System for collecting information about a given surveillance area

Abstract

System for collecting information on a given surveillance area (1), the system (1) comprising: at least two sensor units (3) each having at least one sensor, at least one actuator for varying the orientation and / or position of the at least one sensor, and at least one control unit for controlling the at least one actuator; characterized in that each sensor unit (3) comprises an internal clock and the times of the different sensor units (3) are synchronized with each other; and the control unit of each sensor unit (3) is designed to carry out the associated actuator(s) based on the synchronized time of the respective internal clock.

Description

[0001] The present invention relates to a system for collecting information about a predetermined surveillance area and a corresponding method.

[0002] Conventionally, such systems comprise at least two sensor units, each with at least one sensor, at least one actuator for varying the orientation and / or position of the at least one sensor, and at least one control unit for controlling the at least one actuator.

[0003] It may be necessary to synchronize the different sensor units in a specific manner. There are different approaches for this. To synchronize the actuators, they are regularly connected via a synchronization line, which is different from a line for outputting measurement data to an evaluation unit. A control signal is transmitted directly via this synchronization line, ensuring that the activity of the actuators is synchronized in the desired manner. However, such designs are relatively complex to implement and error-prone (especially with a large number of sensor units whose actuators must be synchronized using a single control signal).

[0004] It is therefore an object underlying the invention to further develop corresponding systems.

[0005] This object is achieved by a system according to claim 1. Advantageous further developments can be found in the dependent claims.

[0006] The system according to the invention for acquiring information about a predetermined monitoring area is characterized in that each sensor unit comprises an internal clock, and the times of the different sensor units are synchronized with each other. The control unit of each sensor unit is configured to operate the associated actuator(s) based on the synchronized time of the respective internal clock.

[0007] In concrete terms, this means that the actuators of the different sensor units are no longer controlled (as was previously the case) on the basis of a common control signal that is exchanged between the different sensor units. Instead, each sensor unit is independent. The control of the associated actuators is based on the internal time of the respective sensor unit. To synchronize the actuators, the actuators (or their control units) do not exchange signals, but rather the times of the different sensor units are synchronized. This offers several advantages. Firstly, a separate and failure-prone synchronization line between the different sensor units can be dispensed with. Secondly, it is particularly easy to add further sensor units to an existing system or to remove or add sensor units.without having to modify the structural design and / or the nature of a synchronization signal from the other system components. Furthermore, when evaluating the signals from the various sensor units, it is no longer necessary to analyze and compensate for possible discrepancies between the synchronization of the actuators and different system times (especially with regard to the overall system time).

[0008] Preferably, the different sensor units are each connected to a common time synchronizer, in particular in the form of a “Precision Time Protocol” PTP server.

[0009] The time of each sensor unit is set directly by the shared time synchronizer, independent of the other sensor units. No communication between the different sensor units is required or provided for this purpose. Such a system is particularly accurate, reliable, and easily expandable with additional sensor units.

[0010] Preferably, the internal clocks of the different sensor units are synchronized using the “Precision Time Protocol” (PTP).

[0011] Such synchronization is particularly precise.

[0012] Preferably, each of the sensor units has a single connection, in particular in the form of an Ethernet and / or a fieldbus interface, wherein this single connection is used for both the synchronization of the times of the different sensor units and the output of measurement data.

[0013] This enables a particularly clear and compact overall design.

[0014] For example, fieldbus protocols, especially Ethernet-based protocols, preferably real-time fieldbus protocols such as Sercos III, EIP, EtherCAT, TSN (Time Sensitive Networking), Modbus TCP, and / or ProfiNet IO, are used for communication or data transmission. For example, Sercos III could be used as the primary fieldbus protocol for transmitting measurement data. This can be combined with EIP as a secondary fieldbus protocol for time synchronization. These two fieldbus protocols can also be combined with Modbus TCP as a third fieldbus protocol for commissioning applications. This allows three different fieldbus protocols to be used side by side (e.g., simultaneously) on the same fieldbus, i.e., on the same fieldbus hardware.

