Field Of Precision Engineering Research Articles

Voice coil motor-driven multi-DOF compliant parallel micropositioning stage based on a large range beam-based spherical hinge and fully symmetrical layout

With the recent rapid developments in the field of precision engineering, demand for the large range multi-degrees-of-freedom (DOF) micropositioning stage has increased significantly. In this paper, to solve the problems of small motion range, local stress concentration, and low motion accuracy caused by the parasitic motion of the traditional flexure hinge in the multi-DOF micropositioning stage, we first propose a type of large-range beam-based flexure spherical hinge (BFSH). Subsequently, based on the proposed BFSH, a large range 3-DOF θxθyz spatial micropositioning stage driven by the voice coil motor is designed employing parallel branch chains and a fully symmetrical layout. This arrangement realizes theoretical motion decoupling in structural design. Furthermore, we use the geometric method to derive kinematic equations of the moving platform, which are used as the decoupling matrix of the control loop. Based on the compliance matrix method and Lagrange’s method, the compliance matrix model of the BFSH, the 3-DOF micropositioning stage, and the stage dynamic model are determined respectively. Additionally, finite element analysis and experimental tests are conducted to verify the accuracy of the analytical model and assess the static and dynamic performance of the designed 3-DOF stage. Moreover, a fractional order phase advanced proportional integral controller is designed for closed-loop control to track the sinusoidal trajectory and spherical trajectory. The results reveal that the stage can achieve the desired large workspace of ± 21.5 mrad × ± 20.3 mrad × ± 3.23 mm, as well as excellent decoupling and trajectory tracking performance.

A precision-drive hysteresis model with an equal-density weight function for GMA feedforward compensation

Giant magnetostrictive actuators (GMAs) are a widely used type of micro-nano actuator, and they are greatly significant in the field of precision engineering. The accuracy of a GMA often depends on its hysteresis model. However, existing models have some limitations, including the difficulty of identifying their parameters and the tradeoff between the quantity of modeling data required and the level of precision achieved. To solve these problems, in this paper, we propose a Preisach inverse model based on equal-density segmentation of the weight function (E-Preisach). The weight function used to calculate the displacement is first discretized. Then, to obtain a finer weight distribution, the discretized geometric units are uniformly divided by area. This can further minimize the output displacement span, and it produces a higher-precision hysteresis model. The process of parameter identification is made easier by this approach, which also resolves the difficulty of obtaining high precision using a small amount of modeling data. The Preisach and the E-Preisach inverse models were investigated and compared using experiments. At frequencies of 1 and 5 Hz, it was found that the E-Preisach inverse model decreases the maximum error of the feedforward compensation open-loop control to within 1 µm and decreases the root-mean-square error in displacement to within 0.5 µm without the need to increase the number of measured hysteresis loops. As a result, the E-Preisach inverse model streamlines the structure of the model and requires fewer parameters for modeling. This provides a high-precision modeling method using a small amount of modeling data; it will have applications in precision engineering fields such as active vibration damping and ultra-precision machining.

Special Issue on the Latest Research in Precision Engineering

Multidisciplinary study and practice of high-precision engineering, metrology, and manufacturing have made a direct contribution to industrial and economic development in the world, providing new value creation and enhancing productivity and product quality. This special issue focuses on the latest studies in the field of precision engineering. The special issue especially features advanced technologies in the manufacturing process, metrology, machine tools, machine elements, and nano/micro mechanisms. Besides these technologies, to enhance reliability and safety in the production processes, there is a need for usability and functionality based on IoT-related technology, which is represented by Industrie 4.0 or the Industrial Internet. Therefore, many researchers have now begun to focus on cyber-physical production systems (CPPS), which can detect anomalies and self-optimize the production process by comparing actual results extracted from sensors and simulation results. From this viewpoint, advanced research related to CPPS, such as simulation-based technique, sensor-based technology, and in-depth understanding and modeling of the manufacturing process, is covered in this special issue. In this special issue of IJAT, there are 14 research papers on precision-engineering-related topics as mentioned above. The papers, revised and extended according to the editors’ request, were originally presented at the 17th International Conference on Precision Engineering (ICPE2018), held in Kamakura, Japan, in 2018. We express our sincere thanks to the authors and reviewers for their meticulous work in helping publish this special issue. We hope these articles will encourage further research on precision engineering.

Compensation of the refractive index of air in laser interferometer for distance measurement: A review

We review the progress made for compensation of the refractive index of air in laser-based distance measurements in the field of precision engineering. First, a comprehensive analysis is introduced to clarify how the overall measurement uncertainty is affected by the refractive index of the ambient air, particularly for dimensional metrology and geodetic survey using laser in open-air environment. Second, it is explained that the measurement uncertainty can be improved to a 10-8 level by adopting empirical dispersion formulae describing the relation of the laser wavelength with the environment parameters such as temperature, pressure, humidity and carbon dioxide concentration. Third, the principle of refractometers is given to describe that the measurement uncertainty can be enhanced to a 10-9 level by identifying the refractive index of air real time in well-controlled environmental conditions. Fourth, the two-color compensation method is discussed which enables precise laser-based distance measurement simply by using two different wavelengths without actual identification of the refractive index of open air. Finally, the recent approach of using femtosecond lasers is described with emphasis on the performance of the two-color method can be enhanced to a 10-9 level by stabilizing the pulse repetition rate as well as frequency stability of ultrashort pulse lasers with reference to the atomic clocks.

