Magnetostrictive sensor apparatus having an analog branch and a digital branch and a method for operating such a magnetostrictive sensor apparatus

Abstract

A magnetostrictive sensor apparatus is provided, comprising at least one magnetic position marker, at least one sensing member with a waveguide to which the at least one magnetic position marker is contactlessly coupled, a detector coil device which is associated with the at least one sensing member, a data processing device which determines a time profile with a shape over time of signals of the detector coil device, wherein a recording of the time profile is provided, and an analysis device which analyzes the time profile.

Claims

1. Magnetostrictive sensor apparatus, comprising: at least one magnetic position marker; at least one sensing member with a waveguide to which the at least one magnetic position marker is contactlessly coupled; a detector coil device which is associated with the at least one sensing member; a data processing device which determines a time profile with a shape over time of signals of the detector coil device, wherein a recording of the time profile is provided; an analysis device which analyzes the time profile; an analog branch which provides first analog signals of the detector coil device; a digital branch which provides digital signals which are processed or become processed by means of the data processing device, the digital branch comprising a digital-to-analog converter which provides second analog signals; and a comparison device for the first analog signals and the second analog signals.

2. Magnetostrictive sensor apparatus in accordance with claim 1, wherein time-varying signals of the detector coil device are voltage signals.

3. Magnetostrictive sensor apparatus in accordance with claim 1, wherein a digitization device for signals of the detector coil device is provided.

4. Magnetostrictive sensor apparatus in accordance with claim 3, wherein the digitization device has a digitization rate of at least 2 million analog-to-digital conversions.

5. Magnetostrictive sensor apparatus in accordance with claim 4, wherein at least one of a control of the sensor apparatus and an analysis of the signals is carried out with data having a lower resolution than according to the digitization rate.

6. Magnetostrictive sensor apparatus in accordance with claim 3, wherein the digitization device comprises an analog-to-digital converter.

7. Magnetostrictive sensor apparatus in accordance with claim 1, further comprising a storage device for signals of the detector coil device.

8. Magnetostrictive sensor apparatus in accordance with claim 1, further comprising a control device controlling an initiation of start impulses for triggering a measurement, and which is signal-operatively coupled to at least one of (i) the data processing device, (ii) a storage device, and (iii) the analysis device.

9. Magnetostrictive sensor apparatus in accordance with claim 1, wherein the comparison device, with respect to the first analog signals, compensates at least one of echo signals and interference signals, which are determined by the analysis device, by way of the second analog signals.

10. Magnetostrictive sensor apparatus in accordance with claim 1, wherein the second analog signals are simulated signals which are determined by means of previous measurements.

11. Magnetostrictive sensor apparatus in accordance with claim 9, further comprising a propagation time determination device which obtains and evaluates compensated analog signals.

12. Magnetostrictive sensor apparatus in accordance with claim 1, wherein a ferromagnetic shield device is associated with the at least one waveguide.

13. Magnetostrictive sensor apparatus in accordance with claim 1, wherein the at least one magnetic position marker is or comprises at least one of the following: a permanent magnet, wherein, in the case of a plurality of permanent magnets, they are spaced apart; an electromagnet; a writable magnet device; a magnetic device provided with at least one magnetically coded track; a magnetically segmented device.

14. Magnetostrictive sensor apparatus in accordance with claim 1, wherein the analysis device comprises at least one subunit for at least one of analyzing and determining and using at least one of the following: an alignment of the at least one magnetic position marker; a rotational position of the at least one magnetic position marker; a position of the at least one magnetic position marker in a direction along the at least one sensing member; a position of the at least one magnetic position marker in a direction transverse to the at least one sensing member; a teaching of a time profile of at least one of a target signal and an echo signal as a pattern signal; a pattern recognition for the time profile of the signals of the detector coil device; an interpolation for signals of the detector coil device for determining a crossing at a certain signal value; an echo determination for signals of the detector coil device; a simulation of at least one of echoes and interference signals; a temperature determination at the waveguide; a monitoring of the sensor apparatus; a diagnosis of the sensor apparatus; a noise compensation; a compensation with regard to transient signals; a quality evaluation of measuring signals; a classification of targets.

15. Method for operating a magnetostrictive sensor apparatus, comprising: determining signals of a detector coil device in a time profile with a shape over time, recording these signals, and analyzing these signals; determining at least one of echo signals and interference signals during the analysis which are taken into account in an evaluation; subtracting the at least one of the echo signals and the interference signals from primary measuring signals; wherein: the primary measuring signals are provided as first analog signals, and second analog signals are provided by means of analyzing the time profile of signals of the detector coil device, and the first analog signals are linked to the second analog signals.

