monitoring device

Abstract

Monitoring device (1) with a safety sensor by means of which an access area (6) to a danger zone (2) on a system controlled by a control unit is monitored, wherein output signals of the safety sensor are fed to the control unit, wherein the safety sensor activates an object detection signal in the event of an object intrusion in the access area (6), by means of which object detection signal the control unit shuts down the system, characterized in that sensor means are provided, the output signals of which are fed to the control unit, wherein an interior area in the danger zone (2) and an exterior area outside the danger zone (2) are monitored by the sensor means, and the sensor means each activate an object detection signal in the event of an object intrusion in the interior area and in the event of an object intrusion in the exterior area, so that after the system has been shut down by means of the control unit, an automatic restart of the system is then carried out,if, first, in a first sequence, the sensor means for the outdoor area and the safety sensor each activate an object detection signal, regardless of the order, and then the sensor means for the indoor area activate an object detection signal, and if, in a second sequence following the first sequence, the sensor means for the indoor area deactivate the object detection signal and then the sensor means for the outdoor area and the safety sensor each deactivate the object detection signal, regardless of the order.

Description

[0001] The invention relates to a monitoring device.

[0002] Such a monitoring device comprises a safety sensor that protects an access area to a hazardous area on a system. The system is controlled by a control unit, in particular a safety controller.

[0003] The danger zone is typically secured with a fence so that people or objects can only enter the danger zone via the access area.

[0004] The safety sensor, which is particularly designed in the form of a light curtain, provides a safety function. The safety sensor monitors the entire access area. The safety sensor generates a binary switching signal as an output signal, the switching states of which indicate whether or not an object is located in the access area. If the safety sensor detects an object in the access area, the switching signal assumes a corresponding switching state, i.e. the switching signal is an object detection signal that indicates object detection. This object detection signal is transmitted to the control unit, which then shuts down the system so that it can no longer pose any danger.

[0005] In order to restart the system afterwards, an operator usually has to check whether the danger area is clear and then manually operate the switching device, which releases the system to restart.

[0006] This is cumbersome and requires additional personnel to manually interact with the system. Furthermore, this approach leads to undesirably long system downtimes.

[0007] Therefore, it is desirable to implement an automatic restart of the system. However, this requires achieving the necessary level of safety. In particular, it must be ensured that the automatic restart of the system does not pose any danger to persons.

[0008] The prEN415-42018 standard proposes an automatic restart system for a pallet magazine. In such a pallet magazine, a forklift transports pallets into the hazardous area of ​​the pallet magazine. To enable automatic restart of the system after a shutdown, it is necessary to check whether a forklift that has entered the hazardous area has actually left it.

[0009] For this purpose, an induction loop is installed in the floor in an indoor area within the danger zone and an outdoor area outside the danger zone. These loops detect metallic objects, particularly the forklift. Like the safety sensor, the induction loops generate switching signals.

[0010] The permissible sequences of the forklift truck entering and leaving the danger area, which trigger an automatic restart of the system, are required. a) Driving in the forklift, - generates the induction loop of the outdoor area, i.e. activates an object detection signal. - the safety sensor generates an object detection signal. - the indoor induction loop generates an object detection signal. b) extending the forklift, - the object detection signal of the indoor induction loop is deactivated. - the object detection signal of the safety sensor is deactivated. - the object detection signal of the outdoor induction loop is deactivated.

[0011] However, these required sequences are not met if the forklift has forks that are so long that they penetrate the access area monitored by the safety sensor before the forklift's chassis is in the area of ​​the induction loop in the outdoor area.

[0012] This means that even though the forklift truck has correctly entered and exited the danger zone, the automatic restart of the system is not enabled.

[0013] The invention is based on the object of providing a monitoring device for a system in which an automatic restart is possible with high availability of the system.

[0014] To achieve this object, the features of claim 1 are provided. Advantageous embodiments and expedient developments of the invention are described in the dependent claims.

