Monitoring system and laser processing machine device

Abstract

The present invention relates to a monitoring system (1) comprising: a plurality of monitoring units (2, 3), wherein the monitoring system (1) is configured to monitor the line of sight (4) between the first monitoring unit (2) and the second monitoring unit (3) via signal transmission between the first monitoring unit (2) and the second monitoring unit (3). The monitoring system (1) is configured to monitor the line of sight (4) via signal transmission in the form of radio transmission between the first monitoring unit (2) and the second monitoring unit (3), particularly via UWB radio transmission. The present invention also relates to a laser processing machine apparatus having such a monitoring system (1).

Description

Technical Field

[0001] This invention relates to a monitoring system comprising a plurality of monitoring units, wherein the monitoring system is configured to monitor the line of sight between the first monitoring unit and the second monitoring unit via signal transmission between the two monitoring units. The invention also relates to a laser processing machine apparatus incorporating such a monitoring system. Background Technology

[0002] EP2886242A1 describes a laser processing machine apparatus having a monitoring system for recording entry into a controlled area. The controlled area includes at least one danger zone around the laser processing head. The monitoring system is configured to automatically shut down the laser processing head if it records entry into the controlled area.

[0003] The monitoring system can be an optical monitoring system, comprising a grating or light barrier for monitoring at least one boundary segment that enables access to the controlled area. The optical monitoring system can have two component devices, such as a transmitter device and a receiver device. The transmitter device can emit one or more control beams, which are recorded by the receiver device. Passage across the boundary segment can be recorded by interruption of the corresponding control beam.

[0004] There are problems when using light barriers or gratings to monitor the line of sight or control area, namely that the transmitter and receiver devices must be precisely aligned with each other, but misalignment can occur. This can cause the control beam to fail to be received by the receiving device, even if the control beam is not interrupted (so-called false alarms). Summary of the Invention

[0005] The fundamental objective of this invention is to provide a monitoring system in which monitoring units do not require precise alignment with each other. A further fundamental objective of this invention is to provide a laser processing apparatus incorporating such a monitoring system.

[0006] The subject of this invention

[0007] This objective is achieved by a monitoring system of the aforementioned type, which is configured to monitor line of sight via signal transmission in the form of radio transmission between a first monitoring unit and a second monitoring unit.

[0008] In the monitoring system according to the invention, a radio barrier is used instead of a light barrier to monitor line of sight. For the radio barrier, radio transmission in the form of radio signals is used instead of a light beam for monitoring line of sight. The radio-based monitoring system or corresponding monitoring unit is configured to identify when a radio absorber (e.g., a person) obstructs or interrupts the line of sight (i.e., a straight line, which is typically straight) between two monitoring units. If the line of sight is partially interrupted by a radio absorber, the radio signal will be detoured by reflections from other objects in the room, which becomes apparent in the measurement of radio transmission, more precisely, in the signal propagation time of the radio signal. The reliability of this monitoring lies in the fact that typical reflections of the radio signal during radio transmission between monitoring units can be identified without causing false alarms. The radio barrier described herein can replace a light barrier. A grating for monitoring multiple lines of sight can also be replaced by a radio grating or a radio-based protective fence, as will be described in more detail below.

[0009] In one embodiment, the monitoring unit is configured for ultra-wideband (UWB) radio transmission. Identifying small objects that partially obstruct the line of sight requires high accuracy in measuring radio signals, or more precisely, in measuring the signal propagation time of radio signals, or—equivalently—in measuring the distance between monitoring units determined based on the corresponding signal propagation time. The required accuracy is typically on the order of a few millimeters. With appropriate measures (see below), distance measurements with resolution or measurement accuracy in the millimeter range can be achieved using UWB radio transmission.

[0010] To date, resolution typically achieved via UWB radio transmission is only on the order of approximately 10 cm. However, even with this level of accuracy, UWB radio transmission is far more precise than other radio technologies used for positioning. Further advancements in UWB radio transmission to millimeter-level accuracy (see below) have increased its advantage over other short-range radio technologies such as Wi-Fi and BLE (Bluetooth Low Energy) in precise positioning.

[0011] Because UWB radio transmission operates in a cleaner, higher frequency band than Wi-Fi and BLE, it does not interfere with the operation of other wireless protocols. UWB radio transmission or UWB positioning can be integrated into existing wireless operating environments without causing disruptive signal interference. Another advantageous feature of UWB technology is its inherently high level of security. Other technologies use signal strength index (RSSI) to determine distance and location, while UWB technology is based on time of flight or time of arrival. Therefore, altering UWB measurements is much more difficult, and the technology is far less susceptible to relay attacks. Furthermore, it is possible to bridge greater distances using UWB technology. In principle, radio transmission could also be carried out in different ways than via UWB, such as through radar, but longwave radio frequencies are generally unsuitable due to their low resolution.

