scholarly journals Development of New Measurement System of Errors in the Multiaxial Machine Tool for an Active Compensation

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Noureddine Barka ◽  
Abderrazak El Ouafi
Keyword(s):  
Machine Tool ◽  
Measurement System ◽  
Degrees Of Freedom ◽  
Error Component ◽  
Operating Conditions ◽  
Compensation Methods ◽  
Compensation Of Errors ◽  
Global Accuracy ◽  
The Moment ◽  
Machine Calibration

Error compensation techniques have been widely applied to improve multiaxis machine accuracy. However, due to the lack of reliable instrumentation for direct and overall measurements, all the compensation methods are based on offline measurements of each error component separately. The results of these measurements are static in nature and can only reflect the conditions at the moment of measurement. These results are not representative under real working conditions because of disturbances from load deformations, thermal distortions, and dynamic perturbations. This present approach involves the development of a new measurement system capable of dynamically evaluating the errors according to the six degrees of freedom. The developed system allows the generation of useful data that cover all machine states regardless of the operating conditions. The obtained measurements can be used to evaluate the performance of the machine, calibration, and real time compensation of errors. This system is able to perform dynamic measurements reflecting the global accuracy of the machine tool without a long and expensive analysis of various error sources contribution. Finally, the system exhibits compatible metrological characteristics with high precision applications.

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

Experimental and Analytical Investigations of a Low Pressure Model Turbine During Forced Response Excitation

2010 ◽  
Author(s):  
Christoph Heinz ◽  
Markus Schatz ◽  
Michael V. Casey ◽  
Heinrich Stu¨er
Keyword(s):  
Degrees Of Freedom ◽  
Timing Analysis ◽  
Dynamic Performance ◽  
Amplitude Distribution ◽  
Low Pressure ◽  
Forced Response ◽  
Operating Conditions ◽  
Linear Regression Method ◽  
Rotor Shaft ◽  
Aerodynamic Damping

To guarantee a faultless operation of a turbine it is necessary to know the dynamic performance of the machine especially during start-up and shut-down. In this paper the vibration behaviour of a low pressure model steam turbine which has been intentionally mistuned is investigated at the resonance point of an eigenfrequency crossing an engine order. Strain gauge measurements as well as tip timing analysis have been used, whereby a very good agreement is found between the methods. To enhance the interpretation of the data measured, an analytical mass-spring-model, which incorporates degrees of freedom for the blades as well as for the rotor shaft, is presented. The vibration amplitude varies strongly from blade to blade. This is caused by the mistuning parameters and the coupling through the rotor shaft. This circumferential blade amplitude distribution is investigated at different operating conditions. The results show an increasing aerodynamic coupling with increasing fluid density, which becomes visible in a changing circumferential blade amplitude distribution. Furthermore the blade amplitudes rise non-linearly with increasing flow velocity, while the amplitude distribution is almost independent. Additionally, the mechanical and aerodynamic damping parameters are calculated by means of a non-linear regression method. Based on measurements at different density conditions, it is possible to extrapolate the damping parameters down to vacuum conditions, where aerodynamic damping is absent. Hence the material damping parameter can be determined.

A Measurement System for Power Inductors in Non-Linear Operating Conditions

2021 ◽  
Author(s):  
Marco Ventimiglia ◽  
Daniele Scire ◽  
Giuseppe Lullo ◽  
Gianpaolo Vitale
Keyword(s):  
Measurement System ◽  
Operating Conditions ◽  
Non Linear ◽  
Power Inductors

ROTATIONS AND VIBRATIONS OF FULLERENES IN THE MOLECULAR COMPLEX C20@C80

2021 ◽  
pp. 35-48
Author(s):  
M.A. Bubenchikov ◽  
◽  
A.M. Bubenchikov ◽  
D.V. Mamontov ◽  
◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Classical Mechanics ◽  
Rotation Frequency ◽  
Dynamic State ◽  
Large Molecules ◽  
Rotational Degrees Of Freedom ◽  
Rotational Motions ◽  
Centers Of Mass ◽  
The Moment