[0015] The invention relates to a monitoring device with a safety sensor, by means of which an access area to a danger zone on a system controlled by a control unit is monitored. The output signals of the safety sensor are fed to the control unit. In the event of an object intrusion in the access area, the safety sensor activates an object detection signal, by means of which the control unit shuts down the system. Sensor means are provided, the output signals of which are also fed to the control unit. The sensor means monitors an interior area in the danger zone and an exterior area outside the danger zone. The sensor means activate an object detection signal in the event of an object intrusion inside and an object intrusion outside.After the system has been shut down, the control unit automatically restarts the system if, in a first sequence, the outdoor sensor and the safety sensor each activate an object detection signal, regardless of the order, and then the indoor sensor activates an object detection signal. If, in a second sequence following the first sequence, the indoor sensor deactivates the object detection signal, and then the outdoor sensor and the safety sensor each deactivate the object detection signal, regardless of the order, the automatic restart of the system is enabled.

[0016] The monitoring device according to the invention comprises a safety sensor with which a safety function is provided such that an access area to a danger zone on a system controlled by a control unit is monitored. Depending on whether an object or a person is present in the access area, the safety sensor generates a binary switching signal whose switching states depend on whether or not an object is intruding in the access area. The switching state of the switching signal upon object detection in the access area represents an object detection signal. If this object detection signal is output to the control unit, which is advantageously a safety controller, the control unit shuts down the system so that it no longer poses any danger.

[0017] Preferably, the safety sensor is a safe optoelectronic sensor (e.g. a safety light curtain) or is based on a safe electromagnetic sensor principle (e.g. safe radar sensor).

[0018] According to the invention, an automatic restart of the system is only possible with the monitoring device according to the invention if it is ensured that the predefined sequence has been observed and is not possible by a person alone (without deliberate manipulation).

[0019] For this purpose, the monitoring device has sensor means that separately monitor an outdoor area outside the danger zone and an indoor area within the danger zone. Depending on whether an object intrusion occurs in the outdoor area, the sensor means generate a binary switching signal. Likewise, the sensor means generate a binary switching signal depending on whether an object intrusion occurs in the indoor area. These switching signals, which are output to the control unit, are configured according to the switching signal of the safety sensor, i.e., the respective switching signal upon detection of an object is an object detection signal.

[0020] An automatic restart of the system is only enabled in the control unit if the sensor means and the safety sensor register a valid first sequence of object detection signals when an object enters the danger area and then a valid second sequence of object detection signals when the object leaves the danger area.

[0021] To increase the security for enabling the automatic restart, it may be required that time limits must be observed for the two sequences in order to enable the automatic restart.

[0022] According to the invention, the sequences do not require a strict order of activations or deactivations of object detection signals of the outdoor sensor means, the safety sensor and the indoor sensor means.

[0023] Rather, a tolerance in the activation and deactivation of object detection signals is permitted such that when the object enters the danger zone, either the object detection signal of the outdoor sensor means or the object detection signal of the safety sensor is activated first, followed by the object detection signal for the indoor area. The same applies to the indoor and outdoor sensor means and the safety sensor when the object exits the danger zone for the deactivation of the object detection signals.

[0024] This provides a tolerance of the two sequences that takes into account the specific geometries of objects, especially vehicles, entering and exiting the danger zone.

[0025] Depending on the design of the object, particularly the vehicle, an object detection signal from the safety sensor can be activated when it approaches the danger zone before the sensor means for the exterior generates an object detection signal. Since this also represents a permissible entry into the danger zone, this first sequence of activation of object detection signals is also permitted according to the invention, as long as the sensor means for the interior subsequently generate an object detection signal. The same applies to the exit of the object, particularly the vehicle, from the danger zone.

[0026] An example of this is an object in the form of a forklift. If the forklift has long forks, these can already extend into the access area and trigger an object detection signal from the safety sensor before the forklift's chassis reaches the outside area and triggers the object detection signal for the outside area.

[0027] Since the sequences according to the invention ensure a high level of fault tolerance as a prerequisite for an automatic restart of the system, the monitoring device according to the invention enables a safe automatic restart of the system with simultaneous fault tolerance of the object detection signals in the sequences, so that unnecessary downtimes of the system are avoided.

[0028] This fault tolerance can advantageously be further increased by the fact that during the sequences the object detection signal for the interior area and the object detection signal of the safety sensor can be activated and deactivated by partially moving an object in and out without violating the condition for automatic restart.

