DE102017119283B4 - Sensor system - Google Patents

Abstract

Sensor system (1) with a multi-beam safety light barrier (2) and with bridging sensors (3) for the detection of objects (4) and / or people (5), the bridging sensors (3) being distance-measuring probing sensors, characterized in that at least one bridging sensor ( 3) is arranged in one end of an arm (12) of a U-shaped housing (6), the U-shaped housing (6) being arranged on the housing (7) of the multiple beam safety light barrier (2) and the housing (7) of the Partly enclosing multiple beam safety light barrier (2), at least one bridging sensor (3) being arranged in each end of an arm (12) of the U-shaped housing (6).

Description

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

A multiple light beam safety barrier according to the prior art and according to the present invention has at least two light transmitters or at least two light receivers. Multiple beam safety light barrier housings with light transmitters and multiple beam safety light barrier housings with light receivers are each arranged opposite one another, so that the light transmitter and light receiver each form a light barrier. A multi-beam light barrier with which a protective field is monitored is formed by several light transmitters or light receivers, which are arranged in a row in a row in a row in the multi-beam safety light barrier housings. The light beams preferably run parallel. Inadmissible persons and objects are detected by interrupting the light beams in the protective field. Due to the detection, safe output signals or object detection signals are generated at a safe output, whereby a dangerous movement can be switched 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 redundant, so that two output switching elements are provided as a pair. As soon as only one output switching element switches off, that is to say 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 switching element is also referred to as OSSD, where OSSD stands for “Output Signal Switching Device”.

The distance between the light transmitters or the distance between the light receivers in the multiple-beam safety light barrier determines the resolution of the multiple-beam safety light barrier.

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

In contrast to a light grille or a light curtain, a multiple beam safety light barrier does not require an arrangement of very closely spaced beams in the housing. With a multi-beam light barrier, there is space 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 from muting sensors, inadmissible people and objects are distinguished from permitted objects. Due to the detection, muting signals are generated, after which the optoelectronic protective device does not generate a switch-off signal, as a result of which a permissible object can pass the protective field of the optoelectronic protective device without a dangerous movement having to be stopped.

The DE 10 2016 005 854 A1 discloses a light curtain with laser range sensors for bridging function.

The EP 2 843 447 A1 shows a U-shaped housing as a holder for receiving a light curtain.

The DE 201 04 248 U1 discloses a light curtain with U-shaped adapters to redirect light beams from a light curtain.

The DE 603 09 362 T2 discloses a light curtain with muting arms.

One object of the invention is to provide an improved sensor system with a multiple beam safety light barrier and bridging sensors which is easier to handle, is more cost-effective and allows faster commissioning. Furthermore, the sensor system should be made more compact.

The object is achieved according to claim 1 by a sensor system with a multi-beam safety light barrier and with bridging sensors for the detection of objects and / or people, the bridging sensors being distance-measuring probing sensors, with at least one bridging sensor being arranged in one end of an arm of a U-shaped housing, wherein the U-shaped housing is arranged on the housing of the multiple light beam safety device and partially encloses the housing of the multiple light beam safety device.

The multiple light beam safety device can also be used as a safety light grid or as a Safety light curtains are designated, whereby safety light grids and safety light curtains have smaller beam spacings and thus higher resolutions.

In the case of the multiple light beam safety device, the distance between the light beams is 300 mm, for example. This distance is provided, for example, for access protection and, after an interruption, requires a reset function to be actuated again in order to enable the machine to restart.

For safety light grids or safety light curtains, the resolution is 14 mm, 20 mm, 30 mm or 40 mm. Safety light grids or safety light curtains are used to protect hazardous areas.

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

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

By detecting the light beams from the bridging sensors, inadmissible people and objects are distinguished from permitted objects. Due to the detection, muting signals are generated, after which the multi-beam safety light barrier does not generate a switch-off signal, whereby a permissible object can pass the protective field of the multi-beam safety light barrier without a dangerous movement having to be stopped.

The U-shaped housing provides a mechanical coupling between the housing of the multiple light beam safety device and the U-shaped housing, whereby the U-shaped housing is aligned with respect to the housing of the multiple light beam safety device.

