EP2016292A1

EP2016292A1 - Microwave position measurement apparatus and position measurement method

Info

Publication number: EP2016292A1
Application number: EP07723491A
Authority: EP
Inventors: Thomas Reininger; Matthias Von Zeppelin; Marcus Maier
Original assignee: Festo SE and Co KG
Current assignee: Festo SE and Co KG
Priority date: 2006-05-06
Filing date: 2007-03-22
Publication date: 2009-01-21
Also published as: WO2007128369A1; DE102006021205A1

Abstract

The invention relates to a position measurement method and a microwave position measurement apparatus for detecting the position of an actuator element (14) of an actuator (11), said element being arranged such that it can move in an interior (12) of an actuator housing (13). The position measurement apparatus has a radio-frequency microwave antenna arrangement (34) for transmission of microwaves (43) into the interior (12) and for reception of reflected microwaves (44, 44') from the interior (12) which are produced by at least partial reflection of the transmitted microwaves (43, 53) on the actuator element (14), and evaluation means (42) for producing, on the basis of the reflected microwaves (44, 44'), a position signal (52) which represents the respective position (x) of the actuator element (14). The microwave position measurement apparatus (30) is characterized in that in the interior of the actuator housing (13) at least one stationary reflective means (50) is arranged and in that the evaluation means (42), for the purpose of calibration, evaluate the microwaves (43) that are reflected by the at least one reflective means.

Description

FESTO AG & Co., Ruiter Strasse 82, 73734 Esslingen

Microwave position measuring device and position measuring method

The invention relates to a position-measuring method and a microwave position-measuring device for detecting the position of an actuator member of an actuator movably arranged in an interior of an actuator housing, having a high-frequency microwave antenna arrangement for transmitting microwaves into the interior and for receiving at least partial reflection of the transmitted Microwaves formed on the actuator member reflection microwaves from the interior, and with evaluation means for forming a respective position of the Aktorglieds representative position signal from the reflection microwaves.

For example, such a position measuring device and a corresponding position measuring method are known from DE 198 33 220 A1. The position measuring device transmits, for example, pulse radar waves or frequency modulated radar waves in the direction of the piston, which are reflected by the piston. The interior forms a waveguide. On the basis of a phase difference or transit time measurement of the transmitted and received microwaves, the evaluation means determine the distance of the piston from the microwave antenna arrangement and thus the position of the piston in the interior space or movement space. In the interior, however, for example, fats or other deposits can accumulate, which influence the propagation behavior of the microwaves. For example, the propagation speed changes depending on the conductivity of an inner wall of the inner space. The measurement accuracy of the position measuring device is thereby worse.

It is therefore the object of the present invention to provide a position measuring device and a position measuring method which have a high measuring accuracy.

To solve the problem is provided in the microwave position measuring device of the type mentioned that at least one stationary reflection means is disposed in the interior of the actuator housing, and that evaluate the evaluation means by means of at least one reflection by means of reflected microwaves. Furthermore, a position measuring method according to another independent claim is proposed for achieving the object.

The fixed reflection means allows calibration of the position measuring device. The position of the reflection medium in the interior of the actuator housing is known. Based on a transit time measurement or a phase comparison between transmitted and received microwaves the evaluation means can determine the propagation velocity of the microwaves in the interior.

The at least one reflection means, for example, has a fixed distance to the microwave position measuring device. But even if the distance changes due to, for example, mechanical influences during operation of the actuator, due to thermal fluctuations or the like, it is possible according to the invention then calibrated Position measuring device, for example, to determine a relative distance of the actuator member to the stationary reflection means for determining the position of the actuator member in the interior. If, for example, the propagation velocity of the microwaves increases due to a cross-sectional enlargement of the interior, this is taken into account by the calibration according to the invention.