[0012] In another embodiment, the monitoring unit has a transceiver, preferably a UWB transceiver, or the monitoring unit is configured as a transceiver, preferably a UWB transceiver or a UWB anchor. In principle, the first monitoring unit can be configured only as a transmitter, and the second monitoring unit can be configured only as a receiver, or vice versa. However, for the distance measurement methods described further below, and for using these monitoring units as nodes in a monitoring network (see below), it is advantageous if these monitoring units are configured as transceivers or have transceivers, i.e., serving as both transmitters and receivers. UWB transceivers perform omnidirectional transmission and reception, thus eliminating the need for alignment. The housings of these monitoring units or UWB transceivers do not need to be optically transparent, and therefore new design variations can be implemented if necessary.

[0013] These monitoring units in a monitoring system are typically connected to a central unit that performs an assessment of radio transmissions to detect line-of-sight interruptions. However, it is equally possible that these monitoring units are autonomous, meaning they detect line-of-sight interruptions on their own and initiate or trigger appropriate measures during the detection. In this case, the monitoring system typically does not have a central monitoring unit.

[0014] In another embodiment, the monitoring system is configured to monitor the line of sight based on the signal propagation time of radio transmissions between a first monitoring unit and a second monitoring unit, specifically based on the distance between the first and second monitoring units, the distance being determined according to the signal propagation time. The distance measurement between the two monitoring units can be achieved in a known manner based on the signal propagation time of the radio transmissions, or more precisely, based on the signal propagation time of one or more radio signals transmitted from one detection unit to the other. The transmission of radio signals between the two detection units occurs at the highest possible repetition frequency to ensure continuous monitoring of the line of sight.

[0015] In a further development of this embodiment, the detection system is configured to detect the interruption of the line of sight based on the deviation between the signal propagation time and the desired signal propagation time, specifically based on the deviation between the distance determined according to the signal propagation time and the desired distance between the first detection unit and the second monitoring unit. Due to the precise distance measurement performed via UWB radio technology, it is possible to detect or record a radio absorber, such as a person or a part of a person's body, located between the two monitoring units and obstructing or interrupting the line of sight. In this case, the measured distance deviates from the desired distance between the two monitoring units, or complete packet loss may occur during the radio transmission. If this is the case, a radio barrier is triggered, i.e., the monitoring system detects the interruption of the line of sight.

[0016] The desired distance typically corresponds to the actual distance (i.e., minimum distance) between two monitoring units, which are usually arranged in a fixed position. The desired distance can also theoretically be determined based on the route passing through a reflector used for radio signals. In this case, the monitored line of sight also passes through the reflector. The desired distance can be determined using the monitoring units, or, if necessary, by another distance measurement method. Typically, in the event of an interrupted line of sight, the measured distance is greater than the desired distance. Monitoring units can be mounted in a fixed manner, but they can also be releasably secured to a wall or other object, for example, in the form of portable UWB transceivers, to monitor the line of sight. This allows for mobile monitoring systems.

[0017] If a desired distance to another monitoring unit is set or predefined at one monitoring unit and stored there, or if this desired distance is measured using these monitoring units when the line of sight is uninterrupted, the corresponding monitoring unit can autonomously determine whether there is a significant deviation between the signal propagation time and the desired signal propagation time, or between the distance and the desired distance, or whether there is complete packet loss during radio transmission, and can detect obstruction or interruption of the line of sight. For example, it can be checked whether the deviation from the desired distance exceeds a threshold. If this is the case, the corresponding monitoring unit can trigger an alarm, for example, by generating an audible and / or visual alarm signal. Alternatively or additionally, the alarm signal can be sent to an alarm center, which can be part of the monitoring system or an external alarm center.