The aim of this work is to apply classical mechanics to a description of the dynamic state of C20@C80 diamond complex. Endohedral rotations of fullerenes are of great interest due to the ability of the materials created on the basis of onion complexes to accumulate energy at rotational degrees of freedom. For such systems, a concept of temperature is not specified. In this paper, a closed description of the rotation of large molecules arranged in diamond shells is obtained in the framework of the classical approach. This description is used for C20@C80 diamond complex. Two different problems of molecular dynamics, distinguished by a fixing method for an outer shell of the considered bimolecular complex, are solved. In all the cases, the fullerene rotation frequency is calculated. Since a class of possible motions for a single carbon body (molecule) consists of rotations and translational displacements, the paper presents the equations determining each of these groups of motions. Dynamic equations for rotational motions of molecules are obtained employing the moment of momentum theorem for relative motions of the system near the fullerenes’ centers of mass. These equations specify the operation of the complex as a molecular pendulum. The equations of motion of the fullerenes’ centers of mass determine vibrations in the system, i.e. the operation of the complex as a molecular oscillator.

A Parallely Actuated Work Support Module for Reconfigurable Machining Systems

1998 ◽  
Author(s):  
Venkat Gopalakrishnan ◽  
Sridhar Kota
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Degrees Of Freedom ◽  
Mechanical Design ◽  
Performance Criteria ◽  
Machining Accuracy ◽  
Parallel Mechanisms ◽  
Element Analysis ◽  
Work Support ◽  
Reconfigurable Machining

Abstract In order to respond quickly to changes in market demands and the resulting product design changes, machine tool manufacturers must reduce the machine tool design lead time and machine set-up time. Reconfigurable Machine Tools (RMTs), assembled from machine modules such as spindles, slides and worktables are designed to be easily reconfigured to accommodate new machining requirements. The essential characteristics of RMTs are modularity, flexibility, convertibility and cost effectiveness. The goal of Reconfigurable Machining Systems (RMSs), composed of RMTs and other types of machines, is to provide exactly the capacity and functionality, exactly when needed. The scope of RMSs design includes mechanical hardware, control systems, process planning and tooling. One of the key challenges in the mechanical design of reconfigurable machine tools is to achieve the desired machining accuracy in all intended machine configurations. To meet this challenge we propose (a) to distribute the total number of degrees of freedom between the work-support and the tool and (b) employ parallely-actuated mechanisms for stiffness and ease of reconfigurability. In this paper we present a novel parallely-actuated work-support module as a part of an RMT. Following a brief summary of a few parallel mechanisms used in machine tool applications, this paper presents a three-degree-of-freedom work-support module designed to meet the machining requirements of specific features on a family of automotive cylinder heads. Inverse kinematics, dynamic and finite element analysis are performed to verify the performance criteria such as workspace envelope and rigidity. A prototype of the proposed module is also presented.

scholarly journals A Non-Delay Error Compensation Method for Dual-Driving Gantry-Type Machine Tool

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 748
Author(s):  
Qi Liu ◽  
Hong Lu ◽  
Xinbao Zhang ◽  
Yu Qiao ◽  
Qian Cheng ◽  
...  
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Prediction Method ◽  
Compensation Method ◽  
Industrial Robots ◽  
Numerical Control ◽  
Heavy Duty ◽  
Positioning Errors ◽  
Compensation Methods ◽  
Type Machine

The drive at the center of gravity (DCG) principle has been adopted in computer numerical control (CNC) machines and industrial robots that require heavy-duty and quick feeds. Using this principle requires accurate corrections of positioning errors. Conventional error compensation methods may cause vibrations and unstable control performances due to the delay between compensation and motor motion. This paper proposes a new method to reduce the positioning errors of the dual-driving gantry-type machine tool (DDGTMT), namely, a typical DCG-principle-based machine tool. An error prediction method is proposed to characterize errors online. An algorithm is proposed to quickly and accurately compensate the errors of the DDGTMT. Experiment results verify that the non-delay error compensation method proposed in this paper can effectively improve the accuracy of the DDGTMT.

