becomes.
  • FIG. 4 a shows an amplitude range A of the signal curve 110, in each of which the switching point for an inventive corrected switching threshold of the previously described rectangular signal according to the previous figures should lie, resulting in a resulting range B over the time axis t for the position of the desired switching points results.
  • an offset correction is carried out in such a way that, for the detection of a switching edge, the slope 111 (FIG. 4b) of the signal 110 (FIG. 4a) continuously calculated from the precursors and following values is checked, and in the case that the slope is smaller than a predetermined one Value C, the hysteresis is increased until the switching point E is in a range of sufficient slope of the output signal of the magnetic sensor array.
  • the hysteresis is increased until the switching point according to FIG. 4b lies at instant F of the maximum slope of the output signal 110 (FIG. 4a) of the magnetic sensor arrangement.
  • FIG. 5 shows two Hall cells H1 and H2 respectively as sensors 2 according to FIG. 1, which are subjected to signal processing after a difference has been formed in a module S, and then the signal 110 is detected with an analogue-to-digital converter A / D Figure 4a produced. Subsequently, in a module ND, a numerical differentiation is carried out to generate the signal 111 according to FIG. 4b.
  • a shift register SR with numerical values entered here into the register blocks is shown in FIG. 6, with which a numerically differentiated signal can be generated at the output corresponding to FIG. 4b.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)

Abstract

L'invention concerne un procédé pour déterminer un point de commutation dans un ensemble capteur magnétique. Selon ce procédé, les flancs de commutation provoqués par un élément émetteur (1) en mouvement sont analysés dans l'ensemble capteur magnétique (2) du fait qu'un dépassement d'une valeur seuil vers le haut ou vers le bas entraîne l'émission d'un signal. Le signal de sortie (110) de l'ensemble capteur magnétique est analysé dans une fenêtre temporelle prédéterminée de la plage du signal et un point de commutation optimal (E, F) est déterminé relativement au gradient (111) et/ou à la position au niveau du passage au point zéro de l'oscillation du signal de sortie (110).
EP05801731A 2004-12-15 2005-10-17 Procede pour determiner un point de commutation lors de l'analyse des signaux d'un ensemble capteur magnetique Withdrawn EP1828723A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102004060300 2004-12-15
DE102005027362A DE102005027362A1 (de) 2004-12-15 2005-06-14 Verfahren zur Bestimmung eines Schaltpunktes bei der Auswertung der Signale einer Magnetsensoranordnung
PCT/EP2005/055288 WO2006063883A1 (fr) 2004-12-15 2005-10-17 Procede pour determiner un point de commutation lors de l'analyse des signaux d'un ensemble capteur magnetique

Publications (1)

Publication Number Publication Date
EP1828723A1 true EP1828723A1 (fr) 2007-09-05

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP05801731A Withdrawn EP1828723A1 (fr) 2004-12-15 2005-10-17 Procede pour determiner un point de commutation lors de l'analyse des signaux d'un ensemble capteur magnetique

Country Status (3)

Country Link
EP (1) EP1828723A1 (fr)
DE (1) DE102005027362A1 (fr)
WO (1) WO2006063883A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006042184A1 (de) * 2006-09-08 2008-03-27 Siemens Ag Schaltungsanordnung und Verfahren zur Umwandlung eines Signals

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5917320A (en) 1996-01-17 1999-06-29 Allegro Microsystems, Inc. Detection of passing magnetic articles while periodically adapting detection threshold
JP3323082B2 (ja) * 1996-09-27 2002-09-09 株式会社日立製作所 内燃機関用回転位置検出装置
JP4190780B2 (ja) * 2002-03-18 2008-12-03 株式会社デンソー 回転検出装置
DE10223514B4 (de) 2002-05-27 2010-01-28 Infineon Technologies Ag Komparatorschaltung
JP4292571B2 (ja) 2003-03-31 2009-07-08 株式会社デンソー 磁気センサの調整方法及び磁気センサの調整装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2006063883A1 *

Also Published As

Publication number Publication date
WO2006063883A1 (fr) 2006-06-22
DE102005027362A1 (de) 2006-06-22

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