[0018] In another further development, the monitoring unit is configured to measure distance using a timestamp-based distance measurement method, preferably by two-way ranging (i.e., by two-way distance measurement), and / or by a phase-based distance measurement method. The distance between two time-asynchronous monitoring units can be achieved, for example, by so-called two-way ranging, see, for example, the article “https: / / en.wikipedia.org / wiki / Symmetrical_double-sided_two-way_ranging” or the article “Error Corrections for Ultrawideband Ranging”, J. Sidorenko et al., IEEE Transactions on Instrumentation and Measurement, Vol. 69, No. 11, November 2020, which, by reference in their entirety, form part of this application. In particular, the distance between the two monitoring units can be measured using a phase-based distance measurement method as described in DE102022202846A1, which, by reference in its entirety, forms part of this application. Specifically, the method described therein enables millimeter-level distance measurement accuracy; see also the link "https: / / www.nxp.com / company / blog / nxp-continues-to-advance-uwb-taking-accuracy-to-mm-level:BL-NXP-ADVANCE-UWB-ACCURACY-MM-LEVEL". UWB transceivers sold by NXP allow for low millimeter-level distance resolution, independent of the bridged distance.

[0019] In another embodiment, the monitoring system is configured to monitor lines of sight between at least two pairs of monitoring units via radio transmissions between the two monitoring units of a corresponding pair of monitoring units. As is common with light barriers, multiple radio barriers (each monitoring one line of sight) can also form a radio grid, and can, for example, create a radio-based fence for monitoring an area. Particularly advantageous in implementing such a radio grid is that the monitoring units do not necessarily need to be aligned relative to each other. It should be understood that these lines of sight do not necessarily extend within a common area, but can also extend in three or more different directions to monitor a control volume or control area.

[0020] Preferably, at least one monitoring unit is configured to monitor at least two lines of sight between itself and at least two other monitoring units via radio transmissions between the monitoring unit and at least two other monitoring units. Unlike light barriers or gratings—in which the corresponding transmitter or receiver can only be used to monitor one line of sight due to alignment requirements—the monitoring unit described herein, particularly a transceiver-type monitoring unit, can be used as a node or (multi-dimensional) node in a monitoring network and can monitor multiple lines of sight simultaneously. Therefore, the two or more pairs of monitoring units described above do not necessarily have to be different monitoring units; instead, the same monitoring unit can be assigned to two or more pairs of monitoring units, each of which monitors a common line of sight.

[0021] In further development, to monitor a planar area, particularly the boundary segment of a control zone, a first set of monitoring units is arranged at the first edge of the planar area, and a second set of monitoring units is arranged at the second edge of the planar area to monitor the lines of sight between the monitoring units in the first set and the monitoring units in the second set. In this case, the planar area can be monitored by arranging multiple monitoring units, for example, in a matrix. For example, a set of monitoring units can be arranged vertically within a monitoring column or similar structure to monitor multiple lines of sight from another set of monitoring units. In principle, a one-to-one allocation can be made between the monitoring units of the corresponding sets, i.e., each pair of monitoring units monitors exactly one line of sight. However, it is generally advantageous to make an N-to-N allocation between the N monitoring units of the corresponding sets, i.e., if each monitoring unit of the first set monitors N lines of sight from the N monitoring units of the second set. If the monitoring units of the corresponding sets or both sets are synchronized in time, optimized measurement methods can be used to improve the measurement frequency and / or measurement accuracy. For example, a common clock signal can be used for time synchronization. It should be understood that the number of monitoring units in the two sets can also be different.

[0022] The monitored area can be, for example, a boundary segment of a control zone in the form of a work area, which includes a danger zone surrounding the laser processing head, as described in EP 2886242A1, which, by reference in its entirety, forms part of this application. Because of this monitoring system, particularly utilizing N-to-N wiring, entry into the control zone can be detected, and the laser processing head can be shut down if necessary. This monitoring system, particularly utilizing N-to-N wiring, can be used not only for the protection of the work area of ​​machines, especially machine tools, but also as a safety device, for example, for burglar protection in large rooms.

[0023] In another embodiment, the monitoring units are configured for radar monitoring, particularly in the form of proximity sensors. Besides serving as nodes for monitoring line of sight, these monitoring units can also function as radar devices or proximity sensors, especially if they are configured as or have UWB transceivers. This radar, for example, allows monitoring of whether personnel are present in the monitored room. In this way, in addition to (or in parallel with) access monitoring, the monitoring system is also capable of indoor monitoring of a controlled area or monitored volume.

