NURBS Curve Fitting Research Articles

Traffic Flow Detection at Road Intersections Based on K-Means and NURBS Trajectory Clustering

In view of the variety and occlusion of vehicle target motion on the urban intersection, it is difficult to accurately detect the traffic flow parameters in all directions and categories of the intersection, so an improved k-means trajectory clustering method based on NURBS curve fitting is designed to obtain the traffic flow parameters. Firstly, the B-spline quadratic interpolation function is used to fit the smooth NURBS curve of vehicle trajectory; secondly, K-means clustering is used to measure the minimum distance, and the location of the first and last end points of the vehicle trajectory is used to realize the automatic division of the intersection area; finally, according to the intersection area where the start and end points of vehicle trajectory belong, respectively, the moving mode of a vehicle is determined, and the traffic flow parameters are classified and counted. Experiments show that the method has high accuracy and simple algorithm, which can meet the application requirements of intelligent transportation. It can provide effective data for traffic congestion analysis and lane occupancy estimation, and it is an important parameter for dynamic time setting of intersection information lights.

Hand-Painted Curve Fitting Method Based on NURBS Curve

In hand-drawn graphics modeling method, the input to the system free hand draw curve is the first step in modeling. Effective fitting the curve of the input is the key to modeling effect is good or bad. For noise, free shape features of hand-painted curve, presents a method of using NURBS curve fitting of hand-painted curves. Experiments show that using NURBS hand-drawn curve fitting, the fitting effect is good, easy to modify, for later use of curve, not only can be used in hand-painted curve modeling system, can also be applied to the mainstream way of WIMP modeling system.

역공학을 위한 가상머신의 적합성에 대한 연구

The purpose of this study is to make virtual machine using a 3D modeller to perform reverse engineering. Through the intuitive designer's ability, approximated model of the object is created and used to extract the data and NC tool path. The extracted data make approximated curve by using NURBS curve fitting. And the curve is used to remodel. From these series of process, the final reverse engineering data of the objects can be obtained. Two conclusions are drawn from this study. First, initial deviation of the intuitive model is one of the important factors that determine the number of repetitions of the experiment. Due to the characteristic of intuitive curve, after a certain number of repetitions the average deviation increase and radiate rather than decrease.

NURBS Curve Fitting Based on Arc Centripetal Parameterization for Tool Path Generation

NURBS curve fitting is used for tool path planning for sculptured surface NC machining. The cutter location data is parameterized by equal chord arc length parameterization, and Centripetal Parameterization is improved. It is not only more approach to curves nature equation in theory, but also closer to the interpolated curves in actual fitting. It is directly to reflect the curvature of curves of cutter location in NC machining.

Research of Accurate NURBS Curve Fitting Based on Genetic Algorithm

In order to control the curve modality of non-uniform rational B-spline accurately, the genetic algorithm is presented to the manipulative precision of NURBS curve fitting. The manipulative precision of curve fitting and the overall side-by-side search ability of genetic algorithm were researched; the excellent unit is founded in the field of weight coefficient. The precision result and the curve figure of curve fitting using the excellent weight coefficient are better. The examples of data fitting are given to show that the curves fitting used genetic algorithms are better in approximation. The precision result of curve fitting is improved. The global optimal search of genetic algorithm provides a reliable tool for scientific data processing.

The CAM System for Scroll Profile with Three CNC Interpolations

The scroll profile is complex with involute curve and high precision is required. Owing to the interpolation method has significant effects on the dynamic behaviour and to obtain the flexibility of the machining, this paper focuses on the development of a computer-aided manufacturing methodology for precision scroll by the combination of curve fitting and CNC interpolation. In this paper, the method for design and manufacture of the scroll profile is established based on the differential geometry and the enveloping theory. The cutter location using the cylindrical end mill is derived and the cutting path sequences are planned. Three types curve fitting methods: linear fitting, circular biarcs curve fitting, and NURBS curve fitting are adopted to approximate the toolpath of the scroll profile. The error control is used as the basis for generating appropriate toolpath to ensure the machining accuracy. The circular biarcs fitting and NURBS curve fitting can obtain continuous smooth toolpath. In the identical chordal deviation, the circular biarcs curve fitting provides the best performance. The toolpath generated by the proposed method is verified through the solid cutting simulation and the trial-cut on a three-axis machine tool.