To satisfy the need for high-speed and high-accuracy machining of NURBS curve. Firstly the form of NURBS curve is analyzed and Talor＇s expansion of the parameter u with respect to time t is used to obtain the algorit...To satisfy the need for high-speed and high-accuracy machining of NURBS curve. Firstly the form of NURBS curve is analyzed and Talor＇s expansion of the parameter u with respect to time t is used to obtain the algorithm of the first order approximation interpolation. Secondly, based on the algorithm of the controlled chord error interpolator, an intelligent interpolation algorithm of the adaptive feedrate control is proposed. According to the actual machining capacity of machine tools, this algorithm uses look-ahead method, which dispenses with the complicated computation of the end point estimation of NURBS curve, to analyze the curve segment required by the maximum deceleration distance. Thus, the feedrate could decrease in advance and vary with the curvature and the variation ratio of curvature, which makes machining motion quite smooth. Not only could high accuracy and fine surface quality be achieved during high-speed machining, but also the overload of cutter tools is avoided on comers. Finally, in order to facilitate the calculation of interpolation, the dynamic matrix representation and efficient algorithm of curvature computation of the NURBS curve are presented,展开更多
The feedrate profile of non-uniform rational B-spline （NURBS） interpolation due to the contour errors is analyzed. A NURBS curve interpolator with adaptive acceleration-deceleration control is presented. In interpo-...The feedrate profile of non-uniform rational B-spline （NURBS） interpolation due to the contour errors is analyzed. A NURBS curve interpolator with adaptive acceleration-deceleration control is presented. In interpo- lation preprocessing, the sensitive zones of feedrate variations are processed with acceleration-deceleration control. By using the proposed algorithm, the machining accuracy is guaranteed and the feedrate is adaptively adjusted to he smoothed. The mechanical shock imposed in the servo system is avoided by the first and the second time derivatives of feedrates. A simulation of NURBS interpolation is given to demonstrate the validity and the effectiveness of the algorithm. The proposed interpolator can also be applied to the trajectory planning of the other parametric curves.展开更多
This paper presents the design considerations and implementation of an area-efficient interpolator suitable for a delta-sigma D/A converter. In an effort to reduce the area and design complexity, a method for designin...This paper presents the design considerations and implementation of an area-efficient interpolator suitable for a delta-sigma D/A converter. In an effort to reduce the area and design complexity, a method for designing an FIR filter as a tapped cascaded interconnection of identical subfilters is modified. The proposed subfilter structure further minimizes the arithmetic number. Experimental results show that the proposed interpolator achieves the design specification,exhibiting high performance and hardware efficiency,and also has good noise rejection capability. The interpolation filter can be applied to a delta-sigma DAC and is fully functional.展开更多
In this paper,a detailed analysis of a phase interpolator for clock recovery is presented. A mathematical model is setup for the phase interpolator and we perform a precise analysis using this model. The result shows ...In this paper,a detailed analysis of a phase interpolator for clock recovery is presented. A mathematical model is setup for the phase interpolator and we perform a precise analysis using this model. The result shows that the output amplitude and linearity of phase interpolator is primarily related to the difference between the two input phases. A new encoding pattern is given to solve this problem. Analysis in the circuit domain was also undertaken. The simulation results show that the relation between RC time-constant and time difference of input clocks affects the linearity of the phase interpolator. To alleviate this undesired effect, two adjustable-RC buffers are added at the input of the PI. Finally,a 90nm CMOS phase interpolator,which can work in the frequency from 1GHz to 5GHz,is proposed. The power dissipation of the phase interpolator is lmW with a 1.2V power supply. Experiment results show that the phase interpolator has a monotone output phase and good linearity.展开更多
基金National Excellent Young Teacher Encouragement Plan of China
文摘To satisfy the need for high-speed and high-accuracy machining of NURBS curve. Firstly the form of NURBS curve is analyzed and Talor＇s expansion of the parameter u with respect to time t is used to obtain the algorithm of the first order approximation interpolation. Secondly, based on the algorithm of the controlled chord error interpolator, an intelligent interpolation algorithm of the adaptive feedrate control is proposed. According to the actual machining capacity of machine tools, this algorithm uses look-ahead method, which dispenses with the complicated computation of the end point estimation of NURBS curve, to analyze the curve segment required by the maximum deceleration distance. Thus, the feedrate could decrease in advance and vary with the curvature and the variation ratio of curvature, which makes machining motion quite smooth. Not only could high accuracy and fine surface quality be achieved during high-speed machining, but also the overload of cutter tools is avoided on comers. Finally, in order to facilitate the calculation of interpolation, the dynamic matrix representation and efficient algorithm of curvature computation of the NURBS curve are presented,
基金Supported by the Natural Science Foundation of Jiangsu Province(BK2003005)~~
文摘The feedrate profile of non-uniform rational B-spline （NURBS） interpolation due to the contour errors is analyzed. A NURBS curve interpolator with adaptive acceleration-deceleration control is presented. In interpo- lation preprocessing, the sensitive zones of feedrate variations are processed with acceleration-deceleration control. By using the proposed algorithm, the machining accuracy is guaranteed and the feedrate is adaptively adjusted to he smoothed. The mechanical shock imposed in the servo system is avoided by the first and the second time derivatives of feedrates. A simulation of NURBS interpolation is given to demonstrate the validity and the effectiveness of the algorithm. The proposed interpolator can also be applied to the trajectory planning of the other parametric curves.
文摘This paper presents the design considerations and implementation of an area-efficient interpolator suitable for a delta-sigma D/A converter. In an effort to reduce the area and design complexity, a method for designing an FIR filter as a tapped cascaded interconnection of identical subfilters is modified. The proposed subfilter structure further minimizes the arithmetic number. Experimental results show that the proposed interpolator achieves the design specification,exhibiting high performance and hardware efficiency,and also has good noise rejection capability. The interpolation filter can be applied to a delta-sigma DAC and is fully functional.
文摘In this paper,a detailed analysis of a phase interpolator for clock recovery is presented. A mathematical model is setup for the phase interpolator and we perform a precise analysis using this model. The result shows that the output amplitude and linearity of phase interpolator is primarily related to the difference between the two input phases. A new encoding pattern is given to solve this problem. Analysis in the circuit domain was also undertaken. The simulation results show that the relation between RC time-constant and time difference of input clocks affects the linearity of the phase interpolator. To alleviate this undesired effect, two adjustable-RC buffers are added at the input of the PI. Finally,a 90nm CMOS phase interpolator,which can work in the frequency from 1GHz to 5GHz,is proposed. The power dissipation of the phase interpolator is lmW with a 1.2V power supply. Experiment results show that the phase interpolator has a monotone output phase and good linearity.
