| In CNC machining,speed planning along the feed direction of machining trajectory has the problem of speed transverse inconsistency.The speed planning method of identifying the feature points of machining trajectory,dividing the speed interval,and using the speed interval as the planning unit,still has the problem of speed transverse inconsistency because the feature points are missing and the trajectory transverse feature points are "sawtooth-shaped".In order to extract the boundary feature points directly from the tool position points,the boundary feature points are not consistent laterally,this paper proposes an algorithm to extract the 3D model geometric feature lines and map the boundary feature points of the optimized speed limit interval to be consistent laterally.The algorithm identifies machining trajectory feature points and extracts 3D model geometric feature lines.The geometric feature line can make up for the identified feature points in the trajectory lateral,and at the same time,because the geometric feature line is very smooth in the trajectory lateral,it can smooth the original feature point lateral "jagged" interval boundary and get the lateral consistent interval boundary.For the speed planning speed lateral inconsistency problem,by identifying the trajectory feature points to divide the speed-limited intervals,this paper proposes a global consistent algorithm of the same speed interval boundary for bi-directional interval planning of the trajectory.The algorithm uses the speed-limited interval boundary after photoshunting to perform velocity planning for each speed-limited interval in the trajectory direction and trajectory lateral,the velocity planning of the speed-limited interval in the trajectory direction will be backtracked and merged due to the interval when it does not satisfy the velocity curve motion law,thus destroying the consistency of the original boundary and leading to the inconsistency of the lateral variable speed points,the planning of the trajectory lateral for some intervals in the lateral interval needs to be backtracked and merged for the lateral The trajectory transversal planning uses consistent backtracking to maintain the transversal consistency of the interval boundary and the transversal consistency of the speed planning variable speed point.The method proposed in this paper was verified by simulation on the iSurfine offline optimization software,and actual machining tests were carried out on the Huazhong 9 highgrade CNC system.A large number of verification experiments showed that the lateral consistency of the tool feed speed was greatly improved,which well proved the feasibility and effectiveness of the method proposed in this paper in speed planning. |
