The Research And Implementation Of Painting Robot Operation Planning System For Complex Surface

Taking High-grade NC Machine Tools and Basic Manufacturing Equipment National Science and Technology Major Project "15Kg painting robot outfit" as the background, this thesis aims to research and achieve the painting robot operation planning method for complex surface.Because of different surface features of complex surface between that of plane and extruded surface, a new method is studied and realized to solve the problem, which is painting robot programming on complex surface. This method can be divided into three parts: surface fragmentation, path planning on sub-surface, and paths connection.Complex free-form surface has complex topological feature (holes etc.) and geometry feature (shape, curvature, etc.), which increases the difficulty of spraying path planning. Therefore, the topological features and geometry features of the surface are analyzed. Then the surface is fragmented so that the complex free-form surface is divided into several simple sub-surface with simple topological feature and geometry feature.For situation where there are holes in the surface, the surface should be divided into several independent sub-surfaces using projection method so that each sub-surface does not contains holes.For the workpiece which contains a hole,two special flat surfaces are selected to devided the surface into several independent sub-surfaces in this thesis. Then the curvature of the sub-surface may has a great change, so the sub-surface need to be fragmented according to the geometric feature by setting adjacent angle threshold and the deviation angle so that the curvature of sub-surface has a little change.Typically each sub-surface is not flat after the surface is fragmented,and the curvature of each sub-surface changes in all directions.So a spray path planning based on seed curve is studied and realized, which has variable speeds and variable stroke distances,to enhance the effect of spraying. Then path planning is carried out on this free-form surface. Firstly, a curve in the surface called seed curve shoule be determined. This curve is used as the baseline and is translated on the surface to get all the painting strokes.The principle of selecting seed curve is that the stroke should be as little as possible and there is no intersection between stokes.Then each stroke is segmented and each segment has different speed. Then all the speeds of segments are optimized so that the coating acculation rate is approximately constant. Then the distances of strokes are optimized. Considering the impact on film thickness of stokes,4 strokes are optimized at once to improve accuracy of spraying. As the speed and the stroke distance optimization have multivariable, BOBYQA optimization method is used. Then all the strokes distances and speeds of all the segments are got, so the spray path of each sub-surface is got.On the basis of path planning on the sub-surface,in order to get the complete painting paths,these separated sub-surface paintint paths should be linked so that all the painting paths are passed and the traveled distance is shortest.This sub-surface connection problem is modeled as generalized TSP.Ant colony algorithm is used to obtain optimal solution.Then the start and end points of the sub-surface painting paths are linked to form a complete painting path,and the general programming language file is generated.Ant colony algorithm has a fast convergence speed and better optimization results which means the length of connecting painting paths is shorter compared to the heuristic search algorithm such as genetic algorithm used before.And these advantages will be more apparent when the number of sub-surface painting paths increases.Finally, the result of path planning and parameter optimization will be simulated on the workpiece.In this thesis, studying and realizing the painting robot operation planning method for complex surface has been completed. This method can plan the spray paths for the complex free-form surface, which can satisfy the needs of the project after the simulation by the spraying operation planning system.