16. Method in accordance with claim 15, wherein the signals of the detector coil device are digitized.

17. Method in accordance with claim 16, wherein a digitization rate for a conversion of analog data into digital date is at least 2 million conversions.

18. Method in accordance with claim 17, wherein at least one of a control of the sensor apparatus and an analysis of the signals is carried out with lower resolution than according to the digitization rate.

19. Method in accordance with claim 15, wherein the analysis is carried out with regard to at least one of the following: an alignment of at least one magnetic position marker; a rotational position of the at least one magnetic position marker; a position of the at least one magnetic position marker in a direction along at least one sensing member; a position of the at least one magnetic position marker in a direction transverse to the at least one sensing member; a pattern recognition for the time profile of the signals of the detector coil device; an interpolation for signals of the detector coil device for determining a crossing at a certain signal value; an echo determination for the signals of the detector coil device; a simulation of at least one of echoes and interferences; a temperature determination at a waveguide; a monitoring of the sensor apparatus; a diagnosis of the sensor apparatus; a noise compensation; a compensation with regard to transient signals; a quality evaluation of measuring signals; a classification of targets.

20. Method in accordance with claim 15, wherein the method is performed on the magnetostrictive sensor apparatus, comprising: at least one magnetic position marker; at least one sensing member with a waveguide to which the at least one magnetic position marker is contactlessly coupled; the detector coil device which is associated with the at least one sensing member; a data processing device which determines the time profile with a shape over time of signals of the detector coil device, wherein a recording of the time profile is provided; and an analysis device which analyzes the time profile.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subsequent description of preferred embodiments serves in conjunction with the drawings for further explanation of the invention. In the drawings:

(2) FIG. 1 shows a schematic depiction of an embodiment of a magnetostrictive sensor apparatus in accordance with the invention, wherein two magnetic position markers are present;

(3) FIG. 2 shows a schematic depiction of a waveguide for explaining its functioning;

(4) FIG. 3 shows an embodiment for signals of a detector coil device of the magnetostrictive sensor apparatus according to FIG. 1 in the time profile thereof, wherein one magnetic position marker is present;

(5) FIG. 4 shows the time profile of signals of the detector coil device of the magnetostrictive sensor apparatus according to FIG. 1 when two magnetic position markers are present;

(6) FIG. 5(a) shows a portion of the signal in the time profile thereof, wherein a predetermined voltage level is marked;

(7) FIG. 5(b) shows an embodiment for determining a time at which the certain voltage level is reached;

(8) FIGS. 6(a) to (c) show typical signal profiles for signals of the detector coil device when a plurality of targets (a plurality of magnetic position markers) are present, wherein the diagrams differ in the spacing of said targets;

(9) FIG. 7(a) shows an example of a magnetostrictive sensor apparatus when two magnetic position markers are present, which are permanent magnets and have different alignments;

(10) FIG. 7(b) shows a typical signal profile for signals of the detector coil device in accordance with the situation according to FIG. 7(a);

(11) FIG. 8 shows a signal profile for explaining a temperature compensation;

(12) FIG. 9(a) shows a magnetostrictive sensor apparatus with a permanent magnet as a magnetic position marker, which may have different rotational positions;

(13) FIG. 9(b) shows different signal profiles over time for signals of the detector coil device at different rotational positions of the magnetic position marker in accordance with FIG. 9(a);

(14) FIG. 10 shows a schematic depiction of an embodiment of a further magnetostrictive sensor apparatus, by means of which a rotational position of a target, which is a permanent magnet, and a position of said target along a waveguide and transverse to the waveguide is determinable;

(15) FIG. 11(a) shows for example the profile of simulated signals at a magnetic position marker as a response to one single interrogation current pulse;

(16) FIG. 11(b) shows for example a diagram with a superposition of interrogations, response signals, and echoes upon continuous repetition of the interrogation current pulses; and

(17) FIG. 12 shows a schematic depiction of a further embodiment of a magnetostrictive sensor apparatus in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

(18) An embodiment of a magnetostrictive sensor apparatus in accordance with the invention, which is schematically shown in FIG. 1 and is denoted by 10, comprises a sensing member 12 with a waveguide 14. A return conductor 16 is associated with the waveguide 14 (FIG. 2).

