1 Introduction to Seakeeping
In the olden days when the propulsion relied on sails, the ships rarely experienced head winds or head waves in the ocean. With the advent of the steam engine, ships could now travel in any direction relative to the wind and waves. However, this led to more slamming and green water (water coming onto the deck) incidents that resulted in more damage to the hull and superstructure. The increased occurrences of these incidents led the naval architect to analyze the motion of a ship in a seaway.
It was observed that in order to reduce the motions that lead to slamming and green waters, the ships needed to operate at reduced power. The naval vessels too needed to operate at reduced power to ensure success in operational missions such as sonar search, helicopter landing and maintaining formation. As newer type of vessels such as catamarans, planing crafts, hydrofoil boats and surface effect ships started coming up, predicting motions for them too became important. The 1950s on onward decades saw an increased interest and eventual development of statistical methods to understand the ocean waves and hydrodynamic theory to predict motions of a ship in a sea.
Learning Outcomes
By the end of this course, students will be able to:
- Explain the dynamics of a single and multiple degree of freedom systems
- Setup an isolated development environment using Docker
- Maintain version control of code using git
- Use ROS2 for interfacing with sensors and recording data
- Successfully conduct and analyze the
Practical
In the practical component, the students will develop a simulator for a ship and a control module for a marine vehicle. Students will learn to use the smartphone as the sensor suite and control the vehicle to perform waypoint tracking.
Course content
Maneuvering of Marine Vehicles
- Kinematics of rotating frame
- Nonlinear 6-DoF and 3-DoF rigid body equation of motion
- Nonlinear and linear hydrodynamic derivatives
- Linear equations of motion for ship
- Stability indices
- Stability and control in the horizontal and vertical planes
- Definitive manoeuvres turning tests
- Influence of ship features on controls fixed stability
- Experimental determination of hydrodynamic derivatives
- Numerical methods used in ship manoeuvring problems
- Ship manoeuvring simulators
- IMO Rules and Recommendations
- Ship manoeuvring sea trials
Control of Marine Vehicles
- Linear system representation and Laplace transforms
- Performance metrics for control systems
- State-space modelling and stability
- Interchange between state-space model and transfer function model
- PID controller and tuning its gains
- Observability and state observers
- Controlability and state feedback controllers
Schedule
The week to week schedule of the course is given below: