Patent Application
20220308557
The invention relates to a method and a system for synchronizing signals which are related to a technical system, in particular a machine and/or a machining process.
A high-precision temporal assignment of machine signals of internal and external sensor systems has not yet been possible. The current machine controllers and the machines themselves do not have an interface to enable superordinate signal processing with foreign signals.
EP 2 434 360 A1 discloses a method for movement control, wherein a first movement controller is connected to a second movement controller via a data bus, wherein first trace data of the first movement controller have a time stamp dependent on a global time and wherein second trace data of the second movement controller have a time stamp dependent on the global time, wherein the different trace data are linked by means of the time stamp.
Provision is thus made in the prior art to acquire data in a time-synchronized manner in order to be able to assign said data to one another later.
In an embodiment, the present disclosure provides a method for synchronizing signals which are related to a machine and/or a machining process, comprising recording data of a first data source to obtain a first signal track, recording data of at least one second data source, which is independent of the first data source, to obtain at least one second signal track, analyzing the first and second signal tracks based on previously known domain knowledge, and temporally connecting the first and second signal tracks.
Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:
In an embodiment, the present invention provides a method and a system using signal tracks of different data sources which are independent of one another and not temporally synchronized which can be correlated in terms of time.
In an embodiment, a method is provided for synchronizing signals which are related to a technical system, in particular a machine and/or a machining process, comprising the following method steps:
a) recording data of a first data source in order to obtain a first signal track,
b) recording data of at least one second data source, which is independent of the first data source, in order to obtain at least one second signal track,
c) analyzing the signal tracks based on previously known domain knowledge,
d) temporally connecting the signal tracks.
Data sources within the context of embodiments the invention may be for example measurement sources, sensors, controllers, etc. The recorded data may be measured data, that is to say measurement data. Furthermore, the data may be input variables or output variables of controllers. Drives of a machine may also constitute data sources. The data may accordingly be data of a drive. The data are recorded in a manner dependent on time. When the data are transmitted, they are transmitted as signals. The time profile of a signal is denoted as signal track or trace.
Domain knowledge globally describes the relationship of vibration excitation by machine components, axis dynamics, absolute position of the kinematic chain, possibly on the basis of the working area, actuators, for example valves, the operating state of a machining unit and noise emissions (sound waves). A laser, a punching apparatus, a press, a milling head, a saw, a drill and a water jet are possible, for example, as the machining unit. In machine tools, the machining units are moved in a particular axial direction via drives and possibly mechanical components connected in between, such as gears or gantries. This is often referred to in short form as an axis. All components, in particular axes, which contribute to a movement of a machining unit are called a kinematic chain. Furthermore, the domain knowledge includes the relationship between individual components, in particular the infrastructure, movement trajectories, machining processes and properties of all components involved.
When the signal tracks are temporally connected, the signal tracks can be temporally synchronized. In particular, the signal tracks can be assigned to a common time axis. In this way, faulty machine states, in particular slowly advancing defects, can be identified at an early stage. Furthermore, noise not originating from the machine or the axes can be suppressed. This improves the signal-to-noise ratio.
Even in the case of two different but expediently selected signal tracks, it is possible to clearly ascertain a temporal synchronicity from the previously mentioned domain knowledge. The more different signal tracks are available, the more reliable the analysis. Using the method according to an embodiment of the invention, synchronization in real time is conceivable, such that real-time evaluations on the basis of different data sources are possible. There are therefore new options for fault detection, fault diagnosis, state monitoring and predictive maintenance of overall systems. In particular, real-time fault diagnosis of overall systems is possible using differently running clocks. Interference sources can be suppressed based on known and expected signal patterns. The machining quality can be improved. False alarms and erroneous fault interpretations can be reduced. The method according to an embodiment of the invention can be implemented in a low-outlay and cost-effective manner since no additional outlay for time synchronization has to be operated. Furthermore, the method according to an embodiment of the invention can be scaled since it can be used for two and more different data sources. A system-wide use is also possible through cascading. Entire production plants or factory halls can therefore be diagnosed.
The signal tracks can be analyzed in a manner based on models. In particular, data values from signal tracks of different data sources can be assigned in terms of time in automated fashion based on domain knowledge in a manner based on models. Deviations, for example of sound pressure, ordinal numbers or mechanical resonances, lead to rapid fault detection, accurate fault identification and efficient fault elimination.
The signal tracks can be analyzed in particular by means of pattern recognition based on reference patterns. The reference patterns are known from the domain knowledge. By means of pattern recognition and pattern comparison, it is possible to overlap signal tracks from different data sources, in particular measurement sources, in terms of time. For example, the kinematic chain produces a known excitation pattern according to the movement profile of the actuators/axes. This excitation pattern can be found translated in various data recordings, in particular measurement recordings. In addition, mechanical resonance points of a machine can be excited, which are likewise shown in known vibration phenomena.
Particular advantages result when the signal tracks are recorded without the recordings being synchronized in terms of time. It is therefore not necessary to provide the signal tracks with a time stamp, as in the prior art.
At least one signal track of a data source inside the machine and at least one signal track of a data source outside the machine can be used. A data source inside the machine may be for example a controller inside the machine or a drive inside the machine. A data source outside the machine may be for example a camera or microphone using which the process which is performed on the machine is observed. When data sources inside and outside the machine are used, the diagnosis of a system and in particular the fault identification can be improved and simplified.
