Research On Curvature Smooth Real-time Interpolation And Motion Planning For Short Linear Segments Machining

High-speed high-precision machining is mainly used in the formation of a series of continuous short-line processing by discrete curves and surfaces.If the CNC system directly processes such toolpaths,the feed motion completely stops at each corner of the path,causing severe inertial oscillations and feed shocks,creating noticeable feed marks on the part surface.In response to this problem,this paper aims to construct a real-time interpolation algorithm of curvature smoothing(G~3 continuous),so that the speed and acceleration of feed motion during machining can be smoothly transferred,improving the processing quality and processing time.After considering the spline interpolation method and the impulse response technology,this paper re-explores the corner,the short-line segment and the overlapping corner profile in the short-line process from the perspective of kinematics,degree limit acceleration curve,a real-time interpolation algorithm that can adaptively feed speed is proposed.The main research contents and achievements of this paper are as follows:Firstly,by analyzing the existing high-speed short-section processing technology,the short-section high-speed processing problems are divided into three different aspects to deal with,namely,the cornering path in the processing path,the short-section of the corner between the corner of the feed motion and overlap corner profile Transfer movement.Secondly,the advantages and disadvantages of spline interpolation technique and impulse response technique are analyzed.The kinematics of the spline curve is studied from the perspective of kinematics,and the motion characteristics of each axis in the jump limit acceleration curve and feed motion are studied in detail.Thirdly,the corner smoothing algorithm is proposed based on the bounding acceleration limit curve,and the corner smoothing algorithm is divided into an accelerating cornering smoothing algorithm and a non-interrupted accelerating cornering smoothing algorithm according to the additional acceleration boundary conditions.Finally,the various parameters of the corner smoothing algorithm are calculated through boundary conditions such as velocity,displacement and the specified contour error parameters.Through simulation and experiment,the two algorithms can realize the smooth interpolation of the corners in the machining path,and the interpolated machining path achieves the smooth curvature,the smooth transition of the velocity and the acceleration,and the uninterrupted feed motion at the corner.But the interrupt acceleration corner smoothing algorithm at the expense of part of the processing time makes the transition in the process of linear displacement shorter,can be suitable for shorter corners of the smooth transition,without interruption of the corner smoothing algorithm more pursuit of the best transfer duration,neglecting the influence of linear displacement length during the transfer process,the linear displacement during the transfer process is longer than the interrupted acceleration corner smoothing algorithm,and is more suitable for the smooth transition of corners at longer distances.Fourly,in this paper,an adaptive feed rate interpolation algorithm is proposed for the short-line segment between the corner contours.The feedrate can be adaptively adjusted according to the length of the short-line segment between the corner contours.In order to meet the real-time interpolation requirements of CNC system,Speed calculation,accurate calculation of the parameter values to accurately determine the maximum feed rate,to achieve the corner of the fine-tuning speed.The algorithm is also based on the hopping limit acceleration curve,and the curvature is smoothed by the mixed machining path after the corner smooth interpolation and the short profile interpolation between the corner profiles.The acceleration and the speed can be smoothly transferred throughout the machining path.Fively,in the end,the special case of overlapped profile in high speed and high precision machining is analyzed and researched.It is put forward that the smooth and overlapping corner profile of the two corner profiles overlapped by suturing,and the smooth transition of speed and acceleration in feed motion can be achieved.The algorithm is divided into 2-stage smooth interpolation algorithm and 4-stage smoothing algorithm according to the length of overlapped corner profile.The function of 4-stage smoothing algorithm is that when the length of overlapped corner profile is relatively long,using2-stage smoothing interpolation algorithm may make the feed path is beyond the original machining path,which can not meet the requirements of the process path closures.Therefore,a 4-stage smoothing algorithm is proposed to precisely control the feed contour after interpolation by increasing the number of stages of the algorithm.In summary,this paper studies three main aspects in the process of high-speed and high-precision finishing in the short-run section,and proposes corresponding real-time interpolation algorithm to finally make the entire machining path after interpolation satisfy the curvature and smooth the speed and acceleration Transfer,get the best balance of time and drive system performance.