Round 1

Reviewer 1 Report

This paper extends the degree of automation and efficiency of the production lines using autonomous robotic systems equipped with manipulators and visual servoing systems. In this paper, the proposed method is used at the laboratory level. The goal of this project is to meet the actual industry needs. The discrepancy between applying this technique at the laboratory level and the actual industry can be analyzed. The method to extend from the laboratory level to the actual industry can be discussed.

Author Response

Dear Referee,

We really appreciate and we wish to thank for careful review of our paper, and for the comments, corrections and suggestions that ensued to improve our paper. All comments were carefully considered in this revision and we hope that the paper has reached the journal’s requirements.

Please find below your comments with the requested answers and actions done:

Comment

This paper extends the degree of automation and efficiency of the production lines using autonomous robotic systems equipped with manipulators and visual servoing systems. In this paper, the proposed method is used at the laboratory level. The goal of this project is to meet the actual industry needs. The discrepancy between applying this technique at the laboratory level and the actual industry can be analysed. The method to extend from the laboratory level to the actual industry can be discussed.

Response

Thank you for the suggestion, we would like to mention that several paragraphs, passages and text fragments were added (see revised version of the paper). However, as we mentioned in the discussion and conclusions sections, the research aimed at a dual purpose, one educational and another as close as possible to the real industry world.

The educational goal aims to familiarize the system designer with everything that defines new industry architecture, including Industry 4.0 concepts and to try to improve the actual technology design with the integration of all new, state of the art aspects of production and engineering, including smart factories, Industrial Internet of Things, smart manufacturing and advanced manufacturing.

Regarding correspondence with the real industrial world, most manufacturing industrial technologies are served by robotic systems that have a fixed position (robotic manipulators). Through this study, we extended the degree of automation and efficiency of these production technologies using mobile robotic systems equipped with manipulators and visual servoing system.

Because many of the hardware and software subsystems presented in this paper work were designed by us at the laboratory level, we approach a more descriptive style to be as explicit as possible.

Following A/D/RML research ideas and designs are of own concepts:

• Flexible cell (FC) equipped with ABB IRM, with SIEMENS 1200;
• ABB IRM programming to perform flexible cell functions;
• Interactive graphic programming of HMI;
• Coupling and connecting the flexible cell to the Hera&Horstmann mechatronics line;
• PLC programming, so that the whole system performs the functions established by the set of assumptions;
• Design and control of autonomous robotic system equipped with mobile visual servoing to be able to perform precision movements and positioning on the recovery and storage of disassembled components.

The contributions, mentioned above, were added at the end of the conclusions chapter.

Modeling of the system using hybrid Petri Nets, in which A/D/RML will be a hybrid SHPN model having the Hera&Horstmann mechatronics line with discrete states and transitions and the ARS subsystem with continuous dynamics, is presented in the paper and represents only an intermediate stage. Task scheduling and the simulation of the model is briefly discussed, which tackle the compatibility between the two subsystems.

The real-time research and implementations is followed and SCADA environment is developed, so that the entire system works autonomously, fully automated to meet the actual industry requirements.  By using new emerging technologies like SCADA, IIOT and MQTT protocol for Cloud interface, this also increases the degree of integration and compatibility with the actual industry needs. Moreover by using the smart and autonomous technologies to operate in a seamless and secured way this meets also the new requested requirements standards of Industry 4.0.

Thank you very much in advance for reviewing my paper and for your cooperation!

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Researchers

Thanks for the valuable manuscript. It is a well written technical paper. There are some points needed to be addressed to improve the quality. Please kindly find my comments as follows:  

·         As I can see the manuscript’s type is Article so the theoretical contributions should be stressed in detail in Introduction.

·         What is the novelty of your approach? This part needs to be written in detail with clear statements after the literature review section.

·         Although it is mentioned that the SCADA system is there but it is important to mention the control strategy utilized by the software. What is the control strategy? Is it Agent Based control? Is it AI based control?...There is no need to go deep into the formulation but you need to clearly state that what the control strategy has been adopted.

·         How the robotic arm will perform in the presence of noise? I suggest to review the following works to have more clear overview on the raised points:

DOI: 10.1155/2020/8564140

DOI: 10.3390/su11051454

DOI: 10.3390/su10093031

·         The importance of the problem considered in this paper should be further addressed.

