Research On Real-time Scheduling Of Light And Small Pieces High-speed Sorting Robot System

With the rapid development of logistics industry,express business volume has grown rapidly.According to the National Bureau of Statistics,China’s express delivery volume reached 108.3 billion pieces in 2021,up 29.9 percent year on year.The number of parcels accounts for more than half of the world’s total,most of which are light and small parcels.Therefore,improving the operation efficiency and reducing the operation cost of light and small parcels sorting can greatly reduce the sorting cost,and thus reduce the overall logistics operation cost.The research object of this paper is a new high-speed sorting robot system for light and small parts,which can perform sorting operations directly on the ground without a dedicated sorting platform(such as the dedicated sorting platform for the sorting Minions system).It has the advantages of good flexibility,low energy consumption and high efficiency.This paper mainly focuses on the real-time scheduling of multi-robots in the system,which is divided into two stages:the first stage is real-time task allocation of multi-robots,and the second stage is real-time path planning of multi-robots.Firstly,the system distributes the sorting task of the current wave to multiple robots,and then performs real-time path planning for the robots with tasks.The main research contents and results are as follows:(1)Multi-robot real-time task allocationConsidering the initial position of the idle robot at the current time,the association relationship between tasks and the cost of task switching,a real-time task allocation model with the goal of minimizing the sorting cost is established.For three kinds of sorting tasks(parcel sorting,empty container handling and full container handling)and two kinds of sorting robots(sorting and handling robot and container handling robot),a twosection and double-layer coding scheme was designed.According to the characteristics of coding,an improved genetic search algorithm combining selection operator,exchange operator,mutation operator and greedy operator was designed to solve the model.The improved Multi-Agent Path Finding(MAPF)benchmark data set was used to verify the model and algorithm.The experimental results show that the model is correct and the algorithm is effective.(2)Multi-Robot Real-Time Route PlanningIn this paper,the centralized scheduling method is adopted to establish a real-time path planning model based on the minimum total path driving cost.Considering the driving conflict between robots,the problem size and the solution timeliness,a two-level path Search algorithm based on robot Priority(PBS)is designed.The algorithm uses a time-step based method to perform dynamic scheduling(planning the next two steps of each robot according to its priority and executing one step until reaching the destination,and finally obtaining the optimal path of this scheduling).The MAPF benchmark data set is used to verify the model and algorithm.The experimental results show that compared with the traditional A*search algorithm,the algorithm designed in this paper has a great improvement in solving speed(the larger the problem size is,the more obvious)and solution quality(the improvement is about 12.3%).(3)Light and small parts high-speed sorting robot production management systemIn this paper,the production management system of high-speed sorting robot for light and small parts is developed based on JAVA,which can run on Windows,Linux and other operating systems.It can schedule multiple robots to complete the corresponding order tasks in real time,and provide functions such as optimal control of robots.At the same time,the system provided multi-level system control,including business layer,task layer and communication layer.The upper layer connected with the Warehouse Management System(WMS)system,and the lower layer connected with multiple robots.