[0029] With the monitoring device according to the invention, dangerous object movements are reliably detected when objects enter and exit the danger zone, ensuring that the automatic restart of the system is not enabled if a person or object is still in the danger zone. In such a case, the sequences of object detection signals are rejected as invalid in the control unit, and the automatic restart is not enabled. In this case, an operator must manually restart the system by activating a switching device.

[0030] According to a first embodiment, the sensor means comprise a first induction loop for object detection in the outdoor area and a second induction loop for object detection in the indoor area.

[0031] The induction loops are installed at suitable locations in the floor of a factory hall or similar in which the system is located.

[0032] According to a second embodiment, the sensor means are formed by a radar sensor, a sensor with a different electromagnetic sensor principle or an optoelectronic sensor, by means of which object detections are carried out in the outdoor and indoor areas.

[0033] The radar sensor's radar wave beams are selected to encompass both the indoor and outdoor areas. The radar sensor's evaluation unit evaluates the received signals separately for the indoor and outdoor areas, generating separate switching signals for the indoor and outdoor areas. The radar sensor can distinguish people from other objects, particularly by analyzing movement profiles or object contours.

[0034] According to an advantageous development, the sensor means comprise sensors that operate according to two different sensor principles, such as a radar sensor and an ultrasonic sensor. The ultrasonic sensor is used to detect objects indoors. The radar sensor is used to detect objects outdoors or both outdoors and indoors.

[0035] The ultrasonic sensor and the radar sensor can advantageously be integrated in one housing.

[0036] The ultrasonic sensor can only detect the presence of an object, without distinguishing whether it is a person or another object. The radar sensor's ability to distinguish between people and objects, even when it only detects objects outdoors, is sufficient to meet the required security level.

[0037] A laser scanner can also be used as a sensor, which can detect objects of a certain minimum size. Such sensors can distinguish between objects and people. These sensors include two switching outputs for the output of output signals for indoor and outdoor use.

[0038] Furthermore, a horizontal light curtain can be used to distinguish between people and objects. This is ideally installed at a height of 100 to 300 mm above the floor. The light curtain is simply divided into sections, and the signals from these sections can be used to monitor both the entry and exit sequences. The advantage of using a safe light curtain is that it can also provide access control.

[0039] According to a further embodiment, the sensor means comprise at least one camera sensor.

[0040] The invention is explained below with reference to the drawings. They show: Fig. 1: First embodiment of the monitoring device according to the invention. Fig. 2: Individual representation of a light curtain for the monitoring device according to Fig. 1. Fig. 3: Second embodiment of the monitoring device according to the invention. Fig. 4: Schematic representation of a radar sensor with integrated ultrasonic sensor for the monitoring device according to Fig. 3. Fig. 5a-5l: Individual phases of entry and exit of a forklift truck into or from the danger zone of the monitoring device in accordance with Fig. 1.

[0041] Fig. 1 schematically shows an embodiment of the monitoring device 1 according to the invention.

[0042] The monitoring device 1 serves to safeguard a hazardous area 2 in a system, which in this case comprises a conveyor belt 3 controlled by a control unit (not shown). The control unit is designed as a safety controller with a fail-safe design. The fail-safe design is achieved in particular by a redundant computer structure and output structure of the control unit.

[0043] On the conveyor belt 3, pallets 4 loaded with goods are transported, for example, such as Fig. 1 shows.

[0044] How Fig. As shown in Figure 1, the system with the danger zone 2 is protected against access by a fence 5. Only on one open front side of the system is there an open access area 6, which is monitored by a safety sensor in the form of a light curtain 7.

[0045] Two induction loops 8 and 9 are installed as sensors in the floor area of ​​the factory hall in which the system is located. The first induction loop 8 monitors an outdoor area outside of the danger zone 2. The second induction loop 9 monitors an indoor area within the danger zone 2.

[0046] The induction loops 8, 9 generate binary switching signals. If an object is present in the outdoor or indoor area, the respective induction loop 8, 9 generates a switching signal in the form of an object detection signal. If there is no object on the induction loop 8, 9, these generate switching signals corresponding to a clear outdoor or indoor area. The switching signals from the induction loops 8, 9 are read into the control unit.

