Research On Path Smoothing And Feedrate Planning Of 5-DOF Hybrid Machining Robot

In the aerospace industry,complex parts are widely used in integrated structural design,and traditional series and parallel machine tools have become increasingly unable to meet the processing needs of new parts.The five-degree-of-freedom hybrid processing robot combines the advantages of a series structure and a parallel mechanism,and has the characteristics of large working space,strong system stability,and high processing accuracy.In addition to the topological structure,the processing algorithm also has a great influence on the processing performance of the robot.This article mainly studies the linear path smoothing,speed planning and interpolation calculation methods.The main contents are as follows:A path smoothing algorithm based on NURBS weight variation is proposed.According to the angle of the linear path,the smoothing method of the path points is divided into two types: local smoothing and global smoothing.The G2 continuity of NURBS paths of different segments is realized by selecting auxiliary control points reasonably.Based on the weight characteristics of NURBS curve control points,use the simulated annealing algorithm optimizes the weight of the control points of the NURBS path to obtain a smooth path that meets the fitting error.The tool tip and the tool axis path use the same nodal vector,and the fitting error and the equidistant error are the optimization goals.The simulated annealing changes the control point weight and auxiliary control point position to obtain the equidistant double NURBS path.A forward-looking feedrate planning method based on periodic S-type acceleration and deceleration motion is proposed.The traditional S-shaped acceleration and deceleration movement is subdivided into 4 types,and the relationship between feedrate and displacement with time and the movement time interpolation periodic equation are derived.Reasonably select the acceleration and deceleration movement type of each NURBS path,set the conditions to plan the forward feedrate of several sections of paths in units of "units",if the initial feedrate of a section of the path changes,backtracking is enabled to obtain a continuous numerical feedrate curve.The bisection adaptive dichotomy is used to calculate the interpolation points.Simulation analysis and experimental verification.The butterfly point path is used for simulation analysis,and the simulation results are compared with the algorithm proposed in this paper.A five-axis hybrid robot was used to perform the S-shaped partial machining experiment,and the experimental results were good.