# A Heterogeneous Robotic Swarm for Long-Term Monitoring of Marine Environments
## 6 Conclusions  
In this paper an implementation of a heterogeneous robotic swarm designed for long-term autonomous monitoring of marine environments was described. The capabilities and roles of two different agent types were given in detail, as well as the interactions possible between them.  
Insight was given into the surface and underwater modes of communication developed for the purpose of allowing the swarm to engage in advanced behaviours. On the surface, a dual network topology consisting of a mesh network and a system of access points was implemented. In underwater communication, inexpensive acoustic modems have proven to be reliable in providing necessary information exchange during experiments by following an acoustic communication protocol based on Time Division Multiple Access. Individual and collaborative capabilities of the robotic swarm were demonstrated through experiments in real-world environments and conditions.  
As part of the further development of the swarm, advanced underwater localisation algorithms will be implemented. The scalability of current algorithms and behaviours will be extensively tested. High-level evolutionary decision-making, task allocation, and scheduling algorithms will be incorporated into the swarm's collaborative behaviours, increasing the range and efficiency of its autonomous exploration and monitoring capabilities.  
Conceptualisation, N.M., S.B. and T.P.; Methodology, A.B., B.A., G.V. and I.L.; Software, A.B., B.A., G.V., I.L. and T.P.; Validation, A.B., B.A., G.V. and I.L.; Supervision, N.M., S.B. and T.P.  
This work was supported in part by the Croatian Science Foundation under Project IP-2016-06-2082 \"Cooperative robotics in marine monitoring and exploration\" and in part by the European Union through the EU H2020 FET-Proactive project \"subCULTron,\" No. 640967. The work of doctoral students [PERSON] and [PERSON] has been supported in part by the \"Young researchers' career development project--training of doctoral students\" of the Croatian Science Foundation funded by the European Union from the European Social Fund.  
The authors wish to thank the members of the consortium of the project'subCULTron' consisting of Artificial Life Lab--University of Graz, Unit of Social Ecology--Universite Libre de Bruxelles, Cybertronica Research, IRCCyN--Ecole des Mines de Nantes, BioRobotics Institute--Scuola Superiore Sant'Anna, CORILA: Consortium for coordination of research activities concerning the Venice lagoon system and ISMAR Istituto di Scienze Marine.  
The authors declare no conflict of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} ASV & Autonomous surface vehicle \\ CDMA & Code-Division Multiple Access \\ FDMA & Frequency-Division Multiple Access \\ FSM & Finite-state machine \\ GPS & Global Positioning System \\ IMU & Inertial measurement unit \\ IR & Infra-red \\ LED & Light emitting diode \\ RTC & Real-time clock \\ RTK & Real-time kinematic \\ TDMA & Time-Division Multiple Access \\ UASN & Underwater acoustic sensor network \\ WANET & Wireless ad-hoc network \\ WMN & Wireless mesh network \\ \end{tabular}