Frequency Converter as a Node for Edge Computing of Big Data, Related to Drive Efficiency, in Industrial Internet of Things
Round 1
Reviewer 1 Report
The title is not compatible with the content of this article.
The authors should give more detail on the following points:
1) What type of algorithm was used in this study?
2) Where is the notion of big data in this study? what data is processed and used?
3) The authors focus on the various techniques known in the field of control of electric machines. what is the originality?
4) How does this study relate to the IOT field?
5) The references are poor.
Author Response
1) What type of algorithm was used in this study?
There were no algorithm developed in the study.
The researchers tried to find a way of computing on the edge (directly in the source) the big data produced in the frequency converter, providing factors useful in the drive management, which can be communicated in the IIoT directly from the drive controller.
The analysis of data available in the drive controller was the basis for trying to define formulas transforming the data to the drive efficiency indicators. The study method was a quantitative comparison of the KPIs computed in the defined way to find out if they correctly show differences in efficiency of the drive operated with various control algorithms in various conditions (load, dynamics, etc.).
Proper texts were added to the Introduction as well as Materials and Methods chapters.
2) Where is the notion of big data in this study? what data is processed and used?
Data produced by the drive controller in every millisecond, which could be processed on the edge in the proposed way, is big.
3) The authors focus on the various techniques known in the field of control of electric machines. what is the originality?
The proposed indicators which can be easily computed in the frequency converter, making it an edge device and IIoT smart sensor, make the work original.
4) How does this study relate to the IOT field?
There are extra text and figure added in the Discussion and Conclusions chapters in the revision process, which can emphasise the relation between the developed and studied KPIs producing methods and transforming the frequency converter into an IIoT device.
5) The references are poor.
Correct, however there is few publications describing the drive control modes studied by us – their detail are protected by device suppliers. We also developed our own indicators, so it was difficult to base on other publications in this area.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors present a real-time measurement system of the efficiency of electric motors, by reading the data captured by a frequency converted attached to the engines. Several signals and voltage/current measurements are shown in the paper for different forms of control of the motors, highlighting their differences.
The authors present this work as a contribution to edge computing and data processing at the edbe. However:
1) No actual processing is performed at the frequency converter, so the computing capability at the edge is not used.
2) Accessing measurements in real-time cannot be considered as a form pf edge application, or edge computing. If any, as a sophisticated sensor.
3) Most of the examples and signals registered during the measurements report well known facts in mechanical/electrical engineering, so their novelty is reduced.
I would suggest to reconsider the focus of this paper, since inscribing the work in the de computing field seems not appropriate.
Author Response
1) No actual processing is performed at the frequency converter, so the computing capability at the edge is not used.
The researchers tried to find a way of computing on the edge (directly in the source) the big data produced in the frequency converter, providing factors useful in the drive management, which can be communicated in the IIoT directly from the drive controller.
The research led to a development of a concept of a system, where the KPIs computed in the studied way can be applied, which is after revision presented in the Figure 12.
Proper texts were added to the Introduction as well as Materials and Methods and Discussion and Conclusions chapters.
2) Accessing measurements in real-time cannot be considered as a form pf edge application, or edge computing. If any, as a sophisticated sensor.
Correct, however there is no word about real-time accessing. By applying the studied computational formulas in the frequency converter, the operational Big Data is processed directly in the drive controller (on the edge), allowing it to be the IIoT smart sensor as well – producing data useful in Internet-based management systems.
3) Most of the examples and signals registered during the measurements report well known facts in mechanical/electrical engineering, so their novelty is reduced.
The analysis of data available in the drive controller was the basis for trying to define formulas transforming the data to the drive efficiency indicators. The study method was a quantitative comparison of the KPIs computed in the defined way to find out if they correctly show differences in efficiency of the drive operated with various control algorithms in various conditions (load, dynamics, etc.).
The proposed indicators which can be easily computed in the frequency converter, making it an edge device and IIoT smart sensor, make the work original.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The article does not present any originality.
Author Response
The last revision addresses the problem of originality of the paper. To state it, the authors added the following content:
- an innovative way of considering the frequency inverter – presented in the Introduction chapter,
- the significance of the data analyses performed within the research in testing out the hypothesis – included in the Materials and Methods chapter,
- the importance of the presentation of gathered data in figures and tables in the development of the data selection and analysis processes – added in the Discussion chapter,
- the explanation of the developed processes application potential – pointed out in the Conclusions chapter.
Author Response File: Author Response.pdf
Reviewer 2 Report
The authors have introduced minimal changes in this revised version, but the motivation for using the system as a computing node is somewhat more clear now. The computing capabilities introduced into the system are straightforward and are more similar to a sensing application, in my opinion. Nevertheless, the work is well presented and might be interesting for practitioners in the field.
Author Response
The last revision addresses the problem of originality of the paper. To state it, the authors added the following content:
- an innovative way of considering the frequency inverter – presented in the Introduction chapter,
- the significance of the data analyses performed within the research in testing out the hypothesis – included in the Materials and Methods chapter,
- the importance of the presentation of gathered data in figures and tables in the development of the data selection and analysis processes – added in the Discussion chapter,
- the explanation of the developed processes application potential – pointed out in the Conclusions chapter.
Author Response File: Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
I wanted to reject this article but I give the authors another chance.
The article is not well organized. The title does not match the content of the article.
The originality of this article is not well presented.
In figure 7 (d and e) there is a lot of ripple on the current waveform, what are the test conditions? why such ripple on the current waveform?
Figure 8 requires further analysis.
The references are very poor, this part needs to be improved.
The authors can use the two articles below to improve their article.
- Design of RST and fractional order PID controllers for an induction motor drive for electric vehicle application, IET Digital Library.
- Robust RST controller design for induction motor drive for electric vehicle application, 2014 First International Conference on Green Energy ICGE 2014
Reviewer 2 Report
This paper advocates the use of a frequency converter as a measurement node for edge computing, in that the device is able to take real-time measurements of an electric engine and these measurements can be used to detect some anomalous behavior, to control the drive or to monitor its operating conditions. The paper is clearly written, the results are clear and well presented, and the motivation is easy to follow, but the paper has a number of issues too:
1) The significance of this research should be better motivated. Indeed, the frequency converter can take measurements of the device which contain a lot of information, but this does not convert the FC into an edge-capable node automatically. Is the FC able to perform some computation or decision on the basis of the observed behavior? Can the FC act on the engines and control their current operating conditions? What sort of computations can the FC conduct? These questions are not answered nor addressed in the paper, so the title fails to be fulfilled here.
2) Overall, the paper shoes a comprehensive set of measurements taken out from the real devices, but no actions or decisions taken to control, modify or correct some (undesirable) performance. Therefore, if only for gathering operating variables and not for actuate on them, what is the ultimate use of the FC? This should be better motivated and discussed by the authors, in addition to collecting performance plots.
3) Some minor corrections are necessary in the manuscript. Tables 7 & 14 show two columns labeled NAN; equation (1) contains a tiny value (10^{-\infty} only for purposes of numerical computation which should be removed from the definition.
As a general comment, the main issue with this work is its lack of definiteness. In its current presentation, it does not go beyond the taking of a set of measurements, showing that this is possible with some standard measurement device. However, this is possibly not enough as research.
