DE102009009789B4 - motion sensor - Google Patents

Abstract

Device for the contactless detection of a rotational movement, the number of revolutions and / or the rotational angular position of a rotatable object (1) comprising an optical radiation source (3), a detector (6) and an evaluation unit (7) for evaluating the measurement signals supplied by the detector (6), wherein radiation (9) generated by the radiation source (3) is directed at least partially onto the object (1) and the detector (6) detects the radiation (4) directly reflected by the object (1), characterized in that the evaluation unit (7 ) is designed to detect recurrent signal patterns in the measurement signals supplied by the detector (6) during complete revolutions of the rotating object (1) and to associate them with a rotation angle of the object (1) in order to establish a correlation between the recurring signal patterns 6) and the angle of rotation of the object (1) and, based on the correlation of the measurements delivered by the detector (6) Ignore by comparison with recurring signal patterns to determine the rotation angle of the object (1) and / or to determine the rotational angular position of the object (1) by comparison with recurrent signal patterns and / or by comparison with stored signal patterns.

Description

The invention relates to a device and a method for contactless determination of a rotational movement, the number of revolutions and / or the rotational angular position of rotating objects. The invention particularly relates to a safety-related, active, optical motion sensor for monitoring a rotational movement of an object relative to the sensor or a rotational movement of rotating objects, such. B. rotating waves.

The invention relates to an optical sensor for non-contact determination of a rotational movement, the number of revolutions and / or the rotational angular position of a rotatable object which comprises an optical radiation source, a detector and an evaluation unit for evaluating the measurement signals supplied by the detector. Such optical sensors are used for example in motors to detect the speed of transmission or drive shafts in an immediate manner. Another application for such optical sensors is the monitoring of the standstill or compliance with a certain range of movement rotatable objects within predetermined tolerance limits.

A commonly used for non-contact sensors measurement method is the reflection or transmitted light principle in which, for example, an arranged on the rotating shaft initiator has translucent sections and opaque sections that are illuminated by the radiation source, which is opposite to a statically arranged relative thereto scanning system. When the rotating shaft or the initiator wheel arranged thereon moves, the translucent sections and opaque sections of the initiator wheel move through the beam path of the radiation source and thereby generate an alternating reflection pattern of the initiator wheel on the scanning system. This ghost image can be scanned in the scanning system with the aid of electrical photoreceivers.

From the DE 10 2005 040 772 A1 is an optical length and speed sensor for non-contact measurement of a relative speed of an object or an object surface to a sensor known. Also the DE 10 2007 029 299 A1 and the US 4 794 384 A reveal the detection of a translational movement of an object.

From the DE 4 116 579 A1 and the DE 198 39 281 A1 are the contactless detection of a rotating object known, according to the DE 198 39 281 A1 on the object mark patterns are attached, which have different reflective properties depending on the rotational position.

The DE 600 34 723 T2 discloses the use of a disc coupled to a shaft for non-contact sensing of a rotating object as an encoder-emitting element for determining a movement amount or a movement rate of the target object.

The known speed sensors have the disadvantage that they usually need a separate Initiatorrad, which increases both the structural complexity and the susceptibility to errors.

The object of the invention is therefore to improve an optical sensor of the type mentioned in that he no longer requires Initiatorrad.

This object is achieved with the present invention by an apparatus and a method having the features defined in the independent claims 1 and 15. Advantageous developments and refinements of the invention are specified in the subclaims 2 to 14 and 16 to 20, respectively.

According to one aspect of the present invention, the above-mentioned object is achieved by a device for non-contact detection of a rotational movement ,, the number of revolutions or the rotational angular position of a rotatable object comprising an optical radiation source, a detector and an evaluation unit for evaluating the measurement signals supplied by the detector, wherein The radiation generated by the radiation source is at least partially directed to the object and the detector detects the radiation directly reflected by the object.

With the sensor device according to the invention, for example, the rotational movement, the number of revolutions or the rotational angle position of a rotatable object can be determined. In this case, no more initiator wheel is needed, which is arranged on the rotating measurement object, but the rotating measurement object can be detected in a direct manner and their number of revolutions are detected directly. In this way, the obsolete Initiatorrad no longer represents a source of error and the active sensor can diagnose itself and the rotating object.

In the device according to the invention for determining the number of revolutions or the rotational angle position of a rotatable object, the light beams emitted by the light source are detected after they have been directly reflected by the surface of the object. In this way, the detector of the invention takes Sensor device to a kind of "reflection track", which can then be used in the evaluation as a reference for determining the number of revolutions and / or the rotational angular position of the object.

In the evaluation unit of the sensor device, for example, by comparing the amplitude profile of two successive measurements over complete revolutions of a rotatable object, its motion can be derived both with respect to the angle of rotation, the direction of rotation, and the distance of the rotational movement of the rotating object. With the aid of the radius of the rotating object, the lateral surface and thus also the distance covered during the rotational movement of the object can be determined. By determining the time for a number of complete revolutions, the rotational frequency of the rotating object can also be determined. Thus, all rotation parameters of the rotational movement can be determined.

If, for example, the rotating object is a shaft with a specific radius about its axis of rotation, it is also possible to intentionally apply structures which have different reflections on the lateral surface of the shaft, depending on location. The different degrees of reflected light radiation when the shaft rotates forms a corresponding intensity pattern on the detector from which conclusions can be drawn on the rotational position of the object, since there are on the lateral surface of the rotating shaft differently strong reflecting structures which the light rays from the radiation source in Depending on the rotational movement and the angle of rotation of the shaft influence.

The present invention can thus be applied to monitoring or measuring rotational motions. The present invention can also be used for monitoring the stoppage of a rotatable object, wherein the object is allowed to perform a rotational movement only within predetermined limits. Standstill is understood to be compliance with a defined position. This means that the object to be monitored must also comply with this position within specified tolerances. In order to distinguish real movements outside specified tolerances from permissible fluctuations within the specified tolerances, permissible electrical and local tolerances of the measuring signals can be specified.

An advantage of the sensor device according to the invention is that the detection of the reflection track over the surface of the rotating object during a complete revolution allows a more accurate detection of the rotational movement, the number of revolutions or the angle of rotation and thus a more sensitive monitoring of the stoppage of an object. Another advantage of the sensor device according to the invention results from the non-contact measurement, which works largely without mechanical signs of wear. Furthermore, the sensor device according to the invention is relatively simple and inexpensive to manufacture.

According to a preferred embodiment of the present invention, the sensor device comprises an evaluation unit, which is designed to detect recurring signal patterns in the measurement signals supplied by the detector. This recurring signal pattern or the reflection track over a complete revolution of a rotating object can then be assigned to the rotational angular position of the rotatable object. Thus, the evaluation unit can detect complete revolutions of the rotating object. The evaluation unit can thus also determine information about the number of revolutions, the rotational frequency, the angle of rotation or the rotational distance of the object.

For these purposes, the evaluation unit is designed to detect and store recurrent signal patterns in the measurement signals supplied by the detector during complete rotations of the rotatable object. The evaluation unit can advantageously carry out the amplitude comparison described above with the measurement signals supplied by the detector. Additionally or alternatively, the evaluation unit is designed to carry out threshold value comparisons with the measurement signals supplied by the detector, for example by comparing the measurement signals with stored signal patterns or reflection tracks or with reference values.

With the evaluation unit, during complete revolutions of a rotatable object, recurring patterns in the measurement signals supplied by the detector or reflection tracks of the rotational movement and the rotation angle of the rotatable object can be assigned. Thus, a correlation between the recurrent patterns in the measurement signals or reflection tracks provided by the detector and the rotation movement and the rotation angle of the rotatable object can be generated. From the measurement signals provided by the detector, the evaluation unit can then determine the rotational movement and the angle of rotation of the rotatable object by comparison with recurring signal patterns in the measurement signals supplied by the detector.

