SENSOR DEVICE AND SENSOR SYSTEM FOR MONITORING A MACHINE

Description

[0001] The present invention relates to a sensor system for monitoring a machine, in particular a construction machine such as an excavator, a crane or a bulldozer, wherein the sensor system comprises a plurality of sensor devices, each comprising a gyroscope sensor unit and / or an accelerometer sensor unit, and a radio interface for data transmission via a radio signal.

[0002] Sensor devices with a gyroscope sensor unit and / or an accelerometer sensor unit are also referred to, for example, as rotation rate sensors, gyroscopic instruments, accelerometers, accelerometers, vibration sensors, oscillators, G-sensors, B-meters or inertial measuring units.

[0003] Such sensor devices and sensor systems are frequently used to monitor machine movements. The individual sensor devices of the sensor systems are typically arranged on different, mutually movable parts of the machine.

[0004] In this context, the term "radio interface" refers to all interfaces that enable wireless data transmission. Typical radio interfaces include RFID interfaces, WLAN interfaces, cellular interfaces, Bluetooth interfaces, and IrDA interfaces.

[0005] A sensor system for monitoring the movement of an excavator is known from US Patent 2018 / 0372498 A1. The sensor system comprises a plurality of inertial measuring units arranged on moving parts of the excavator. To determine the spatial position of the excavator and its individual parts, particularly the excavator bucket, the sensor data from the plurality of sensor devices are fused using a complex evaluation algorithm. To improve the accuracy of the sensor system, additional sensor devices of other types are preferably used, such as a GPS device, a radar device, or cameras.

[0006] WO 2018 / 236343 A1 discloses a sensor device comprising a gyroscope sensor unit or accelerometer sensor unit.

[0007] The scientific article "5G Position and Orientation Estimation through Millimeter Wave MIMO" reveals that 5G mobile communication technology can be used for position determination.

[0008] Against this background, the task arises to enable a relatively simple yet reliable monitoring of machine movements.

[0009] This problem is solved by a sensor system for monitoring a machine with the features of claim 1.

[0010] The sensor system according to the invention for monitoring a machine comprises a plurality of sensor devices described below.

[0011] According to the invention, each sensor device—in addition to the gyroscope sensor unit and / or the accelerometer unit and the radio interface—has a distance determination unit configured to analyze a received radio signal and, based on the radio signal, to determine an antenna distance to an antenna device from which the received radio signal was transmitted. For distance determination, for example, a radio signal propagation time and / or a radio signal amplitude can be evaluated. The determined antenna distance provides additional information about the spatial position of the sensor device without requiring any additional sensors.

[0012] The additional position information enables, when using several such sensor devices in the sensor system according to the invention, a relatively simple and simultaneously precise determination of the spatial position of individual machine parts relative to one another, and thus a relatively simple and reliable monitoring of a machine. Furthermore, the additional position information allows for a correction of measurement data from the gyroscope sensor unit and / or the accelerometer sensor unit, thereby enabling a particularly precise determination of the spatial orientation of the individual sensor device and thus of the corresponding machine part.

[0013] According to the invention, the sensor system further comprises a position determination unit, to which measurement data from the gyroscope sensor unit and / or the accelerometer unit, as well as the antenna spacing of at least two of the sensor devices, are provided. This unit is configured to determine position data for the at least two sensor devices based on the provided gyroscope sensor unit measurement data and / or accelerometer unit measurement data, as well as the provided antenna spacing. The determined position data indicates the spatial orientation of the at least two sensor devices relative to each other. The measurement data from the gyroscope sensor unit and / or the accelerometer unit generally indicate the spatial orientation of the respective sensor device.Based on the respective spatial orientation and antenna spacing of the sensor devices, the positional data can be determined—essentially via geometric relationships. This positional data specifies at least the distance between the corresponding sensor devices. Preferably, the positional data specifies relative 3D coordinates for the respective sensor devices, i.e., 3D coordinates in a machine reference system. If absolute 3D coordinates, i.e., 3D coordinates in the Earth reference system, are known for one of the sensor devices, the relative 3D coordinates can be easily converted into absolute 3D coordinates by the position determination unit or a downstream data processing unit.No additional sensor devices are required to determine the position data, so that the sensor system according to the invention enables relatively simple yet reliable monitoring of machine movements.

