DE102017119283A1 - sensor system - Google Patents

Abstract

Sensor system (1) with a multi-beam safety light barrier (2) and with bridging sensors (3) for detecting objects (4) and / or persons (5), wherein the bridging sensors (3) are distance-measuring momentary sensors, wherein at least one bridging sensor (3) in one end of an arm (12) of a U-shaped housing (6) is arranged, wherein the U-shaped housing (6) on the housing (7) of the multi-beam safety light barrier (2) is arranged and the housing (6) of the multi-beam safety light barrier (2 ) partially encloses.

Description

The present invention relates to a sensor system with a multi-beam safety light barrier according to the preamble of claim 1.

A multi-beam safety light barrier according to the prior art and according to the present invention has at least two light transmitters or at least two light receivers. Multi-beam safety light barrier housings with light transmitters and multi-beam safety light barrier housings with light receivers are arranged opposite each other so that the light emitter and light receiver each form a light barrier. By a plurality of light emitter or light receiver, which are arranged successively spaced in a row in the multi-beam safety light barrier housings, a multi-beam photocell is formed, with which a protective field is monitored. The light beams are preferably parallel. By interrupting the light beams in the protective field impermissible persons and objects are detected. Due to the detection safe output signals or object detection signals are formed at a safe output, whereby a dangerous movement can be turned off.

The object detection signal is output via output switching elements. The output switching elements are usually connected to a machine control. For safety reasons, the output switching elements are present redundantly, so that two output switching elements are provided as a pair. As soon as only one output switching element switches off, that is, for example, changes from a high level, for example 24 volts to a low level, for example zero volts, a connected machine is switched off. The output switch element is also referred to as OSSD, where OSSD stands for Output Signal Switching Device.

The distance between the light emitter to each other or the distance of the light receiver to each other in the multi-beam safety light barrier determines a resolution of the multi-beam safety light barrier.

The multi-beam safety light barrier is a safety system according to machine safety, for example according to the Standard EN / ISO 13849-1 or the Standard EN / IEC 62061 which, for example, provides the framework for functional safety of safety-related electrical control systems and their subsystems on machines. The multi-beam safety light barrier is, for example, a safe non-contact protective device or a safe optoelectronic sensor according to EN 61496-1 / 2 ,

In a multi-beam safety light barrier, in contrast to a light grid or a light curtain, an arrangement of very closely adjacent beams in the housing is not necessary. In the case of a multi-beam light barrier, space is available between the individual receiver modules or the individual transmitter modules in the housing.

An optoelectronic protective device with muting sensors is for example from DE 10 2007 040 692 B4 known.

By detecting the light beams of muting sensors impermissible persons and objects are distinguished from permissible objects. Due to the detection muting signals are generated, according to which no shutdown signal is generated by the optoelectronic protective device, whereby a permissible object can pass through the protective field of the optoelectronic protective device without a dangerous movement must be stopped.

An object of the invention is to provide an improved sensor system with a multi-beam safety light barrier and lock-up sensors, which is easier to handle, less expensive and allows faster commissioning. Next, the sensor system should be made more compact.

The object is achieved according to claim 1 by a sensor system having a multi-beam safety light barrier and with bridging sensors for detecting objects and / or persons, wherein the bridging sensors are distance-measuring momentary sensors, wherein at least one bypass sensor is arranged in one end of an arm of a U-shaped housing, wherein the U-shaped housing is arranged on the housing of the multi-beam safety light barrier and partially encloses the housing of the multi-beam safety light barrier.

The multi-beam safety light barrier can also be referred to as a safety light grid or as a safety light curtain, with safety light grids and safety light curtains having smaller beam spacings and thus higher resolutions.

In the multi-beam safety light barrier, the distance of the light beams is, for example, 300 mm. This distance is provided for example for access protection and requires after an interruption again actuation of a reset function to allow a restart of the machine.