[0015] Preferably, the different sensor units are connected to a common evaluation unit, in particular in the form of a “personal computer”.

[0016] This enables the central collection and combined evaluation of the measurement data from the different sensor units.

[0017] The sensors in the sensor units are preferably optical sensors.

[0018] Optical sensors enable simple and reliable recording of a wide variety of information about the respective monitoring area.

[0019] The sensor units are preferably 2D or 3D laser scanners, preferably LiDAR sensors.

[0020] Such sensor units are particularly well suited for reliably recording precise spatial information about the respective surveillance area.

[0021] Preferably, the control units of the different sensor units are designed to control the associated actuators based on the synchronized time of the associated internal clock in a predefined phase offset relative to the actuators of the other control units.

[0022] In other words, the intended synchronization of the different actuators causes the different actuators to operate periodically in synchronism with a predefined phase offset. For example, the control unit of a first sensor unit controls a rotary actuator of a first sensor such that it points in a first predetermined direction every full second. The control unit of a second sensor unit controls a rotary actuator of a second sensor such that it points in a second direction, opposite to the first direction, every full second. This facilitates the combined evaluation of the measurement data from the different sensor units.

[0023] Preferably, the different sensor units are designed to output their measurement data with a time stamp.

[0024] This facilitates the combined evaluation of the measurement data from the different sensor units, especially given their synchronized time.

[0025] Preferably, the provided actuators are designed for purely rotational variation of the orientation of the associated sensors.

[0026] Such systems are structurally simple, space-saving, robust and reliable to implement.

[0027] A corresponding method for the synchronous control of actuators of at least two different sensor units comprises the synchronization of the internal time of the different sensor units, in particular by means of a "Precision Time Protocol" (PTP), and the control of the actuators of the different sensor units based on the thus synchronized time of the individual sensor units.

[0028] This results in the advantages described above.

[0029] The invention is described below purely by way of example with reference to the drawings. It shows: Fig. 1 schematically shows an exemplary system for collecting information on a given surveillance area according to the prior art; and Fig. 2 schematically shows an exemplary system for collecting information about a given surveillance area according to the present invention.

[0030] Accordingly Fig. 1, a conventional system 1 comprises two sensor units 3 that are connected, or at least connectable, to a common evaluation unit 5, in this case in the form of a "personal computer." In the example shown, the two sensor units 3 are each connected to an Ethernet switch 9 via a separate data line 7. This switch, in turn, is connected to the evaluation unit 5 via a separate data line 7.

[0031] Even if this is not explicitly shown here, each of the sensor units 3 comprises at least one sensor, at least one actuator for varying the orientation and / or position of the at least one sensor, and at least one control unit for controlling the at least one actuator.

[0032] The two sensor units 3 are connected to each other directly (i.e., not via the Ethernet switch 9) via a further provided synchronization line 11 ("IO port connection"). The two sensor units 3 can exchange a synchronization signal, particularly in the form of a control signal, via this synchronization line 11. Specifically, one of the two sensor units 3 (for example, the left one) can be configured as a "master sensor unit." The control unit of this "master sensor unit" can be configured as a "slave sensor unit" not only to output a control signal to its own actuator, but also to output a control signal to the control unit or actuator of the other sensor unit 3 (in this case, the right one).

[0033] The synchronization of the actuators of the different sensor units 3 is conventionally achieved through direct communication between the two sensor units 3, in particular via a dedicated synchronization line 11. A conceivable synchronization of the times of the internal clocks of the two sensor units 3 occurs separately or independently of the synchronization of the actuators. Specifically, in the above example, the control of at least the actuator of the "slave sensor unit" is independent of the internal time of the "slave sensor unit."

[0034] Referring to Fig. 2, in contrast, a system modified according to the invention does not require a synchronization line 11 between the different sensor units 3.

[0035] As in Fig.2, each of the sensor units 3 comprises a single connection 13 both for synchronizing their internal clocks and for outputting measurement data to the common evaluation unit 5.