[0024] In another embodiment, the monitoring unit is configured to locate, track, determine, and / or navigate a moving object, preferably with a UWB tag. Specifically, the monitoring system is capable of switching between a first operating mode for monitoring at least one line of sight and a second operating mode for locating, determining, and / or navigating the moving object. The monitoring system can be configured to locate and / or determine the position of a moving object that is typically tagged with a UWB tag and can be located, determined, or navigated via monitoring units in the form of UWB anchors. In the first operating mode (which is activated, for example, at night), the monitoring system can function as an alarm system and can monitor access to a monitored controlled area (e.g., in a museum): the monitoring system triggers an alarm once the line of sight is lost. In the second operating mode (which is activated, for example, during the day or during the museum's opening hours), objects (e.g., as visitors) can be located and determined, or can be navigated through the museum (e.g., based on Omlox or Fira). In this case, the monitoring units are used in a dual-purpose mode. Similarly, in the second operating mode, the location of one or more mobile objects (e.g., drones) can be determined to perform automated inventory checks in a warehouse or similar location, while the alarm function of the monitoring system is used in the first operating mode. Regardless of whether switching between these two operating modes is possible, objects (e.g., in the form of valuables) can also be tagged with UWB and located or tracked. It is also possible to use a "thrown-out light barrier," in which one or more lines of sight between a mobile monitoring unit and one or more fixed monitoring units are monitored, and an interruption of these lines of sight triggers an alarm.

[0025] The present invention also relates to a laser processing machine apparatus, comprising: a control area in which a laser processing head is arranged; and a monitoring system as further described above, configured to detect entry into the control area, preferably detection of passage through a boundary segment of the control area. The monitoring system may be configured to automatically shut down the laser processing head if it detects entry into the control area. Specifically, the monitoring system may detect passage through a boundary segment of the control area, which may, for example, be located between two sets of monitoring units that create a radio-based protective fence within the boundary segment. It should be understood that the monitoring system may also be configured to monitor areas other than the control area of ​​the laser processing machine, such as areas within a building.

[0026] Other advantages of the invention become apparent from the specification and drawings. The features mentioned above and below can be used individually, or multiple features can be used in any desired combination. The embodiments shown and described should not be construed as exhaustive enumeration, but rather have an exemplary nature for describing the invention. Attached Figure Description

[0027] As shown in the figure:

[0028] Figure 1a , Figure 1b This is a schematic diagram of a monitoring system with two monitoring units, used to monitor line of sight via UWB radio transmission;

[0029] Figure 2 This is a schematic diagram of a monitoring system, which has two sets of monitoring units at the edge of a planar area in order to monitor the planar area.

[0030] Figure 3 This is a schematic diagram of a laser processing machine apparatus, which includes a monitoring system for detecting entry into the control area.

[0031] In the following description of the accompanying drawings, the same reference numerals are used for the same or functionally identical parts. Detailed Implementation

[0032] Figure 1a , Figure 1b A radio-based monitoring system 1 is shown, comprising two monitoring units 2 and 3 in the form of UWB transceivers. These two fixed monitoring units 2 and 3 are arranged along a line of sight 4 at a distance A, which is 10 meters in the illustrated example. The monitoring system 1 is configured to monitor the line of sight 4 by transmitting signals in the form of UWB radio transmissions between the two monitoring units 2 and 3, both of which are configured for UWB radio transmission.

[0033] Monitoring of line-of-sight 4 using UWB radio transmission is based on signal propagation time or on the propagation times T and T' of the UWB radio signals exchanged between the two monitoring devices 2 and 3. For example... Figure 1a As shown, the transmission of UWB radio signals between the two monitoring units 2 and 3 can occur along two different signal paths 5 and 5', where the first, shorter signal path 5 extends along the line of sight 4, while the second, longer signal path 5' extends via reflector 6. This reflector 6 is not positioned between the two monitoring units 2 and 3 for the purpose of radio transmission; rather, the UWB radio signals are actually reflected at every object present in the room.

[0034] The signal propagation time T' along the second signal path 5' guided by reflector 6 is longer than the signal propagation time T along the first signal path. The two monitoring units 2 and 3 are configured to determine the distance A between them based on the signal propagation times T and T'. T Among them, when the distance A is determined T Only the shorter or minimum signal propagation time T is considered. The distance A determined by the signal propagation times T and T' is... T The expected distance corresponding to the actual distance A between the two monitoring units 2 and 3 is A = 10 m.

[0035] exist Figure 1a In the example shown, the line of sight 4 between the two monitoring units 2 and 3 is not interrupted, while... Figure 1b In the example shown, the line of sight 4 between the two monitoring units 2 and 3 is interrupted because personnel 7 are positioned within the line of sight 4. Since the shorter signal path 5 extending along the line of sight 4 is interrupted, signal transmission can only proceed along the second, longer signal path 5' with a longer signal propagation time T'. Figure 1b In the example shown (in this example, reflector 6 is positioned midway between the two monitoring units 2 and 3 and is 10 cm from the line of sight 4), the distance A determined by monitoring units 2 and 3 based on the longer signal propagation time through reflector 6... T 'For A T = 10.002 m.