For safety light curtains or safety light curtains, the resolution is 14 mm, 20 mm, 30 mm or 40 mm. Safety light curtains or safety light curtains are used for hazardous area protection.

The resolution of 14 mm is intended for finger protection, whereby an intervention with a single finger is already detected. A resolution of 20 mm or 30 mm is used to detect an intervention with one hand. At least the flat back of the hand is detected and detected. With a resolution of 40 mm, at least one human arm is detected.

The bridging sensors have at least one light transmitter or at least one light receiver.

By detecting the light beams of the bridging sensors impermissible persons and objects are distinguished from permissible objects. Due to the detection, muting signals are generated, according to which no shutdown signal is generated by the multi-beam safety light barrier, as a result of which a permissible object can pass through the protective field of the multi-beam safety light barrier without having to stop a dangerous movement.

By the U-shaped housing, a mechanical coupling between the housing of the multi-beam safety light barrier and the U-shaped housings is provided, whereby the U-shaped housing relative to the housing of the multi-beam safety light barrier are aligned.

The bridging sensors are designed such that at least one bridging sensor is aligned with a region in the conveying direction of objects in front of or behind the multi-beam safety light barrier.

This makes it possible to detect objects in front of or behind the protective field of the multi-beam safety light barrier. If the bridging sensors are arranged only in front of the multi-beam safety light barrier, then, for example, material extending from a danger zone can be transported through the protective field.

The bridging sensors are preferably arranged on a side wall of the U-shaped housing, which is arranged transversely to a conveying direction of the objects, or a side wall of the U-shaped housing is arranged parallel to the light beams of the multi-beam safety light barrier.

However, it can also be provided that the bridging sensors are arranged on an end wall of the arms of the U-shaped housing, which is arranged parallel to the conveying direction of the objects or transversely to the light beams of the multi-beam safety light barrier.

The use of distance-measuring momentary sensors has the advantage that the distance between the objects and the multi-beam safety light barrier can be determined. For example, if the object is too narrow to completely cover the protected area of the multiple beam safety light barrier, the bridging is canceled. If the object is allowed, the bridging will continue.

In addition, it is by the distance-measuring probing sensors, for. As light sensors as bridging sensors also possible to obtain accurate information about an object contour that could not be detected by a simple beam interruption by means of a light barrier. An object can be measured by the distance-measuring momentary sensors, or the object can be classified as a permissible or impermissible object on the basis of the detected object contour, and an object detection signal or safety switching signal can be generated depending on this result. With the sensor system according to the invention, it is thus possible to determine a lateral contour of the object while the object passes through the protective field.

If an object is transported, for example, on a conveyor belt through the multi-beam safety light barrier, then the distance contour data of a side of the object facing the respective transmission / reception strip can be detected and stored by the bridging sensors. By the sensor system according to the invention, a lateral distance contour can be detected and used to assess the object.

According to a preferred embodiment of the invention, at least one bypass sensor is disposed in each one end of an arm of the U-shaped housing.

The lock-up sensors are arranged so that at least one lock-up sensor is arranged on a region in the conveying direction of objects in front of and behind the multi-beam safety light barrier.

This makes it possible to transport objects in both directions through the protective field of the multi-beam safety light barrier. This allows, for example, permissible objects, for example processing material, to be conveyed through the protective field in both directions without A dangerous movement of a machine must be stopped.

In a development of the invention, the distance-measuring momentary sensors are light transit time sensors or triangulation sensors.

A light transit time sensor is based for example on a time-of-flight chip according to the PMD method, which carry out distance measurements on the basis of a phase position measurement of modulated light.

A distance sensor or light sensor according to the time of flight principle has at least one light transmitter which emits successive light pulses into a measuring range and at least one light receiver, which receives the light pulses reflected back at an object in the measuring range and supplies them in the form of electrical received signals to a control and evaluation unit taking into account the speed of light from the time between transmission and reception of the light pulse, a distance signal representative of the distance of the object to the light sensor is determined.