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

This makes it possible to detect objects in front of or behind the protective field of the multiple light beam safety device. If the bridging sensors are only arranged in front of the multiple light beam safety barrier, material emerging from a danger area 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 multiple light beam safety device.

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 multiple light beam safety device.

The use of distance-measuring probing sensors has the advantage that the distance between the objects and the multiple light beam safety device can be determined. If, for example, the object is too narrow to completely cover the protected area of the multiple light beam safety device, the bridging is canceled. If the object is permitted, the bridging will continue.

In addition, it is by the distance measuring probing sensors such. B. light scanners as bridging sensors also possible to obtain precise information on 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 probing sensors or the object can be classified as a permissible or impermissible object on the basis of the recorded 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 the protective field.

If an object is transported through the multiple beam safety light barrier, for example on a conveyor belt, the spacing contour data of a side of the object facing the respective transmitting / receiving strip can be recorded and stored by the bridging sensors. With 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 bridging sensor is arranged in each end of an arm of the U-shaped housing.

The bridging sensors are arranged such that at least one bridging sensor is arranged in front of and behind the multiple beam safety light barrier in an area in the conveying direction of objects.

This makes it possible to transport objects in both directions through the protective field of the multiple light beam safety device. In this way, for example, permissible objects, for example processing material, can be conveyed through the protective field in both directions without a dangerous movement of a machine having to be stopped.

In a further development of the invention, the distance-measuring probing sensors are time-of-flight sensors or triangulation sensors.

A time-of-flight sensor is based, for example, on a time-of-flight chip using the PMD method, which measures distance based on a phase position measurement of modulated light.

A distance sensor or light scanner based on the time-of-flight principle has at least one light transmitter that emits successive light pulses into a measuring area and at least one light receiver that picks up the light pulses reflected on an object in the measuring area and feeds them in the form of electrical reception signals to a control and evaluation unit that Taking into account the speed of light, a distance signal representative of the distance between the object and the light scanner is determined from the time between transmission and reception of the light pulse.

Various time-of-flight methods with a corresponding evaluation can be implemented for distance measurement.

A pulse method can be provided. For example, one or more time-to-digital converters (time-to-digital converters) are provided for the pulse method in which each individual photon event is provided with a time stamp. In the case of a useful signal, several time stamps therefore occur in a correlated manner. The measured values are generated statistically. Background light, on the other hand, generates randomly distributed time stamps.

Furthermore, a CW method (Continuous Wave) or the synonymous continuous wave method can be used, a light signal modulated continuously over time being used. With this method, the single photon events are divided into two counters via a gating signal and a phase is calculated from the ratio of the counters.

In one embodiment, the distance-measuring sensing sensor is designed as a triangulation light scanner. The light receiver then has a spatially resolving receiving element. With the 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 reflection incidence on the receiver serves as a measure of the object distance. The light transmitter is designed to emit a transmitted light cone and / or a collimated light beam, and the transmitted light cone is so small in a close range that a light spot that strikes an object is imaged on the spatially resolving receiver in such a way that the distance of the object becomes the triangulation probe can be determined via the location of the light spot on the receiver. Depending on the point of impact of the light spot on the spatially resolving receiving element, a distance to the object can then be determined.

The spatially resolving receiving element can be designed as a spatially resolving row or matrix. The spatially resolving line is inexpensive and a detected distance can be assigned to a small detection area. The spatially resolving matrix enables a larger detection area. The size of the receiving elements of the row or the matrix can be different. The receiving elements are largest for a close range, since a change in the light spot on the receiving element with a change in distance is large compared to a change in distance in the far range. In the far range the receiving elements are made smaller in order to enable 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 from the bridging sensors and the light beams from the multiple light beam safety device are arranged at an acute angle to one another.

As a result, the light beams from the bridging sensors from opposing bridging sensors are aligned in such a way that the light beams from the two bridging sensors are each directed away from the multiple-beam safety light barrier and intersect in a two-dimensional projection in the longitudinal direction of the housing of the multiple-beam safety light barrier.

In a further development of the invention, a control and evaluation unit is accommodated in the housing of the multiple-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 that monitor one another. For example, a redundant structure with two identical microcontrollers or a diverse structure with two different microcontrollers can be provided.

