Study Of Ship Collision Avoidance Based On Optimal Control

Research on ship collision has been a long history, but nowadays there are still many ships being damaged as well as loss of lives because of ship collision. Accidents involving collision of ships accounts for a large proportion in distress at sea, which are caused by human factor as much as 80%. Therefore, in order to avoid collision between ships, the study of ship automatic collision avoidance still playing an important role to ensure navigation safety. The study on ship collision avoidance has carried out in this context.First of all, the basic knowledge in the field of ship collision avoidance has been introduced, especially the safety distance has been analyzed in detail, according to the relative orientation information between the local ship and target ship, the encounter situation of ships has been divided, meanwhile as the situation at sea, collision avoidance of more than two ships has been mentioned.Then, the collision avoidance system has been studied. Taking the main parameter such as course, speed and location information of the local ship and target ship to the parameter calculation of collision avoidance, and collision risk evaluation model has been established based on fuzzy mathematics theory. Based on the model, not only the collision risk index of any target ship can be calculated, but also the most dangerous ship can be found. Lastly, considering the international regulations for ship collision avoidance at sea, the avoidance liability and collision avoidance scheme have been summarized.Then, optimal control method is used to ship collision avoidance problem description, the ship motion mathematical model with six degrees of freedom has been selected and transformed into a form of first-order differential equations as a system of equations, the objective function and constraints have also been established, and inspired by the related research, the problem has been converted into a path planning problem about ship collision avoidance. Combined with genetic algorithm, the fitness function has been confirmed with both security and the shortest path goals. So the controller design of collision avoidance under the two goals has been completed, which makes course, speed and location information of the local ship and target ship as the main parameter for the input, and the collision avoidance trajectory for the output.Finally, the ship collision avoidance system software is devised under the MATLAB simulation environment, the results shows that the system can safely avoid the target ship with the shortest path, at the same time, the control algorithm has been verified. In a word, this design has a certain application value to the research of ship automatic collision avoidance system.