The actuator element is expediently a piston of a fluid-technical, for example pneumatic actuator, e.g. a pneumatic working cylinder. Although in the following embodiment, a pneumatic cylinder is described with a piston rod, the invention also includes rodless construction variants. Furthermore, the actuator can also be an electric drive or a combined fluidic and pneumatic drive, wherein the actuator is, for example, the rotor of an electric motor, in particular a linear motor. It goes without saying that the position determination and calibration of the position measuring device according to the invention is also possible with rotary drive principles.

The position measuring device can determine spatially mutually spaced targets in the interior, for example the actuator member on the one hand and the at least one reflection means on the other hand. This is possible, for example, with a pulse train or an FMCW radar (FMCW = Frequency Modulated Continuous Wave). The position measuring device operates advantageously based on the so-called time domain reflectometry.

Based on the measured transit time and the known distance between see the high-frequency microwave antenna assembly and the stationary reflection means is a current propagation speed of the microwaves for the calibration of the position measuring device, in order to later determine the position of the actuator element precisely calibrated at this propagation speed. Geometric and / or electromagnetic influences in the interior of the actuator housing, which forms a waveguide, on the propagation velocity of the microwaves are thus taken into account in the calibration, so that the measurement accuracy in the position measurement of the actuator member is improved.

A reflection means according to the invention can also be, as it were, a geometric and / or electrical impurity which influences the propagation and reflection of microwaves. Furthermore, electrical reflector sites, for microwaves partially transparent areas, for example in the manner of semitransparent mirror, or the like reflection means.

As it were passive reflection means can be, for example, metallizations, geometric changes in the region of the interior, for example projections, recesses, stops or the like. A fluid channel, for example a channel for supplying and removing air to a pneumatic cylinder, may also form a calibration reflection means. For example, a change in cross section, for example a jump in cross section or stop, is present in the region of an end position damping of a pneumatic cylinder. Also grooves, protrusions or the like can serve as calibration reflection means. The grooves, projections or other geometric elements in the interior, which serve as Kalibrier- reflection means have expediently such a dimension, eg depth or height, which is reflected part of the microwaves. It is expedient that the interior space has a substantially electrically conductive surface and a recess serving as a calibration reflection means is filled with a dielectric, for example plastic. This creates a mechanically continuous surface.

The reflection means may be arranged at different points in the interior of the actuator housing, for example on a peripheral wall or a lid, in particular an end face of the actuator housing. If the lid is a removable lid, it is easier to produce the reflective material. By way of example, the reflection means is arranged on a rear end wall of the actuator housing opposite the microwave antenna arrangement or is formed by the end wall.

The at least one stationary reflection means may also comprise active reflection means, for example transponders. The transponder receives the microwaves and affects them before sending them back to the position measuring device. For example, the transponder amplifies the microwaves, modulates them, changes their polarization and / or frequency or the like.

It is also possible to provide a plurality of transponders, for example a first transponder on the actuator element and a second transponder as a calibration reflection means in the sense of the invention.

Active and / or passive modules are advantageous as transponders. For example, a nonlinear device may be provided as a passive assembly that generates one or more mixing frequencies from two or more received frequencies. For example, as a transponder a kind of RFID chip (RFID = Radio Frequency Identification) be provided, which modulates a signal characteristically by means of surface acoustic waves, for example.

In this case, it is already an independent idea according to the invention to arrange only one transponder on the actuator element. This variant can also be implemented if, so to speak, passive fixed calibration reflection means or no stationary calibration reflection means are present and no calibration according to the invention is carried out. However, if a calibration according to the invention takes place, it is advantageous if the at least one first transponder arranged on the actuator member and the at least one calibration reflection means, e.g. an impurity and / or the at least one second transponder forming a calibration reflec- tion means has different reflection properties for the microwaves transmitted by the position-measuring device. The position measuring device thus receives different reflection microwaves, for example microwaves with different modulation, polarization or the like, and can thus distinguish the microwaves reflected by the transponder on the actuator element from the microwaves reflected by the calibration reflection means.