THE FORMATION OF THE CORPS OF INDUSTRIAL PERSONNEL IN CHECHENO- INGUSHETIA IN 1960 -1980

The article analyzes the development of the vocational education system in the Chechen-Ingush ASSR in the context of the public policy of the USSR in the sphere of modernization of industry in Checheno-Ingushetia in 1960-1980. The creation of a corps of qualified personnel has become one of the basic factors of industrial growth of the Chechen-Ingush ASSR. The historical experience of the development of the vocational education system can be used in the process of modernization of the economy, business and scientific-educational sphere of the Chechen Republic. The results of the study show that the diversified production with high potential for technological development, created in the Chechen-Ingush Autonomous Soviet Socialist Republic by the mid-1980s, was a promising basis for further development of the vocational education system, including training of specialists and skilled workers in the most modern professions in the field of precision engineering and information technologies. The demand for these educational fields and their relevance to the social and cultural needs of the Chechen youth are proved by the modern trends of innovative development of vocational education in the Chechen Republic. Modernization process in the Chechen Republic in the early XXI century demonstrates the effectiveness of combining traditional cultural values with innovative technologies in education, industrial production and social sphere and with creation of dynamic competitive economy and educational system in the Republic.

THE FORMATION OF THE CORPS OF INDUSTRIAL PERSONNEL IN CHECHENO- INGUSHETIA IN 1960 -1980

The article analyzes the development of the vocational education system in the Chechen-Ingush ASSR in the context of the public policy of the USSR in the sphere of modernization of industry in Checheno-Ingushetia in 1960-1980. The creation of a corps of qualified personnel has become one of the basic factors of industrial growth of the Chechen-Ingush ASSR. The historical experience of the development of the vocational education system can be used in the process of modernization of the economy, business and scientific-educational sphere of the Chechen Republic. The results of the study show that the diversified production with high potential for technological development, created in the Chechen-Ingush Autonomous Soviet Socialist Republic by the mid-1980s, was a promising basis for further development of the vocational education system, including training of specialists and skilled workers in the most modern professions in the field of precision engineering and information technologies. The demand for these educational fields and their relevance to the social and cultural needs of the Chechen youth are proved by the modern trends of innovative development of vocational education in the Chechen Republic. Modernization process in the Chechen Republic in the early XXI century demonstrates the effectiveness of combining traditional cultural values with innovative technologies in education, industrial production and social sphere and with creation of dynamic competitive economy and educational system in the Republic.

The factors affecting surface roughness measurements of the machined flat and spherical surface structures – The geometry and the precision of the surface

The quantitative determination of surface roughness is of vital importance in the field of precision engineering. This paper presents an experimental study of the roughness analyses for the flat and spherical surfaces of machined metal in order to compare the roughness data taken from the cloud data produced by the stylus type profilometer and two optical-based measurement instruments, namely the infinite focus microscope and the confocal laser scanning microscope. In this experimental study, the roughness measurements for fifteen flat and six spherical surfaces were repeated six times using three different measurement instruments. Great care was paid to measure the same location for each measurement. For the comparison of the measurement techniques, the same measurement process was applied to the flat and spherical surfaces individually, and the configurations of the measurement instruments (filter type, cut-off, resolution etc.) were synchronized. R a , two-dimensional (2D) roughness parameter and S a , three-dimensional (3D) roughness parameter were also compared. The measurement results for the samples having spherical surfaces indicated a considerably high difference in values taken from the stylus profilometer and two optical-based measurement instruments in contrast to those for flat surfaces.

A Newly Developed X-Y Planar Nano-Motion Table System with Large Travel Ranges

Precision motion control technology has been widely used in high accuracy applications such as advanced scientific instruments and semiconductor fabrication equipment. In particular, the nano-motion control system with multiple degrees of freedom positioning in large travel ranges has been required in the field of precision engineering. In order to realize such a system, it is necessary and indispensable to develop a planar motion table system based on a new design concept. This paper presents a newly developed X-Y planar nano-motion table system with large travel ranges. This system is composed of a fine motion table and a coarse motion mechanism. The fine motion table is supported by porous aerostatic bearings and driven by voice coil motors with a laser interferometer feedback in a perfect non-contact condition. In addition, the table is driven at the center of gravity during the X-Y planar motion. The coarse motion mechanism has the frame structure with the coils of voice coil motors for the fine motion table. In order to enlarge the table travel ranges, the coarse motion mechanism follows the fine table motion. Performance evaluation results confirm that the developed table system has a remarkable performance which includes nanometer positioning capability over large travel ranges.

