Modeling and control of trawl systems

This thesis is motivated by the possible benefits of a more precise trawl control system with respect to both environmental impact and fishing efficiency. A mathematical model of the trawl system is developed, including an accurate model of the hydrodynamic forces on the trawl doors. This model estimates both the steady state and the transient forces on trawl doors moving in six degrees of freedom. Various concepts for trawl door control are evaluated, and a new trawl door control concept is proposed. The trawl door control concept is developed to fulfill the demands on both energy consumption, robustness and control performance. It is improved using numerical optimization based on time- domain simulations of the trawl system. A trawl control architecture is presented. This takes industrial constraints into account, such as the energy supply on the trawl doors. The control system is based on model predictive control and facilitates complex objectives, constraints and process models.

Autorentext

Karl-Johan Reite was born in 1971 in Norway. He holds a PhD in marine cybernetics at the Norwegian University of Science and Technology (NTNU) and has experience as mate onboard a Norwegian fishing vessel. He is now employed by the Norwegian research company SINTEF Fisheries and Aquaculture.