scholarly journals Modeling and machining of integral impeller based on NURBS curve

2021 ◽  
Vol 113 (7-8) ◽  
pp. 2243-2255
Author(s):  
Juan Wei ◽  
Xiaodong Hou ◽  
Guipeng Xu ◽  
Guangming Zhang ◽  
Hongwei Fan
Keyword(s):  
Nurbs Curve

scholarly journals A Feedrate Planning Method for the NURBS Curve in CNC Machining Based on the Critical Constraint Curve

2021 ◽  
Vol 11 (11) ◽  
pp. 4959
Author(s):  
Peng Guo ◽  
Yijie Wu ◽  
Guang Yang ◽  
Zhebin Shen ◽  
Haorong Zhang ◽  
...  
Keyword(s):  
Planning Method ◽  
Cnc Machining ◽  
Arc Length ◽  
Kinematic Constraint ◽  
Nurbs Curve ◽  
Planning Strategy ◽  
Feedrate Planning ◽  
Curvature Constraint ◽  
Planning Methods ◽  
The Relationship

The curvature of the NURBS curve varies along its trajectory, therefore, the commonly used feedrate-planning method, which based on the acceleration/deceleration (Acc/Dec) model, is difficult to be directly applied in CNC machining of a NURBS curve. To address this problem, a feedrate-planning method based on the critical constraint curve of the feedrate (CCC) is proposed. Firstly, the problems of existing feedrate-planning methods and their causes are analyzed. Secondly, by considering both the curvature constraint and the kinematic constraint during the Acc/Dec process, the concept of CCC which represents the relationship between the critical feedrate-constraint value and the arc length is proposed. Then the CCC of a NURBS curve is constructed, and it has a concise expression conforming to the Acc/Dec model. Finally, a feedrate-planning method of a NURBS curve based on CCC and the Acc/Dec model is established. In the simulation, a comparison between the proposed method and the conventional feedrate-planning method is performed, and the results show that, the proposed method can reduce the Acc/Dec time by over 40%, while little computational burden being added. The machining experimental results validate the real-time performance and stability of the proposed method, and also the machining quality is verified. The proposed method offers an effective feedrate-planning strategy for a NURBS curve in CNC machining.

scholarly journals Two view NURBS reconstruction based on GACO model

2021 ◽  
Author(s):  
Deepika Saini ◽  
Sanoj Kumar ◽  
Manoj K. Singh ◽  
Musrrat Ali
Keyword(s):  
Optimization Algorithms ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Least Square ◽  
Ant Colony ◽  
Free Form ◽  
Reconstruction Process ◽  
Nurbs Curve ◽  
Data Points ◽  
Ant Colony Optimization Algorithms

AbstractThe key job here in the presented work is to investigate the performance of Generalized Ant Colony Optimizer (GACO) model in order to evolve the shape of three dimensional free-form Non Uniform Rational B-Spline (NURBS) curve using stereo (two) views. GACO model is a blend of two well known meta-heuristic optimization algorithms known as Simple Ant Colony and Global Ant Colony Optimization algorithms. Basically, the work talks about the solution of NURBS-fitting based reconstruction process. Therefore, GACO model is used to optimize the NURBS parameters (control points and weights) by minimizing the weighted least-square errors between the data points and the fitted NURBS curve. The algorithm is applied by first assuming some pre-fixed values of NURBS parameters. The experiments clearly show that the optimization procedure is a better option in a case where good initial locations of parameters are selected. A detailed experimental analysis is given in support of our algorithm. The implemented error analysis shows that the proposed methodology perform better as compared to the conventional methods.

Velocity control algorithm in glass polishing based on the cubic NURBS curve

2017 ◽  
Vol 232 (4) ◽  
pp. 685-696 ◽  
Author(s):  
Junzhao Han ◽  
Wenhua Chen
Keyword(s):  
Control Algorithm ◽  
Linear Acceleration ◽  
Control Points ◽  
Velocity Control ◽  
Polishing Process ◽  
Nurbs Curve ◽  
Weighting Factors ◽  
Final Velocity ◽  
Contact Points ◽  
Glass Polishing

To limit velocity fluctuations and to achieve a controllable jerk value in a glass polishing process, a new velocity control algorithm is proposed based on nonuniform rational B-splines (NURBS). The key of this algorithm is replacing the traditional linear acceleration–deceleration with flexible NURBS acceleration–deceleration. Based on the linear acceleration–deceleration algorithm, the control points of the NURBS curve are confirmed, and the final velocity of the polishing wheel center is solved using the Preston equation. With jerk continuity and limitations of the servo system, nonlinear equations are constructed, and the weighting factors corresponding to the control points are obtained. Cubic velocity control equations can be derived from the obtained feature parameters, which include the final velocity, control points, weighting factors and knot vectors. Based on the proposed NURBS acceleration–deceleration algorithm, a fourth-order Runge–Kutta formula was used to obtain the initial points, and the Milne–Hamming equation was used to predict and correct the next point. The predictor-corrector interpolation algorithm for parametric trajectory was implemented during the polishing process. The experimental results indicate that the proposed approach guarantees limited fluctuations of the relative velocity at contact points and ensure smoother velocity changes at dangerous points.

Conformal and G1 Continuous Connection of NURBS Curves

2013 ◽  
Vol 756-759 ◽  
pp. 3826-3830
Author(s):  
Pei Sen Deng ◽  
Shao Ping Chen ◽  
Jun Cheng Shen
Keyword(s):  
Knot Insertion ◽  
Nurbs Curve ◽  
Nurbs Curves ◽  
Insertion Algorithm ◽  
Vector Rotation

This paper converts a NURBS curve to piecewise rational Bézier curves by knot insertion algorithm, and then discusses the algorithm of continuous connection of NURBS curves. Meanwhile, explores the method to keep the same shape of the NURBS curves after connecting through the point translation and vector rotation theory. Finally, gives an instance to verify the validity of the algorithm.

scholarly journals Modelling and Rapid Prototyping of Centrifugal Pump Impeller Based on UG

2019 ◽  
Vol 291 ◽  
pp. 02009
Author(s):  
Yongmei Jiang ◽  
Zilong Wang ◽  
Zhao Jingnan
Keyword(s):  
Rapid Prototyping ◽  
Centrifugal Pump ◽  
3D Model ◽  
Pump Impeller ◽  
Innovative Design ◽  
Design Modification ◽  
Nurbs Curve ◽  
Curve Interpolation ◽  
Centrifugal Pump Impeller

The 3D model of centrifugal pump impeller in Unigraphics (UG) was optimized by implementing the principles of NURBS curve interpolation. The impeller was then manufactured by rapid prototyping equipment using polystyrene. The technique improves the efficiency in innovative design, modification, and fabrication.

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