(19) Further, a damping element 18, which is positioned at an end region of the waveguide 14, is associated with the waveguide 14 (cf. FIG. 2).

(20) The magnetostrictive sensor apparatus 10 comprises one or a plurality of magnetic position markers 20 (FIG. 2) and 20a, 20b (FIG. 1), respectively.

(21) In one embodiment, a magnetic position marker 20 and 20a, 20b, respectively, is a permanent magnet.

(22) The magnetic position marker 20 or position markers 20 contactlessly couple to the sensing member 12.

(23) A magnetostrictive sensor apparatus functions basically as follows (see FIG. 2):

(24) An interrogation current pulse 22 originating from a measuring interface triggers a measurement as a measuring signal. The interrogation current pulse 22 is hereby triggered by means of a start signal. A control device 24 (FIG. 1) hereby initiates the impingement with start signals.

(25) The interrogation current impulse 22 on the waveguide 14, which is a wire waveguide, for example, generates a circular magnetic field 26. This magnetic field 26 is bundled in the waveguide 14 due to the soft magnetic properties of the latter.

(26) The magnetic position marker 20 acts on the waveguide 14 at a measuring point 28 thereof. The measuring point 28 characterizes the position of the magnetic position marker on the sensing member 12.

(27) This position is hereby basically a position in relation to a longitudinal direction 30 of the waveguide 14 (in a measuring range).

(28) In principle, though, it is also possible, as described in more detail below, for the corresponding position to alternatively or additionally be a position in a direction 32 transverse to the longitudinal direction 30.

(29) For example, in one embodiment, magnetic field lines 34 of the magnetic position marker 20 run at a right angle to the circular magnetic field 26 and are likewise bundled in the waveguide 14.

(30) In a region in which the circular magnetic field 26 and the magnetic field generated by the position marker 20 overlap, an elastic deformation occurs in the micro-range of the structure of the waveguide 14 due to magnetostriction. This overlapping area is precisely the measuring point 28. The elastic deformation causes an elastic wave propagating along the waveguide 14 in opposite directions 36, 38. The directions 36 and 38 are hereby in particular parallel to the longitudinal direction 30 of the waveguide 14 (in a measuring range).

(31) A propagation speed of this wave in the waveguide 14 is in particular on the order of magnitude of about 2800 m/s and is largely impervious to environmental influences.

(32) The damping element 18 at one end 40 of the waveguide 14 damps away the transsonar wave running to this end 40, so that the portion of the wave that is reflected back is negligible in relation to the directly propagating wave upon signal detection (see below).

(33) Arranged at another end 42 of the waveguide 14 is a detector coil device 44 with at least one pick-up coil. By reversing the magnetostrictive effect through induction, the detector coil device 44 generates an electric signal and delivers it to the measuring interface. The electrical signal that is provided by the detector coil device 44 is an analog signal and in particular a voltage signal.

(34) The wave prorogation time from the place of origin to the detector coil device 44 is directly proportional to the distance between the position marker 20 and the detector coil device 44. The distance between the detector coil device 44 and the position marker 20 (wherein the position of the position marker 20 determines the measuring point 28) may thus be determined with high accuracy by means of a time measurement. The primary measuring signal for the time measurement is the interrogation current pulse 22, this in turn having been triggered by the start signal. The primary measuring signal is delivered, offset in time as a function of the distance between the detector coil device 44 and the position marker 20, from the detector coil device 44 to the measuring interface.

(35) With respect to the basic functioning of magnetostrictive sensor apparatuses (and magnetostrictive displacement or path transducer apparatuses, respectively) reference is made to E. Hering, G. Schönfelder (publisher), “Sensoren in der Wissenschaft and Technik”, Wiesbaden, 2012 and there in particular to the chapter 3.1.5. Reference is made further to T. Burkhardt, A. Feinäugle, S. Fericean, A. Forkl, “Lineare Weg- and Abstandssensoren”, Verlag Moderne Industrie, Munich, 2004.

(36) As already mentioned, the detector coil device 44 delivers analog signals. In accordance with the invention, provision is made for a time profile of said signals (and in particular voltage signals) to be determined, recorded, and analyzed. In particular the signal shape is determined, recorded, and analyzed.

(37) In particular, a digitization device 46 (cf. FIG. 1) is provided which generates digital data from analog data with a relatively high digitization rate (sampling rate).

