Path Smoothing And Trajectory Generation For Robotic Machining

As a key technical innovation of intelligent manufacturing,machining operations with industrial robots has gained a great interest in the world.Compared with multi-axis machine,industrial robot has higher flexibility,automation and coordination,which makes it more suitable for machining large and complex parts.In order to realize accurate and efficient machining processing,it is important to study pose optimization,path smoothing and trajectory generation.However,there are still some unsolved problems in the up mentioned areas: the performance index of the robot stiffness is not considered while transferring NC codes to robotic language;none of the proposed methods in current literatures can realize restriction of transition error and parametric synchronization while smoothing position and orientation of the end-effector;the nonlinear kinematics are not considered in the current trajectory generation methods.In order to handle the problems mentioned above,this research is curried out with the following context.Firstly,a novel pose optimization method is presented.In this method,robot stiffness is considered,which can improve dynamic characteristics and reduce deformation caused by cutting force.Secondly,a 6-dof path smooth method is presented to improve machining and contouring performance.Two 3-order bezier curves are used to blend position and orientation of the end-effector.to restrict smoothing error,orientation is represented by 3 Euler angles.The transition length is adjusted to realize parametric synchronization.Then,a real-time look-ahead trajectory generation method is proposed.in this method,seven segment S-shape feedrate scheduling technique is employed to schedule a feedrate profile with continuous acceleration.The nonlinear kinematics is considered to optimize the maximum velocity and acceleration.The effectiveness of the proposed method is evaluated by simulations and experiments.Finally,"iRobotCNC" off-line programming software is developed based on UG.This software is a convenient and open robot programming platform,including post-processing,dynamics modeling,error compensation and movement simulation.