News Release

Helping Navy Transport Critical Cargo to U.S. Troops

San Diego, CA, June 4, 2008 --Researchers at UC San Diego are helping the U.S. Navy improve ship-to-ship cargo transfer even during bad weather when waves can make ships sway unpredictably. In doing so, the researchers, led by mechanical and aerospace engineering professor Miroslav Krstic, are developing real-time optimization and active control techniques for a 3D model with hydrodynamics effects.

3D Ship UCSD

A large seabase ship connected in a stern-to-bow configuration to a small connector vessel (T-craft) through a ramp.

Ship-to-ship cargo transfer over a ramp in moderate to high seas presents significant challenges for ship and control system designers due to the sometimes unpredictable swaying of the ramps that connect two vessels. Cargo transfer between container ships and connector ships is critical to the U.S. Navy’s ability to provide logistical support to military operations abroad. Navy cargo ships transport items weighing tens of tons – everything from tanks, Humvees and other vehicles to combat equipment, fuel and ammunition.

“Our research is related to the Navy’s goal to deploy equipment and other critical goods to troops as soon as possible without having to rely on good weather,” said Krstic, director of the UCSD Jacobs School of Engineering’s Cymer Center for Control Systems and Dynamics.

Currently, Navy ships and connector vessels are equipped to move cargo when wave heights are up to 2 feet.  Under a current contract from the Office of Naval Research, Krstic and his team are developing a method that would allow the Navy to efficiently transfer cargo between two ships in wave heights up to 8 feet. The goal of the project is to determine the actuation/sensing requirement and to devise control and real-time optimization algorithms for minimizing the oscillations of the pitch angle, roll angle and the swaying of the ramp. The purpose of the research is to also prove that the smaller of two ships involved in a ship-to-ship transfer can be actuated to control the ramp motion, particularly during cargo transfer.

“One of the problems is the orientation of the two ships relative to the wave front,” Krstic said. “The other problem is adjustment of the ramp length so that when the two ships undergo large vertical oscillations, the ramp doesn’t undergo large oscillations in pitch and roll. In addition, when you connect the two ships with a ramp, the smaller one can be actuated using hydrodynamic actuators, like ailerons on aircraft, to change the pitch of the smaller ship, and thus of the ramp.”

The UCSD researchers have created a simulation model to help determine the best way to position the two vessels and the ramp in order to achieve optimum performance. As part of the project, Krstic and his team are working with defense information technology giant SAIC on implementing their algorithms into SAIC’s interactive ship fluid dynamics model.

“These Navy ships are interacting with the water, which makes for a very complex problem,” Krstic said. “The cargo transfer has to be performed in an environment that you can never fully predict. The Navy has tried different solutions to this problem and they haven’t really worked. So they are looking for a new angle.”

Krstic’s Navy cargo transfer research coincides with the Jacobs’s School’s quest to come up with innovative solutions for the National Academy of Engineering’s Grand Challenges for Engineering in the 21st Century. 




Media Contacts

Andrea Siedsma
Jacobs School of Engineering