(38) For that purpose, analog signals 48 of the detector coil device 44 are supplied to the digitization device 46 in an evaluation branch. The digitization device 46 comprises an analog-to-digital converter 50 which correspondingly generates digital data.

(39) A digitization rate at the analog-to-digital converter 50 is at least 2 million conversions per second for the conversion of analog data into digital data. In particular, said digitization rate is at least 5 million A/D conversions per second and preferably at least 8 million A/D conversions per second. In a concrete embodiment, the digitization rate is at about 10 million A/D conversions per second.

(40) The shape of the signal of the detector coil device 44 is determined in its time profile by way of a data processing device 52. In a storage device 54 which is connected downstream of the digitization device 46, the digitized signals are then correspondingly stored as digital data; they characterize in digital form the time profile of the signals of the detector coil device 44.

(41) An analysis device 56 evaluates this data in its time profile.

(42) The control device 24 is signal-operatively coupled to the storage device 54 and to the analysis device and as a whole to the data processing device 52.

(43) Thus a correlation between start signals and stop signals may be produced; in particular, a correlation between the triggering of a measuring operation and the measuring data may be produced.

(44) The storage device 54 is an FIFO memory and/or an SDRAM memory, for example. The control device 24 is, e.g., realized in a DSP, an FPGA (field programmable gate array), or in a microcontroller or in a combination thereof. In principle, the digitization device 46 and/or the storage device 54 may be integrated into the control device 24.

(45) The analysis device 56 may also be integrated into the control device 24.

(46) In one embodiment, the analysis device 56 is realized by a DSP (digital signal processor).

(47) In principle, in the solution in accordance with the invention, the time profile (including pulse shape) of signals of the detector coil device 44 is provided in digitized form, in particular in the storage device, for each measuring cycle.

(48) Shown in FIG. 3 is an example for the signal profile as a function of time when one single magnetic position marker 20 in the form of a permanent magnet is present.

(49) An excitation noise 58 is recognizable in the time profile (as it is then stored at least approximately in the storage device 54). This is a result of the interrogation current pulse 22.

(50) Furthermore, a “target signal” 60 is recognizable. The target signal 60 is that signal which in principle is used for the propagation time determination.

(51) Further echo signals 62a, 62b, 62c, 62d, etc. are recognizable in the signal profile, wherein the corresponding signal profile in FIG. 3 is also shown in inlay diagrams in 5-times and 25-times magnification.

(52) A region in which signal echoes are present is indicated in FIG. 3 with the reference numeral 64. Further, a region in which noise dominates is indicated with the reference numeral 66.

(53) A similar diagram is shown in FIG. 4, wherein in this case two magnetic position markers 20a, 20b in the form of permanent magnets are present.

(54) There is an excitation noise 68 due to the interrogation current pulse 22.

(55) Furthermore, there are target signals 70, 70′; due to the two magnetic position markers 20, 20b there are two target signals 70, 70′.

(56) There further exist echo signals 72a, 72a′, 72b, 72b′, etc.; the echo signals, too, are doubled due to the two magnetic position markers 20a, 20b.

(57) There is in turn a region 64 with echo signals and a region 66 which is dominated by noise. The target signals 70, 70′ are present in a region 74.

(58) Knowing the signal profile as a function of time and thereby also knowing the shape of the complete pulse train (cf. FIGS. 3 and 4) may be used and exploited in different ways. For that purpose, the analysis device 56 performs corresponding analyses and calculations.

(59) The analysis possibilities by way of the analysis device 56 make it possible to use magnetic position markers (one or a plurality thereof) in a large range of variation and to select them for corresponding applications.

(60) For example, an electromagnet or a writable magnet device may be used as a magnetic position marker. One or a plurality of magnetic devices may be used, which have at least one magnetically coded track (in particular as a sequence of north pose fields and south pole fields) and, respectively, magnetic position markers that are magnetically segmented.

(61) In particular more than two magnetic position markers may be used.

(62) Furthermore, magnetic position markers and also permanent magnets may be used in different alignments (cf. FIGS. 7(a) and 9(a)). This is explained in more detail below.

(63) By means of the analysis device 56, it is possible, for example, to determine the alignment of a magnetic position marker (or of a plurality of magnetic position markers). In particular, a rotational position may be determined.

(64) For example, by way of the analysis device 56, in particular by way of determining an alignment of a position marker 20, a target (the position marker 20) may be identified, and in particular identified by way of its rotational position to the waveguide 14.

