Research On Robot Polishing And Grinding Trajectory Planning Method And Off-line Programming For Free-form Surfaces

The polishing and grinding of free-form surface such as faucets,blades,and artificial hip joints is relatively complicated,and it is still dominated by artificial polishing.Because of its high production efficiency,versatility,high flexibility,and good flexibility,robot processing have become an effective way to solve free surface polishing and grinding,but still rely on inefficient manual teaching operations.Robots are also used in all aspects of manufacturing.At present,the application of robots in industry is mainly manual operation.In order to realize automatic machining of free-form surface,the method of trajectory planning was proposed,and offline programming software was developed.Firstly,a trajectory planning method on NURBS interpolation was proposed to obtain the free surface machining trajectory in this article and then a comprehensive trajectory passability judgment method was used to determine the passability of the trajectory.Finally,the robot polishing and grinding off-line programming software based on the research results of the free-form surface and the trajectory passability judgment method was developed.The versatility and effectiveness of the method for generating free-form surface processing trajectory and the feasibility of off-line programming software were verified through experiments.The main research work of this paper is as follows:(1)It is proposed that a NURBS surface trajectory planning method based on IGS file to meet the high bow error.First;the mathematical expression of the NURBS surface was used to reconstruct the surface in this method.Then based on the bow height error,the curve parameters in the two directions were interpolated,and the trajectory of curve was obtained according to the one-to-one mapping of NURBS curve parameters and vectors.Finally,through the space coordinate transformation and robot kinematics,the trajectory based on the work piece coordinate system was mapped to the joint space of robot.Because the interpolation method was combined with the interpolation cycle of the robot,the obtained machining trajectory was consistent with the actual machining process of the robot.(2)It was proposed that a method for the feasibility of the trajectory of considering collision detection,wrist rotation,singularity,accessibility and minimum curvature interference conditions.the method of Latin hypercube sampling(LHS)is used to solve the reachable workspace of robot.Differential change method was used to determine the singularity of the trajectory.(3)Based on the theory of the planning and feasibility determination of trajectory,the off-line programming software for robot polishing and grinding has been developed,which includes five modules:input and output,trajectory planning,verifying,3D virtual motion simulation and communication module.The off-line programming software can be used to generate free surface machining trajectory,simulate the machining process,and judge passablity of trajectory.(4)the off-line programming software for robot polishing and grinding was applied in the actual machining,and the results showed that the trajectory planning method and off-line programming software was feasible and effective.