The at least one reflection means is expediently arranged in a region between the microwave antenna arrangement and an end position of the actuator member. This end position is, for example, a front, a maximum of the microwave antenna arrangement zoomed or a rear, maximum remote end position. If the reflection means are arranged as far forward as possible in front of the front end position of the actuator member, it is possible to calibrate the position measuring device independently of the position of the actuator member, for example, before startup, during operation or the like. However, it is important in this case that the reflection microwaves, which as it were generate the actuator element and the calibration reflection means as an echo, are distinguishable from one another.

An expedient variant of the invention provides that the actuator member, e.g. on the piston of a pneumatic cylinder, an area which is at least partially permeable to the microwaves, at least for those microwaves used for the calibration. For example, the calibration microwaves may pass through the actuator member and reach a rear end wall of the actuator housing where they are reflected and then form calibration microwaves. However, it is also conceivable that the calibration microwaves reach a calibration reflection means arranged behind the actuator member on a circumferential wall of the actuator housing. The microwaves can then pass through the actuator member and / or past the actuator member to the calibration reflection means.

The permeable region is, for example, a passageway, e.g. an air passage, a peripheral seal on the outer periphery of the actuator member, a distance between an inner wall of the actuator housing and an outer periphery of the Aktorglieds or the like. It has been shown in practice that, for example, about 10% of transmitted microwaves are not reflected by the actuator element, but pass past it in a rear region remote from the microwave antenna arrangement. These microwaves are evaluated according to the invention for calibration purposes.

For calibration purposes, microwaves with special properties, for example suitable frequencies, can advantageously be used. are sent, which reach particularly well over the at least partially transmissive region of the actuator member to the calibration reflection means and are reflected by this for calibrating the position measuring device.

The microwave antenna arrangement comprises, for example, a coupling probe held by a holding body. According to the invention, one or more reflection means, for example metallizations on a dielectric material, or the like can be arranged on the holding body. Furthermore, it is conceivable that, for example, at least one inventive calibration reflection means is arranged on a baffle body which serves to protect the microwave antenna arrangement relative to the actuator member or other environmental influences.

The position measuring device expediently has transmitting means which are suitable for transmitting calibration microwaves intended for calibration purposes. The calibration microwaves are different from the microwaves used for the position measurement of the actuator element. For example, the calibration microwaves have different frequencies or are different frequency or pulse modulated compared to the position measuring microwaves.

Furthermore, it is conceivable that the position-measuring microwaves and the calibration microwaves have different polarizations, for example linear and circular polarizations or vice versa.

The at least one reflection means is expediently adapted to the calibration microwaves. For example, a geometry of the reflection means is such that in particular the calibration microwaves are reflected, the Influence on the position measuring microwaves, however, different, especially lower.

Even with the active reflection means, for example the transponder explained above, it is expedient if the transponder is tuned to the calibration microwaves.

In polarized calibration microwaves, it is advantageous that the reflection means only reflects microwaves of a predetermined polarization, frequency or the like. For example, an angular position or rotational position of a reflecting means arranged on a rear end wall of the actuator housing is such that only microwaves of a predetermined polarization or angular position of the polarization are reflected. However, it is also possible that at least one reflection means changes a polarization of microwaves, for example linearly polarized microwaves, into circularly polarized microwaves or vice versa. Differentially polarized reflection microwaves can be distinguished from the position measuring device, so that they can distinguish calibration and position measuring microwaves.

The radio-frequency microwave antenna arrangement expediently has a separate antenna for transmitting the position-measuring microwaves and the calibration microwaves, namely a position-measuring antenna and a calibration antenna. The antennas may be separate units or an integrated unit. For example, the two antennas may be arranged on a common carrier structure of a coupling probe. The carrier structure is formed, for example, by a dielectric, onto which metal surfaces for forming the microwave antennas are applied, for example vapor-deposited or the like. Further, it is conceivable that the antenna is formed directly by a holding body, the for example, has corresponding metallizations. For the different antennas separate connections are expediently available.