[0047] Fig. Figure 2 shows the light curtain 7. The light curtain 7 comprises a transmitter unit 10, in whose housing a series arrangement of transmitters 12 in the form of transmitting diodes emitting light beams 11 is arranged. The light curtain 7 further comprises a receiver unit 13, in whose housing a series arrangement of receivers 14 in the form of receiving diodes or the like is provided.

[0048] The transmitter unit 10 and the receiver unit 13 are arranged at opposite edges of a surveillance area. When the surveillance area is clear, the light beams 11 emitted by each transmitter 12 strike an associated, opposite receiver 14. A transmitter 12 and the associated receiver 14 each form a beam axis. Transmitter operation is controlled and evaluated by a transmitter controller 15 in the transmitter unit 10. Receiver operation is controlled by an evaluation unit 16 in the receiver unit 13. The transmitters 12 and receivers 14 of the individual beam axes are cyclically activated individually or in groups one after the other by optical synchronization of the light curtain 7.

[0049] In the evaluation unit 16, the received signals from the receivers 14 are evaluated to generate a binary switching signal as an output signal. The first switching state is an object detection signal, while the second switching state corresponds to a clear monitoring area.

[0050] The light curtain 7 forms a safety sensor for use in safety technology. For this purpose, the light curtain 7 has a fail-safe design. In particular, the evaluation unit 16 has a multi-channel, redundant design, for example, in the form of two cyclically monitoring computer units.

[0051] Fig. 3 shows a second embodiment of the monitoring device 1 according to the invention. This differs from the monitoring devices 1 according to Fig. 1 only in that a radar sensor 17 is provided as a sensor means for monitoring the outdoor and indoor areas.

[0052] Radar sensor 17 monitors the outdoor and indoor areas separately, generating a binary switching signal for both monitoring modes and outputting it to the control unit. Radar sensor 17 can distinguish between objects and people.

[0053] It is advantageous to combine two sensor principles, e.g. an ultrasonic sensor 18 is integrated in the radar sensor 17, as Fig. 4. The ultrasonic sensor 18 is located in the sensor housing 19 of the radar sensor 17, which contains, in a known manner, a transmitting element 20 emitting radar beams and a receiving element 21 receiving radar beams, as well as a control and evaluation unit 16 (not shown) for signal evaluation. The ultrasonic sensor 18 has, in a known manner, an ultrasonic transducer 22 emitting and receiving ultrasonic waves, to which a control and evaluation unit 16 (not shown) for signal evaluation is assigned.

[0054] In this case, the ultrasonic sensor 18 only monitors the interior area 9. The radar sensor 17 can monitor the exterior area and, if necessary, the interior area as well. The ultrasonic sensor 18 cannot distinguish between objects and people.

[0055] As the Fig. As shown in Figures 5a to 5e, pallets 4 can be fed to or removed from the conveyor belt 3 using a vehicle in the form of a forklift 23. For this purpose, the forklift 23 has forks 24 on one front side in a known manner.

[0056] To deliver and remove pallets 4, the forklift truck 23 must pass through access area 6 and thus the safety sensor as well as the outside and inside areas monitored by the sensors.

[0057] The monitoring device 1 according to the invention operates in such a way that the access area 6 is monitored by the safety sensor, i.e., the light curtain 7. If an object is detected in the access area 6 by the safety sensor, a safety function is triggered such that the object detection signal generated by the safety sensor is output to the control unit, causing the control unit to shut down the system, i.e., the conveyor belt 3, thereby transferring the system to a safe state.

[0058] According to the invention, the monitoring device 1 according to the invention enables an automatic restart of the system if it is ensured that no object, in particular no person, has completely completed the sequence.

[0059] For this purpose, the monitoring device 1 has the sensor means with which the outdoor area outside the danger zone 2 and the indoor area within the danger zone 2 are monitored separately.

[0060] An automatic restart of the system is only released in the control unit if the sensor means and the safety sensor register a valid first sequence of object detection signals when an object (or a person) enters the danger zone 2 and then a valid second sequence of object detection signals when the object (or the person) leaves the danger zone 2.

