scholarly journals Optimization of Selective Assembly for Shafts and Holes Based on Relative Entropy and Dynamic Programming

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1211
Author(s):  
Mingyi Xing ◽  
Qiushuang Zhang ◽  
Xin Jin ◽  
Zhijing Zhang
Keyword(s):  
Dynamic Programming ◽  
High Precision ◽  
Relative Entropy ◽  
Optimization Method ◽  
Geometric Error ◽  
Selective Assembly ◽  
Assembly Method ◽  
Assembly Accuracy ◽  
Mating Surface

Selective assembly is the method of obtaining high precision assemblies from relatively low precision components. For precision instruments, the geometric error on mating surface is an important factor affecting assembly accuracy. Different from the traditional selective assembly method, this paper proposes an optimization method of selective assembly for shafts and holes based on relative entropy and dynamic programming. In this method, relative entropy is applied to evaluate the clearance uniformity between shafts and holes, and dynamic programming is used to optimize selective assembly of batches of shafts and holes. In this paper, the case studied has 8 shafts and 20 holes, which need to be assembled into 8 products. The results show that optimal combinations are selected, which provide new insights into selective assembly optimization and lay the foundation for selective assembly of multi-batch precision parts.

The method of selective assembly for the RV reducer based on genetic algorithm

2017 ◽  
Vol 232 (6) ◽  
pp. 921-929 ◽  
Author(s):  
Xuyang Chu ◽  
Huihuang Xu ◽  
Xiaomin Wu ◽  
Jiping Tao ◽  
Guifang Shao
Keyword(s):  
Genetic Algorithm ◽  
Complex Structure ◽  
Selective Assembly ◽  
Matching Algorithm ◽  
Assembly Method ◽  
Assembly Accuracy ◽  
Manufacturing Errors ◽  
Rv Reducer ◽  
Assembly Precision ◽  
Very High

As a precision gear reducer, the RV reducer has a low-transmission backlash (very high assembly accuracy). Therefore, the selective assembly method is the only assembly method which can guarantee the assembly precision of the RV reducer. However, the RV reducer has a complex structure; it consists of a high number of parts whose machining tolerance cannot be very low. Furthermore, there are numerous parts, the tolerances of which influence the RV reducer transmission backlash. Therefore, it is difficult to achieve high assembly accuracy by using the traditional selective assembly method. In this paper, a method of selective assembly is proposed to make the backlash of the RV reducer meet the requirements through the analysis of the characteristics of the RV reducer structure, the processing and assembly process of the parts, and the influence of manufacturing errors on the backlash. Then, a mathematical model was established for the RV reducer assembly issue. And a matching algorithm based on a genetic algorithm was developed. Finally, the algorithm was applied to the selective assembly of the RV reducer for verifying the feasibility and validity of the proposed matching method.

scholarly journals Multistage Asymmetric Rotors Coaxial Measurement Stacking Method Based on Minimization of Exciting Force

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1054
Author(s):  
Yongmeng Liu ◽  
Yingjie Mei ◽  
Chuanzhi Sun ◽  
Pinghuan Xiao ◽  
Ruirui Li ◽  
...  
Keyword(s):  
Vibration Amplitude ◽  
High Speed ◽  
Geometric Error ◽  
Exciting Force ◽  
Propagation Model ◽  
Assembly Method ◽  
Geometric Center ◽  
Asymmetric Rotor ◽  
Rotor Equipment ◽  
Geometric Error Measurement

The unbalanced exciting force of high-speed rotary asymmetric rotor equipment is the main factor causing rotor vibration. In order to effectively suppress the vibration of the asymmetric rotor equipment, the paper establishes a multistage asymmetric rotor coaxial measurement stacking method that minimizes the exciting force. By analyzing the propagation process of the centroid of the multistage asymmetric rotor assembly and analyzing the relationship between the geometric center and the centroid of a single asymmetric rotor, a multistage asymmetric unbalanced rotor propagation model based on geometric center stacking is established. The genetic algorithm is used to optimize the unbalance of the multistage asymmetric rotors. Combined with the vibration principle under the exciting force, the vibration amplitude of the left bearing at different rotation speeds under the minimization of the exciting force and the random assembly phase is analyzed. Finally, the experimental asymmetric rotors are dynamically measured, combined with the asymmetric rotors’ geometric error measurement experiment. The experimental results confirm that the vibration amplitude of the assembly phase with the minimum exciting force is smaller than the vibration amplitude under the random assembly phase at three-speed modes, and the optimization rate reached 73.2% at 9000 rpm, which proves the effectiveness of the assembly method in minimizing the exciting force.