Digital Control of Interferometric Metrology Lines

A recent paper presented principles and digital control of Fabry-Perot interferometers, showing some ongoing and potential applications in the field of precision engineering. Among these, metrology lines were mentioned, the aim being to reveal sub-nanometric displacements in view of dimensional stabilization/monitoring of demanding space telescopes. The core is a confocal optical cavity, in vacuum, whose light path is sensitive to supporting structure length variations. The latter are tracked and revealed by a frequency actuator which acting on the incident light keeps the interferometer signal (the tracking error) centered to zero although the optical path varies. Concept and digital control of metrology lines are outlined and some experimental results from an on-ground breadboard are discussed. Due to on-ground and test contingencies, a displacement actuator (piezo-electric ceramics) was also active on the cavity, which required actuator coordination. Digital control was designed around a stylized model of plant and disturbance, called the Embedded Model, to be included in the control unit. Control algorithms and code are derived from the model; control gains either derive from the model or from closed-loop eigenvalues. No performance optimization is sought, but requirements are met and stability/performance is guaranteed in the presence of neglected dynamics and actuator/sensor constraints.

Multiple orientation technique for the calibration of cylindrical workpieces on CMMs

Coordinate measuring machines (CMMs) are widely used in various fields of precision engineering and science. Although they are highly accurate instruments, for some tasks, e.g. calibration of reference artifacts, the accuracy even of the best available instruments is not sufficient. In this paper, we describe a highly accurate technique using a CMM for the measurement of cylindrical workpieces. The proposed method is a combination of multiple orientation and substitution techniques and compensates for all geometrical errors of a CMM, systematic probing effects and the bending of the workpiece due to gravity. We demonstrate the method on a cylinder gauge with flat ends that incorporates a number of different geometrical features. The evaluation of the measurement uncertainties for each characteristic was performed manually and using the Virtual CMM (VCMM) [Trapet E, Franke M, Haertig F, Schwenke H, Waeldele F, Cox M, et al. Traceability of Coordinate Measurements According to the Method of the Virtual Measuring Machine: Final Project Report MAT1-CT94-0076, PTB-Report F-35, Parts 1 and 2; 1999; Haertig F, Trapet E, Waeldele F, Wiegand U. In: Proceedings of the 5th IMEKO TC-14. Traceability of coordinate measurements according to the Virtual CMM concept; 1995. p. 245–54.]. The results show, that very low uncertainties can be achieved by the proposed measurement techniques. It is also demonstrated that the VCMM approach considers reversal effects correctly for the calculation of measurement uncertainties.

Design and analysis of two-dimensional zero-reference marks for alignment systems

The demand for ultrahigh resolution in positioning and alignment is increasing in the field of precision engineering. By superimposing a pair of specially coded two-dimensional (2D) gratings, the correct alignment position of the two gratings can be detected with high resolution and accuracy. Due to the small dimensions of the grating, the diffraction effect is strong and it cannot be ignored. In this article, design considerations for such 2D zero-reference gratings are presented and the behavior of the diffraction of the zero-reference gratings is analyzed theoretically. The transmission function obtained by diffraction analysis agrees with the result from the autocorrelation method by neglecting the diffraction effect. The alignment is independent of the small variation in the gap between two gratings.

Special Issue on Japanese-French Congress of Mechatronics

The lst Japanese-French Congress of Mechatronics was held at Besancon City in France from October 20 to 23, 1992. The congress was cosponsored by the Japan Society for Precision Engineering and 1'Institut des Microtechniques de Frenche-Comte. A total of 216 persons participated in the congress, 72 from Japan and 144 from France and other European countries. The total number of announced papers was 84, 49 from Japan and 35 from Europe. In addition, three special addresses were made each from Japan and Europe. The number of robotic addresses totalled 30, the largest number by field. Among these 30 addresses, 23 were made by Japanese participants. Studies in a wide range of mechatronics were also announced which were related to sensors and measurement system and machine vision. Besancon is the capital of Doubs and is an ancient city with a history of 2000 years. Doubs is bordered by Switzerland and has been active in the precision industry, such as watches, since old times. It is mostly industrialized and has been interested in mechatronics. Unique studies have been conducted by some research and educational institutes including Ecole Nationale Superieure de Mechanique et des Microtechniques. The congress received attention as being unique and attracted many participants for the following reasons: there was very little interaction between Japan and France in the field of precision engineering or mechatronics and the French industry, a specific existence in Europe, has recently taken a great interest in Japanese technology. The editorial committee of this periodical urged authors to contribute papers suitable for the periodical among those announced at the congress and contained their contributions in it. Technological interactions between Japan and Europe will become more important. In 1994, the 2nd Japanese-French Congress of Mechatronics (International) will be held at Takamatsu City in Japan. I hope that many researchers and engineers of mechatronics worldwide will join the congress and have discussions on mechatronics to stimulate its growth.