Research On Multiple Mobile Robots Path Planning In Smart Factory

Compared to traditional industrial robot,mobile robots can move throughout large scale environment autonomously,therefore they are able to do more flexible tasks.Moreover,multiple robots system have higher flexibility and fault tolerance than single robot system,so it is more suitable for smart factory.Therefore multiple mobile robots system are drawing more and more attention.Multiple mobile robots system doesn't mean adding multiple robots together directly,the system need to handle problems like coordination and collision avoiding between different robots.The goal of multiple mobile robots path planning is to find an optimal and collision-free path for each robot from current position to goal position.The smart factory environment is different from non-industrial environment and warehouse environment,mobile robots need to move along some pre-defined paths,so existing algorithms are not suitable.This paper focuses on multiple mobile robots path planning in smart factory.Firstly,different control architectures of multiple mobile robots system are studied.In order to improve expandability and reusability,this paper propose an architecture based on ROS(Robot Operation System)and RT-Middleware(Robotics Technology Middleware).This system uses ROS to develop single robot and then use RT technology to encapsulate each robot into a RT component,then the system can control robot components and a coordination component flexibly.This kind of architecture makes multiple robots system have high flexibility,transportability and expansibility.Secondly,multiple robots path planning methods are studied.This paper proposes a modified time windows method to solve multiple mobile robots path planning.This method introduces priority control into traditional time windows.On the one hand,graph theory is used to decide planning order so that result will not be influenced by task order.On the other hand,separate mobile robots with cyclic priority from other mobile robots and use different planning methods on them.This method can solve more situations than traditional time windows method.Besides,this paper uses ROS to develop localization and obstacle detection modular,and then design local planner to realize closed-loop control.Using local planner can make the system more robust and safer.At last,experiments in real world and simulation environment are designed.The result shows that this method can be used on different mobile robots and have higher success rate than traditional method.