The position measuring method according to the invention can be used in different operating states. For example, it is triggered by a control command. The control command can be triggered manually, for example locally on the position measuring device, by an external control, for example a programmable logic controller, or a monitoring device, for example a personal computer. It is advantageous if the position measuring device performs the calibration automatically, for example, before startup, interruptions in operation or the like. A cyclic or continuous calibration during the operation of the actuator is also advantageous.

With the aid of the calibration according to the invention, it is possible to determine, for example, aging phenomena, environmental influences, foreign bodies or other extrinsic influences on the propagation behavior of the microwaves and thus also to take into account changes and fluctuations in the propagation speed in the long term. The plastic-filled groove on the inner circumference of the waveguide does not change fluid-technical, in particular pneumatic properties of the housing interior, which encompasses a movement space for the piston member. The position measuring antenna is expediently arranged on the front side, that is to say in the direction of movement of the actuator member, in the interior space. The calibration antenna is advantageously oriented transversely to the direction of movement of the actuator member. The calibration antenna has, for example, a single electrode, two angularly, in particular at right angles, mutually arranged electrodes or the like. Embodiments of the invention will be explained in more detail with reference to the drawing. Show it:

FIG. 1 shows a sectional and partially schematic view of an actuator equipped with a first position-measuring device according to the invention;

FIG. 2 is a sectional and partially schematic view of a second actuator equipped with a second position measuring device according to the invention, and FIG

Figure 3 is a perspective view of a microwave antenna for a position measuring device according to the invention.

A pneumatic working cylinder 10 forms an actuator 11, in particular a fluidic actuator. In an inner space 12 of an actuator housing 13, an actuator member 14 is arranged linearly reciprocatingly. The actuator member 14 is formed by a piston 15 of the working cylinder 10. In the embodiment, it is a pneumatic working cylinder with a piston rod, which also rodless versions, electric drives, combined electropneumatic actuators, especially linear drives, are readily possible.

A valve assembly 16, for example, has a 2/2 valve, feeds compressed air 17 from a compressed air source 18 via compressed air connections 19, 20 in the interior 12 or allows the outflow of compressed air from the compressed air connections 19, 20 to drive the piston 15 , the interior 12 in two unspecified sub-chambers separates. Between an outer periphery 27 of the piston 15 and an inner wall 28 of a central part 22 of the housing 13, a seal 21 is provided for example for this purpose.

The middle part 22 is closed at the end by a bearing cap 23 5 with a rear end wall 26 and a cover plate 24, and thus limits the interior 12 b, which comprises or forms a piston chamber. The bearing cap 23 is penetrated by a piston rod 25, which forms a Kraftabgriffselement of the working cylinder 10.

A position measuring device 30 serves to detect the position of the actuator member 14 within the interior space 12, for example a distance 31 of the piston 15 from an end stop 32. The end stop 32 is advantageously formed by a protective device 33, for example a plastic element which transmits a microwave Antenna assembly 34 of the position measuring device 30 against mechanical influences, such as pressure surges, impact of the piston 15 or the like, protects.

The microwave antenna assembly 34 includes a coupling probe 2o 35 for transmitting and receiving high frequency microwave, for example, in a frequency range of about 10 MHz to 30 GHz. The coupling probe 35 may be, for example, a metallic probe. In the present case, however, the coupling probe 35 contains a plastic element 36 which has an emission area 5 towards the interior 12, to which a channel section 37 adjoins to the rear. The channel section 37 forms a coaxial conductor. The radiation area 38 is designed, for example, in a stepped cylinder. The plastic element 36 (it could also be made of ceramic or another dielectric) is internally and externally provided with an electrically conductive coating 39, 40. The channel section 37 connects the emission area 38 with a high-frequency device 41, for example a high-frequency board or the like, and an evaluation device 42.