[0061] According to the invention, the sequences do not require a strict order of activations or deactivations of object detection signals of the outdoor sensor means, the safety sensor and the indoor sensor means.

[0062] Rather, a tolerance in the activation and deactivation of object detection signals is permitted such that when the object enters danger zone 2, either the object detection signal of the outdoor sensor means or the object detection signal of the safety sensor is activated first. The same applies to the indoor sensor means 9 and outdoor sensor means and the safety sensor when the object exits danger zone 2.

[0063] This provides a tolerance of the two sequences that takes into account the specific geometries of objects, in particular vehicles, entering and exiting danger zone 2.

[0064] Depending on the design of the object, in particular the vehicle, an object detection signal from the safety sensor can be activated as it approaches the danger zone 2 before the sensor means for the outside area generates an object detection signal. This can be the case with the forklift truck 23. If the forklift truck 23 has long forks 24, these can already protrude into the access area 6 and lead to the activation of an object detection signal from the safety sensor before the chassis of the forklift truck 23 reaches the outside area and leads to the activation of the object detection signal for the outside area. Since this also represents a permissible entry into the danger zone 2, this first sequence of activation of object detection signals is also permitted according to the invention, as long as the sensor means for the inside area subsequently generate an object detection signal.The same applies to moving the object, in particular the vehicle, out of danger zone 2.

[0065] The individual phases of entering and exiting danger zone 2 are described in the Fig. 5a to 5e.

[0066] To control, manage and enable an automatic restart, a system signal SYS and a sequence signal SEQ are defined in the control unit, which each assume the signal states ON or OFF depending on the activation and deactivation of object detection signals of the safety sensor and the sensor means, in this case the induction loops 8.

[0067] The characters Fig. 5a to 5d show a valid first sequence for an automatic restart when the forklift truck 23 enters danger zone 2.

[0068] Fig. Figure 5a shows the forklift 23 in an initial position outside the danger zone 2 and outside the perimeter. Neither the safety sensor nor the induction loops 8, 9 activate an object detection signal, since the forklift 23 is not detected by these units. The SYS and SEQ signals are both in the OFF state.

[0069] Fig. Figure 5b shows the beginning of the first sequence for an automatic restart. The forklift 23 is only detected by the induction loop 8, which monitors the outside area, so only this generates an object detection signal, but not the induction loop 9 and the safety sensor. The SYS signal is in the ON state, the SEQ signal is in the OFF state.

[0070] Fig. Figure 5c shows the forklift truck 23 moving further into the danger zone 2, with its forks 24 interrupting at least one of the light beams 11, so that in addition to the induction loop 8, the safety sensor also generates an object detection signal. The SYS signal is in the OFF state, and the SEQ signal is in the OFF state.

[0071] Fig. Figure 5d shows the forklift truck 23 moving further into the danger zone 2, so that in addition to the induction loop 8 and the safety sensor, the induction loop 9 activates an object detection signal. The SYS signal is in the OFF state, the SEQ signal is in the ON state.

[0072] The Fig. 5i to 5l show a valid sequence for the forklift truck 23 to exit danger zone 2. There, the object detection signals of induction loop 9, the safety sensor, and then the induction loop 8 are deactivated one after the other, i.e., in the reverse order of the activation of the object detection signals of induction loop 8, the safety sensor, and the induction loop 9 when the forklift truck 23 enters (first sequence). The SYS signal remains OFF, and the SEQ signal remains ON, until the forklift truck 23 has exited the area of ​​the induction loop 8, which completes the second sequence and enables automatic restart.

[0073] According to the invention, a valid first sequence is also present if the forklift 23 has longer forks 24, so that the safety sensor then activates an object detection signal before the forklift 23 enters the area of ​​the first induction loop 8, so that only then does the latter generate an object detection signal. Accordingly, the resulting modified second sequence of deactivating object detection signals is also recognized as valid, so that the system automatically restarts in this case as well.

