Research On Unmanned Surface Vehicle And Path Planning Algorithm

The autonomous environment awareness,autonomous cruise and other functions of unmanned surface vehicle(USV),which plays an important role in civil,commercial and military applications,make it capable of various autonomous tasks.And the USV,including fully automatic USV with independent environmental awareness,self-determination and autonomous cruise functions,semi-automatic USV with built-in procedures to control missions,and non-automatic USV with remote control,involves such techniques as pattern recognition,system identification,intelligent robotics,machine learning and optimal control.The research content mainly includes ship model establishment,heading control,site tracking,dynamic obstacle avoidance,path planning,and USV communication.And the most important feature of unmanned surface vehicle(USV)is underactuation,which uses two inputs to control three degrees of freedom of motion.Considering the movement characteristics of the USV,the hull movement is simplified to a three-degree-of-freedom operation model.Then,the dynamic equation and motion equation of the USV are established,and the USV simulation model is built.Then based on this model,the linear test,the yaw moment trajectory test and the interference torque test of the USV are carried out.The underactuated heading controller based on fuzzy theory is designed.It is divided into two aspects: speed control and steering control.In the aspect of ship speed control,the mainstream PID algorithm is used to provide forward force.In the aspect of steering control,the fuzzy steering controller is used to provide the control input torque of the USV,and then the simulation is verified by the offshore underactuated heading controller.To solve the trajectory tracking problem,algorithm analysis is carried out at two levels: linear trajectory tracking and site trajectory tracking.At the linear tracking level,the design compares the advantages and disadvantages between the traditional cascade PID(Proportional,Integral,Differential)underactuated USV linear tracking controller and the LQR(Linear-Quadratic-regulator)underactuated USV linear tracking controller,and then the simulation comparison verification is carried out.On the issue of tracking site,a global nonlinear time-varying synovial controller is designed.And the transition boundary protection layer and integral compensation term are added to eliminate the interference of tracking error,and then the static point tracking and moving point tracking are verified.The research about the path planning is conducted in two obstacle avoidance aspects of both dynamic and static.From the aspect of dynamic obstacle avoidance,theoptimal obstacle avoidance strategy for USV,taking itself as a starting point for rapid avoidance and considering the perspective of collision risk,is calculated and analyzed under the premise of ensuring safety.Under the avoidance strategy,the USV can drive out from the dangerous distance and quickly return to the original route.In the static obstacle avoidance level,The VFH+ algorithm is used to avoid static obstacles.