[0014] Preferably, the sensor system comprises at least one sensor device calibration unit configured to calibrate the gyroscope sensor unit and / or the accelerometer unit of at least one of the sensor devices based on the antenna spacing of at least two of the sensor devices. If the distance between two sensor devices and the antenna spacing of the two sensor devices are known, the spatial orientation of the two sensor devices can be determined using geometric relationships. The gyroscope sensor unit and / or the accelerometer unit of the corresponding sensor devices can then be calibrated such that the spatial position indicated by the measurement data of the gyroscope sensor unit and / or the accelerometer unit corresponds to the spatial position determined from the distances.To know the distance between the two sensor devices, a predefined machine state can be set, for example. Alternatively, the distance between the two sensor devices can also be determined using one or more additional sensor devices. The sensor system can include a single central sensor device calibration unit, which can be located, for example, in a central data processing device and is configured to perform the calibration of several, preferably all, sensor devices. Alternatively, it is also conceivable that each sensor device has a separate sensor device calibration unit, which is provided with the antenna spacing of at least one other sensor device, as well as the distance to that at least one other sensor device, and which is configured to perform only the calibration of the respective sensor device itself.The sensor device calibration unit enables the provision of particularly accurate and reliable measurement data and thus particularly reliable monitoring of a machine by the sensor device according to the invention.

[0015] Advantageously, the sensor system includes at least one centrifugal force compensation unit which is configured to: determine a rotation axis distance to a rotation axis of the machine to be monitored based on the position data for at least one sensor device; estimate a centrifugal force acting on the corresponding sensor device based on the rotation axis distance and the measurement data of the gyroscope sensor unit and / or the accelerometer sensor unit; and perform a correction of the measurement data of the gyroscope sensor unit and / or the accelerometer sensor unit of the corresponding sensor device based on the estimated centrifugal force.Specifically, the centrifugal force compensation unit is designed to correct the measurement data from the gyroscope sensor unit and / or the accelerometer unit in such a way as to compensate for measurement errors caused by the centrifugal force acting on the gyroscope sensor unit and / or the accelerometer unit. To enable a simple and reliable determination of the distance to the axis of rotation, one of the sensor devices is preferably designed to be mounted at a fixed distance from the machine's axis of rotation, so that the distance to the axis of rotation can be directly derived from the distance to this sensor device. Particularly preferred is a sensor device designed to be mounted directly on the machine's axis of rotation, such that the distance to this sensor device essentially corresponds to the distance to the machine's axis of rotation.The sensor system can comprise a single central centrifugal force compensation unit, which may, for example, be arranged in a central data processing device and is configured to correct the measurement data of several, preferably all, sensor devices. Alternatively, it is also conceivable that each sensor device has a separate centrifugal force compensation unit configured to calibrate only the respective sensor device itself. The centrifugal force compensation unit enables the provision of particularly accurate and reliable measurement data and thus particularly reliable monitoring of a machine by the sensor device according to the invention.

[0016] Preferably, the radio data interface of the plurality of sensor devices is each a 5G mobile communication interface, which on the one hand enables a relatively exact determination of the antenna distance due to the properties of the 5G radio signal and on the other hand enables a direct, relatively high-bandwidth internet connection of the sensor device without the need for additional radio base stations in the vicinity of the sensor device.