[0036] To synchronize the internal clocks of the various sensor units 3, a common time synchronizer 15 in the form of a PTP server is connected to the Ethernet switch 9 via a single synchronization line 11 and, from there, to the various sensor units 3 via the respective data lines 7. Thus, only a single synchronization line 11 is required for any number of sensor units.

[0037] This time synchronizer 15 synchronizes the times of the internal clocks of the individual sensor units 3. The actuators of the different sensor units 3 are controlled based on the individual (synchronized) time of each of the sensor units 3 and are thus effectively independent of the control of the actuators and / or the time in the other sensor units 3. The synchronization of the actuators of the different sensor units is thus only indirectly achieved. However, it is naturally desirable that the time in each of the sensor units 3 correspond to a common system time defined by the time synchronizer 15.

[0038] A particularly precise synchronization of the internal clocks of the different sensor units 3 can be achieved via “Precision Time Protocol” (PTP).

[0039] An incorrect synchronization of the time of individual sensor units 3 has no negative impact on the function of the remaining sensor units 3 due to the independent control of the actuators of the different sensor units. Furthermore, it is possible to connect additional sensor units 3 to the Ethernet switch 9, to decouple sensor units 3 from the Ethernet switch 9 and / or to replace faulty sensor units 3 without having to make complex adjustments to the other components of the system.

[0040] The specific control of the actuators of each of the sensor units 3 depending on their respective time can be specified in the control unit of each of the individual sensor units 3. The different sensor units 3 are therefore preferably independent units that can operate completely independently of other sensor units and / or special input signals after a one-time setting or synchronization of their time and programming of their control unit.

[0041] The measurement data from the different sensor units 3 are then combined and evaluated in the evaluation unit 5. To facilitate the evaluation of the measurement data and to detect possible errors, the sensor units 3 can provide their respective measurement data with their personal time stamp. List of reference symbols 1 system for collecting information on a given surveillance area 3 Sensor unit 5 Evaluation unit 7 Data line 9 Ethernet switch 11 Synchronization line 13 combined connection 15 Time synchronizer / PTP server

Claims

[1] System for collecting information on a given surveillance area (1), the system (1) comprising: at least two sensor units (3), each having at least one sensor, at least one actuator for varying the orientation and / or position of the at least one sensor, and at least one control unit for controlling the at least one actuator; characterized by , that each sensor unit (3) comprises an internal clock and the times of the different sensor units (3) are synchronized with each other; and the control unit of each sensor unit (3) is designed to carry out the associated actuator(s) based on the synchronized time of the respective internal clock. [2] System (1) according to claim 1, wherein the different sensor units (3) are each connected to a common time synchronizer (15), in particular in the form of a "Precision Time Protocol" PTP server. [3] System (1) according to claim 1 or 2, wherein the internal clocks of the different sensor units (3) are synchronized by means of “Precision Time Protocol” (PTP). [4] System (1) according to one of the preceding claims, wherein each of the sensor units (3) has an individual connection (13), in particular in the form of an Ethernet and / or a fieldbus interface, wherein both the synchronization of the times of the sensor units (3) and the output of measurement data take place via this individual connection (13). [5] System (1) according to one of the preceding claims, wherein the different sensor units (3) are connected to a common evaluation unit (5), in particular in the form of a “personal computer”. [6] System (1) according to one of the preceding claims, wherein the sensors of the sensor units (3) are optical sensors. [7] System (1) according to one of the preceding claims, wherein the sensor units (3) are 2D or 3D laser scanners, preferably LiDAR sensors. [8] System (1) according to one of the preceding claims, wherein the control units of the different sensor units (3) are designed to control the associated actuators based on the synchronized time of the associated internal clock in a predefined phase offset relative to the actuators of the other control units (3). [9] System (1) according to one of the preceding claims, wherein the sensor units (3) are designed to output their measurement data with a time stamp. [10] System (1) according to one of the preceding claims, wherein the provided actuators are designed for purely rotational variation of the orientation of the associated sensors.

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