For distance measurement, different light transit time methods can be implemented with a corresponding evaluation.

It may be provided a pulse method. For example, one or more time-to-digital converters are provided for the pulse method in which each single-photon event is time-stamped. For a useful signal, therefore, multiple timestamps occur correlated. The measured value is generated statistically. Background light, however, generates randomly distributed timestamps.

Furthermore, a CW method (continuous wave) or the synonymous continuous wave method can be used, wherein a continuous light signal is used throughout. In this method, the single-photon events are distributed in two counters via a gating signal, and a phase is calculated from the ratio of the counter readings.

In one embodiment, the distance-measuring momentary sensor is designed as a triangulation light sensor. The light receiver then has a spatially resolving receiving element. In the case of triangulation measurement, the location of an imaged light spot on the spatially resolving receiver is dependent on the distance of the detected object. The location of the remission incidence on the receiver serves as a measure for the object distance. In this case, the light emitter is designed to emit a transmitted light cone and / or a collimated light beam, and the transmitted light cone is so small in a near area that a light spot incident on an object is imaged on the spatially resolving receiver such that the distance of the object to Triangulation button on the location of the light spot on the receiver can be determined. Depending on the point of incidence of the light spot on the spatially resolving receiving element, a distance of the object can then be determined.

The spatially resolving receiving element can be designed as a spatially resolving line or matrix. The spatially resolving line is inexpensive and a detected distance can be assigned to a small detection area. The spatially resolving matrix allows a larger detection area. The size of the receiving elements of the row or of the matrix can be different. The receiving elements are greatest for a near zone, since a change in the light spot on the receiving element in a distance change is large compared to a distance change in the far field. In the far range, the receiving elements are made smaller to allow a finer resolution of the distance detection.

In a further development of the invention, the bridging sensors are arranged at an angle in the U-shaped housing, so that the light beams of the bridging sensors and the light beams of the multi-beam safety light barrier are arranged at an acute angle to each other.

As a result, the light beams of the bridging sensors of opposite bridging sensors are aligned such that the light beams from the two bridging sensors are respectively directed away from the multibeam safety light barrier and intersect in a two-dimensional projection in the longitudinal direction of the housing of the multibeam safety light barrier.

In a development of the invention, a control and evaluation unit is accommodated in the housing of the multi-beam safety light barrier in the U-shaped housing of the bridging sensors or in a third external housing.

The control and evaluation unit has, for example, a two-channel structure with, for example, two microcontrollers, which monitor each other. In this case, for example, a redundant structure may be provided with two identical microcontrollers or a diverse structure with two different microcontrollers.

In a development of the invention, the control and evaluation unit receives distance information or binary object detection signals from the bypass sensors.

If only binary object detection signals are transmitted, then only the information is determined as to whether an object was detected or not. This is the simplest information that can be used to implement very simple object detection logic.

Both the distance information and the binary information can be transmitted digitally or analogously. Digital information transmission takes place, for example, via SPI, IO-Link, RS485 or similar interfaces. Analog information transmission takes place, for example, via a current interface with values of 4 to 20 mA or a voltage interface with values of 0 to 10 volts.

For example, a plug connection or a connection cable is provided between the U-shaped housing and the housing of the multi-beam safety light barrier.

In a further development of the invention, the bridging sensors have additional alignment light transmitters for emitting visible alignment light beams. As a result, the lock-up sensors can be better aligned visually, since an alignment optical transmitter that is parallel to the light transmitter can be used for the adjustment. For example, the alignment light transmitter is active only within a certain period of time during an adjustment and is inactive during operation.

In a development of the invention, the light transmitters of the bridging sensors are designed to emit visible light.

As a result, the light transmitter of the lock-up sensor used for the distance-measuring feeler sensor is at the same time the alignment light transmitter.

In a development of the invention, the control and evaluation unit is designed to distinguish impermissible and permissible objects on the basis of stored contour shapes, with a constant speed of movement of the objects being present.

