Real-Time B-Spline Interpolator with Look-Ahead Scheme for High-Speed CNC Machine Tools

2010 ◽  
Vol 455 ◽  
pp. 599-605
Author(s):  
Yong Qiao Jin ◽  
Yu Han Wang ◽  
Jian Guo Yang
Keyword(s):  
Real Time ◽  
High Speed ◽  
Tool Path ◽  
Cnc Machine Tools ◽  
Interpolation Algorithm ◽  
Cnc Machine ◽  
Machining Time ◽  
B Spline ◽  
Optimal Speed ◽  
Look Ahead

NC tool paths of digital CAD models are currently generated as a set of discrete data points. The CNC interpolator must convert these points into continuous machine tool axis motions. In order to achieve high-speed and high-accuracy machining, the development of a real-time interpolation algorithm is really indispensable, which can deal with a large number of short blocks and still maintain smooth interpolation with an optimal speed. In this paper, a real-time local cubic B-spline interpolator with look-ahead scheme is proposed for consecutive micro-line blocks interpolation. First, the consecutive micro-line blocks that satisfy the bi-chord error constraints are fitted into a C1 continuous cubic B-spline curve. Second, machining dynamics and tool path contour constrains are taken into consideration. Third, local cubic B-spline interpolator with an optimal look-ahead scheme is proposed to generate the optimal speed profile. Simulation and experiment are performed in real-time environment to verify the effectiveness of the proposed method. Compared with the conventional interpolation algorithm, the proposed algorithm reduces the machining time by 70%.

Multi-Period Turning Interpolation Algorithm for High-Speed Machining of Continuous Line Segments With Limited Acceleration, Jerk and Chord Error

2012 ◽  
Author(s):  
Lixian Zhang ◽  
Xiao-shan Gao ◽  
Hongbo Li
Keyword(s):  
Real Time ◽  
High Speed ◽  
Control Method ◽  
Dynamic Performance ◽  
Interpolation Algorithm ◽  
Cnc Machine ◽  
Look Ahead ◽  
Geometric Precision ◽  
S Curve ◽  
Accumulated Error

In this paper, a multi-period turning interpolation algorithm, with real-time look-ahead scheme based on S-curve control method, is presented. In this interpolation algorithm, the geometric precision and the dynamic performance are both satisfied. The machining efficiency is improved by multi-period turning transition, and the precision is also improved by S-curve control method. The computational efficiency of this algorithm meets the need of real-time machining. In addition, there is no accumulated error. At last, this algorithm is verified the validation by the experiments on 3-axis CNC machine.

A Real-Time C3 Continuous Local Corner Smoothing and Interpolation Algorithm for CNC Machine Tools

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Qin Hu ◽  
Youping Chen ◽  
Xiaoliang Jin ◽  
Jixiang Yang
Keyword(s):  
Real Time ◽  
Machine Tools ◽  
Tool Path ◽  
Control Period ◽  
Cnc Machining ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Interpolation Algorithm ◽  
Cnc Machine ◽  
Highly Nonlinear

Linear tool path segments of computer numerical control (CNC) machine tools need to be smoothed and interpolated in order to guarantee continuous and steady machining. However, because of the highly nonlinear relation between arc lengths and spline parameters, it is difficult to develop algorithms to simultaneously achieve real-time corner smoothing and interpolation with high-order continuity, although it is important to guarantee both high calculation efficiency and good dynamic performance of high-speed CNC machining. This paper develops a computationally efficient real-time corner smoothing and interpolation algorithm with C3 continuous feature. The corners at the junction of linear segments are smoothed by inserting Pythagorean-hodograph (PH) splines under the constraints of user-defined tolerance limits. Analytical solutions of the arc length and curvature of the smoothed tool path are obtained by evaluating a polynomial function of the spline parameter. The smoothed tool path is interpolated in real time with continuous and peak-constrained jerk. Simulations and experimental results show that the proposed tool path smoothing and interpolation algorithm can be executed in real time with 0.5 ms control period. Acceleration and jerk continuity of each axis are achieved along the tool path. Comparisons with existing corner smoothing algorithms show that the proposed method has lower jerk than existing C2 algorithms and the real-time interpolation algorithms based on the Taylor series expansion.

