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Nonlinear Control of a Subscale Submarine in Emergency Ascent

  • December 11, 2017
  • 4:00 p.m.
  • 117A Surge Building,
  • Dr. Francis Valentinis, Senior Defence Scientist with the Defence Science and Technology (DST) Group in Australia,
  • Faculty Host: Dr. Craig Woolsey

Abstract: The problem of guaranteeing safe emergency ascent to the surface is a significant design driver for modern submarine platforms. Simulating this scenario accurately is non-trivial, given the nonlinearities in the forces due to the unsteady hydrodynamics and the concurrent effects of the control surfaces and the ballast water discharge. The inherent nonlinearities present in this scenario make the application of nonlinear control interesting as a research problem. This seminar presents a parametric model and motion control system for a scale model submarine undertaking an emergency ascent. An energy-based model is presented that represents the underactuated submarine in a non-neutrally buoyant state. This model is then used to synthesize a control law using Port-Hamiltonian theory and interconnection and damping assignment passivity-based control. Lyupanov analysis is used to demonstrate stability of the closed-loop system, and a simulation-based study is presented to demonstrate performance of the control law. The results demonstrate that a closed loop non-linear controller is able to improve the quality of emergency rise by automatically compensating for parasitic effects in the hydrodynamics that can compromise ascent performance.

Bio: Dr. Francis Valentinis is a Senior Defence Scientist with DST (formally DSTO). His primary responsibility is leading and conducting R&D relating to dynamics and control of marine craft. His professional interests include mechatronic systems design, real-time software design, system dynamics modeling and application of both linear and nonlinear control methods to the control of marine craft and aircraft.

He submitted his PhD thesis at RMIT University in 2000, where he also worked as a sessional lecturer in the Aerospace Engineering department. Following this, he joined Meteor CAE in Italy as designer of the flight control system for the Falco UAV.

He left Meteor in 2003 to join DSTO as a contractor, aiding programs related to UAV and UUV systems. Francis joined DSTO staff in 2006, as part of the Maritime Platforms Division UUV group. Within this group, Francis’ research was focussed on real-time software implementation technologies and autopilot design for two DSTO UUVs. He was the principal design architect for one of these vehicles, called Mullaya.

Since 2009, his work has included manned submarine dynamics and control. As part of his work in this area, he has developed comprehensive models of submarine system dynamics, and conducted studies into applying nonlinear control to submarine autopilot design.

Francis is also an Adjunct Professor with QUT in Brisbane, Australia, is currently serving as the national chair for the Engineers Australia National Committee on Mechatronics and is an Associate Editor with the Journal of Marine Science and Technology. Francis is currently serving as a Visiting Scholar in the AOE department in Virginia Tech.