Furthermore, the evaluation unit can use the measurement signals supplied by the detector by counting recurring signal patterns in the measurement signals supplied by the detector or by counting complete reflection tracks the number of revolutions and / or the rotational frequency of the determine the rotatable object. From the comparison with recurrent signal patterns or reflection tracks and / or by comparison with stored signal patterns or reflection tracks, the direction of rotation of the object can also be determined. In addition, the rotational position of the object can be determined from the measurement signals supplied by the detector by comparison with recurrent signal patterns and / or by comparison with stored signal patterns.

The present invention is therefore based on the assumption that the surface of the rotatable object illuminated by the radiation source naturally has differently reflecting regions, such that as the angle of rotation of the object changes, the intensity pattern which reflects from the illuminated surface of the object and changes from the Detector is detected. Such areas of different reflectance may also be intentionally mounted on the surface of the object. Furthermore, these differently reflecting regions can have defined reflectivities and / or reflectances that continuously change with the rotational position of the rotating object.

By way of example, the surface of the rotatable object illuminated by the radiation source can have regions with a steadily increasing degree of reflection in the measuring direction and / or regions with a steadily decreasing reflectance whose position is associated with the rotation angle of the object and the reflection images which are different when illuminated by the radiation of the radiation source generate the detector. In addition or as an alternative, the surface of the object illuminated by the radiation source can have regions with minimal reflectance and / or regions with maximum reflectance whose position is associated with the rotation angle of the rotatable object and which generate different reflection images on the detector when illuminated by the radiation of the radiation source.

The detector of the sensor device according to the invention is advantageously capable of producing optical and / or electrical measuring signals as a function of the detected radiation. For this purpose, for example, offers a spatially resolving optoelectronic detector, which converts the reflected intensity pattern into corresponding electrical signals, which are forwarded for further evaluation to an electronic evaluation unit. In this case, the detector preferably generates a spatially resolving image of the radiation which is reflected by the illuminated surface of the object. Since, depending on the angular position of the rotating object, a different reflection image is detected by the detector, the number of revolutions, the rotational frequency and / or rotational position of a rotating object can be determined therefrom.

In order to make the radiation of the surface of the rotatable object as optimal as possible, may be provided in the beam path between the radiation source and the detector optical means for bundling and / or scattering of the radiation, such. B. collecting lenses or scattering lenses.

A signal line to the evaluation unit can be designed with two channels as well as with one channel with a diagnostic option. The signal line can be designed, for example, compatible with sine / cosine encoders, in TTL / HTL format or as a serial, safety-monitored data stream, eg. B. T-BUS safe compatible.

• • Beleuchten des Objekts durch eine optische Strahlungsquelle, so dass die Strahlung vom Objekt reflektiert wird;
• • Erfassen der vom Objekt direkt reflektierten Strahlung mittels eines Detektors; und
• • Auswerten der Messsignale durch eine Auswerteeinheit.

According to a further aspect of the present invention, the above-mentioned object is further achieved by a method for the non-contact detection of a rotational movement, the number of revolutions and / or the rotational angular position of an object, comprising at least the following steps:

• Illuminating the object by an optical radiation source so that the radiation is reflected by the object;
• Detecting the radiation directly reflected by the object by means of a detector; and
• • Evaluation of the measuring signals by an evaluation unit.

In the method according to the invention, the evaluation of the measuring signals comprises the detection of recurring signal patterns in the measuring signals supplied by the detector. Furthermore, an amplitude comparison or a threshold value comparison between the measurement signals supplied by the detector and previously detected or stored measurement signals or predetermined threshold values can be carried out for evaluating the measurement signals. In this case, the measurement signals supplied by the detector can be compared with stored signal patterns or with reference values.

According to a further preferred embodiment of the method according to the invention, the evaluation of the measurement signals comprises detecting and storing recurring signal patterns in the measurement signals or reflection tracks provided by the detector during complete revolutions of a rotatable object.