[0017] An embodiment of a sensor system according to the invention with a plurality of sensor devices according to the invention is described below with reference to the accompanying figures, wherein Figure 1 schematically shows a sensor system according to the invention with a plurality of sensor devices arranged on an excavator and a mobile communication antenna device, Figure 2 a schematic top view of the sensor system and the mobile communication antenna device Figure 1 shows, among other things, antenna distances between the individual sensor devices of the sensor system and the mobile communication antenna device, sensor device distances between the individual sensor devices of the sensor system and a rotation axis distance between a sensor device and a machine rotation axis, Figure 3 schematically depicts the structure of the sensor devices. Figure 1 shows, and Figure 4 schematically depicts the structure of a central data processing unit of the sensor system. Figure 1 shows.

[0018] Figure 1 Figure 1 shows an excavator 1 with an undercarriage 2, an upper carriage 3 rotatably mounted on the undercarriage about a pivot axis D, a boom 4 pivotally attached to the upper carriage 3, an excavator stick 5 pivotally attached to the boom 4 and an excavator bucket 6 pivotally attached to the excavator stick 5.

[0019] Figure 1further shows an antenna device 7, which in the present embodiment is a 5G mobile communication antenna device, i.e. is configured to send and receive mobile communication signals FS in accordance with the 5G standard.

[0020] A sensor system 10 according to the invention is arranged on the excavator 1 to detect the spatial position and orientation of the excavator 1 and the individual parts 2-6 of the excavator 1.

[0021] In the present embodiment, the sensor system 10 comprises four sensor devices 12_1-12_4, which are interconnected via a data transmission network 14. The first sensor device 12_1 is arranged on the superstructure 3, the second sensor device 12_2 is arranged on the boom 4, the third sensor device 12_3 is arranged on the excavator arm 5, and the fourth sensor device 12_4 is arranged on the excavator bucket 6. In the present embodiment, the first sensor device 12_1 is arranged directly on the axis of rotation D.

[0022] Figure 2 schematically shows a top view of the excavator 1 with the boom 4 and excavator stick 5 fully extended. Figure 2Figure 1 also schematically shows antenna distances AA_1-AA_4 between the individual sensor devices 12_1-12_4 and the antenna device 7, sensor device distances SA_12, SA_23, SA_34 between adjacent sensor devices 12_1-12_4, and, by way of example, a rotation axis distance DA_4 between the fourth sensor device 12_4 and the rotation axis D.

[0023] Figure 3 Figure 1 schematically shows the structure of the sensor devices 12_1-12_4. Since the sensor devices 12_1-12_4 are essentially identical in the present embodiment, the following are used for simplification: Figure 3 as well as generic reference numerals, i.e. reference numerals without index 1-5, are used in the following description, provided that they relate to all sensor devices 12_1-12_4 or any one of the sensor devices 12_1-12_4.

[0024] Each sensor device 12 comprises a wired interface 16 for connection to the data transmission network 14 and a radio interface 18 for data transmission via a radio signal FS. In the present embodiment, the radio interface 18 is a 5G mobile communication interface, i.e., configured to send and receive mobile communication signals in accordance with the 5G standard.

[0025] In the present embodiment, each sensor device 12 further comprises a three-axis gyroscope sensor unit 20, which is configured to detect rotational velocities along three spatial axes and to provide corresponding gyroscope sensor unit measurement data, and a three-axis accelerometer sensor unit 22, which is configured to detect accelerations along three spatial axes and to provide corresponding accelerometer unit measurement data.

[0026] Each sensor device 12 further comprises a computing unit 24, which is connected to the gyroscope sensor unit 20 and to the accelerometer sensor unit 22 and is configured to process the gyroscope sensor unit measurement data and the accelerometer sensor unit measurement data. The computing unit 24 comprises a distance determination unit 26, which is configured to analyze a radio signal FS received by the antenna device 7 and, based on the radio signal FS, to determine an antenna distance AA from the respective sensor device 12 to the antenna device 7.

[0027] In the present embodiment, the sensor system 10 further comprises a central data processing unit 28, which is arranged on the superstructure 3. The central data processing unit 28 is connected to all sensor devices 12 via the data transmission network 14 and has access to the gyroscope sensor unit measurement data of the gyroscope sensor unit 20, the accelerometer unit measurement data of the accelerometer unit 22, and the antenna spacing AA of each individual sensor device 12 determined by the distance determination unit 26.

