Research on shape error of microstructure array fabricated by fly cutting

The uniformity of the wafer in a chemical mechanical polishing (CMP) process is vital to the ultra-fine and high integration of semiconductor structures. In particular, the uniformity of the polishing pad corresponding to the tool directly affects the polishing uniformity and wafer shape. In this study, the profile shape of a CMP pad was predicted through a kinematic simulation based on the trajectory density of the diamond abrasives of the diamond conditioner disc. The kinematic prediction was found to be in good agreement with the experimentally measured pad profile shape. Based on this, the shape error of the pad could be maintained within 10 μm even after performing the pad conditioning process for more than 2 h, through the overhang of the conditioner.

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Low-Cost Calibration of Matching Error between Lidar and Motor for a Rotating 2D Lidar

Applied Sciences ◽

10.3390/app11030913 ◽

2021 ◽

Vol 11 (3) ◽

pp. 913

Author(s):

Chang Yuan ◽

Shusheng Bi ◽

Jun Cheng ◽

Dongsheng Yang ◽

Wei Wang

Keyword(s):

Point Cloud ◽

Low Cost ◽

Shape Error ◽

3D Point Cloud ◽

Motor Shaft ◽

Matching Error ◽

Triangular Plate ◽

Attitude Error ◽

Shaft Angle ◽

The Cost

For a rotating 2D lidar, the inaccurate matching between the 2D lidar and the motor is an important error resource of the 3D point cloud, where the error is shown both in shape and attitude. Existing methods need to measure the angle position of the motor shaft in real time to synchronize the 2D lidar data and the motor shaft angle. However, the sensor used for measurement is usually expensive, which can increase the cost. Therefore, we propose a low-cost method to calibrate the matching error between the 2D lidar and the motor, without using an angular sensor. First, the sequence between the motor and the 2D lidar is optimized to eliminate the shape error of the 3D point cloud. Next, we eliminate the attitude error with uncertainty of the 3D point cloud by installing a triangular plate on the prototype. Finally, the Levenberg–Marquardt method is used to calibrate the installation error of the triangular plate. Experiments verified that the accuracy of our method can meet the requirements of the 3D mapping of indoor autonomous mobile robots. While we use a 2D lidar Hokuyo UST-10LX with an accuracy of ±40 mm in our prototype, we can limit the mapping error within ±50 mm when the distance is no more than 2.2996 m for a 1 s scan (mode 1), and we can limit the mapping error within ±50 mm at the measuring range 10 m for a 16 s scan (mode 7). Our method can reduce the cost while the accuracy is ensured, which can make a rotating 2D lidar cheaper.

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Task-relevant and task-irrelevant variability causally shape error-based motor learning

Neural Networks ◽

10.1016/j.neunet.2021.07.015 ◽

2021 ◽

Author(s):

Lucas Rebelo Dal’Bello ◽

Jun Izawa

Keyword(s):

Motor Learning ◽

Shape Error ◽

Task Irrelevant ◽

And Task

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Influence of Supporting Characteristics on Sphericity of Ceramic Balls in Rotated Dual-Plates Lapping Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.69-70.69 ◽

2009 ◽

Vol 69-70 ◽

pp. 69-73 ◽

Cited By ~ 2

Author(s):

Bing Hai Lv ◽

Ju Long Yuan ◽

F. Cheng ◽

Fan Yang

Keyword(s):

Numerical Calculation ◽

Fourier Analysis ◽

Support System ◽

Spherical Surface ◽

Surface Generation ◽

Shape Error ◽

Lower Natural Frequency ◽

Sinusoidal Waveform ◽

Higher Spin ◽

Ball Surface

Ceramic balls have become an important component in advanced bearings, and the sphericity of balls is a key qualification focused in lapping process. An investigation on the effect of dynamic behavior of ball support system on the performance of ball lapping in rotated dual-plates lapping method is carried out. Sinusoidal waveform in terms of Fourier analysis is employed to express the shape error of the ball surface, and a dynamic model for support is setup. It is found with numerical calculation that the variation of lapping load lags behind the variation of the shape error for the damping of support. A lower natural frequency of the support system, higher spin speed of balls and a larger value of spin angle in RDP lapping are better to rectify the shape error of balls and reduce the lagged effect. It is concluded that dynamics of lapping system must be taken into consideration in order to understand comprehensively the spherical surface generation mechanism.

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Study on the Generalized Holo-Factors Mathematical Model of Dimension-Error and Shape-Error for Sheet Metal in Stamping Based on the Back Propagation (BP) Neural Network

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4033156 ◽

2016 ◽

Vol 138 (6) ◽

Cited By ~ 4

Author(s):

Lizhi Gu ◽

Tianqing Zheng

Keyword(s):

Neural Network ◽

Mathematical Model ◽

Sheet Metal ◽

Bp Neural Network ◽

Back Propagation ◽

Shape Error ◽

Back Propagation Algorithm ◽

Minor Strain ◽

Major Strain ◽

Forming Precision

Precision improvement in sheet metal stamping has been the concern that the stamping researchers have engaged in. In order to improve the forming precision of sheet metal in stamping, this paper devoted to establish the generalized holo-factors mathematical model of dimension-error and shape-error for sheet metal in stamping based on BP neural network. Factors influencing the forming precision of stamping sheet metal were divided, altogether ten factors, and the generalized holo-factors mathematical model of dimension-error and shape-error for sheet metal in stamping was established using the back-propagation algorithm of error based on BP neural network. The undetermined coefficients of the model previously established were soluble according to the simulation data of sheet punching combined with the specific shape based on the BP neural network. With this mathematical model, the forecast data compared with the validate data could be obtained, so as to verify the fine practicability that the previously established mathematical model had, and then, it was shown that the generalized holo-factors mathematical model of size error and shape-error had fine practicality and versatility. Based on the generalized holo-factors mathematical model of error exemplified by the cylindrical parts, a group of process parameters could be selected, in which forming thickness was between 0.713 mm and 1.335 mm, major strain was between 0.085 and 0.519, and minor strain was between −0.596 and 0.319 from the generalized holo-factors mathematical model prediction, at the same time, the forming thickness, the major strain, and the minor strain were in good condition.

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