With the help of the high-frequency device 41 microwaves 43 can be generated, which couples the coupling probe 35 into the interior 12. The interior space 12 is substantially electrically conductive and forms a waveguide which conducts the microwaves 43 to the actuator member 14 which reflects the microwaves 43 and forms reflection microwaves 44. The coatings 39, 40 are electrically connected to the high-frequency device 41, which contains unspecified coupling elements and coupling elements, for example capacitors, millimeter-wave integrated circuits (MMICs), directional couplers or the like. These components are arranged on a substantially planar rear end-face support structure 45. The radio-frequency device 41 can transmit the microwaves 43 e.g. frequency modulated and / or pulse modulated send, for example by means of a voltage controlled oscillator (VCO) or the like.

The high-frequency device 41 as well as the evaluation device 42, which contains or forms evaluation means in the sense of the invention, are electrically connected to one another and expediently arranged on the same support structure 45.

The evaluation device 42 determines based on the transit time and / or the phase difference between the microwaves 43, 44 a respective position x, for example, the distance 31 corresponds to the actuator member 14 within the interior 12. The evaluation device 42 includes, for example, a processor 46, a memory 47 and / or other electronic components see, for example ASICs (Application Specific Integrated Circuits) or the like. The evaluation By means of at least one predetermined condition, for example a temporal condition or a control command, the position measuring device 30 carries out a calibration by means of a position signal 48 with the position x, for example wired (not shown) or wirelessly. With the aid of this calibration, the measurement accuracy of the position measuring device 30 is improved, which is caused for example by electrical and / or geometric and / or thermal changes in the interior 12, which forms an electrical conductive structure or a waveguide. For example, fat deposits on the inner wall 28 lead to changes in the transit times of the microwaves 43 and 44, so that the distance x can no longer be measured with sufficient accuracy.

For calibrating the position-measuring device 30, calibration reflection means 50 are arranged fixedly in the interior 12.

Hereinafter, some variants of reflection means according to the invention, which may be provided individually or in combination with each other, are presented on the basis of the reflection means 50.

The reflection means 50 comprise, for example, one or both compressed-air connections 19, 20. The evaluation device 42 measures, for example, cyclically, based on an externally given control command, before the activation of the actuator 11 or the like a running time of the microwaves 43, the latter until a reflection at the terminals 19 and 20, the fluid channels 51 form, need.

Furthermore, cross-sectional changes, protrusions, grooves or the like in the interior 12 can form components of the reflection means 50. For example, the end stop 32 could be used as a Librier reflection means 50 for the position measuring device 30 serve.

However, separate reflection means 50, which are especially suitable for the reflection of calibration microwaves, can also be positioned in the interior 12 in a stationary manner. For example, the otherwise electrically insulating or consisting of dielectric material protection device 33 includes an electrically conductive surface 52, which reflects the microwaves 43 and can be used for calibration purposes.

The microwaves 43 may advantageously comprise microwaves of different frequencies, frequency- and / or pulse-modulated microwaves, it being possible for the purpose of the calibration to use microwaves with other properties to advantage, such as for determining the position of the actuator member 14.

Further, in a rear portion 29 of the inner space 12, calibration reflection means 50 are positioned. The positioning in the rear region 29 has the advantage that influences which are significant for the calibration, for example due to contamination of the inner space 12, to the microwaves 43 and to calibration microwaves 53 described in more detail below, are particularly great.

The microwaves 43 pass, for example, on the outer circumference 27 of the piston 15 to a recess 55, for example a groove, on the inner wall 28 of the peripheral wall of the actuator housing 13. The recess 55 is filled with a dielectric 56, for example a plastic material. As a result, mechanical, in particular pneumatic view of the inner wall 28 is continuous and has no gradation. Nevertheless, the recess 55 changes the reflection behavior of the hollow conductor or inner space 12 in the rear region 29, so that the Evaluation device 42 reflected reflection microwaves 44, which are reflected by the piston 15 and reflection microwaves 44 ', which are influenced by the recess 55 different.