[0028] The central data processing unit 28 comprises a position determination unit 30, which is configured to determine individual position data for each sensor 12 based on the measurement data and antenna spacing AA provided by the sensor devices 12. This position data specifies the spatial position of the sensor devices relative to each other. The position determination unit 30 is further configured to provide the position data to the individual sensor devices 12.

[0029] In the present embodiment, the individual position data include, among other things, sensor device distances SA of the respective sensor device 12 to the respective other sensor devices 12. The sensor device distance SA between any two sensor devices 12 can be easily determined via geometric relationships from the antenna distances AA of the two sensor devices 12 and the measurement data of the two sensor devices. For example, the distance SA between the antenna devices AA of the two sensor devices AA and the measurement data of the two sensor devices can be determined using the geometric relationships described in the diagram. Figure 2 The sensor device distance SA_12 shown in the diagram can be determined as follows: SA _ 12 = AA _ 1 2 + AA _ 2 2 − 2 ⋅ AA _ 1 ⋅ AA _ 2 ⋅ cos 180 ° − α _ 12 − β _ 12 where the angles α _12 and β_12 can be derived from the measurement data of the first sensor devices 12_1 and the measurement data of the second sensor devices 12_2. Similarly, all other sensor device distances SA between two sensor devices 12 can also be derived based on the antenna distances AA of the corresponding sensor devices 12 and the angles derivable from the measurement data of the corresponding sensor devices 12. α and β be determined.

[0030] Preferably, the position data further comprise relative 3D coordinates, i.e., coordinates related to a machine reference system, and / or absolute 3D coordinates, i.e., coordinates related to the Earth reference system, for the respective sensor device 12.

[0031] The central data processing unit 28 further comprises a sensor device calibration unit 32, which is configured to perform a calibration of the gyroscope sensor unit 20 and / or the accelerometer sensor unit 22 of one or more of the sensor devices 12 based on the antenna spacing AA of the sensor devices 12. If the sensor device spacing SA between two sensor devices 12 is known, for example, if a defined excavator state is set, the values ​​specified in the following can be used, for example: Figure 2 drawn angle α _12 and β _12 can be determined from the antenna spacing AA_1, the antenna spacing AA_2 and the sensor device spacing SA_12 as follows: α _ 12 = arccos AA _ 2 2 − AA _ 1 2 − SA _ 12 2 − 2 ⋅ AA _ 1 ⋅ SA _ 12 β _ 12 = arccos AA _ 1 2 − AA _ 2 2 − SA _ 12 2 − 2 ⋅ AA _ 2 ⋅ SA _ 12

[0032] Based on the specified angles α _12 and β_12 the gyroscope sensor unit 20 and / or the accelerometer sensor unit 22 of the first sensor device 12_1 and the second sensor device 12_2 can each be calibrated such that the angles derivable from the measurement data of the two sensor devices 12 α _12 and β _12 with the angles determined based on the antenna spacing AA and the sensor device spacing SA α _12 and β _12 agree. Similarly, the gyroscope sensor unit 20 and / or the accelerometer sensor unit 22 of all other sensor devices 12 can also be calibrated based on the respective antenna distances AA and the respective sensor device distance SA.

[0033] The central data processing unit 28 further comprises a centrifugal force compensation unit 34, which is configured to determine a rotation axis distance DA to the rotation axis D for the individual sensor devices 12, based on the position data determined by the position determination unit 30. Since the first sensor device 12_1 is arranged directly on the rotation axis D in the present embodiment, the rotation axis distance DA_1 of the first sensor device 12_1 is zero, and the rotation axis distances DA_2-DA_4 of the other sensor devices 12_2-12_4 correspond essentially to the sensor device distance SA between the respective sensor device 12 and the first sensor device 12_1.The centrifugal force compensation unit 34 is further configured to determine, based on the determined rotation axis distances DA and the measurement data of the individual sensor devices 12, a centrifugal force acting on the individual sensor devices 12 during a rotation about the rotation axis D, and to perform a correction of the gyroscope sensor unit measurement data and / or the accelerometer sensor unit measurement data of the individual sensor devices 12 based on the determined centrifugal force.