Synthesis of a High-Precision Missile Homing System with an Permissible Stability Margin of the Normal Acceleration Stabilization System

2021 ◽  
Vol 22 (7) ◽  
pp. 365-373
Author(s):  
Quang Thong Do
Keyword(s):  
High Precision ◽  
Parametric Optimization ◽  
Stability Margin ◽  
Optimization Method ◽  
Synthesis Process ◽  
Stabilization System ◽  
Gain Margin ◽  
The Stability ◽  
Automatic Systems ◽  
Normal Acceleration

The proportional guidance method-based missile homing systems (MHS) have been widely used the real-world environments. In these systems, in order to destroy the targets at different altitudes, a normal acceleration stabilization system (NASS) is often utilized. Therefore, the MHS are complex and the synthesis of these systems are a complex task. However, it is necessary to synthesize NASS during the synthesis of the MHS. To simplify the synthesis process, a linear model of the NASS is used. In addition, we make use of the available commands in Control System Toolbox in MATLAB. Because the Toolbox has the commands to describe the transfer function, determine the stability gain margin, and the values of the transient respond of the linear automatic systems. Thus, this article presents two methods for synthesizing the missile homing systems, including (i) a method for synthesizing the MHS while ensuring the permissible stability gain margin of the NASS, and (ii) a method for synthesizing the MHS while ensuring the permissible stability margin of the NASS by overshoot. These techniques are very easy to implement using MATLAB commands. The synthesis of the proposed MHS is carried out by the parametric optimization method. To validate the performance of the proposed techniques, we compare them withthe MHS synthesized by ensuring the stability margin of the NASS bythe oscillation index. The results show that, two our proposed methods and the existing method provide the same results in terms of high-precision. Nevertheless, the proposed methods are simple and faster than the conventional method. The article also investigates the effect of gravity, longitudinal acceleration of the rocket, andblinding of the homing head on the accuracy of the synthesized MHS. The results illustrate that they have a little effect on its accuracy.

scholarly journals High precision and fast solution method for linearized assembly contact point of geometric error surface

2019 ◽  
Vol 563 ◽  
pp. 032021
Author(s):  
Zhihua Liu ◽  
Zhijing Zhang ◽  
Xin Jing ◽  
Weiming Zhang ◽  
Zifu Wang ◽  
...  
Keyword(s):  
High Precision ◽  
Solution Method ◽  
Contact Point ◽  
Geometric Error ◽  
Error Surface ◽  
Fast Solution

Accuracy design of high precision machine tools using error sensitivity analysis methodology

2016 ◽  
Vol 231 (18) ◽  
pp. 3401-3413 ◽  
Author(s):  
Wenjie Tian ◽  
Shaopeng Liu ◽  
Xingxing Liu
Keyword(s):  
Sensitivity Analysis ◽  
Machine Tool ◽  
Machine Tools ◽  
Geometric Error ◽  
Sensitivity Index ◽  
Assembly Accuracy ◽  
Machining Test ◽  
Precision Machine Tools ◽  
Design And Manufacture ◽  
Source Errors

Geometric accuracy is a crucially important performance factor for machine tools. Theoretically, the effects of source errors on pose accuracy (positional and angular accuracy) of 3-, 4- or 5-axis machine tools cannot fully be compensated by software, and only those pose errors associated with the permission motions are compensatable by means of error compensation. Therefore, the uncompensatable pose errors should be strictly guaranteed in the processes of design and manufacture. In this paper, after the geometric error model is established, the source errors affecting the uncompensatable pose accuracy are identified out of all the source errors. In order to enhance the understanding of which source errors have more influences on the pose accuracy, a probabilistic sensitivity analysis method is proposed, and the global sensitivity index is defined to evaluate the influence in the overall workspace. According to the sensitivity analysis results, the uncompensatable pose accuracy index is allocated to each source error. And then, assembly accuracy acceptance criteria are proposed as a guideline for machine assemblers. As an application example, the presented approaches are applied to the accuracy design and manufacture of a 4-axis machine tool, and double ball bar measurement and machining test are carried out to check the accuracy of the designed machine tool.

Study on the Method of Error Identification and Compensation for Gear Measuring Center

2012 ◽  
Vol 482-484 ◽  
pp. 1821-1828
Author(s):  
Peng Wan ◽  
Jun Jie Guo ◽  
Hai Tao Li
Keyword(s):  
High Precision ◽  
Error Detection ◽  
Geometric Error ◽  
Precision Measurements ◽  
Tooth Surface ◽  
Geometric Errors ◽  
Detection Technology ◽  
Accuracy Of Measurement ◽  
Measuring Machine ◽  
Multi Body

Gear Measuring Center(GMC) is commonly used to test error of the tooth surface of the gear, whose geometric accuracy directly impacts on the accuracy of measurement. How to quickly and accurately detect space geometric error of the measuring machine and compensate becomes the essential means of high-precision measurements. According to the problem above, in the paper, three-beams laser detection technology is proposed. The detection of the geometric errors of the linear axis was achieved. The accurate measurement for the position and attitude of the plane mirror on measurement seat was achieved based on laser telemetry principle. The positioning error, the pitching angle errors, the deflection angle errors and the straightness errors were separated. And then based on multi-body system theory, by using of homogeneous coordinate transformation, the error compensation model of 4-axis measuring machine which includes three shifting pairs and one revolute pair was established, and the algorithm was given in the paper. The theoretical foundation for real-time compensation of 4-axis GMC was established. The geometric errors of GMC can be improved by the method of the error detection and compensation. The method plays a very important role in high-precision measurements.

Sign in / Sign up

Export Citation Format

Share Document