[0036] exist Figure 1b In the example shown, monitoring system 1 is based on the deviation between the signal propagation time T' and the expected signal propagation time T along the line of sight 4, or more precisely, on the distance A determined according to the signal propagation time T'. T 'Distance A from the expected distance T (The expected distance A) TThe system detects an interruption in line of sight 4 based on a deviation from the actual distance. Monitoring system 1 or corresponding monitoring units 2 and 3 can trigger an alarm and / or take or initiate other measures upon detecting an interruption in line of sight 4.

[0037] based on Figure 1a , Figure 1b The example described clearly shows that, when determining distance A... T A T The accuracy of the distance measurement should be within a few millimeters to reliably identify interruptions in the line of sight 4. To achieve this accuracy, monitoring units 2 and 3 are configured to measure distance A using a timestamp-based distance measurement method (more precisely, a two-way ranging method) and / or a phase-based distance measurement method. T A T As described in, for example, DE102022202846A1. The expected signal propagation time T corresponding to the signal propagation along the line of sight 4 can be stored or saved in the two monitoring units 2 and 3. This expected signal propagation time T can be determined, for example, in the calibration mode of the monitoring system 1, in which the line of sight 4 is ensured to be uninterrupted. However, the expected signal propagation time T can also be determined in another way.

[0038] Figure 2 A monitoring system 1 is shown, comprising two groups G1 and G2, each group having four monitoring units 2a-d and 3a-d for monitoring an area region F. The first group of G1 monitoring units 2a-d are arranged vertically relative to each other in a monitoring post 8a located at the first left edge of the area region F. Correspondingly, the second group of G2 monitoring units 3a-d are arranged vertically relative to each other in a monitoring post 8b located at the second right edge of the area region F, to monitor the line of sight 4 between the monitoring units 2a-d in the first group of G1 and the monitoring units 3a-d in the second group of G2. Due to the large number of monitored lines of sight 4, the entire area region F between the two monitoring posts 8a and 8b can be monitored.

[0039] The corresponding monitoring units 2a-d of the first group G1 are configured to simultaneously monitor four lines of sight 4 for one of the corresponding monitoring units 3a-d of the second group G2. Correspondingly, the corresponding monitoring units 3a-d of the second group G2 are configured to simultaneously monitor four lines of sight 4 for one of the corresponding monitoring units 2a-d of the first group G1. Therefore, Figure 2The monitoring system 1 shown is used to monitor 4×4=16 lines of sight 4, which form a planar network or radio-based protective fence for monitoring the planar area F. Therefore, the monitoring system 1 is able to detect the passage of personnel through the planar area F.

[0040] For example, a planar region F can be formed Figure 3 One of the four boundary segments 9a-d of the control zone 10 shown is used to monitor entry into the control zone via a monitoring device 1, which has... Figure 2 The four monitoring columns 8a-d shown are in... Figure 3 The diagram is shown in plan view. A planar region, in the form of boundary segments 9a-d, is formed between the corresponding two monitoring columns 8a-d. The boundary segments 9a-d are connected via the above description. Figure 2 The method described further is monitored.

[0041] A laser processing machine 11 is arranged in the control area 10 and has a laser processing head 12 that emits laser radiation during laser processing. If the monitoring system 1 detects passage through one of the boundary segments 9a-d, the laser processing head 12 is shut down. The laser processing machine 11, together with the monitoring device 1, forms a laser processing machine apparatus 13.

[0042] Monitoring system 1 can also be used to monitor other rooms or areas, and can be used for purposes other than monitoring line of sight 4 or area F. This utilizes the fact that monitoring units 2 and 3, in the form of UWB transceivers, can also be used for other purposes. For example, one or more monitoring units 2a-d, 3a-d, ... of the corresponding monitoring columns 8a-d can also be used for radar monitoring or as proximity sensors, and can detect when a person or object approaches the corresponding monitoring column 8a-d to a predefined distance D, such as... Figure 3 As shown in the example of the first monitoring column 8a.