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

If only binary object detection signals are transmitted, then only the information is determined as to whether or not an object was detected. This is the simplest piece of information, which means that very simple logic for recognizing objects can be implemented.

Both the distance information and the binary information can be transmitted digitally or analogously. Digital information transfer 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 from 4 to 20 mA or a voltage interface with values from 0 to 10 volts.

For example, a plug connection or a connecting cable is provided between the U-shaped housing and the housing of the multiple 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 bridging sensors can be visually aligned better, since an alignment light transmitter parallel to the light transmitter can be used for the adjustment. For example, the alignment light transmitter is only active within a certain period of time during an adjustment and is inactive during operation.

In a further 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 bridging sensor that is used for the distance-measuring sensing sensor is also the alignment light transmitter.

In a further development of the invention, the control and evaluation unit is designed to differentiate between impermissible and permissible objects on the basis of stored contour shapes, with the objects moving at a constant speed.

In certain applications, it is provided that predefined, permitted objects can pass the protection area without a safety switching signal being generated. For example, when permissible objects cross the protected area, for example by means of a conveyor belt, no safety switching signal is triggered, while when conveying an impermissible object, for example a person, through the protected area - even if the person is to the side of the permissible object and does not protrude beyond it - a corresponding safety switching signal triggered.

According to this embodiment, for example, characteristic contours of the permissible objects are taught in by teaching in the distance values that result when the emitted light signals are reflected on the respective object and storing them in a memory. If an object enters the protected area, the measured distance values are compared with the stored distance values before the safety switching signal is generated, and no safety switching signal is generated if the measured distance values match the distance values of permissible objects within a specified tolerance range.

Depending on the shape of the permissible objects, several permissible distance values can be stored, which can be different depending on the point of impact of the light beams, especially when using several light scanners or bridging sensors. If an impermissible object enters the protected area or if a permitted object is not correctly positioned, the determined distance does not match the permitted 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;

In the following, the invention will also be explained with regard to further advantages and features with reference to the accompanying drawings using exemplary embodiments. The figures in the drawing show in:

• 1 to 3 a multi-beam light barrier with muting sensors according to the prior art;
• 4th to 6th a sensor system according to the invention with a bridging sensor in three different views each;
• 7th a sensor system with two opposing bridging sensors for guiding objects out of a danger zone;
• 8th to 13 a sensor system with four bypass sensors for monitoring objects from and into a danger zone;
• 14th a sensor system with eight override sensors;

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

1 shows a multiple light beam safety device 2 According to the state of the art. The multiple light beam safety device 2 is arranged vertically and has three parallel light beams. The muting sensors 15th are spatially separated from the multiple light beam safety device 2 arranged, which results in a high wiring effort and a high installation effort and a relatively large amount of space is required. The light beams from the muting sensors 15th are crossed. The possible conveying direction is marked with an arrow.

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

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

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

5 FIG. 3 is a side view of FIG 4th .

6th Figure 13 is a plan view according to 4th . 7th to 14th also show a top view.

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

The object shown 4th moves in the direction of the arrow out of a danger area or safety area through the protective field 16 the multiple light beam safety device 2 . This becomes the allowed object 4th initially from the bridging sensors 3 detected. Once the object 4th from the bypass sensors 3 The multiple light beam safety device is validly detected 2 completely or at least partially bridged so that the object 4th the multiple light beam safety device 2 can happen without shutting down a machine.

With the multiple light beam safety device 2 the distance between the light beams is, for example, 300 mm. This distance is provided, for example, for access protection.

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

By detecting the light beams from the bridging sensors 3 become inadmissible people and objects 4th of allowed objects 4th distinguished. Muting signals are generated on the basis of the detection, after which the multi-beam safety light barrier 2 no shutdown signal is generated, creating a valid object 4th the protective field 16 the multiple light beam safety device 2 can happen without a dangerous movement having to be stopped.

Through the U-shaped housing 6th is a mechanical coupling between the housing 7th the multiple light beam safety device 2 and the U-shaped housing is provided, whereby the U-shaped housing 6th opposite the housing 7th the multiple light beam safety device 2 are aligned.

