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Fig. 5. AUV and ASV (Unmanned Surface Vehicle) Telecommunication system.

Fig. 6. Global AUV demand by sector 2011-2020 [97].

factors about compression and communication architecture
[83] is the bandwidth and distances between AUV and the Remote Monitoring and Control Centre (RMCC), or home ship
limitations [84]. These factors will determine the correct choice
of hardware and software configurations for each purpose
[85]. Underwater environment limits the use of regular electromagnetic signals, such as radiofrequency (RF) [86] or Wi-Fi
[87]. Together with the non-homogeneous density of seawater due to salinity or temperature, it leads the use of acoustic
modem technology bandwidth-limited in the range of kbps,
with long connection gaps [88]. There are some proposals combining data transmission in submarine technology by using
geo-positioning systems, such as Global Positioning System
(GPS) [89] or Global Navigation Satellite System [90] and WiFi, 4G or L-band for aerial data connections, and using these
for RMCC, satellite and vehicles communications [91], [92]
(Fig. 5).

Some recent studies about offshore mapping, the meticulous testing of sea resources and ocean infrastructure
inspections have clearly demonstrated the validity and effectiveness of ROVs and AUVs configured with suitable acoustic
and imaging systems [98]. These vehicles stand out in the
acquisition of data that allow the definition of the seafloor
morphology and topology, the evaluation of underwater habitats and the analysis of marine infrastructure [99].
Management politics and legal implications about AUVs
are important requirements for increasing the reliability of
AUVs in the scientific sector due to the high cost of equipment
employed and the data collected. This interest has generated
several studies to evaluate and manage the risk associated
with AUV improvements [100]. The increasing use of AUVs
will demand updating in relation to legal matters and diplomatic authorization. Probably these rules will be different
for each type of user, i.e., commercial, military or scientific
research [101]. The legal definition of AUV generates many
doubts regarding the kind of vehicle classification. These
bureaucratic issues will become important in situations of rescue, dangerous trajectories, incursions in unauthorized areas,

Discussion and Future Challenges
The instrumentation and measurement systems for AUVs are
not thoroughly studied in the literature. The main paradigms
to cover in AUVs include progress in routing, mapping sonar,
energy storage and drive systems. Non-linear mathematical
methods for the control units are beginning to be used [93] to
cover the needs of new and advanced materials, e.g., "smart
materials" [94] and vehicle shape and morphology, for modifying hydrodynamic conditions using flexible hull with new
composite materials above mentioned, and modulating the
drag and mass qualities of the hull to get better control of the
vehicle's forward speed.
The current irruption of transcendental markets in both
commercial and defense government departments has led to
increased activity of transforming the research to industrial
production of AUVs. Demand in 2020 is forecast to be 105%
higher than 2016, but the commercial demand will be only 4%
of total AUV demand [95] (Fig. 6). The curve of applications
time evolution of these vehicles shows a state of economic
benefit, illustrated in Fig. 7. It is encouraging an outstanding
development drive on the part of component suppliers to customize their product manufacture to improve the AUVs [96].
The outcome is a quick growth of AUV performances [97].
April 2020

Fig. 7. Possible timetable for the development of AUV technology shows a
current state of continous research strategy for the future economic return [8].

IEEE Instrumentation & Measurement Magazine 109

Instrumentation & Measurement Magazine 23-2

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