Three-Dimensional Tracking Control of Mid-water Trawl System Based on Backstepping Method

A three-dimensional trajectory tracking control policy of a mid-water trawl net is presented. For the entire trawl system, a four material points simplified model is established, which can embody the horizontal expansion effect of the trawl mouth. Based on the backstepping method, a output-tracked controller of the proposed simplified model is designed. Because of the non-strict feedback characteristics of the trawl system, a control allocation method is used to reduce the higher-order variables, and several parallel sliding mode PID controllers are locally used to substitute some virtual control inputs. The proposed control method has been proved to be asymptotic stability via the Lyapunov theorem. Finally a simulation contrast test indicates that the controller has good robustness and high precision.