Formation Control And Obstacle Avoidance Of Ship Based On A Multi-agent System With Consensus Theory

With the development of science and technology as well as the increasing exploration of the ocean, single-ship operation has been unable to meet the demands of complicated missions in the ocean. Therefore, multi-ship cooperation has become more and more important than before. When it comes to multi-ship problems, multi-ship formation needs tobe solved mostly. Being centered on solving multi-ship formation problems, this paper improves formation control and obstacle avoidance theory. The simulation foundation for multi-ship cooperation is provided at the same time. This paper puts forward a solution to solve local path planning problem with consensus theory. The problems include objectives oriented formation control and obstacle avoidance are solved by the improved theory.Firstly, doing some research on formation control and obstacle avoidance to establish main methods including Behavior Based method, artificial potential field method, consensus theory. Basic knowledge and basic concepts about these three methods are introduced. The stability principle is proved to provide a theoretical basis for the following stability.Secondly, this section is divided into 3 more parts to carry out the research process of formation control and obstacle avoidance of ship. It is based on a multi-agent system with consensus theory according to second-order multi-agent system model. The first part is formation control, which makes the multi-agent system achieve expected formation through the improved formation controls. The second part is consensus control, its purpose is to make the speed of the multi-agent system in consensus with suitable consensus protocol. The third part is obstacle avoidance, which makes the multi-agent system able to avoid obstacles effectively with obstacle avoidance algorithm based on repulsive field. Combining the consensus control, formation control and obstacle avoidance control together, the formation and avoidance algorithm based on the multi-agents consensus is improved and proved stable in simulation. The simulations are made under conditions of single static obstacle, single moving obstacle and static multi-obstacle. A method is proposed to determine whether the expected formation was achieved and to estimate when to reach the expected formation. The influence on the multi-agent system caused by the external interference is analyzed. Then the conclusion is used to estimate whether the influence on the multi-agent system caused by the obstacle exists.In the last part of this paper, improvements and innovations are made on these two aspects by researching on formation control and obstacle avoidance. On the one hand,anticipating is made before the obstacle avoidance control to make the multi-agent system achieving expected formation faster than before. On the other hand, consensus theory based on gravitational potential field is adopted to solve local path planning problem in this paper.In this point, velocity needs to be in consensus instead of following the position of virtual intelligence. There is a feedback item in the speed function of the virtual agent too. The method avoids agents being trapped in the local minimum point efficiently when planning local path. Combined with all those control input, the method solves the problem of objectives oriented formation control and obstacle avoidance of ship, which is verified by simulation.