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

In addition, it is by the distance measuring probing sensors such. B. Light buttons as bridging sensors 3 it is also possible to obtain precise information on an object contour that could not be detected by a simple beam interruption by means of a light barrier. Through the distance measuring sensors, an object can 4th be measured or the object based on the captured object contour 4th as a permitted or prohibited object 4th are classified 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 create a lateral contour of the object 4th to be determined while the object passes the protective field.

Becomes an object 4th for example on a conveyor belt through the multiple light beam safety device 2 transported, so can through the bridging sensors 3 the distance contour data of one of the respective transmitting / receiving strips of the multiple beam safety light barrier 2 facing side of the object 4th can be recorded and saved. By the sensor system according to the invention 1 a lateral distance contour can be recorded and used to assess the object 4th be used. According to 7th are the override sensors 3 in one end of an arm 12 of the U-shaped housing 6th arranged.

According to 8th to 13 are the override sensors 3 arranged so that at least two override sensors 3 each to an area in the conveying direction of objects 4th in front of and behind the multiple light beam safety device 2 are arranged.

This makes it possible to use objects 4th in both directions through the protective field 16 the multiple light beam safety device 2 to transport. This allows, for example, permitted objects 4th , for example processing material, in both directions through the protective field 16 be conveyed without having to stop a dangerous movement of a machine.

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

According to 9 detect the object 4th inclined bridging sensors 3 the object 4th and the multiple light beam safety device 2 is muted or bridged. The protective field 16 the multiple light beam safety device 2 Is still available. The rear of the object 4th away facing bridging sensors 3 detect no object yet 4th .

According to 10 detect the front ones, those of the object 4th inclined bridging sensors 3 and the multiple light beam safety device 2 , the object 4th . The rear of the object 4th away facing bridging sensors 3 detect no object yet 4th .

According to 11 detect the front ones, those of the object 4th inclined bridging sensors 3 , the multiple light beam safety device 2 and the rear of the object 4th away facing bridging sensors 3 the object 4th .

According to 12 detect the rear of the object 4th away facing bridging sensors 3 and the multiple light beam safety device 2 the object 4th .

According to 13 has the object 4th leave the detection area and have the multiple light beam safety device 2 as a valid object 4th happened successfully.

According to the figures, the distance-measuring probing sensors can be time-of-flight sensors or triangulation sensors.

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

This causes the light beams to be the bypass sensors 3 from opposing bridging sensors 3 aligned so that the light beams from the two bypass sensors 3 each from the multiple light beam safety device 2 are directed away and are in a two-dimensional projection in the longitudinal direction of the housing 7th the multiple light beam safety device 2 cross over.

According to 7th to 14th is a control and evaluation unit in the housing 7th the multiple light beam safety device 2 housed.

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

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

List of reference symbols

1

Sensor system

2

Multiple light beam safety device

3

Bypass sensors

4th

Objects

6th

U-shaped housing

7th

casing

10

Light transmitter (of the bridging sensors)

11

Light receiver (of the bridging sensors)

12

poor

13

Light transmitter (of the multiple light beam safety device)

14th

Light receiver (of the multiple light beam safety device)

15th

Muting sensors

16

Protective field

Claims (8)

Sensor system (1) with a multi-beam safety light barrier (2) and with bridging sensors (3) for the detection of objects (4) and / or people (5), the bridging sensors (3) being distance-measuring probing sensors, characterized in that at least one bridging sensor ( 3) is arranged in one end of an arm (12) of a U-shaped housing (6), the U-shaped housing (6) being arranged on the housing (7) of the multiple beam safety light barrier (2) and the housing (7) of the Partly enclosing multiple beam safety light barrier (2), at least one bridging sensor (3) being arranged in each end of an arm (12) of the U-shaped housing (6). Sensor system according to Claim 1 , characterized in that the distance-measuring probing sensors are time-of-flight 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 from the bridging sensors (3) and the light beams from the Multiple light beam safety devices (2) are arranged at an acute angle to one another. Sensor system according to at least one of the preceding claims, characterized in that a control and evaluation unit is housed in the housing (7) of the multiple beam safety light barrier (2), in the U-shaped housing (6) of the bridging sensors (3) or in a third external housing is. 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) have 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 differentiate between impermissible and permissible objects on the basis of stored contour shapes, the objects (4) moving at a constant speed.

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