Research On Path Planning And Cooperative Obstacle Avoidance Of Multi-mobile Robots

With the increasing development of science and technology,robotics has attracted more and more attention from scholars at home and abroad.Due to the accelerating pace of life and the continuous increase of people's needs,in many occasions,it is difficult for a single mobile robot to complete the task.Therefore,multi-robot collaborative control technology has become a hot research topic.The joint operation of multiple robots can greatly improve work efficiency.Through distributed control,information can be shared among various robots,which greatly improves the fault tolerance rate when performing tasks.In practical applications,robots with different functions and sizes are required to work together.The path planning and obstacle avoidance performance determine the work efficiency.Therefore,it is necessary to study the path planning and cooperative obstacle avoidance of multiple mobile robots.This thesis mainly contributes to the following aspects.The construction of ROS robot platform.Firstly,ROS communication mechanism and workspace architecture are described;Secondly The chassis control unit,embedded control module,lidar ranging module and steering gear control module of Turtle Bot3 robot are introduced;Finally,the kinematics model of mobile robot is established on the basis of coordinate transformation and the Footprint model is explained.Improved A* algorithm for path planning of multiple mobile robots.Aiming at the problems of many inflection points and unsmooth paths in the original A* algorithm,the kinematic of mobile robots are fully considered and an improved A* algorithm is proposed based on the dynamic window algorithm(DWA).In the improved A*algorithm,combining with the evaluation of the consistency of the current movement direction and the target movement direction,a new deflection factor expression is designed and a new heuristic function is obtained.Finally,the effectiveness of the algorithm is verified through simulations and experiments.Multi-mobile robots collaborative obstacle avoidance with improved reciprocal velocity obstacles(RVO)method.In view of the problem that the original RVO method did not consider the kinematics limitation,which often causes the problem that the velocity of robot exceeds the limit when avoiding obstacles,combining the characteristics of the RVO algorithm and the DWA algorithm,the two algorithms are merged.On the basis of considering the limitation of the motor torque,the optional obstacle avoidance velocity,acceleration and braking limit are restricted;Furthermore,considering that it is not the optimal strategy for the robots of different sizes to evenly allocate collision avoidance tasks in the cooperative obstacle avoidance process,the proportional reciprocal velocity obstacles method(PRVO)is proposed based on the RVO algorithm.The algorithm allocates collision avoidance tasks according to the radius,which fully reflects the flexibility of robots;Finally,the PRVO algorithm is integrated with the DWA algorithm.The PRVO-DWA algorithm not only optimizes the collision avoidance task,but also increases the practicality of the algorithm through kinematic constraints.Simulations and experiments show that the method is feasible and has dynamic obstacle avoidance effect.