[0034] It should be explicitly noted that the functions of the central data processing unit 28 present in the present embodiment can also be fully or partially taken over by the computing unit 24 of one or more sensor devices 12. In particular, the position determination unit 30, the sensor device calibration unit 32, and / or the centrifugal force compensation unit 34 can also be included in the computing unit 24 of one of the sensor devices 12. Furthermore, it is also conceivable that several decentralized position determination units, sensor device calibration units, and / or centrifugal force compensation units are present, each performing the corresponding functions for only a subset of the sensor devices 12.For example, each sensor device 12 can have a separate position determination unit, sensor device calibration unit and / or centrifugal force compensation unit that performs the corresponding functions only for the respective sensor device 12 itself.

[0035] Furthermore, it should be explicitly noted that the sensor system according to the invention can, in principle, be used for monitoring any type of machine. In particular, the sensor system according to the invention can also be used for monitoring other construction machinery, for example, cranes or bulldozers. Reference symbol list

[0036] 1 Excavator 2 Undercarriage 3 Superstructure 4 Boom 5 Digger arm 6 Digger bucket 7 Antenna device 10 Sensor system 12 Sensor devices 14 Data transmission network 16 Wired interface 18 Radio interface 20 Gyroscope sensor unit 22 Accelerometer unit 24 Computing unit 26 Distance determination unit 28 Central data processing unit 30 Position determination unit 32 Sensor device calibration unit 34 Centrifugal force compensation unit A Antenna distances D Rotation axis D Rotation axis distances F Radio signal S Sensor device distances

Claims

1. Sensor system (10) for monitoring a machine (1), comprising: - a plurality of sensor devices (12), wherein each sensor device comprises: • a gyroscope sensor unit (20) and / or an acceleration sensor unit (22), • a radio interface (18) for data transmission via a radio signal, and • a distance determination unit (26) which is configured to analyze a received radio signal (FS) and, based on the radio signal (FS), to determine an antenna distance (AA) to an antenna device (7) from which the received radio signal (FS) was transmitted, and - a position determination unit (30) to which measurement data from the gyroscope sensor unit (20) and / or the acceleration sensor unit (22) as well as the antenna distance (AA) of at least two of the sensor devices (12) are provided, and which is configured to determine, based on the provided measurement data and antenna distances (AA), position data for the at least two sensor devices (12), wherein the position data indicate a spatial position of the at least two sensor devices (12) relative to one another.

2. Sensor system (10) according to claim 1, further comprising a sensor device calibration unit (32) which is configured to perform, based on the antenna distances (AA) of at least two of the sensor devices (12), a calibration of the gyroscope sensor unit (20) and / or the acceleration sensor unit (22) of at least one of the sensor devices (12).

3. Sensor system (10) according to claim 1 or 2, further comprising a centrifugal-force compensation unit (34) which is configured to: - determine, based on the position data for at least one sensor device (12), a rotational-axis distance (DA) to a rotational axis (D) of the machine (1) to be monitored, - estimate, based on the determined rotational-axis distance (DA) and the measurement data of the gyroscope sensor unit (20) and / or the acceleration sensor unit (22) of the corresponding sensor device (12), a centrifugal force acting on the corresponding sensor device (12), and - perform, based on the estimated centrifugal force, a correction of the measurement data of the gyroscope sensor unit (20) and / or the acceleration sensor unit (22) of the corresponding sensor device (12).

4. Sensor system (10) according to one of the preceding claims, wherein the radio interface (18) of each of the plurality of sensor devices (12) is a 5G mobile radio interface.