Furthermore, it is possible for the microwaves 43, which pass on the outer circumference 27, to be influenced by a dielectric 58, which is arranged in a recess 57 on the rear end wall 26, during the formation of the reflection microwaves 44 '.

The piston 15 has a permeable portion 59 for passing the microwaves 43 and / or the microwaves 53 and reflection microwaves 44 and 54 formed therefrom. The permeable portion 59 comprises, for example, a passageway 60 containing fluid, e.g. Air, through. The passageway 60 allows the microwaves 43 to one at the rear

End wall 26 arranged reflector 61 by. The passage 60 extends substantially parallel to the direction of movement 67 of the actuator member 14.

The reflector 61 may be a passive reflector, for example a recess filled with a dielectric. It is also conceivable that the reflector 61 is a transponder 71 which, for example, alters a frequency of and / or a pulse sequence and / or a polarization of the microwaves 43.

The microwave antenna arrangement 34 and the high-frequency device 41 are configured to transmit calibration microwaves 53 and form corresponding transmission means 62. The calibration microwaves 53 are different from the position-measuring microwaves 43. For example, the calibration microwaves 53 are frequency-modulated or pulse-modulated microwaves. As explained above, it is conceivable that the same microwaves 43, 44 can be used for position measuring purposes and Kalibriermesszwecken.

In the embodiment of the invention described below in conjunction with FIG. 2, the position measuring microwaves 43 are, for example, linearly polarized microwaves, the calibration microwaves 53 are circularly polarized microwaves or vice versa. Further, the microwaves 43, 53 may be microwaves linearly polarized at different angles to each other.

The microwaves 53 pass, for example, on the outer circumference 27 of the piston 15 and thus reach the rear end wall 26, where the reflector 61 is arranged specifically for the calibration microwaves 53. As far as the actuator 11 shown in FIG. 2 with a position measuring device 30 'with its position measuring device 30' corresponds to the actuator 11 and the position measuring device 30, the same reference numerals are used for identical or equivalent components.

A microwave antenna arrangement 34 'corresponds in part to the microwave antenna arrangement 34. In addition to the coupling probe 35 provided for transmitting the position measuring microwaves 43, which thus forms a position measuring antenna 63, the antenna arrangement 34' contains a Kalbrier antenna 64 for transmitting the Calibration microwaves 53 and for receiving the resulting reflection microwaves 54. The calibration antenna 64 contains perpendicular to each other positioned transmit and receive electrodes 65, 66. The electrodes 65, 66 are oriented transversely to a direction of movement 67 of the actuator member 14. For example, the electrodes 65, 66 are metalizations on the protective device 33. The electrodes 65, 66 are connected, for example, with electrical lines 70 to the radio-frequency device 41.

The protective device 33 is in the embodiments, a holding body 68 for holding the coupling probe 35 vorgela- siege separate, lid-like device.

It is understood that instead of the holding body 68 and the protective device 33, a one-piece component can be provided on which, for example, the reflection means 50 and / or the electrodes 65, 66 can be arranged.

At the rear end wall 26 of the actuator II ¹ , a polarization reflection means 69 is arranged. The polarization reflection means 69 is designed for the reflection of the polarized calibration microwaves 53. By way of example, the reflection means 69 is arranged on the rear end wall 26 in an angular position or inclined position oriented in the direction of polarization of the calibration microwaves 53. Furthermore, it is conceivable for the reflection means 69 to change a polarization of the calibration microwaves 53, for example to convert a circular into a linear polarization or vice versa.

The coupling probe 35 has a circular cross section and is expediently positioned coaxially with the piston 15 or the piston rod 25 in the inner space 12. Instead of the coupling probe 35, for example, a coupling probe 80 shown in FIG. 3 could also be used.