(65) In a segmented magnetic device and, e.g., a magnetic device which is provided with a magnetically coded track, the corresponding magnetic coding may be read, for example by way of the analysis device 56. This may be used, e.g., for identifying the target (the magnetic position marker 20).

(66) For a magnetic position marker 20 with varying rotational position to the sensing member 12, the rotational position may be qualitatively and/or quantitatively determined by way of the analysis device 56. In particular, a rotational angle may be determined. It is in principle also possible for a plurality of position markers to be present, or for position markers to be removed from the sensor apparatus 10, or for new magnetic position markers to be added.

(67) Such a “removal” and “supplementation”, respectively, of at least one position marker may take place, for example, by positioning the corresponding position marker or, for example, by switching on or switching off a position marker if that latter comprises an electromagnet.

(68) Provision is made, for example, for signal profiles to be serviced to be stored for a predetermined position marker 20. Such a storage may take place at the factory, or upon an installation of the magnetostrictive sensor apparatus 10 or even at a later point. A diagnosis of the magnetostrictive sensor apparatus may then be carried out, in particular by means of a comparison with the actual signal profile, and/or, e.g., signal patterns and echo signal patterns may be determined and evaluated, respectively, in order to, for example, carry out parameter adjustments, carry out cross-correlation analyses, carry out pattern recognition analyses, etc. In particular, a long-term diagnosis may be carried out over the service life of the magnetic sensor apparatus 10.

(69) By way of the analysis device 56, signal portions which overlap linearly or non-linearly may be separated with respect to the different signal components thereof. As a result, it is possible, for example, to resolve a spatial overlapping of magnetic fields of adjacent magnetic position markers, or to resolve the overlapping of the magnetic field of a magnetic position marker with an interference field. For example, interference signals which are caused, e.g., by the electronics of the magnetostrictive sensor apparatus 10 may also be identified.

(70) By means of the magnetic sensor apparatus 10 with the analysis device 56, the position of two or more magnetic position markers may be determined simultaneously, even if the magnetic fields thereof overlap.

(71) In principle, the digitization occurs in the digitization device 46 with a high digitization rate. The signal profile may be stored in the storage device 54 with the same digitization rate or with a lower digitization rate in order to save storage space and computing time. In principle, an analysis in the analysis deice 56 may be carried out with a lower resolution than a resolution according to the digitization rate of the digitization device 46.

(72) For example, it is also possible for the storage and analysis, respectively, to be carried out at different temporal regions of the (digitized) signals of the detector coil device 44 with different resolutions.

(73) When a complete signal (cf. FIGS. 3 and 4) is scanned and is analyzed by way of the analysis device 56, then, in principle, the dynamic signal components (the target signals 60, 70, 70′) and the corresponding resulting echo signals 62a, 72a, 72a′ etc. may be detected and evaluated. Static or slowly varying signal components (like, e.g., a background signal due to a parasitic magnetic field) may be recognized and a compensation may be carried out, as the case may be. Noise which in particular is stationary or quasi-stationary or periodic and quasi-periodic, respectively, may be recognized and a compensation may be carried out. Transient signals or signal components that arise, for example, due to mechanical influences or electromagnetic influences may be detected and a compensation may be carried out, as the case may be.

(74) For example, a diagnostic test is performed continuously and regularly, respectively, upon installation of the magnetostrictive sensor apparatus and/or as needed.

(75) For this purpose, for example, quality determinations are carried out at the analysis device 56 with regard to the signal of the detector coil device 44. In particular, a corresponding check is performed with regard to position in the longitudinal direction 30 of one or a plurality of position markers 20, alignment, rotation, spacing in the direction 32, etc. For example, a check with regard to an identification code of a position marker 20 is performed.

(76) For a given measurement, a comparison of the actual measurement data with this predetermined data is performed and, in principle, a measurement quality may thereby be quantitatively described.

(77) The magnetostrictive sensor apparatus 10 itself becomes analyzable by means of the analysis device 56. The states of the magnetostrictive sensor apparatus may be characterized and estimated, respectively. As a result, for example, the remaining lifetime of the magnetostrictive sensor apparatus 10 may be determined and estimated, respectively. If, for example, it is detected that a noise gradually or abruptly changes, and/or if it is detected that distorted signals are generated, or if it is detected that a signal strength for target recognition (for the target signals 60 and 70, 70′, respectively) is detected, or if a change in the signal shape (for target signals 60, 70, 70′ and/or echo signals 62a, 72a, 72a′ etc.) is detected, or if corresponding amplitude changes are detected, or if fluctuations in parameters of the magnetostrictive sensor apparatus 10 are detected, then this may point to corresponding problems and, e.g., to an end of the service life of the magnetostrictive sensor apparatus 10.

