Research And Design On Robot System For Pipe Intersecting Curve Air Plasma Cutting

In recent years,China's demographic dividend is gradually disappearing,and its labor shortage is spreading.Internationally,the major developed countries all offer strong support for the development of their own robot industry and advanced robotics technology,and strive to improve the level of the intellectualization and the automation of local manufacturing industry.From pipe intersecting curve cutting industry,most of the domestic enterprises use a semi-automatic way.At first,they use the computer to design the pipe intersecting curve trajectory picture,and then print the picture by 1:1.Finally,they put this intersecting curve trajectory picture on the pipes to cut.This method has low labor intensity and low production rate.A small number of enterprises use special machine to cut pipe intersecting curve,but the special machine takes a large area and has a poor versatility.General industrial robot market has long been monopolized by foreign robot manufacturers.Some special robot functions such as cutting,welding need to be bought with extra money.Under this background,in order to improve the cutting productivity of pipe intersecting curve,save the cost of enterprises,reduce the gap between the domestic and the foreign advanced robotics technology,a detailed analysis on the research status and development trend of the domestic and foreign industrial robot was carried out,and a robot system for pipe intersecting curve air plasma cutting was researched and designed.This robot system uses a universal industrial robot with 6 degrees of freedom and a positioner with single axis.The software of the system is based on Kithara RealTime Suite which is a Windows real-time extension software developed by German Kithara company.The communication protocol is EtherCAT and the communication cycle is Ims.The user only needs to input 7 key parameters and 4 teaching points to handle the cutting operation,which is more automated and intelligent.At first,a mathematical model of the 6 DOF robot was established in a coordination transformation way.Based on this model,a relation between the robot base frame and the end of the connecting rod frame was built,the position and orientation of the end of the connecting rod frame under the robot base frame was represented with X,Y,Z and Z-Y-X coordinate values of Euler,and the forward and inverse solutions of robot kinematics was analyzed.Then the theoretical basis of fixed reference point calibration method of the robottool frame was introduced in a geometric method,the calibration process of the 6 points calibration method was analyzed and an error parameter was presented to evaluate the calibration results.And then a mathematical model of the pipe intersecting curve was established,the cutting algorithms of the pipe intersecting curve main pipe and branch pipe were especially analyzed,in which the intersecting curves of main pipe and branch pipe were divided into an axial motion and a rotary motion carried out by 6 DOF robot and positioner respectively.And the motions were planned with dichotomy,linear acceleration and deceleration algorithm.At last,an experiment proofed that this robot system was practicable and efficient,in which the result of the intersecting curve could meet the requirements of the following welding process,and the whole teaching and cutting process of each pipe could be executed within one minute.