At a Koaxialleiterabschnitt 81 a support structure 82 of the coupling probe 80, a plate member 83 is arranged in front. The plate member 83 has, for example, a rectangular contour. The support structure 82 is preferably made of a Dielectric provided with metal surfaces, for example, coated, steamed, etc. By way of example, an electrically conductive surface 84 of a position-measuring antenna 86 on a front end side of the plate part 83 serves to transmit and / or receive the position-measuring microwaves 43, 44. Arranged on lateral edge regions of the plate part 83 are also electrically conductive surfaces 85 are electrically insulated from the surface 84, for example by suitable distances from the surface 85. The surfaces 85 form electrodes of a calibration antenna 87 for transmitting and receiving, for example, the calibration microwaves 53, 54.

Claims

claims

1. Microwave position measuring device for position detection of an in an interior space (12) of an actuator housing (13) movably arranged actuator member (14) of an actuator (11,

5 11 ') _/ with a high-frequency microwave antenna arrangement (34, 34') for transmitting microwaves (43, 53) into the interior space (12) and for receiving at least partial reflection of the transmitted microwaves (43, 53) Reflection microwaves (44, 44 ', 54) formed by the actuator element (14) from the internal space (12), and with evaluation means (42) to form a position signal (52) representing the respective position (x) of the actuator element (14). Based on the reflection microwaves (44, 44 ', 54), characterized in that in the interior (12) of the actuator housing (13) at least one stationary reflection means (50) is arranged, and that the evaluation means (42 ) to evaluate their calibration on the basis of at least one reflection means (50) reflected microwaves (43, 53).

2. Position measuring device according to claim 1, characterized marked records that the at least one reflection means (50) an electrically insulating or conductive surface (52), in particular a metallization, and / or a projection and / or a recess (55) and / / or a stop (32) on the actuator housing (13) or the high-frequency microwave antenna 5 arrangement (3.4, 34 ') and / or a fluid channel (51) of the actuator housing (13).

3. Position measuring device according to claim 2, characterized in that the inner space (12) substantially has an electrically conductive surface and the recess (55) is filled with a dielectric (56).

s 4. Position measuring device according to one of the preceding claims, characterized in that the at least one reflection means (50) on a peripheral wall (28) of the actuator housing (13) is arranged.

5. Position measuring device according to one of the preceding lo claims, characterized in that the at least one

Reflection means (50) in a cover (23, 24) of the actuator housing (13) is arranged.

6. Position measuring device according to one of the preceding claims, characterized in that the at least one reflection means (50) arranged on one of the high-frequency microwave antenna arrangement (34, 34 ') opposite rear end wall of the actuator housing (13) or from the rear End wall is formed.

7. Position measuring device according to one of the preceding 20 claims, characterized in that the at least one

Reflection means (50) in a region between the high-frequency microwave antenna assembly (34, 34 ') and an end position of the Aktorglieds (14) is arranged, in which the Aktorglied (14) maximum to the high-frequency microwave antenna assembly (34, 34 ') is positioned on it.

8. Position measuring device according to one of the preceding claims, characterized in that the actuator member (14), in particular a piston (15), a microwave for at least partially transmissive region (59) through which of microwaves (43, 53) transmitted to the microwave antenna arrangement (34, 34 ') to the rear end wall (26) and to the rear end wall reflected microwaves (44, 54) in the direction of the microwave antenna arrangement (34, 34') through 5 can occur.

9. Position measuring device according to claim 8, characterized in that the at least partially permeable region (59) has a passage channel (60) and / or a circumferential seal (21) and / or a distance between an inner wall (28) of the actuator housing (13 ) and an outer periphery of the actuator member (14).

10. Position measuring device according to one of the preceding claims, characterized in that the high-frequency microwave antenna arrangement (34, 34 ') comprises a holding body (68) held by a coupling probe (35), and that the reflection means (50) the holding body (68) is arranged or formed by the holding body (68).

11. Position measuring device according to one of the preceding claims, characterized in that it comprises transmitting means (62).