Parametric Resonance of a Two Degrees-of-Freedom System Induced by Bounded Noise

2009 ◽  
Vol 76 (4) ◽  
Author(s):  
Jinyu Zhu ◽  
W.-C. Xie ◽  
Ronald M. C. So ◽  
X. Q. Wang
Keyword(s):  
Lyapunov Exponents ◽  
Parametric Resonance ◽  
Degrees Of Freedom ◽  
Singular Perturbation Method ◽  
Bounded Noise ◽  
Two Degrees Of Freedom ◽  
Moment Lyapunov Exponent ◽  
The Moment ◽  
Combined Resonance ◽  
Moment Lyapunov Exponents

The dynamic stability of a two degrees-of-freedom system under bounded noise excitation with a narrowband characteristic is studied through the determination of moment Lyapunov exponents. The partial differential eigenvalue problem governing the moment Lyapunov exponent is established. For weak noise excitations, a singular perturbation method is employed to obtain second-order expansions of the moment Lyapunov exponents and Lyapunov exponents, which are shown to be in good agreement with those obtained using Monte Carlo simulation. The different cases when the system is in subharmonic resonance, combination additive resonance, and combined resonance in the absence of noise, respectively, are considered. The effects of noise and frequency detuning on the parametric resonance are investigated.

scholarly journals A Research and Application of the Processing Methods of Railway Measurement Based on Self-Mobile Scanning Measurement System

2020 ◽  
Author(s):  
Jiancai Zhang ◽  
Hang Mu ◽  
Feng Han ◽  
Shumin Han
Keyword(s):  
Measurement System ◽  
High Speed ◽  
Automatic Segmentation ◽  
Laser Scanner ◽  
Region Growing ◽  
Image Sensor ◽  
Operating Conditions ◽  
Secondary Development ◽  
Railway Line ◽  
Region Growing Segmentation

With the gradual improvement of China’s railway net, the opening of international railways as well as the continuous growth of railway operating mileage, the workload of remeasuring railways is increasing. The traditional methods of remeasuring railways can not meet current high-speed and high-density operating conditions anymore in terms of safety, efficiency and quality, so a safer and more efficient measurement method is urgently needed.This thesis integrated various sensors on a self-mobile instrument, such as 3D laser scanner, digital image sensor and GNSS_IMU, designing a set of intelligent and integrated self-mobile scanning measurement system. This thesis proposed region growing segmentation based on the reflection intensity of point cloud. Through the secondary development of CAD, the menu for automatic processing of self-mobile scanning measurement system is designed to realize rail automatic segmentation, extraction of rail top points, fitting of plane parameters of railway line, calculation of curve elements and mileage management.The results show that self-mobile scanning measurement system overcomes the shortcomings of traditional railway measurement to some extent, and realizes intelligent measurement of railways.

scholarly journals An investigation of the fuel injector dedicated to the aircraft opposed-piston two-stroke diesel engine

2019 ◽  
Vol 177 (2) ◽  
pp. 151-155
Author(s):  
Ksenia SIADKOWSKA ◽  
Mirosław WENDEKER ◽  
Łukasz GRABOWSKI
Keyword(s):  
Diesel Engine ◽  
Combustion Process ◽  
Mie Scattering ◽  
Operating Conditions ◽  
Fuel Spray ◽  
Chamber Pressure ◽  
Fuel Injector ◽  
Measuring Point ◽  
Fuel Delivery ◽  
The Moment

The paper presents the research results of the injector construction with the modified injection nozzle. The injector is designed for a prototype opposed-piston aircraft diesel engine. The measurements were based on the Mie scattering technique. The conditions of the experiment corresponded to maximum loads similar to those occurring at the start. The measuring point was selected in line with the analysis of engine operating conditions: combustion chamber pressure at the moment of fuel delivery (6 MPa) and fuel pressure in the injection rail (140 MPa). The analysis focused on the average spray range and distribution, taking into account the differences between holes in the nozzle. As a result of the conducted research, the fuel spray range was defined with the determined parameters of injection. The fuel spray ranges inside the constant volume chamber at specific injection pressures and in the chamber were examined, and the obtained results were used to verify and optimize the combustion process in the designed opposed-piston two-stroke engine.

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