In certain applications, predefined allowable objects may pass through the protected area without generating a safety switch signal. Thus, for example, when crossing the protected area of permissible objects, for example by means of a conveyor belt, no safety switching signal is triggered, while conveying an impermissible object, for example a person, through the protected area - even if the person is laterally of the permissible object and this does not tower - triggered a corresponding safety switch signal.

According to this embodiment, for example, characteristic contours of the permissible objects are taught in that the distance values which result when reflecting the emitted light signals at the respective object are learned and stored in a memory. If an object enters the protected area, the measured distance values are compared with the stored distance values before the safety switch signal is generated, and no safety switch signal is generated if the measured distance values coincide with the distance values of permissible objects within a predetermined tolerance range.

Depending on the shape of the permissible objects, a plurality of permissible distance values may be stored which, in particular when using a plurality of light sensors or bridging sensors, may differ depending on the location of incidence of the light beams. If an inadmissible object enters the protected area or if a permissible object is not positioned correctly, the determined distance does not coincide with the permissible distance, so that in this case a safety switching signal is generated.

• 1 bis 3 jeweils eine Mehrstrahllichtschranke mit Mutingsensoren nach dem Stand der Technik;
• 4 bis 6 ein erfindungsgemäßes Sensorsystem mit einem Überbrückungssensor in jeweils drei verschiedenen Ansichten;
• 7 ein Sensorsystem mit zwei gegenüberliegenden Überbrückungssensoren zum Ausleiten von Objekten aus einer Gefahrenzone;
• 8 bis 13 ein Sensorsystem mit vier Überbrückungssensoren zum Überwachen von Objekten aus und in eine Gefahrenzone;
• 14 ein Sensorsystem mit acht Überbrückungssensoren;

The invention will be explained below with regard to further advantages and features with reference to the accompanying drawings with reference to embodiments. The figures of the drawing show in:

• 1 to 3 one multi-beam photoelectric sensor with muting sensors according to the prior art;
• 4 to 6 an inventive sensor system with a lock-up sensor in three different views;
• 7 a sensor system with two opposite bypass sensors for discharging objects from a danger zone;
• 8th to 13 a sensor system with four bypass sensors for monitoring objects from and into a danger zone;
• 14 a sensor system with eight bypass sensors;

In the following figures, identical parts are provided with identical reference numerals.

1 shows a multi-beam safety light barrier 2 According to the state of the art. The multi-beam safety light barrier 2 is arranged vertically and has three parallel light beams. The muting sensors 15 are each consuming spatially separated from the multi-beam safety light barrier 2 arranged, whereby a high wiring complexity and a high installation effort arises and a relatively large amount of space is required. The light rays of the muting sensors 15 are crossed. The possible conveying direction is marked with an arrow.

2 also shows a multi-beam safety light barrier 2 according to the prior art, wherein the light beams of the muting sensors 15 parallel on one side of the multi-beam safety light barrier 2 are arranged.

3 shows a multi-beam safety light barrier 2 according to the prior art, wherein the light beams of the muting sensors 15 parallel on both sides of the multi-beam safety light barrier 2 are arranged.

4 shows a schematic illustration of a sensor system according to the invention 1 with a multi-beam safety light barrier 2 in a front view directly on the light transmitter 13 or light receiver 14 the multi-beam safety light barrier 2 , Next are the arms 12 of the U-shaped housing 6 with the bypass sensors 3 is shown. The bypass sensors have a light emitter 10 and a light receiver 11 on.

5 is a side view according to 4 ,

6 is a plan view according to 4 , 7 to 14 also show a top view.

7 shows a sensor system 1 with a multi-beam safety light barrier 2 and with bypass sensors 3 for the detection of objects 4 and / or persons, wherein the bridging sensors 3 distance measuring probing sensors are, wherein at least one bypass sensor 3 in one end of an arm 12 a U-shaped housing 6 is arranged, wherein the U-shaped housing 6 on the housing 7 the multi-beam safety light barrier 2 is arranged and the housing 7 the multi-beam safety light barrier 2 partially encloses.