Development of Real-Time Look-Ahead Methodology Based on Quintic PH Curve with G2 Continuity for High-Speed Machining

2013 ◽  
Vol 464 ◽  
pp. 258-264 ◽  
Author(s):  
Jing Shi ◽  
Qing Zhen Bi ◽  
Yu Han Wang ◽  
Gang Liu
Keyword(s):  
Real Time ◽  
High Speed ◽  
Tool Path ◽  
Approximation Error ◽  
Machining Process ◽  
Transition Curve ◽  
Look Ahead ◽  
Cad Cam ◽  
Feedrate Fluctuation ◽  
Ph Curve

Curving tool paths composed of straight lines, which are often represented as G01 blocks, are still the most widespread format form in the machining process chain of CAD/CAM/CNC. At the junctions between consecutive segments, the tangency and curvature discontinuities may lead to feedrate fluctuation and acceleration oscillation, which would deteriorate the machining efficiency and quality. In this paper, a real-time look-ahead interpolation methodology is proposed, which adopts a curvature-continuous PH curve as a transition to blend corner at the junction of adjacent lines in the tool path. The blending algorithm can guarantee the approximation error exactly, and the control points of the curve can be calculated analytically. On the other hand, the arc length and the curvature of the transition curve, which are important items in speed planning, also have analytical expressions. All the advantages are the guarantee of calculation efficiency during the interpolation. Except for a curvature-continuous tool path, our look-ahead algorithm adopts a speed planning window strategy to achieve a balance between the calculation capabilities and the real-time interpolation requirements. In this window, the corner transition algorithm and speed planning are implemented simultaneously and dynamically during the interpolation. By defining the width of this window, which is actually the number of linear segments contained in this window, can adjust the time consuming of speed planning. Simulation and experiments on our own developed CNC platform are conducted. The results demonstrate the feasibility and efficiency of the proposed algorithms.

The Research of Circular Interpolation Motion Control Based on Rectangular Coordinate Robot

2016 ◽  
Vol 693 ◽  
pp. 1792-1798
Author(s):  
Xiu Min Shi ◽  
Wei Jie Fei ◽  
San Peng Deng
Keyword(s):  
Target Tracking ◽  
High Speed ◽  
Simple Algorithm ◽  
Single Pulse ◽  
Tracking Algorithm ◽  
Cnc Machine Tools ◽  
Interpolation Algorithm ◽  
Cnc Machine ◽  
Direct Target ◽  
Circular Interpolation

The high-speed pulse outputs of PLC can control motion of stepper motor or servo motor. So PLC can complete interpolation function which CNC can do using a kind of simple algorithm. What’s more, the PLC can be developed to be a controller of economical CNC machine tools. Based on the experiment platform of modern robot industrial, the paper introduced how to control the motion of servo system by PLC in detail, and completed the two-dimensional interpolation program through PLC using the direct target tracking as interpolation algorithm. The direct target tracking algorithm could form a series of micro straight line segments approach the desired interpolation trajectory through directly calculating a series of minimum interval points on the interpolation line and connecting these points end to end. Compared to the single pulse interpolation, the direct target tracking algorithm simplified interpolation algorithm and adapted to the PLC program, so it is suitable to economical CNC system. By programming and running in the experimental platform, it can achieve better results using the direct target tracking method as interpolation procedures.

Research on Five-Axis Dual-NURBS Adaptive Interpolation Algorithm for Flank Milling

2010 ◽  
Vol 443 ◽  
pp. 330-335 ◽  
Author(s):  
Yu Han Wang ◽  
Jing Chun Feng ◽  
Sun Chao ◽  
Ming Chen
Keyword(s):  
Tool Path ◽  
Flank Milling ◽  
Interpolation Algorithm ◽  
Machining Time ◽  
Surface Machining ◽  
Tool Axis ◽  
Scanning Area ◽  
Nurbs Interpolation ◽  
Milling Method ◽  
Five Axis

In order to exploit the advantages of five-axis flank milling method for space free surface machining to the full, a definition of non-equidistant dual-NURBS tool path is presented first. On this basis, the constraint of velocity of points on the tool axis and the constraint of scanning area of the tool axis are deduced. Considering both of these constraints, an adaptive feed five-axis dual-NURBS interpolation algorithm is proposed. The simulation results show that the feedrate with the proposed algorithm satisfies both of the constraints and the machining time is reduced by 38.3% in comparison with the constant feed interpolator algorithm.

FPGA-Based Intelligent Software Hardening Chip for Computer Numerical Control System

2011 ◽  
Vol 105-107 ◽  
pp. 2217-2220
Author(s):  
Mu Lan Wang ◽  
Jian Min Zuo ◽  
Kun Liu ◽  
Xing Hua Zhu
Keyword(s):  
High Speed ◽  
High Performance ◽  
Large Scale ◽  
Position Control ◽  
Computer Numerical Control ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Cnc System ◽  
Intelligent Software

In order to meet the development demands for high-speed and high-precision of Computer Numerical Control (CNC) machine tools, the equipped CNC systems begin to employ the technical route of software hardening. Making full use of the advanced performance of Large Scale Integrated Circuits (LSIC), this paper puts forward using Field Programmable Gates Array (FPGA) for the functional modules of CNC system, which is called Intelligent Software Hardening Chip (ISHC). The CNC system architecture with high performance is constructed based on the open system thought and ISHCs. The corresponding programs can be designed with Very high speed integrate circuit Hardware Description Language (VHDL) and downloaded into the FPGA. These hardening modules, including the arithmetic module, contour interpolation module, position control module and so on, demonstrate that the proposed schemes are reasonable and feasibility.

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