The periods in which the data of the data sources are recorded preferably overlap. It is therefore possible to harmonize the recorded signal tracks in terms of time and in particular to synchronize them after the analysis.
After the signal tracks have been synchronized, a time-frequency transformation, for example a Fourier transformation, can be carried out. The analysis and fault finding can therefore be simplified.
In order to improve the analysis result, provision is made for each signal track to comprise at least a predetermined number of data points. This number may depend on the frequency at which data points are detected. This may differ by many orders of magnitude. An NC controller controls in the millisecond range; the interpolation of the NC controller is even quicker. This is the frequency at which for example drives are activated, for example the motor current is adjusted in a regulation process in order to achieve a target speed. This would thus be around 1 kHz. Optical or acoustic sensors can measure in a wide frequency band. A camera, for example in the order of magnitude of 10 or 100 Hz, can possibly measure even higher for special applications. Photodiodes measure in the range of MHz or even GHz. Acoustic sensors resolve for example in the audible range, that is to say in the kHz range; however, there are also sensors in the MHz or GHz range. Two traces can therefore be connected to one another when a characteristic signal from the data sources involved can also be resolved and a corresponding number of measurement points has been recorded (depending on the measuring frequency or recording frequency).
The technical system, in particular the first or second data source, and thus the recorded data can be manipulated in a targeted manner, in particular mechanical resonance points can be excited in a targeted manner. Input variables, for example from controllers, can be manipulated in a targeted manner. When input variables are manipulated in a targeted manner, a specific result or behavior in the recorded data is expected. It is then possible to analyze whether the recorded signal exhibits the expected behavior. Based on this analysis, it is possible to infer possible fault sources.
Each data recording can be time-normalized per se and contain the Nyquist criterion. In this way, the reliability of the analysis can be improved.
Based on the analyzed signal tracks, it is possible to carry out fault identification, fault diagnosis, state monitoring and/or predictive maintenance.
Applications for the method according to an embodiment of the invention are for example machine diagnosis, such as for example axis diagnosis, process diagnosis and diagnosis of other, external causes. Embodiments of the invention permit evaluation of aggregated and correlating data sources for early identification of imminent faults.
Also falling within the scope of the invention is a system for synchronizing signals, comprising a first data source which delivers a first signal track and a second data source which delivers a second signal track, an analysis device to which the signal tracks are fed and which is connected to a storage device or comprises same, in which storage device domain knowledge is stored, wherein the analysis device is set up to temporally connect the signal tracks based on the stored domain knowledge. Such a system can be used to temporally synchronize signal tracks which originate from different data sources and which do not have a time stamp. It is therefore possible to analyze the system and where necessary identify faults. At least one data source is preferably arranged inside the machine and at least one data source is preferably arranged outside the machine.
Further features and advantages of the invention are evident from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which shows details essential to the invention, and from the claims. The features shown here are to be understood as not necessarily to scale and are illustrated in such a way that the characteristic features according to the invention can be made significantly more visible. The various features can be realized in each case individually by themselves or as a plurality in any desired combinations in variants of the invention.
The schematic drawing illustrates exemplary embodiments of the invention and these are explained in more detail in the description which follows.
In the exemplary embodiment shown, a further second data source 5 is arranged outside the machine. For example, the second data source 5 may be a microphone or a camera. The data of the data source 5 are likewise recorded and likewise transmitted to the analysis device 4 as a signal track. The data recording of the data of the data sources 3 and 5 is carried out independently of one another. In particular, it is carried out without a synchronized time stamp of the data sources 3, 5 with the analysis device 4 and with one another.
What is known as domain knowledge is stored in the memory 6. Said domain knowledge may be previously recorded measurement data, simulation results, historical data of the machine 2 itself, data from other machines, etc. The analysis device 4 can access the domain knowledge. The signal tracks of the data sources 3, 5 are analyzed based on the domain knowledge and temporally connected to one another. The result can be displayed on a display device 7.
The method according to an embodiment of the invention is intended to be explained based on
In
As a result of the fact that the signal tracks were initially related to one another in terms of time, it was possible to harmonize the spectra ascertained from the signal tracks. No peak at the frequency 566.4 Hz has been ascertained in the torque-forming currents of the other axes. It was thus possible to exclude the fact that the fault which caused the interference was caused by one of the other axes. On account of the domain knowledge, it is known where peaks at certain frequencies originate. It is therefore possible to ascertain where a fault is present and to eliminate this in a targeted manner on account of the signal tracks recorded.
The graph of
It can be seen here that the signal tracks on account of excitations through the motor and on account of excitations on account of a toothed engagement of the pinion and toothed rack and also signal tracks which have been recorded by means of a microphone have been related to one another in terms of time in order to obtain information about the behavior of the machine. It can be seen that resonances arise at 550 Hz for different speeds of the X axis. This suggests that the resonances are attributed to a structural element of the machine and not to the drive (motor).
In the flow diagram of
While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 135 493.5 | Dec 2019 | DE | national |
This application is a continuation of International Application No. PCT/EP2020/087165 (WO 2021/123265 A1), filed on Dec. 18, 2020, and claims benefit to German Patent Application No. DE 10 2019 135 493.5, filed on Dec. 20, 2019. The aforementioned applications are hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2020/087165 | Dec 2020 | US |
| Child | 17840644 | US |
