| Nowadays,as ocean resources exploitation becomes one of the most significant access to industrial resources,research on intelligent marine equipment also plays important role in the development strategy of maritime power with the tendency of automatic and intelligent industry.In this situation,as one concerned intelligent marine equipment,unmanned surface vehicle(USV)enables the environment modeling based on various sensor data and executes predetermined tasks in complicate water area.USV is developed for various of marine operations,such as area patrolling and monitoring,hydrographic surveying and charting,inspecting of water quality and detecting of water surface pollution.Path planning system enables USV navigates and executes types of missions safely and efficiently,therefore it has important researching significance for development of intelligent USV.Based on the precondition has introduced above,the design of an appropriate and modularized path planning system for USV is the main research object,the architecture of ROS-based path planning system is proposed and implemented in this paper.A simulation which aims to test feasibility and performance of three core components of planning system,the global path planner,local path planner and planning bus,the practical experiment is also done on the real ROS USV platform,through confident result of the simulation and experiment,the proposed system enables a meaningful reference of universal path planning system for USV provided.First,as a reference,the ROS mobile robot navigation system is separated into a core unit and a peripheral unit,the core unit implements the path planning for USV navigation mission,while the peripheral unit offers the necessary parameters and information for the core unit.The communicating and calling mechanisms between each component of the core unit and the specific type of parameters provided for the core unit by the peripheral unit are all concluded.Otherwise,the required components of peripheral unit are reserved,and some inapplicable components are replaced or modified according to the similarity and difference between common wheeled mobile robot and USV,the complete architecture of ROS-based USV path planning system is proposed.Secondly,after the theory and feature of variety of widely used path planning algorithms and the improved versions of them are analyzed and compared,an appropriate path planning algorithm is selected and improved according to the practical implementation and the kinematic constraint of USV.While the algorithms of path planning are well proposed,the types of USV state during the navigation are designed and provided to the dispatching logic as the accordance to implement the management of path planners,planning of global path and local obstacle avoiding.Then,the design and implementation of the components of necessary peripheral unit are specifically introduced and analyzed,including the two-dimension cost map model which is used to describe the working environment and the spatial state of USV,the map server which provides the information of global map to path planning system and the odometry and position filter to implement the localization of USV.Meanwhile,the map server is extended with a map loader module to download the global map sources from the upper control unit according to the practical implementation of the USV upper controlling.At last,the simulation is made to test the components of core unit of the path planning system based on the simulator Gazebo and Rviz,which are integrated in the frame of ROS,the feasibility and reliability of path planners and planning bus are well verified through the simulation.At the same time,the practical experiment is also conducted on the unmanned surface mobile platform H2OmniX,which is developed by the laboratory for underwater system and technology of Zagreb University,Croatia and produced by H2O-Robotics company,the data of experiment is collected and analyzed to further verify the performance of proposed path planning system. |