Additionally or alternatively, during complete revolutions of the rotatable object, recurrent patterns in the measurement signals supplied by the detector can also be assigned to the rotation angle of the object, so that a correlation between the recurring patterns in the measurement signals supplied by the detector and the rotation angle of the object is generated. Based on this correlation, the rotation angle of the object can be determined from the measurement signals supplied by the detector by comparison with recurring signal patterns.

According to a further preferred embodiment of the method according to the invention, the evaluation of the measuring signals comprises the counting of recurring signal patterns in the measuring signals supplied by the detector in order to determine the number of revolutions or the rotational frequency of the object. It can be assumed that recurring signal patterns in the measurement signals supplied by the detector are due to complete revolutions of a rotatable object.

By comparing the measurement signals with recurrent signal patterns and / or by comparison with stored signal patterns, the direction of rotation of the object can be determined. In addition, the rotational position of a rotating object can be determined by comparing the measurement signals with recurrent signal patterns or by comparison with stored signal patterns. In the following, the present invention will be explained in more detail with reference to a preferred embodiment with reference to the accompanying drawings.

1 shows a schematic representation of a sensor device according to an application of the present invention for detecting the rotation parameters of rotatable objects. At the in 1 Illustrated embodiment of the present invention is the sensor device for monitoring a rotating shaft 1 used. The sensor device according to the invention essentially comprises a radiation source 3 , a detector 6 and an evaluation unit 7 , The radiation source 3 generates a light radiation 9 pointing to the surface of the rotatable object 1 is directed.

The rotatable object is a shaft in the illustrated embodiment 1 with a radius R that rotates about the longitudinal axis of its cylindrical shaft body. The surface 2 of the rotatable object 1 consequently corresponds to the lateral surface 2 of the cylinder of the rotating shaft 1 , From the surface 2 of the rotatable object 1 or from the lateral surface 2 the rotating shaft 1 becomes the radiation 4 reflected.

The detector 6 includes at the in 1 For example, for example, a detector screen having a number of photocells corresponding to that of the illuminated surface 2 the wave 1 reflected rays 4 detect. Previously, those from the surface 2 the wave 1 reflected rays 4 by one or more optical means, such. B. a condenser lens 5 , be bundled or scattered to the beam path 4 optimal on the detector screen 6 to distribute.

At the detector 6 For example, it is a spatially resolving, optoelectronic detector that detects the intensity pattern of the reflected radiation 4 converts into corresponding electrical signals. The detector generates 6 preferably a spatially resolving image of the radiation 4 coming from the illuminated surface 2 the wave 1 is reflected. For further evaluation, those from the detector 6 generated electrical measuring signals to an electronic evaluation unit 7 forwarded.

Due to the fact that the of the radiation source 3 illuminated jacket surface 2 the wave 1 has different strong reflective areas, resulting in a change in the angle of rotation of the shaft 1 also an altered reflection image of the radiation 4 that from the illuminated surface 2 the wave 1 is reflected. There depending on the angular position of the rotating object 1 a different reflection image from the detector 6 is detected, it can in the manner described above all rotation parameters, such. As the number of revolutions, the rotational frequency or rotational position of the rotating object 1 be determined.

If, as in the illustrated embodiment, the rotatable object is a rotating shaft 1 can act on the lateral surface 2 the wave 1 Also depending on the location of different reflectively reflecting structures (not shown) have been applied in advance. The differently reflective areas on the illuminated surface 2 the wave 1 can have defined reflectance or with the angle of rotation of the shaft 1 have continuously changing reflectance.

The with rotating shaft 1 depending on the angular position of the shaft 1 differently reflected light radiation 4 forms a corresponding reflection image or a corresponding intensity pattern on the detector 6 from, from the conclusions on rotational position of the shaft 1 can be pulled. For this purpose, the differently reflective structures on the lateral surface 2 the rotating shaft 1 previously with the corresponding rotational positions of the rotating shaft 1 be correlated.