[0074] According to the invention, the system is automatically restarted even if there is a delay between the first sequence of the forklift truck 23 entering the danger zone 2 ( Fig. 5a to 5d) and the second sequence of the forklift truck 23 moving out of the danger zone 2 ( Fig. 5i to 5l) a partial entry and exit of the forklift truck 23 into or out of the danger zone 2 takes place, as in the Fig. 5e to 5h. It is important that the forklift 23 does not leave the area of ​​the first induction loop 8. During the partial retraction and extension of the forklift 23, the SYS signal remains in the OFF state and the SEQ signal remains in the ON state. List of reference symbols 1 monitoring device 2 Danger zone 3 Conveyor belt 4 pallets 5 Fencing 6 Access area 7 Light curtain 8 Induction loop 9 Induction loop 10 Transmitter unit 11 Light beam 12 channels 13 Receiver unit 14 recipients 15 Transmitter control 16 Evaluation unit 17 Radar sensor 18 Ultrasonic sensor 19 Sensor housing 20 transmitting elements 21 Receiving element 22 ultrasonic transducers 23 forklifts 24 Gabel

Claims

[1] Monitoring device (1) with a safety sensor by means of which an access area (6) to a danger area (2) on a system controlled by a control unit is monitored, wherein output signals of the safety sensor are fed to the control unit, wherein the safety sensor activates an object detection signal in the event of an object intrusion in the access area (6), by means of which the control unit shuts down the system, characterized bythat sensor means are provided, the output signals of which are fed to the control unit, wherein the sensor means monitor an interior area in the danger zone (2) and an exterior area outside the danger zone (2), and the sensor means each activate an object detection signal in the event of an object intrusion in the interior area and in the event of an object intrusion in the exterior area, that after the system has been shut down by means of the control unit, the system is automatically restarted if, in a first sequence, the sensor means for the exterior area and the safety sensor each activate an object detection signal, regardless of the order, and then the sensor means for the interior area activate an object detection signal,and if, in a second sequence following the first sequence, the indoor sensor means deactivate the object detection signal and thereafter the outdoor sensor means and the safety sensor each deactivate the object detection signal, regardless of the order. [2] Monitoring device (1) according to claim 1, characterized by that during the sequences the object detection signal for the interior area and the object detection signal of the safety sensor can be activated and deactivated by partially moving an object in and out without violating the condition for automatic restart. [3] Monitoring device (1) according to one of claims 1 or 2, characterized by that time limits must be observed for the two sequences in order to enable automatic restart. [4] Monitoring device (1) according to one of claims 1 to 3, characterized bythat the activations and deactivations of object detection signals during the sequences are caused by a vehicle entering and leaving the danger zone (2). [5] Monitoring device (1) according to claim 4, characterized by that the vehicle is a forklift truck (23). [6] Monitoring device (1) according to one of claims 1 to 5, characterized by that the safety sensor is a light curtain (7). [7] Monitoring device (1) according to one of claims 1 to 6, characterized by that the sensor means have a first induction loop (8) for object detection in the outdoor area and a second induction loop (9) for object detection in the indoor area. [8] Monitoring device (1) according to one of claims 1 to 6, characterized by that the sensor means are formed by a radar sensor (17), by means of which object detections are carried out in the outdoor and indoor areas. [9] Monitoring device (1) according to one of claims 1 to 8, characterized by that the sensor means form a combination of two sensor principles. [10] Monitoring device (1) according to claim 9, characterized by in that the sensor means comprise a radar sensor (17) and an ultrasonic sensor (18), wherein object detections are carried out indoors with the ultrasonic sensor (18) and wherein object detections are carried out outdoors or outdoors and indoors with the radar sensor (17). [11] Monitoring device (1) according to claim 10, characterized by that the ultrasonic sensor (18) and the radar sensor (17) are integrated in one housing. [12] Monitoring device (1) according to one of claims 1 to 6, characterized by that the sensor means comprise at least one camera sensor. [13] Monitoring device (1) according to one of claims 1 to 6, characterized bythat a laser scanner is used as a sensor. [14] Monitoring device (1) according to one of claims 1 to 6, characterized by that a horizontal light curtain (7) is present as a sensor means. [15] Monitoring device (1) according to one of claims 1 to 5, characterized by that the safety sensor is a light curtain, safety laser scanner, safety radar sensor or a safety active IR sensor.

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