(78) As mentioned above, it is also possible in principle, in particular if the magnetic position marker 20 is known, to quantitatively determine the distance thereof in the direction 32 transverse to the longitudinal direction 30 to the waveguide 14.

(79) For example, the magnetostrictive sensor apparatus 10 may emit a warning signal when a relevant change, for example in the target signal 60 and 70, 70′, respectively, with regard to shape and/or amplitude is present, in particular with regard to different positionings in the longitudinal direction 30 or in the development over time, wherein it is determinable in principle by the analysis device 56, in turn, whether such changes are to be attributed to temperature changes and rotation of the magnetic position marker 20 and due to damping upon wave propagation, respectively, and whether these effects can then be taken into consideration.

(80) In principle, it is also possible, for example, if the magnetostrictive sensor apparatus 10 is provided with a magnetic position marker 20, to determine (upon installation) whether said magnetic position marker 20 is even compatible with the magnetostrictive sensor apparatus 10 (with the waveguide 14). Corresponding diagnostic signals and warning signals, respectively, may then be emitted.

(81) By checking the magnetic position marker 20 by means of the analysis device 56, the magnetic position marker 20 may be detected and classified, respectively. It is thereby possible, in turn, to determine and set a wave shape and amplitude, respectively, for the interrogation current pulse 22 which is optimized for the operation of the magnetostrictive sensor apparatus 10 with the specific magnetic position marker 20 (or a plurality of thereof). In particular, an optimization then takes place with respect to the signal-to-noise ratio and/or with respect to measuring accuracy and/or with respect to the repetition rate for measuring cycles etc.

(82) In principle, such determinations may also be carried out frequently and thus a plug and play function may be achieved, for example.

(83) As a result of the solution in accordance with the invention with determination and storage of the signal shape of the signals of the detector coil device 44 and analysis with the analysis device 56, a data loss due to noise in the system may be prevented. False stop signals for the termination of a measurement cycle can also be detected.

(84) Furthermore, an incorrect operation due to incorrect alignment of one or a plurality of magnetic position markers 20 may be prevented.

(85) Further, if a plurality of magnetic position markers 20a, 20b are provided, they may be used even with a relatively small spacing (with overlapping of the magnetic fields thereof).

(86) A correspondingly high data rate may be achieved.

(87) Furthermore, large dead zones, in particular around the damping element 18 may be avoided.

(88) In principle, a relatively large number of magnetic position markers 20 may be used simultaneously.

(89) An amplitude, in particular of a target signal 60 and 70, 70′, respectively, is substantially not a main source for an inaccuracy.

(90) Furthermore, a temperature influence of the environment on the waveguide 14 may be compensated.

(91) It is possible by way of the analysis device 56 to eliminate and to not take into account for an evaluation and, in particular, for a propagation time measurement, respectively, signal components that are not caused by one or a plurality of magnetic position markers 20.

(92) For example, it is also possible to carry out a combination with a conventional comparator solution (for analog signals) in which a stop signal is generated by a comparator, wherein a time window (“Enabling Time Window”) is determined for the comparator or is predicted by way of the analysis of a previous signal shape for signals of the detector coil device 44. It is also possible, for example, for a generated stop signal to be directly tracked by means of the analysis device 56.

(93) No data loss occurs and a phantom detection of position markers 20 may be prevented.

(94) This results in a higher signal reliability and data reliability.

(95) Magnetic position markers 20 positioned closely adjacent to each other, which are also able to pass each other, may also be detected, and such situations may be resolved and it results in a correct measurement.

(96) An increase in an output data rate occurs. An increase in a rate with respect to start-before-stop measurements occurs, i.e. when measuring cycles overlap. As a result of this, in turn, the reliability increases, the position prediction increases, filter operations are possible, and adaptive modes of operation.

(97) In one embodiment (FIGS. 5(a) and (b)), a “level crossing time” is determinable by linear regression by way of the analysis device 56. A certain signal value 76 is specified on a signal profile. This may be a null value or a finite value. At sampled signal points in the neighborhood of this signal value 76, a linear regression is carried out with a corresponding regression line 78 (FIG. 5(b)). As a result, precisely the “level crossing time” may be determined by way of the signal profile.

