Path-following Guidance And Control Of Sail-propelled Ships

To some extent,oceanic wind energy is able to replace the conventional fossil energy to provide power for the ships as it is widely distributed and clean.As the most direct way,the application of wind sail widely exists in the new-energy ships.Considering the fact that the existing path-following guidance and control algorithms of the common power ships are not fit for the sail-propelled ships and the input saturation and the limited acting frequency of actuators are not addressed,this paper classifies the sail-propelled ships into three types,namely the sail-assisted ship,the unmanned single-hull sailboat and the unmanned sail catamaran,and aims to design their path-following guidance and control schemes with the favorable engineering background.For guidance,the LOS and the parallel guidance principles are designed for the unmanned sailboat(including the single-hull sailboat and the sail catamaran)to follow the reference paths of the waypoint-based straight line and the parametric smooth curve.For control,the optimization controller of the sail sheeting angle and the MLP adaptive fuzzy controller of the rudder angle are designed for the sail-assisted ship,the event-triggered controllers of the rudder angle and the sail sheeting angle are designed for the unmanned sailboat.At first,for the path following of the sail-assisted ships,the juxtaposed ES-FLS optimization controller of the sail sheeting angle and the MLP adaptive fuzzy controller of the rudder angle are designed in the frame of parametric LOS guidance.This optimization controller synthesizes the operator expertise,the ES algorithm,the FLS learning and the saturation resetting mechanism,which achieves the maximum speed of the ship without the chattering of the ES.Based on the dynamics of the yaw motion,this paper adopts the FLS to approximate the unknown model dynamics and design the rudder controller by using the MLP technique and the adaptive backstepping method.As only one adaptive parameter is used,this controller is succinct in computation.Next,for the waypoint-based straight-line path following of the unmanned single-hull sailboats,the parametric LOS guidance principle for this kind of sailboats and the MLP adaptive fuzzy controller of the rudder angle are designed.The proposed guidance principle considers the tacking and gybing maneuvers of the sailboat(namely the operator should evade the heading of the sailboat towards the upwind and downwind "no-go zones",and make the sailboat navigate a zigzag route),and uses the sign functions describing the heading switching of the sailboat,which leads to the easy programming.The double RESOs are employed to estimate the drift angle,which ensures the high estimation precision to the large drift angle.In addition to the succinct computation,the proposed controller solve the problem of the uncertain lift parameter of the rudder blade by fabricating the tanh function component.Resorting to the double time-varying system,this paper proves the convergence of the path following errors.Finally,for the parametric smooth curve path following of the unmanned sail catamaran,the parallel guidance principle and the event-triggered robust controllers are designed.The guidance principle segments the reference path according to the wind information,and synthesizes the Serret-Frenet coordinate system,the LOS guidance and the lane limitation of tacking and gybing,which ensures its applicability to the unmanned sail catamaran.In the control design,the FLS is adopted to approximate the unknown model dynamics and the S-type functions to approximate the saturation uncertainties of the rudder angle and the propulsion of the sail.The triggering conditions of the rudder angle and the sail sheeting angle are respectively designed,and the robust fuzzy controllers of them are fabricated through the backstepping method.The proposed controller can ensure the effective tracking of the unmanned sail catamaran to the reference speed and heading under the saturation constraints of actuators,as well as the less acting frequencies of the actuators.In conclusion,this paper deeply investigates the path following guidance and control of the sail-propelled ships following the waypoint-based straight line and the parametric smooth curve reference paths.In guidance,the proposed guidance principles reconcile the conflict between the path following and the tacking and gybing maneuvers of the unmanned sailboats.In control,the proposed controllers solve the problems of propulsion optimization,the saturation constraints of actuators,the high-frequency acting of the actuators and so on,which have the excellent practical prospect and facilitate the industrialization of devices of the sail-propelled ships.