The directions to further and improve the work should be added as future recommendation section after ‘conclusions’ section. 

Author Response

Dear Referee,

We really appreciate and we wish to thank for careful review of our paper, and for the comments, corrections and suggestions that ensued to improve our paper. All comments were carefully considered in this revision and we hope that the paper has reached the journal’s requirements.

Please find below your comments with the requested answers and actions done:

1.a. Comment 1

As I can see the manuscript’s type is Article so the theoretical contributions should be stressed in detail in Introduction.

1.b. Response 1

The contributions we claim refer to both the hardware design part and the software part.

Many elements of the system were designed by us in the laboratory, so we mention:

• Flexible cell (FC) equipped with ABB IRM, with SIEMENS 1200 PLC;
• ABB IRM programming to perform flexible cell functions, assembly, disassembly and repair with cylinder replacement;
• Interactive graphic interface programming of HMI KTP700;
• Coupling and connecting the flexible cell to the Hera&Horstmann mechatronics line;
• PLCs programming (SIEMENS S7 1200 and S7 300), using TIA Portal V.15, so that the whole system performs the functions established by the set of assumptions, using TIA Portal V.15;
• Design and control of autonomous robotic system (ARS) equipped with mobile visual servoing to be able to perform precision movements and positioning on the recovery and storage of disassembled parts. ARS can be assimilated to a cyber physical system.

We reorganized the structure of the Introduction section in order to give reader a better overview of the research idea, especially the novelty of the paper and the contributions, mentioned above were briefly discussed. Therefore, we mentioned the major points from this paper work and the novelty of this approach- what brings new, we explained in detail the important benefit of this implementation of a flexible assembly line assisted by autonomous robotic system at the laboratory level, we explain the dual purpose of this manuscript, an educational one and second the implementation of multifunctional flexible manufacturing technology in a laboratory system, to be as close as possible to the real industrial world.

2.a. Comment 2

What is the novelty of your approach? This part needs to be written in detail with clear statements after the literature review section.

2.b. Response 2

Thank you for the suggestion, we would like to mention that major points from this  paper work  that represented concept, methodologies and algorithms, provides new research ideas, knowing the fact that organizations often depend on market and technology research for new product development to stay competitive within the industry.

As a result of your suggestion, we added extra paragraphs, passages and text fragments in the paper, after the literature review section, in order to underline the new product features and the major phases of research which brings new ideas for the flexible assembly technology designs. Most manufacturing industrial technologies are served by robotic systems that have a fixed position (robotic manipulators), therefore, we argue that the important benefit of this research is the manufacturing technology implementation at the laboratory level, which works in real time and which if used industrially, in the real world, would increase efficiency, reliability and precision. From our knowledge, there are no multifunctional flexible manufacturing technologies in the industrial world served by autonomous robotic systems, which can perform component recovery or product repair, operating fully automated and to meet the requirements and norms of Industry 4.0.

3.a. Comment 3

Although it is mentioned that the SCADA system is there but it is important to mention the control strategy utilized by the software. What is the control strategy? Is it Agent Based control? Is it AI based control?...There is no need to go deep into the formulation but you need to clearly state that what the control strategy has been adopted.

3.b. Response 3

The presented control strategy is a hybrid structure which consists of two interconnected systems, features both distributed and centralized topology, with specific tasks for all the manufacturing stages. On top of that, for controlling assembly/disassembly and repair for flexible manufacturing line the algorithm architecture is agent-based control in which the PLC from the flexible cell station, acts as a main control unit or “master PLC“ for centrally manage both subsystems of the complete A/D/RML, by means of synchronization and confirmation signals. Therefore master PLC synchronizes with subsystems PLC's to automate their respective areas and for operating and control locally their components, after confirmation from the main control unit is applied.

In this control setup every subsystem or slave from the A/D/RML assisted by ARS technology as presented in Chapter 2.3.1, is considered to be an agent which includes a separate control, managed by an agent software synchronized with master PLC.

The master PLC includes the main IO field of the system and related resources.

The assembly/disassembly and processing/reprocessing routines are managed strictly through Siemens S7-1200 PLC from the FC, which acts as a Central System, communicating and synchronizing with the other subsystems and their agent software entities and handles visualization and manage the overall operation of the complete A/D/RML

4.a. Comment 4

How the robotic arm will perform in the presence of noise?

