Research On Collaborative Anti-collision Of Multi-welding Robots Based On Finite State Machine

With the development of industrial automation,industrial robots with high efficiency,good welding quality,high repeatability advantages,in the machinery manufacturing industry has been more and more widely used,especially in the automotive industry,the body in white spot welding,spraying and other production tasks are basically completed by industrial robots.In actual production,the structure of body in white is complex,the number of solder joints is large,and the welding task is heavy.In the design of production line,in order to improve work efficiency,two or more robots will often be placed on the same station,and the solder joints on the white car will be allocated to more than one robot,in order to reduce the working time of the whole station.However,for multi-robots,the number of solder joints is not evenly distributed,and multiple robots in a limited space are prone to interference and collision between robots,which leads to low welding efficiency and even damage to equipment in the production line.Therefore,it is of great significance to study the reasonable assignment of solder joint welding task and the non-interference collision cooperation between multiple robots on the station.In this paper,Siemens PDPS software was used to build a 3D model of side welding of the body in white.The solder joints on the side assembly were reasonably distributed to several industrial robots,and the path planning of a single robot was completed.Finally,the discrete model of the robot is built in the Stateflow platform,and the action sequence of the robot is adjusted to complete the non-collision planning among the multiple robots.The main work of this paper is as follows:Firstly,the structural characteristics of the side assembly of the body of the white body are briefly analyzed.In order to establish the welding work unit of the side assembly of the body,the welding robot and welding gun models required by the work unit are selected according to the structural characteristics of the side assembly and the distribution of solder spots.Import the prepared data resources into the software Process Designer,and reasonably plan the station layout of the welding unit to provide a basis for the subsequent theoretical research.Secondly,the welding task is assigned to each robot in the welding unit.In the completed side assembly welding work unit,solder spots need to be allocated to each robot for welding.For reasonable allocation,the solder joint distribution for the knapsack problem,analyzing the effect factors of the solder joint distribution,determine the allocation principle,according to the constraint conditions related to solder joint distribution mathematical model is set up,using genetic algorithm and hybrid algorithm combining the gravitational search algorithm,to solve mathematical model,complete the reasonable distribution of the solder joint,the planning of the robot welding path,in the software Process simulation,Simulate the complete path of the welding unit of work for the SOP analysis.Then,the whole welding work unit is discretized.The welding path of each robot has been determined,and the collision area between each robot is obtained by using the collision detection function of PS software.For coordinating collision area of all the action,the robot will be discrete processing continuous welding robot motion,and based on the finite state machine theory foundation,set up single robot and the finite state machine model of the entire station system,the welding robot motion is converted to transfer between the system's internal states,providing theoretical basis for the next step of multi-robot coordination.Finally,the simulation platform of Simulink/Stateflow was used to model the single robot and the whole station system,and the single robot model was verified to confirm the correctness of the established finite state machine model.By determining the priority of robot motion and adjusting the motion sequence among robots,the optimal working time of the welding working unit was obtained,and the SOP analysis of the welding working unit was carried out to ensure the completion of the welding task without interference and collision between robots in the station.