A new real-time trajectory generation method modifying trajectory based on trajectory error and angular speed for high accuracy and short machining time

Ishizaki, Kousuke; Shamoto, Eiji

doi:10.1016/j.precisioneng.2022.02.012

Cited by 8 publications

(2 citation statements)

References 14 publications

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“…Nowadays the linear toolpath (G01 blocks), composed of a set of short line segments, is the most common toolpath format used in CNC machining [1]. However, the G1 and G2 discontinuities at the junctions of two linear segments will inevitably induce frequent feedrate fluctuation and acceleration variation [2], which has a significant negative influence on machining quality and efficiency in high-speed machining. Therefore, toolpath smoothing operation is essential in numerical control systems to improve the toolpath continuity [3].…”

Section: Introductionmentioning

confidence: 99%

Global toolpath smoothing for CNC machining based on B-spline approximation with tool tip position adjustment

Huang

et al. 2023

Int J Adv Manuf Technol

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B-spline curve approximation is widely used for fitting linear toolpaths to improve machining quality and efficiency in CNC machining. For a high-quality smoothing method, the control of both approximation error and curve curvature needs to be considered. To reduce the maximum curve curvature while meeting the precision requirements, a B-spline approximation scheme with tool tip position adjustment is proposed in this paper. Toolpaths are first divided into several subdivisions according to the discrete curvature of each tool tip point. For subdivisions that need adjustment, tool tip positions are adjusted to minimize the maximum discrete curvature. An existed approximation method named Energy-term-incorporated Progressive and Iterative Approximation for Least Square fitting (ELSPIA) is selected and improved to fit the adjusted toolpaths and lower the chord errors. For improving the numerical stability of ELSPIA method, the way of searching appropriate foot point parameters is discussed in this paper. Deviation expansion factors of tool tip points are also defined to make the ELSPIA method suitable for fitting the adjusted toolpaths. Both simulations and experimental studies are conducted to prove that the proposed method can significantly decrease the maximum curvature of fitted B-spline curves and improve the machining efficiency without exceeding the tolerance. For example, experimental results show that for the tested butterfly and rabbit toolpaths, the proposed method can improve the machining efficiency by 2.61% and 2.37%, compared with the ELSPIA method without tool tip position adjustment.

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Section: Introductionmentioning

confidence: 99%

Global toolpath smoothing for CNC machining based on B-spline approximation with tool tip position adjustment

Huang

et al. 2023

Int J Adv Manuf Technol

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“…Although the trapezoidal feed rate scheduling method is simple to implement [17], the discontinuity in acceleration can cause vibrations during frequent acceleration and deceleration, leading to a decrease in the lifespan of the motion equipment. The G1 and G2 discontinuities occurring at the junctions of two linear segments inevitably result in frequent feed rate fluctuations and acceleration variations [18]. Therefore, toolpath smoothing operations are crucial in numerical control systems to improve path continuity [19].…”

Section: Introductionmentioning

confidence: 99%

A High-Precision Planar NURBS Interpolation System Based on Segmentation Method for Industrial Robot

Liu,

Xu,

Cao

et al. 2023

Applied Sciences

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NURBS curve parameter interpolation is extensively employed in precision trajectory tasks for industrial robots due to its smoother performance compared to traditional linear or circular interpolation methods. The trajectory planning systems for industrial robots necessitate four essential functional modules: first, the spline curve discretization technique ensuring chord error compliance; second, the contour scanning technique for determining the maximum feasible feed rate for multi-constraint and multi-segment paths; third, the technique for achieving a smooth feed rate profile; and fourth, the continuous curve parameter interpolation technique. Therefore, this paper proposes a high-precision planar NURBS interpolation system for industrial robots. Firstly, a segmentation method for NURBS curves based on a closed-loop chord error constraint is proposed, which segments the original global NURBS curve into a collection of Bezier curves that strictly meet the chord error constraint. Secondly, a bidirectional scanning technique is presented to meet the joint space constraint, establishing an analytical mapping between the tool tip kinematic constraint and the joint kinematic constraint. Then, based on the traditional S-shaped feed rate profile, an adaptive algorithm with a displacement constraint is introduced, considering the real-time speed adjustment requirements of robots. Finally, a compensation interpolation strategy based on arc length parameterization is adopted to solve the accumulated error problem in parameter interpolation. The effectiveness of and potential for enhancing the quality of planar machining of the proposed planar NURBS interpolation system for industrial robots are validated through simulations and experiments. The results demonstrate the system’s applicability and accuracy, and its ability to improve planar machining quality.

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Three-dimensional parametric contact analysis of planetary roller screw mechanism and its application in grouping for selective assembly

He,

Wei,

Liu

et al. 2024

Front. Mech. Eng.

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A new real-time trajectory generation method modifying trajectory based on trajectory error and angular speed for high accuracy and short machining time

Cited by 8 publications

References 14 publications

Global toolpath smoothing for CNC machining based on B-spline approximation with tool tip position adjustment

Global toolpath smoothing for CNC machining based on B-spline approximation with tool tip position adjustment

A High-Precision Planar NURBS Interpolation System Based on Segmentation Method for Industrial Robot

Three-dimensional parametric contact analysis of planetary roller screw mechanism and its application in grouping for selective assembly

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