(98) In a further example according to FIGS. 6(a) to (c), two magnetic position markers 20a, 20b are present. The target signals 70, 70′ thereof differ depending on the spacing of the magnetic position markers 20a, 20b.

(99) In a diagram according to FIG. 6(a), said transducers have a greater spacing, wherein this spacing gets smaller. FIGS. 6(b) and (c) shows the corresponding signal profiles, wherein the spacing in the signal profile in accordance with FIG. 6(c) is smaller than in the signal profile in accordance with FIG. 6(b).

(100) This results, in principle, in a non-linear overlapping.

(101) In principle, by way of the analysis device 56, the individual signals may be removed, even if a distortion due to the non-linear overlapping is present.

(102) This enables the use of a plurality of magnetic position markers, even if they have a small distance from each other, or even are guided past each other.

(103) Shown in FIG. 7(a) is a situation with a first magnetic position marker 80 and a second magnetic position marker 82. These are each permanent magnets, differing in their alignment.

(104) A signal profile for this is provided in FIG. 7(b). The alignment of the magnetic position marker 80 and 82, respectively, to the waveguide 14 may be determined on the basis of the different signal shape of target signals 84 and 86, respectively. It is determinable whether north and south pole follow each other in a direction which is parallel to the longitudinal direction 30 (as in the case of the second magnetic position marker 82) or, for example, north and south pole follow each other in the transverse direction 32 to the longitudinal direction 30, as in the case of the first magnetic position marker 80.

(105) The analysis device 56 may thus determine the corresponding alignment.

(106) In principle, it is such that a time T (FIG. 8) between a target signal 88 (FIG. 8) and a second echo signal 90 is that time which sound requires to pass twice through the waveguide 14. If the speed of sound is temperature-dependent, then said time T is basically dependent on the temperature of the waveguide 14. It provides an integral measure for the temperature of the waveguide 14; at a different temperature, this time T changes.

(107) It is thereby at least an indirect measure for the prevailing temperature in the waveguide 14.

(108) Thus in this case, the second echo signal 90 is used for an at least qualitative temperature determination.

(109) With appropriate calibration, a quantitative temperature determination is also possible.

(110) In a further embodiment (FIGS. 9(a), (b)), a magnetic position marker 20 is present, which in particular is a permanent magnet, wherein its rotational position to the waveguide 14 and in particular the longitudinal direction 30 thereof is variable. An angle 92 characterizes a rotational position of the magnetic position marker 20 to the waveguide 14. This angle 92 is determined, for example, by an angular position in a direction of succession between north and south pole of the magnetic position marker 20 to a line parallel to the longitudinal direction 30 of the waveguide 14.

(111) Shown in FIG. 9(b) are different signal profiles of a target signal in the case of different rotational angles 92.

(112) The signal profiles are different. The analysis device 56 may thereby in principle determine the rotational angle 92 from a signal profile.

(113) Shown in FIG. 10 is an embodiment of a magnetostrictive sensor apparatus 94 which is configured basically the same as the magnetostrictive sensor apparatus 10 and comprises a ferromagnetic shield device 96 as a further component. The shield device 96 is arranged between a part of the waveguide 14 that is a measuring range and the damping element 18. Furthermore, the shield device 96 also shields the detector coil device 44.

(114) The magnetic position marker 20 may change in its rotational position to the waveguide 14. Furthermore, its position in a direction 98 parallel to the longitudinal direction in the measuring range may change. Moreover, its position may change in a transverse direction 100 to the direction 98.

(115) By means of the magnetostrictive sensor apparatus 94 with the analysis device 56 thereof, both the rotational position (corresponding to an angle 92 as in the embodiment in accordance with FIG. 9(a)) is quantitatively determinable, and a position in the longitudinal direction 98 and position (a distance) in the transverse direction 100 is determinable.

(116) For example, a “start-before-stop operation” may also be carried out with the magnetostrictive sensor apparatus 94 in accordance with the invention.

(117) For example, a target signal 104 and echo signals 108 are simulated for a target (a magnetic position marker 20), starting from an excitation interference signal (or an excitation 102).

(118) An overlapping of simulated signals with an offset in time between the interrogations is shown in FIG. 11(b). The offset in time is less than a measuring length-equivalent signal propagation time 106. An interrogation with the numbering N and with the numbering N+1 is shown.

(119) It correspondingly results in target signals 112 and echo signals 114. With suitable selection of a corresponding period for the excitations 110, precisely a “start-before-stop operation” may be achieved, wherein a repetition rate is selected in dependence on a measuring length and a current or extrapolated target position, such that the target signals are overlapped neither by echo signals 114 nor by excitation interference signals.