The represented object 4 moves in the direction of the arrow from a danger zone or safety area through the protective field 16 the multi-beam safety light barrier 2 , The permitted object becomes this 4 initially from the bypass sensors 3 detected. Once the object 4 from the bypass sensors 3 the multi-beam safety light barrier is validly registered 2 completely or at least partially bridged, so that the object 4 the multi-beam safety light barrier 2 can happen without causing a shutdown of a machine.

At the multi-beam safety light barrier 2 For example, the distance of the light beams is 300 mm. This distance is intended, for example, for access protection.

The bypass sensors 3 have at least one light transmitter 10 or at least one light receiver 11 on.

By a detection of the light beams of the bypass sensors 3 become inadmissible persons and objects 4 of permitted objects 4 distinguished. Due to the detection muting signals are generated, after which by the multi-beam safety light barrier 2 no shutdown signal is generated, creating a legal object 4 the protective field 16 the multi-beam safety light barrier 2 can happen without a dangerous movement having to be stopped.

Through the U-shaped housing 6 is a mechanical coupling between the housing 7 the multi-beam safety light barrier 2 and the U-shaped housings, whereby the U-shaped housing 6 opposite the housing 7 the multi-beam safety light barrier 2 are aligned.

The bypass sensors 3 are preferably on a side wall of the U-shaped housing 6 arranged transversely to a conveying direction of the objects 4 is arranged or a side wall of the U-shaped housing 6 parallel to the light beams of the multi-beam safety light barrier 2 is arranged.

In addition, it is by the distance-measuring probing sensors, for. B. Light sensor as a bridging sensors 3 also possible to obtain precise information about an object contour that could not be detected by a simple beam interruption by means of a light barrier. The distance measuring probing sensors can be an object 4 be measured or due to the detected object contour, the object 4 as permissible or inadmissible object 4 be classified and generated depending on this result, an object detection signal or safety switch signal. With the sensor system according to the invention, it is thus possible to have a lateral contour of the object 4 while the object passes the protective field.

Becomes an object 4 for example, on a conveyor belt through the multi-beam safety light barrier 2 transported, so can by the bridging sensors 3 the distance contour data of one of the respective transmit / receive bar of the multi-beam safety light barrier 2 facing side of the object 4 be captured and stored. By the sensor system according to the invention 1 a lateral distance contour can be detected and used to assess the object 4 be used.

According to 7 are the bypass sensors 3 in one end of an arm 12 of the U-shaped housing 6 arranged.

According to 8th to 13 are the bypass sensors 3 arranged so that at least two bridging sensors 3 each on an area in the conveying direction of objects 4 in front of and behind the multi-beam safety light barrier 2 are arranged.

This makes it possible objects 4 in both directions through the protective field 16 the multi-beam safety light barrier 2 to transport. This allows, for example, permissible objects 4 , For example, processing material, in both directions through the protective field 16 be promoted without a dangerous movement of a machine must be stopped.

According to 8th is the object 4 still outside the detection area. The object 4 is conveyed in the direction of the arrow, for example, by a conveyor belt, not shown.

According to 9 detect the object 4 inclined bypass sensors 3 the object 4 and the multi-beam safety light barrier 2 is muted or bridged. The protective field 16 the multi-beam safety light barrier 2 Is still available. The back of the object 4 directional bypass sensors 3 do not detect any object yet 4 ,

According to 10 detect the front, the object 4 inclined bypass sensors 3 and the multi-beam safety light barrier 2 , the object 4 , The back of the object 4 directional bypass sensors 3 do not detect any object yet 4 ,

According to 11 detect the front, the object 4 inclined bypass sensors 3 , the multi-beam safety light barrier 2 and the back of the object 4 directional bypass sensors 3 the object 4 ,

According to 12 detect the back of the object 4 directional bypass sensors 3 and the multi-beam safety light barrier 2 the object 4 ,

According to 13 has the object 4 leave the detection area and has the multi-beam safety light barrier 2 as permissible object 4 successfully happened.

