Syllabus for “Underwater Systems”

Instructors: - Andrea Munafo (andrea.munafo@unipi.it) - Riccardo Costanzi (riccardo.costanzi@unipi.it)

Course content

The course discusses key properties of the ocean sea water, with the objective to serve as basis for the understanding of sound transmission in the oceans.

Then it explains how this knowledge is applied in underwater instruments for positioning, signal transfer, mapping, measurements and ocean sampling.

Primarily, we will talk about Sensing, Communications and Autonomy - Effective autonomy can compensate for limits in sensing and communications. - Effective communications can compensate for limits in sensing and autonomy.

Intelligence/Perceptiveness/Connectedness is part of a bigger picture where: - Smarter systems means more can be done with fewer systems. - Smarter systems means more can be done with less capable (lower cost) systems.

Specific topics include:

  • Ocean acoustics
  • The acoustic channel
  • Ray tracing
  • Elements of Oceanography and Environmental Variability
  • The Wave Equations
  • Acoustic Systems
  • The Sonar Equations
  • Sonar Practical Equations
  • Networked systems
  • Maritime Navigation

Week 1: Introduction to the course

This is the first week of our journey. We will introduce the course and start looking at the main applications of marine robotics: science, environmental monitoring, offshore, energy renewable, search and rescue. We will introduce key concepts of marine robotics and ocean acoustics and discuss some key definitions and terminology that we will use throughout the course.

Week 2: Ocean Acoustics and Elements of Oceanography

We formally introduce ocean acoustics. As we will see, acoustics strongly depends on oceanography. For this reason, we will also introduce some key elements of oceanography and environmental variability, discussing how it affects acoustic propagation using ray theory. Among all this, we will take a short detour to briefly talk about the Robot Operating System (ROS), which is the software that we will use during the course projects.

Week 3: The Wave Equations

This is the most mathematically heavy week of the course. We will understand the Wave Equation, its derivation and analysis. Finally, we will apply it to ocean acoustics studying the Helmholtz equation and its solutions (ray models, normal modes, parabolic equation, fast field).

This week we will also look at the interface between water and sea bottom, starting with the simplest case of all: coherent reflection at a fluid-fluid interface. We will talk about critical and intromission angles, and understand shallow water propagation. We will then look at more realistic bottom types and look at what happens when sound propagates across a fluid-solid interface and look at scattering when the interface is not flat and smooth.

Week 4: Scattering

We will continue looking at what scatterign is, modeling formally through the Lambert Law. We will also look at acoustic systems and how to sense and make sense of the sound waves we receive through transducers, beamforming, source-receiver directionality and beampatterns.

This week we will also start talking about SONARS. We will talk about range - resolution trade-off, noise in the ocean and we formalise the most important equations of all: the SONAR equations. We will discuss three cases: passive sonars, active monostatic and active bistatic sonars.

Week 5: Sonar application

We will discuss the two main sonar systems: side scan sonars and multibeam sonars. We discuss differences and see when they are useful. We will also discuss acoustic modems, i.e., sonar systems that we use to communicate underwater.

Week 6: Underwater Navigation

We close the first part of the course discussing how to navigate underwater, and specifically what role acoustics plays. We conclude with a summary of modern technologies and future trends.

Week 7–9: Dynamic Models of Underwater Vehicles

In this block we shift focus from sensing and navigation to the physics of motion: how underwater vehicles move, how we model that motion, and how those models connect to simulation and control.

We will introduce the purpose of dynamic models and build the core mathematical framework. We then move to the basic principles of underwater vehicle dynamics, discussing forces and moments, added mass, hydrodynamic damping, buoyancy and restoring terms, and the structure of standard 6-DOF models. During week 7, students will be grouped for the final projects, and we will define project themes, expectations, and milestones.

We will then discuss what changes when we move from simplified models to more realistic ones: parameter identification, nonlinearities, coupling between degrees of freedom, and practical modeling choices that improve fidelity without making the model unusable. Building on this, we will connect modeling to control systems for underwater vehicles, showing how model structure influences control design and how simulation becomes a tool for validating control strategies before real-world deployment.

Finally, we will study how acoustic systems interact with vehicle dynamics, not just as “sensors,” but as elements that affect operational behavior, constraints, and performance—especially in real missions where motion, sensing, and environment are tightly coupled. We close the block with case studies and current research in underwater vehicle dynamics, discussing modern approaches and open challenges. Week 9 is also the official start of the final projects, where groups begin implementing, testing, and refining their chosen work.

Week 10–12: Final Projects

The last part of the course is structured around hands-on group work, aimed at consolidating everything learned into a coherent technical outcome.

This part of the course is primarily dedicated to project development, with in-class time devoted to implementation, analysis, and troubleshooting. Along the way, each group will regularly share progress through short reports and discussions, using feedback to improve clarity, technical choices, and experimental design.

Week 12 is the final stretch. We will use the first sessions for final preparations, to make sure that the project deliverables are complete and polished, and that the presentation clearly articulates motivation, methods, results, and limitations. The course concludes with final project presentations and discussions, where each group presents their work, reflects on lessons learned, and connects outcomes to broader themes in marine robotics research and practice.

Additional Notes:

  • Guest Lectures:
    • Dr. Florian Schultz, ATLAS Elektronik, “Acoustic Communications and Its Practical Applications” (May 2026)
    • Dr. Roberto Petroccia NATO STO CMRE, “Robotic Networks” (April/May 2026)
  • Assessment:
    • Group Reports and discussions at periodic intervals
    • Final project related to designing or analyzing an acoustic system, a case study in ocean acoustics, or underwater robotics
    • Final oral examination to assess comprehensive understanding

Learning outcome

After having completed the course the students shall have obtained a solid understanding of the processes in the world ocean as well as in design, contruction and working principle of various maritime systems.

Specific learning objectives are: - Knowledge of the world oceans, including depths, ocean currents, temperature conditions and salinity/seawater density. - Knowledge and understanding of design and operational conditions for the main underwater vehicles as ROVs and AUVs.
- Know and understand various underwater positioning and navigational systems. Being able to write (group) reports about complex underwater operations, including time surveying of the mother ship. - Knowledge related to important issues that need to be considered during design, installation and operation of underwater systems, including robots.

Course materials

  • J.M. Hovem, Marine Acoustics, Peninsula Pub., 2013

  • X. Lurton, Introduction to Underwater Acoustics, Praxis, 2002

  • D.L. Bradley, R. Stern, Underwater Sound and the Marine Mammals Acoustic Environment, prepared for the US Marine Mammals Commission, 2008

  • J.M. Hovem, “Underwater Acoustics: Propagation, devices and systems”, J. Electroceramics, 19, 339 - 347, 2007

  • F.B. Jensen, W.A. Kuperman, M.B. Porter, H. Schmidt, Computational Ocean Acoustics, Springer, 2011

  • The Ocean Acoustic Library: http://oalib.hlsresearch.com/ acoustic modeling, data processing software and data

Various text books, lecture notes and relevant available information on internet.

Frequently Asked Questions (FAQ)