20 for transmitting position measuring microwaves (43) to a position measurement of the Aktorglieds (14) and for sending caliber calibration microwaves (53) for calibration, which are different from the position measuring microwaves (43).

12. Position measuring device according to claim 11, characterized 5 indicates that the calibration microwaves (53) and / or the position measuring microwaves (43) comprise frequency-modulated and / or pulse-modulated microwaves.

13. Position measuring device according to claim 11 or 12, characterized in that the position-measuring microwaves (43) linearly polarized microwaves and the calibration microwaves (53) comprise circularly polarized microwaves or vice versa.

14. Position measuring device according to one of claims 11 to 5 13, characterized in that the at least one reflection means (50) is adapted to the calibration microwaves (53).

15. Position measuring device according to one of the preceding claims, characterized in that the at least one reflection means (50) comprises a transponder (71).

16. Position measuring device according to one of the preceding claims, characterized in that the at least one reflection means (50) is designed for mixing and / or modulating received microwaves.

17 17. Position measuring device according to claim 16, characterized in that the at least one reflection means (50) has a non-linear mixing characteristic and / or is designed for modulation based on surface acoustic waves.

20 18. Position measuring device according to claim 16 or 17, characterized in that the at least one reflection means (50) comprises a passive component, in particular a nonlinear component, for mixing and / or modulating.

19. Position measuring device according to one of the preceding 5 claims, characterized in that the at least one reflection means (50) reflects only microwaves of a predetermined polarization.

20. Position measuring device according to one of the preceding claims, characterized in that the at least one reflection means (50) changes a polarization of the microwaves.

5 21. Position measuring device according to one of the preceding claims, characterized in that the reflection means (50) in an aligned on polarization of the calibration microwaves (53) angular position in the interior (12), in particular the rear end wall (26), of the actuator Housing (13) lo is arranged.

22. Position measuring device according to one of the preceding claims, characterized in that the high-frequency microwave antenna arrangement (34, 34 ') for transmitting the position measuring microwaves (43) a position measuring antenna (63; i5 86) and for transmitting the Calibration microwaves (53) have a calibration antenna (64; 87).

23. Position measuring device according to claim 22, characterized in that the position-measuring antenna (63; 86) in a movement direction (67) of the actuator member (14) and the Ka

20 librier antenna (64; 87) transverse to the direction of movement (67) of the Aktorglieds (14) are oriented.

24. Position measuring device according to claim 22 or 23, characterized in that the calibration antenna (64; 87) and the position measuring antenna (63; 86) are arranged on a common carrier structure (82) of a coupling probe (35) of the high-frequency sensor. Microwave antenna arrangement (34, 34 ') arranged or formed by the support structure (82).

25. Position measuring device according to one of claims 22 to 24, characterized in that the calibration antenna (64; 87) is arranged on a holding body (68) of the high-frequency microwave antenna arrangement (34, 34 ') or is formed by or from the holding body (68).

26. Position measuring method for position detection of an actuator element (14) of an actuator (11, 11 '), wherein the actuator element

(14) is movably arranged in an interior (12) of an actuator housing (13), with the steps:

- transmitting microwaves (43, 53) into the interior space (12) with a high-frequency microwave antenna arrangement (34, 34 '), lo - receiving at least partial reflection of the transmitted microwaves (43, 53) on the actuator member (14 ) reflection microwaves (44, 44 ', 54) from the interior (12),

- Forming a respective position (x) of the actuator member i5 (14) representing position signal (52) based on the reflection microwaves (44, 44 ', 54) by means of evaluation (42), characterized by

- Calibrating the evaluation means (42) based on microwaves 20 (43, 53), which are reflected by at least one in the interior (12) of the actuator housing (13) fixedly arranged reflection means (50).

27. Position measuring method according to claim 26, characterized in that it is carried out before commissioning and / or during a 5 ner interruption of operation and / or cyclically and / or continuously and / or at a control command.