(120) A further embodiment of a magnetostrictive sensor apparatus 116 (FIG. 12) comprises a sensing member 12 with a waveguide 14 which are constructed as described above on the basis of the magnetostrictive sensor apparatus 10. Further, a corresponding detector coil device 44 is present. (The same reference numerals are used for the same elements.)

(121) A digital branch 118 is coupled to the detector coil device 44. Analog signals of the detector coil device 44 (voltage signals) are provided to said digital branch. The digital branch 118 hereby comprises a data processing device 52 which is configured basically as above.

(122) A digital-to-analog converter 120 which provides second analog signals 122 is connected to said data processing device 52.

(123) The magnetostrictive sensor apparatus 116 further comprises an analog branch 124 which is coupled to the detector coil device 44. First analog signals 126 of the detector coil device 44 are provided to the analog branch 124.

(124) A comparison device 128 is provided, which compares the first analog signals 126 with the second analog signals 122 and in particular subtracts the second analog signals 122 from the first analog signals 126 by means of a differential amplifier 129.

(125) In particular, the comparison device 128 comprises a comparator 130 or is formed by the same, respectively, which is connected downstream of the differential amplifier 129.

(126) Provision is hereby made in particular for the second analog signals 122 to be simulated signals which are calculated by way of the analysis device 56 on the basis on previous measurements. In particular, the second analog signals 122 contain echo signals and/or interference signals.

(127) These echo signals and/or interference signals are then subtracted from the first analog signals 126 by way of the comparison device 128.

(128) This results in a compensated signal 135 which contains the target signals 112 substantially free of interference. A stop signal 136 is provided from the compensated signal 135 by means of the comparator 130. Said stop signal 136 is supplied to a stop input of a TDC-converter 132 (Time-to-Digital converter).

(129) Said TDC-converter 132 is preferably supplied with a start signal 134 by the control device 24.

(130) A propagation time measurement is then carried out accordingly on corrected signals.

(131) In order to avoid the detection of false signal edges, the TDC-converter 132 is preferably supplied with a blocking signal 138.

(132) A corresponding evaluated signal is then free of interference effects like echoes or other foreseeable interference effects.

(133) Furthermore, the analysis device 56 may, for example, carry out an analysis in real time and thereby communicate to the TDC-converter 132 if false stops are present and, respectively, can detect at least false stops.

(134) The analysis device 56 may also calculate the propagation time itself from the corresponding target signals.

(135) In particular, a lower sampling frequency may be achieved by way of the magnetostrictive sensor apparatus 116 and lower resolutions for the analog-to-digital converter 50 may be achieved, respectively. There is still a high data repetition frequency. For example, a plurality of magnetic position markers may be used. A flexible combination of measurements with low resolution and high resolution with respect to selected targets may be carried out.

REFERENCE NUMERAL LIST

(136) 10 magnetostrictive sensor apparatus 12 sensing member 14 waveguide 16 return conductor 18 damping element 20 magnetic position marker 20a magnetic position marker 20b magnetic position marker 22 interrogation current pulse 24 control device 26 magnetic field 28 measuring point 30 longitudinal direction 32 direction 34 magnetic field lines 36 direction 38 direction 40 end 42 end 44 detector coil device 46 digitization device 48 analog signals 50 analog-to-digital converter 52 data processing device 54 storage device 58 analysis device 58 excitation noise 58′ excitation noise 60 target signal 62a echo signal 62b echo signal 62c echo signal 62d echo signal 64 region 66 region 68 excitation noise 70 target signal 72 target signals 72a echo signals 72a′ echo signals 72b echo signals 72b′ echo signals 74 region 76 signal value 78 regression line 80 first magnetic position marker 82 second magnetic position marker 84 target signal 86 target signal 88 target signal 90 second echo signal 92 angle 94 magnetostrictive sensor apparatus 96 shield device 98 direction 100 direction 102 excitation 104 target signal 106 signal propagation time 108 echo signal 110 excitation 112 target signal 114 echo signal 116 magnetostrictive sensor apparatus 118 digital branch 120 digital-to-analog converter 122 second analog signals 124 analog branch 126 first analog signals 128 comparison device 129 differential amplifier 130 comparator 132 TDC-converter 134 start signal 135 compensated (corrected) signal 136 stop signal 138 blocking signal