4.b. Response 4

The robotic arm is equipped with an anti-collision map tested on the simulation stage, the robotic arm moves until the object detected is in the center, and if the time needed to get to the object is higher than expected or a supplementary torque is detected, for example an obstacle has been placed in the trajectory, the robotic arm returns to the home position and notifies the user that the trajectory path following has been unsuccessful.

A more sophisticated approach has not been implemented, as the deviations that appear are just on the x or y axis due to the complex autonomous robot transportation errors.

5.a. Comment 5

I suggest to review the following works to have more clear overview on the raised points:

DOI: 10.1155/2020/8564140

DOI: 10.3390/su11051454

DOI: 10.3390/su10093031

5.b. Response 5

Thank you for your recommendations, I found this articles very interesting and certainly some of the key outcomes from these papers are in the same research area where the current manuscript is. A novel suite of complementary analytical tools and methods are well presented and tackled, for successful manufacturing system and for identifying issues to increase the production line performance and efficiency.

Unfortunately in our manuscripts the time-study optimization problem and performance evaluation is less addressed but provides useful ideas for continuing research in this topic to check the current line efficiency whether it is or not at its optimum condition due to blockages and idle times.

On the other hand the manufacturing systems control strategy presented in these articles as a multi-agent based control is also addressed in our paper (is also discussed in one of your previous comments).

6.a. Comment 6

The importance of the problem considered in this paper should be further addressed.

The directions to further and improve the work should be added as future recommendation section after ‘conclusions’ section.

6.b. Response 6

Thank you for the suggestion, we added extra paragraphs to underline the main key points of this paperwork importance, as well as discussing present and new arguments, directions and recommendations for the next study at the end of the Conclusions section.

The paper proposes an extension both in hardware as well in software, which allows the implementation of a flexible and multifunctional technology, able to manufacture different products and to recover components or to repair products that do not correspond to the desired quality. All these functionalities are made with high precision due to the integration of an industrial robotic manipulator, a complex autonomous system that is equipped with a mobile visual servoing system and a multi-agent algorithm and communication structure between the flexible cell and the mechatronics line that allows synchronizations of the requested operations.

The presented research is still in progress, it is place for further improvements and fine tunings, we argued that the important benefit and contribution of this research is the implementation of manufacturing technology assisted by autonomous robotic systems at the laboratory level, which works in real time and which if used industrially, in the real world, would increase efficiency, reliability and precision. Therefore the final purpose is to develop a fully automated multifunctional flexible manufacturing technology without the intervention of the human operator, for a predefined production volume, with the recovery of components of bad assembled products which did not pass the quality tests and integrating new emerging technologies like SCADA, IIOT and MQTT protocol for Cloud interface.

This technology can be extended further to real industry, where high accuracy and positioning is needed. Multispectral video sensors, providing new imaging capabilities without adding size or weight can be used, in order to reduce errors in reflectance estimation, for remote sensing on production line inspection or workparts validation and quality check, to more strongly demonstrate the reliability, increase speed and efficiency by integrating with the ARS of the presented manufacturing line technology, especially for recovery and accurate positioning operations.

The presented control architecture is a hybrid structure, multi agent-based control.  Unlike using this control strategy, the system can be enhanced with artificial intelligence (AI), which is a combination of situational awareness and creative problem solving, to identify and fix potential assembly problems much faster and can diagnose and prevent further issues by directly alerting through SCADA systems when anomalous units are identified.

Additionally, we will also focus on the time study system performance evaluation and optimization methods of the complete production process to improve the performance and better product quality and also implementation of robust control architectures to uncertainties will be considered, for all systems: autonomous robotic system, flexible cell and mechatronics line.

Thank you very much in advance for reviewing my paper and for your cooperation!

Author Response File: Author Response.docx

Reviewer 3 Report

I find this a very good manuscript which deserves publication after a few revisions.

I would suggest to remove/replace the keywords which are already written in the title.

I would suggest to better organize the introduction as it has to give to the reader a clear overview of the state of the art. The introduction in its present form often appears an anticipation of materials and methods. The introduction should describe the state of the art and, only at the end, the aim of the study. The citation numbers are not evenly distributed throughout the text and are often grouped in a couple of lines.

I would suggest to organize this manuscript in the conventional way: introduction, materials and methods, results and discussion, conclusions

In the discussion and in the conclusions the future application of this system in the industry should be discussed.