[0043] Monitoring system 1, or more precisely, monitoring units 2, 3, 2a-d, 3a-d, can also be used to locate and / or determine the position of moving objects, typically tagged with UWB tags. Such a moving object 14 (located outside the control area 10) is... Figure 3 The following is illustrated by way of example. It is possible that the monitoring system 1 can switch between a first operating mode for monitoring at least one line of sight 4 and a second operating mode for locating, determining the position, and / or navigating a moving object 14. For example, when the monitoring system 1 is used in a museum or similar location, the second operating mode can be activated during the day to navigate people through the museum, and the first operating mode can be activated at night to use the monitoring system 1 as an alarm system.

Claims

1. A monitoring system (1), comprising: Multiple monitoring units (2, 2a-d, 3, 3a-d). The monitoring system (1) is configured to monitor the line of sight (4) between the first monitoring unit (2) and the second monitoring unit (3) through signal transmission between the first monitoring unit (2) and the second monitoring unit (3). Its features are, The monitoring system (1) is configured to monitor the line of sight (4) via signal transmission in the form of radio transmission between the first monitoring unit (2) and the second monitoring unit (3).

2. The monitoring system according to claim 1, wherein, The monitoring units (2, 2a-d, 3, 3a-d) are configured for UWB radio transmission.

3. The monitoring system according to claim 1 or 2, wherein, The monitoring unit (2, 2a-d, 3, 3a-d) has a transceiver, preferably a UWB transceiver, or the monitoring unit (2, 2a-d, 3, 3a-d) is configured as a transceiver, preferably a UWB transceiver.

4. The monitoring system according to any one of the preceding claims, configured to monitor the line of sight (4) based on the signal propagation time (T, T') of the radio transmission between the first monitoring unit (2) and the second monitoring unit (3), particularly based on the distance (A) between the first monitoring unit (2) and the second monitoring unit (3). T A T' ) to monitor the line of sight (4), the distance (A) T A T' The value is determined based on the signal propagation time (T, T').

5. The monitoring system according to claim 4, configured to detect interruptions in the line of sight (4) based on the deviation between the signal propagation time (T') and the desired signal propagation time (T), particularly based on a distance (A) determined according to the signal propagation time (T'). T' The expected distance (A) between the first monitoring unit (2) and the second monitoring unit (3) and the first monitoring unit (2) and the second monitoring unit (3) T The deviation of the line of sight (4) is used to detect the interruption of the line of sight (4).

6. The monitoring system according to claim 4 or 5, wherein, The monitoring units (2, 3) are configured to measure the distance (A) using a timestamp-based distance measurement method. T A T' Preferably, the distance is measured by bidirectional ranging (A). T A T' ), and / or, by measuring the distance using a phase-based distance measurement method (A T A T' ).

7. The monitoring system according to any one of the preceding claims is configured to monitor the line of sight (4) between at least two pairs of monitoring units (2a-d, 3a-d) via radio transmission between two monitoring units (2a-d, 3a-d) of corresponding pair of monitoring units (2a-d, 3a-d).

8. The monitoring system according to any one of the preceding claims, comprising at least one monitoring unit (2a-d, 3a-d), the at least one monitoring unit (2a-d, 3a-d) being configured to monitor at least two lines of sight (4) between the monitoring unit (2a-d, 3a-d) and at least two other monitoring units (3a-d, 2a-d) via radio transmission between the monitoring unit (2a-d, 3a-d) and at least two other monitoring units (3a-d, 2a-d).

9. The monitoring system according to claim 7 or 8, wherein, In order to monitor the area (F), especially the boundary segment (9a-d) of the control area (10), a first group (G1) of monitoring units (2a-d) is arranged at the first edge of the area (F), and a second group (G2) of monitoring units (3a-d) is arranged at the second edge of the area (F) to monitor the line of sight (4) between the monitoring units (2a-d) in the first group (G1) of monitoring units (2a-d) and the monitoring units (3a-d) in the second group (G2) of monitoring units (3a-d).

10. The monitoring system according to any one of the preceding claims, wherein, The monitoring units (2, 3, 2a-d, 3a-d) are configured for radar monitoring, particularly in the form of proximity sensors.

11. The monitoring system according to any one of the preceding claims, wherein, The monitoring units (2, 3, 2a-d, 3a-d) are configured to locate, determine and / or navigate a mobile object (14) preferably having a UWB tag, wherein the monitoring system (1) is preferably able to switch between a first operating mode for monitoring one or more lines of sight (4) and a second operating mode for locating, determining and / or navigating the mobile object (14).

12. A laser processing machine apparatus (13), comprising: Control area (10), in which a laser processing head (12) is arranged, and The monitoring system (1) according to any one of the preceding claims is used to detect entry into the control area (10), preferably to detect passage through the boundary segments (9a-d) of the control area (10).

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