According to the figures, the distance-measuring probing sensors may be light transit time sensors or triangulation sensors.

According to 7 to 14 are the bypass sensors 3 at an angle in the U-shaped housing 6 arranged so that the light rays of the bypass sensors 3 and the light beams of the multi-beam safety light barrier 2 are arranged at an acute angle to each other.

As a result, the light beams of the bypass sensors 3 from opposite bypass sensors 3 aligned so that the light rays from the two bridging sensors 3 each of the multi-beam safety light barrier 2 are directed away and in a two-dimensional projection in the longitudinal direction of the housing 7 the multi-beam safety light barrier 2 cross.

According to 7 to 14 is a control and evaluation unit in the housing 7 the multi-beam safety light barrier 2 accommodated.

According to 7 to 14 the control and evaluation unit receives distance information or binary object detection signals from the bypass sensors 3 , Both the distance information and the binary information can be transmitted digitally or analogously.

According to 14 are in every arm 12 the U-shaped housing 6 two bridging sensors each 3 arranged, whose light beams are each arranged at an acute angle to each other. As a result, the number of detection beams is increased, resulting in a better detection of objects 4 and / or persons is possible.

LIST OF REFERENCE NUMBERS

1

sensor system

2

Multibeam safety light barrier

3

bridge sensors

4

objects

6

U-shaped housing

7

casing

10

Light transmitter (the bypass sensors)

11

Light receiver (the bypass sensors)

12

poor

13

Light transmitter (the multi-beam safety light barrier)

14

Light receiver (the multi-beam safety light barrier)

15

muting

16

protection field

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007040692 B4 [0007]

Cited non-patent literature

• Standard EN / ISO 13849-1 [0005]
• Standard EN / IEC 62061 [0005]
• EN 61496-1 / 2 [0005]

Claims (9)

Sensor system (1) with a multi-beam safety light barrier (2) and with bridging sensors (3) for detecting objects (4) and / or persons (5), wherein the bridging sensors (3) are distance-measuring momentary sensors, characterized in that at least one bridging sensor ( 3) in one end of an arm (12) of a U-shaped housing (6) is arranged, wherein the U-shaped housing (6) on the housing (7) of the multi-beam safety light barrier (2) is arranged and the housing (6) of Multi-beam safety light barrier (2) partially encloses. Sensor system after Claim 1 , characterized in that at least one bridging sensor (3) in each case one end of an arm (12) of the U-shaped housing (6) is arranged. Sensor system according to at least one of the preceding claims, characterized in that the distance-measuring probing sensors are light transit time sensors or are triangulation sensors. Sensor system according to at least one of the preceding claims, characterized in that the bridging sensors (3) are arranged at an angle in the arm (12) of the U-shaped housing (6), so that the light beams of the bridging sensors (3) and the light beams of the Multi-beam safety light barrier (2) are arranged at an acute angle to each other. Sensor system according to at least one of the preceding claims, characterized in that a control and evaluation unit in the housing (7) of the multi-beam safety light barrier (2) in the U-shaped housing (7) of the lock-up sensors (3) or in a third external housing is housed , Sensor system according to at least one of the preceding claims, characterized in that the control and evaluation unit receives distance information or binary object detection signals from the bridging sensors (3). Sensor system according to at least one of the preceding claims, characterized in that the bridging sensors (3) comprise alignment light transmitters (9) for emitting visible alignment light beams. Sensor system according to at least one of the preceding claims, characterized in that the light transmitters (10) of the bridging sensors are designed to emit visible light. Sensor system according to at least one of the preceding claims, characterized in that the control and evaluation unit is designed to distinguish impermissible and permissible objects due to stored contour shapes, wherein a constant speed of movement of the objects (4) is present.

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