Thank you and good luck for your article.

Author Response

Dear Referee,

We really appreciate and we wish to thank for careful review of our paper, and for the comments, corrections and suggestions that ensued to improve our paper. All comments were carefully considered in this revision and we hope that the paper has reached the journal’s requirements.

Please find below your comments with the requested answers and actions done:

1.a. Comment 1

I would suggest to remove/replace the keywords which are already written in the title.

1.b. Response 1

We thank the Reviewer for this comment, we corrected this issue by removing the words already written in the title. We kept only the most important terms, main concepts, relevant for this research topic. The proposed keywords section, now, will be:  programmable logic controller; modbus TCP; open platform communications; visual servoing system; wheeled mobile robot; industrial robotic manipulator;

2.a. Comment 2

I would suggest to better organize the introduction as it has to give to the reader a clear overview of the state of the art. The introduction in its present form often appears an anticipation of materials and methods. The introduction should describe the state of the art and, only at the end, the aim of the study. The citation numbers are not evenly distributed throughout the text and are often grouped in a couple of lines.

2.b. Response 2

We appreciate your suggestion and indeed we reorganized the structure of the introduction section in order to give reader a better overview of the research idea, especially the novelty of the paper.

As a result of your suggestion, we added extra paragraphs, passages and text fragments in the introduction section, in order to underline the new product features and the major phases of research which brings new ideas for the flexible assembly technology designs. We payed extra attention to references citations when reorganizing this section to be even distributed throughout the entire section.

The aim of the study is moved at the end of the Introduction and the extra details regarding hardware design and concept were moved to Materials and Methods section.

 Therefore, we mentioned the major points from this paper work and the novelty of this approach, what brings new, we explained in detail that the important benefit is the implementation of a flexible assembly line assisted by autonomous robotic system at the laboratory level, which works in real time and the correspondence with the real industrial world, which we argued that would make the technologies much more efficient, reliable and precise. The discrepancy between applying this technique at the laboratory level and the actual industry, compatibility with the actual industry needs is analyzed further. Through this study, we extended the degree of automation and efficiency of these production technologies using mobile robotic systems equipped with manipulators and visual servoing system. To our knowledge, there are no multifunctional flexible manufacturing technologies in the industrial world served by autonomous robotic systems, which can perform component recovery or product repair, operating fully automated and to meet the requirements and norms of Industry 4.0.

3.a. Comment 3

I would suggest to organize this manuscript in the conventional way: introduction, materials and methods, results and discussion, conclusions

3.b. Response 3

We revised the structure of the manuscript according to MDPI Inventions layout regulations, which is as following:

1. Introduction
2. Materials and Methods
3. Results
4. Discussion
5. Conclusions
6. Patents (if needed)

Moreover, we payed extra attention to Figures and references citations when reorganizing the structure of the paper.

4.a. Comment 4

In the discussion and in the conclusions the future application of this system in the industry should be discussed.

4.b. Response 4

Thank you for the suggestion, we added extra paragraphs in the discussion and conclusion section, to underline the main key points of this paperwork importance as well as discussing present and new arguments, directions and recommendations for the next study.

We argued that the important benefit is the design, simulation and implementation of a fully automated assembly line. The work is still in progress, it is place for further improvements and fine tunings, having as final objective the operation of the technology completely automatically for a given production volume.

This technology can be extended further to real industry, where high accuracy and positioning is needed. Multispectral video sensors, providing new imaging capabilities without adding size or weight can be used, in order to reduce errors in reflectance estimation, for remote sensing on production line inspection or workparts validation and quality check, to more strongly demonstrate the reliability, increase speed and efficiency by integrating in the ARS of the presented manufacturing line technology, especially for recovery and accurate positioning operations.

The presented control architecture is a hybrid structure, multi agent-based control.  Unlike using this control strategy, the system can be enhanced with artificial intelligence (AI), which is a combination of situational awareness and creative problem solving, to identify and fix potential assembly problems much faster and can diagnose and prevent further issues by directly alerting through SCADA systems when anomalous units are identified.

Additionally, we will also focus on the time cycle system optimization and also implementation of robust control architectures to uncertainties will be considered, for all systems: autonomous robotic system, flexible cell and mechatronics line.

Thank you very much in advance for reviewing my paper and for your cooperation!

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Thanks for the revision, all points have been addressed.