Here are my review comments on the article Swarm Robotics.
Comment of Reviewer - Overall definition
I think this is fine, except for the third sentence.
"The design of robot swarms is guided by swarm intelligence principles, which promote the realization of systems that are fault tolerant, scalable and flexible. "
This doesn't make sense, since swarm intelligence principles are in essence as observed/deduced from biology, whereas the 2nd part of the sentence is about possible engineering benefits. I recommend to split the sentence, i.e.
"The design of robot swarms is guided by swarm intelligence principles. Such principles may lead to engineering benefits including artificial systems that are fault tolerant, scalable and flexible. "
The phrase was restructured as suggested. Note that we kept "promote the realization" as we think that "may lead to" is too weak and does not convey the fact that the swarm intelligence principles are followed to obtain these engineering benefits; "may lead to" seems to convey more the idea that the engineering benefits are just an uncontrolled/unwanted effect.
Comment of Reviewer - Characteristics
Recommend removal of 'large and', so "A robot swarm is a highly redundant group of..." This avoids problems of how robots many is large, etc?
Recommend replacing the work results with 'emerges', in the final sentence of this para.
Reworded as suggested.
Comment of Reviewer - Desirable properties
Recommend replacing 'are deemed to' with 'may' in the first sentence.
Recommend adding the word 'ideally' in 1st sentence of 3rd para, i.e. "...in their group size: ideally the introduction of..."
Regarding the first comment, we kept "are deemed to", for the same reason explained in the answer to 1.
We followed the second comment as suggested.
Comment of Reviewer - Potential applications
Recommend rewording 2nd sentence in 2nd para:
Therefore, a solution that is fault tolerant is necessary, ... as Therefore, a fault-tolerant approach is required, ...
Reworded as suggested.
Comment of Reviewer - Current Research Axes
Since you start this section by referring the reader to Brambilla et al, you *must* ensure that this paper is accessible to all and not behind a paywall, preferably with a link from here, to a pdf.
Unfortunately, we cannot ensure that the paper is open access. Therefore, we rephrased the way the paper is introduced.
Comment of Reviewer - Analysis
Recommend remove 'very' from 2nd line of 2nd para, i.e. "...due to the large number of robots involved"
In the section on Macroscopic models section you might consider adding a reference to Liu W and Winfield AFT, 'A Macroscopic Probabilistic Model for Collective Foraging with Adaptation', International Journal of Robotics Research, 29 (14), 1743-1760, 2010. Since this work is one of very few examples of successfully modelling an *adaptive* swarm.
Done, thanks for the suggested literature.
Comment of Reviewer - Collective behaviours
Although you briefly mention human-swarm interaction, I *strongly* recommend that this merits a section of its own within Current Research Axes. I believe one of the important missing elements in swarm robotics in human-swarm interaction -since even though the indvidual robots may be autonomous the swarm, there still needs to be an effective means for commanding, monitoring and intervening (should things go wrong) with the swarm as a whole, and recommend you highlight the excellent work of both Vaughan et al, and Gambardella et al. I.e.
Shokoofeh Pourmehr and Valiallah Mani Monajjemi and Richard T. Vaughan and Greg Mori. "You two! Take off!": Creating, modifying and commanding groups of robots using face engagement and indirect speech in voice commands Proceedings of the IEEE International Conference on Intelligent Robots and Systems (IROS'13), Tokyo, Japan 2013
A. Giusti, J. Nagi, L. Gambardella, S. Bonardi, G. A. Di Caro, Human-Swarm Interaction through Distributed Cooperative Gesture Recognition 7th ACM/IEEE International Conference on Human-Robot Interaction (Video Session) (HRI), Boston, MA, USA, March 5-8, 2012
We enlarged the part dedicated to human-swarm interaction and added the suggested literature.
Comment of Reviewer - Open Issues
I think this section needs to be strengthened. For instance I think that effective Human Swarm Interaction (HSI) is an impediment to real world application. Others are the lack of any compelling demonstrators for outdoor swarm robotic systems (i.e. waste collection), and the lack of any business case or business model that demonstrates the swarm robotics approach would be more cost effective that any conventional robotics - or none robotics - approaches.
We modified the section as suggested.
Comment of Reviewer - References
Please replace this: C. Dixon, A. Winfield, and M. Fisher. Towards temporal verification of emergent behaviours in swarm robotic systems. In Towards Autonomous Robotic Systems, LNCS 6856, pp. 336–347, 2011. Springer. With a more recent paper: Dixon C, Winfield A, Fisher M and Zheng C, Towards Temporal Verification of Swarm Robotic Systems, Robotics and Autonomous Systems, 60 (11), 1429-1441, Nov 2012.
Done, thanks for the suggestion.
Comment of Reviewer - Additional General Comments
i. Someone familiar with conventional multi-robot systems would be puzzled to find no mention here. It would be good to constrast the swarm robotics approach with traditional multi-robot systems (which are sometimes mistakenly called swarm systems).
ii. I'm surprised there is no mention of homogeneity and heterogeneity, i.e. that most existing lab swarm robotics systems are homogeneous, but that the approach does encompass heterogeneous systems. Of course Swarmanoids is a great example.
iii. It may be interesting to include a section on the history of swarm robotics.
iv. the article could be improved by some explanation of the rationale, i.e. the close and symbiotic relationship between the study of social insects/animals and swarm robotics - perhaps this could be included in the Scientific Implications section..?
Note: I was assisted in this review by Dr W Liu.
i. We added a mention of multi-robot systems in Section 1. We think that a formal comparison between swarm robotics and other multi-robot systems would be out of the scope of this article. Our intent is to describe swarm robotics through its characteristics, which are also the characteristics that distinguish swarm robotics from other robotics systems
ii. We added a mention to this in Section 1.
iii. and iv. We added a section on the origins of swarm robotics in which we also presented briefly the historical relationship between biology and swarm robotics.