In the evaluation unit, those from the detector 6 generated electrical measurement signals are subjected to a number of analytical calculations. For example, in the evaluation unit 7 by comparing the amplitude curve of two consecutive measurements over complete revolutions of the object 1 whose movement is derived both in terms of the angle of rotation, the direction, as well as the distance of the rotational movement of the object. By means of the given radius R of the shaft 1 can its outer surface and thus the distance traveled during the rotational movement of the shaft 1 determine.

By measuring the time required for a number of complete revolutions of the object 1 was required, can also be the rotational frequency of the rotating object 1 determine. Thus, all the rotation parameters of the rotational movement of the rotating object 1 be determined. The evaluation unit 7 is with signal lines 8th connected by the results of the calculations in the evaluation unit 7 can be forwarded or transmitted.

In the preceding description of the figures, the present invention has been explained with reference to the embodiment shown in the drawing, which is suitable for monitoring or measuring rotational movements. Alternatively or additionally, the sensor device according to the present invention can also be used for monitoring or measuring movement parameters of relative movements of a monitored object relative to the detector of the sensor device.

LIST OF REFERENCE NUMBERS

1

rotatable object or rotating shaft

2

Surface of the rotatable object or lateral surface of the rotating shaft

3

radiation source

4

reflected light rays from the lateral surface of the rotating shaft

5

converging lens

6

Detector or detector screen with photocells

7

evaluation

8th

signal lines

9

light rays generated by the radiation source

R

Radius of the rotatable object or the rotating shaft 1

Claims (20)

