With the development of industrial technology,industrial robots are applied more and more widely in coating field,and it has become a trend for automatic coating equipment to replace manual labor.Therefore,it is of great practical significance and value to improve the performance of automatic coating system.In automatic coating,the free curve shape of the relevant workpiece needs to be described and parameterized to make the end of the robot move along the contour line at a constant speed.According to the requirements of coating technology,the control method of space free curve robot with uniform motion is studied in this paper.Firstly,the NURBS interpolation method of spatial free curve is studied.This paper introduces the basic theory of NURBS curve and its solution method,and introduces an adaptive NURBS curve interpolation method,which is convenient for computer storage and calculation,fast calculation speed,high profiling accuracy and smoother curve.Secondly,the trajectory planning of multi-segment straight line with continuous uniform velocity is carried out.Based on trapezoidal velocity planning,the trajectory planning method of multi-segment linear continuous motion is introduced,and the trajectory generation of multi-segment linear continuous constant motion is realized.In this paper,a kind of attitude planning based on point cloud model is proposed to solve the problem of spraying on the surface of vertical workpiece.Then,the end velocity after trajectory planning is optimized based on genetic algorithm.This method is based on the PUMA 560 robot to establish the optimization model of the continuous motion trajectory of the end,and the time optimal criterion is used to optimize the trajectory of this section,and the optimal velocity and acceleration within the constraint conditions are obtained.Finally,the uniform motion experiment of the space free curve robot is carried out.In the robot experiment environment,the free curve NURBS interpolation motion experiment is carried out,and the speed of the end is measured with the help of laser displacement sensor.The experiment proves the advantages and universality of NURBS interpolation.The method of NURBS interpolation and multi-section straight-line continuous uniform motion introduced in this paper can get the excellent motion performance of the robot end,which can meet the requirements of painting process parameters that the velocity of robot spraying end fluctuates within 5% in the automotive aftermarket. |