Device for the non-contact detection of a rotational movement, the number of revolutions and / or the rotational angular position of a rotatable object ( 1 ) comprising an optical radiation source ( 3 ), a detector ( 6 ) and an evaluation unit ( 7 ) for the evaluation of the detector ( 6 ) supplied by the radiation source ( 3 ) generated radiation ( 9 ) at least partially on the object ( 1 ) and the detector ( 6 ) from the object ( 1 ) directly reflected radiation ( 4 ), characterized in that the evaluation unit ( 7 ) is adapted for complete revolutions of the rotating object ( 1 ) recurring signal patterns in the from the detector ( 6 ) and a rotational angle of the object ( 1 ) to correlate the recurring signal patterns with those of the detector ( 6 ) supplied measurement signals and the rotation angle of the object ( 1 ) and by correlation from those from the detector ( 6 ) supplied measurement signals by comparison with recurrent signal patterns, the rotation angle of the object ( 1 ) and / or by comparison with recurrent signal patterns and / or by comparison with stored signal patterns, the rotational angular position of the object ( 1 ) to investigate. Apparatus according to claim 1, wherein the evaluation unit ( 7 ) is designed with the detector ( 6 ) carried out an amplitude comparison. Device according to one of the preceding claims, wherein the evaluation unit ( 7 ) is designed with the detector ( 6 ) to perform a threshold comparison. Device according to one of the preceding claims, wherein the evaluation unit ( 7 ) is adapted from the detector ( 6 ) to compare measured signals with reference values and from this the rotational angular position of the rotatable object ( 1 ). Device according to one of the preceding claims, wherein the evaluation unit ( 7 ) is adapted to the from the detector ( 6 ) supplied by counting recurring signal patterns in the detector ( 6 ) supplied measurement signals, the number of revolutions and / or the rotational frequency of the rotatable object ( 1 ) to investigate. Device according to one of the preceding claims, wherein the evaluation unit ( 7 ) is adapted to the from the detector ( 6 ) supplied measurement signals by comparison with recurring signal patterns and / or by comparison with stored signal patterns, the direction of rotation of the rotatable object ( 1 ) to investigate. Device according to one of the preceding claims, wherein signal lines ( 8th ) between the detector ( 6 ) and the evaluation unit ( 7 ), which are both two-channel and single-channel with a diagnostic option, compatible with sine / cosine sensors, as a serial interface, as a safety-monitored interface T-BUS Safe compatible and / or designed to TTL / HTL format compatible. Device according to one of the preceding claims, wherein the radiation source ( 3 ) illuminated surface of the rotatable object ( 1 ) has different reflective areas, so that when the angle of rotation of the rotatable object changes ( 1 ), the intensity pattern changing from the illuminated surface of the object ( 1 ) is reflected. Device according to one of the preceding claims, wherein the radiation source ( 3 ) illuminated surface of the rotatable object ( 1 ) Has regions with a steadily increasing reflectance in the measuring direction and / or regions with a continuously decreasing reflectance in the measuring direction, whose positions correspond to the angle of rotation of the object ( 1 ) and when illuminated by the radiation ( 9 ) of the radiation source ( 3 ) different reflection images on the detector ( 6 ) produce. Device according to one of the preceding claims, wherein the radiation source ( 3 ) illuminated surface of the rotatable object ( 1 ) Has areas with minimum reflectance and / or areas with maximum reflectance whose positions correspond to the angle of rotation of the object ( 1 ) and when illuminated by the radiation ( 9 ) of the radiation source ( 3 ) different reflection images on the detector ( 6 ) produce. Device according to one of the preceding claims, wherein the detector ( 6 ) is designed, depending on the detected radiation ( 4 ) to generate optical and / or electrical measurement signals. Device according to one of the preceding claims, wherein the detector ( 6 ) as an optoelectronic detector ( 6 ), which generates an electronic signal as a function of the intensity of the radiation ( 4 ) generated by the illuminated surface of the object ( 1 ) is reflected. Device according to one of the preceding claims, wherein the detector ( 6 ) a spatially resolving image of the reflection of the radiation ( 4 ) generated by the illuminated surface of the object ( 1 ) is reflected. Device according to one of the preceding claims, wherein in the beam path between the radiation source ( 3 ) and the detector ( 6 ) optical means ( 5 ) for bundling and / or scattering the radiation ( 4 ) are provided. Method for the contactless detection of a rotational movement, the number of revolutions and / or the rotational angular position of a rotatable object ( 1 ) at least comprising the following steps: illuminating the object ( 1 ) by an optical radiation source ( 3 ), so that the radiation ( 9 ) from the object ( 1 ) is reflected; • Capture the object ( 1 ) directly reflected radiation ( 4 ) by means of a detector ( 6 ); and evaluation of the measurement signals by an evaluation unit ( 7 ) by: • detecting recurring signal patterns in the detector (s) 6 ) supplied measuring signals during complete revolutions of the object ( 1 ); • associating the recurring signal patterns with those of the detector ( 6 ) supplied to the rotation angle of the rotatable object ( 1 ) for • generating a correlation between the recurrent signal patterns in the detector ( 6 ) supplied measurement signals and the rotation angle of the object ( 1 ); • Compare from the detector ( 6 ) supplied measuring signals with recurrent signal patterns to the rotation angle of the rotatable object ( 1 ) and / or • comparing from the detector ( 6 ) supplied measuring signals with recurrent signal patterns and / or with stored signal patterns to the rotational angular position of the rotatable object ( 1 ) to investigate. The method of claim 15, wherein the evaluation of the measurement signals further comprises that with that of the detector ( 6 ) an amplitude comparison is performed. Method according to one of claims 15 to 16, wherein the evaluation of the measuring signals further comprises, with those of the detector ( 6 ) to perform a threshold comparison. Method according to one of claims 15 to 17, wherein the evaluation of the measurement signals further comprises, from the detector ( 6 ) to compare supplied measurement signals with reference values. Method according to one of claims 15 to 18, wherein the evaluation of the measuring signals further comprises, from the detector ( 6 ) supplied by counting recurring signal patterns in the detector ( 6 ) supplied measurement signals, the number of revolutions and / or the rotational frequency of the rotatable object ( 1 ) to investigate. Method according to one of claims 15 to 19, wherein the evaluation of the measurement signals further comprises, from the detector ( 6 ) supplied measurement signals by comparison with recurring signal patterns and / or by comparison with stored signal patterns, the direction of rotation of the rotatable object ( 1 ) to investigate.

Images