High Speed Precision Research Articles

Research and design of scanning servo device for airborne microwave radiometer

The Microwave Radiometer can obtain various characteristics of the measured target. The remote sensing aircraft has several outstanding advantages such as stronger mobility and larger capacity, which makes the Airborne Microwave Radiometer become the most important part of Microwave Remote Sensing technology. The mechanical structure was designed in this paper, which included airborne microwave radiometer scanning servo device structure and servo control system according to the requirements of the project. The statics and dynamics simulation of the scanning servo device were analyzed, the maximum value is 46.48MPa at the connection between the left support pedestal and the left drive shaft in the statics analysis and the first-order natural frequency of the scanning servo device is 50.516Hz in the modal analysis. The results showed that the mechanical structure meets the requirements of airborne working environment. The current - speed double closed loop control system was used to achieve the high precision speed control. The current - speed double closed loop control system was used to meet the high precision speed control requirements of high precision airborne microwave remote sensing technology.

Research on Image Processing of Signal-to-Noise Ratio and Resolution Based on Seismic Profile

In view of the characteristics of low frequency of seismic data coverage, strong surface interference, low signal-to-noise ratio and low resolution, this paper studies a set of pre-stack combined denoising technology, adaptive predictive deconvolution technology, anisotropic motion Correction and high-precision speed analysis, Kirchhoff restack time migration imaging and other key technologies are the core processing methods. The layer-by-layer similarity learning method is used to reconstruct high-resolution images, especially when the image is enlarged, it can still be clearer. Restore the detailed features of the texture of the seismic profile image. The actual profile test shows that the quality of image reconstruction has been improved, and good results have been obtained in terms of visual effects and peak signal-to-noise ratio.

Depth recovery in time of flight range sensors via compressed sensing algorithm

Stereo vision, structured light, and time of flight (ToF) are different range imaging techniques that acquire a scene and provide different features such as a depth map and an amplitude image. Compared to other imaging techniques, ToF can measure depth with high speed and good precision according to state of the art. However, it faces multipath interference (MPI) problems that give rise to an error in radiance information. Exploiting the sparsity of the received signal, we solved the multipath interference problem with the help of compressed sensing sparse recovery algorithms with some modification such as applying positivity constraint and proximity constraint. The modification in the algorithm has increased its robustness and proved to be successful in detecting the interference up to two paths successfully. We validated the approach by providing experimental results on synthetic data with ground truth that demonstrated its efficiency and accuracy to give MPI free output. Moreover, we applied a modified sparse recovery algorithm to real data and compared the result with the state-of-the-art methods. It shows better performance in separating the direct path from the multipath component with high accuracy.

Vibration and Dynamic Analysis of Right-Angle Geared Drives

<div class="section abstract"><div class="htmlview paragraph">The dynamics of hypoid or spiral bevel gears like most high-speed precision gears employed in the powertrains of automobiles, commercial trucks, and off highway vehicles are significantly influenced by the design of the shafts. The finite element modeling approach is one of the useful methodologies applied to perform gear dynamic analysis. One of the major advantages of the finite element modeling approach is that it can account for the gear-shaft-bearing assembly design more accurately than other modeling approaches, for example, the lumped parameter modeling approach. In this paper, the finite element formulation, which can generally represent more complete characteristics of the gear-shaft-bearing assembly design, is employed to investigate how the temperature change, shaft material type and shaft size influence the dynamics of spiral bevel gear system.</div></div>

Numerical simulation of particle motion characteristics in quantitative seed feeding system

High-speed precision seed metering device is the key to achieve efficient and precise seed planting in agricultural industry. In this work, a novel quantitative seed feeding system containing a feeding device and a venturi feeding tube is investigated using the coupled CFD and DEM approach. The flow behavior of seed particles and airflow field in this system are analyzed in detail, and the effects of different variables related to venturi tube and operations are examined. The results show that as the nozzle convergence angle increases, the pressure at the nozzle gradually decreases and the pressure gradient extends. As a result, particle movement mobility is enhanced and particle accumulation is reduced. With the increase of the feeding angle, seed particles tend to deposit and collide with the bottom wall. The results also show that when wind pressure reaches above 10 kPa, the spacing between two adjacent seed particles is more consistent, and seed particles are more uniformly discharged from the venturi tube. The results demonstrate that for a better design of the quantitative seed feeding system, the proper nozzle convergence angle is roughly at 70°, and the feeding angle is at around 45°

The optimized algorithm based on machine learning for inverse kinematics of two painting robots with non-spherical wrist.

This paper studies the inverse kinematics of two non-spherical wrist configurations of painting robot. The simplest analytical solution of orthogonal wrist configuration is deduced in this paper for the first time. For the oblique wrist configuration, there is no analytical solution for the configuration. So it is necessary to solve by general method, which cannot achieve high precision and high speed as analytic solution. Two general methods are optimized in this paper. Firstly, the elimination method is optimized to reduce the solving speed to 20% of the original one, and the completeness of the method is supplemented. Based on the Gauss damped least squares method, a new optimization method is proposed to improve the solving speed. The enhanced step length coefficient is introduced to conduct studies with the machine learning correlation method. It has been proved that, on the basis of ensuring the stability of motion, the number of iterations can be effectively reduced and the average number of iterations can be less than 5 times, which can effectively improve the speed of solution. In the simulation and experimental environment, it is verified.

Development of High Speed and High Precision Stepping Scanning Platform in Ultra-High Flux Gene Sequencing Imaging System

As a critical component of ultra-high flux gene sequencing imaging system, high speed and high precision stepping scanning platform is used to carrying the gene chips to be measured, and it is also the core component for ensuring the high flux and high accuracy of sequencing instrument. In this paper, taking the high speed and high precision stepping scanning platform in ultra-high flux gene sequencing imaging system as design objective, the research work is carried out from three aspects, i.e., the design of platform overall architecture, the design of dynamic response analysis on system-level structure, and the design of high precision positioning control system, utilizing the optimized design of coupling topology between continuum and discrete body, the high precision vibration test and modal analysis method, variable structure anti-saturation precision control, as well as other key techniques. Finally, a high speed and high precision stepping scanning platform of long-stroke is developed successfully, with stepping speed of 200mm/s, stepping acceleration of 9.8m/s2, stable stepping control precision of 150nm, stable stepping duration of 100ms, and the total stepping stroke of 200mm. It lays a solid foundation for the popularization and application of stepping scanning platform in ultra-high gene sequencing instrument.

A Corrected Adaptive Balancing Approach of Motorized Spindle Considering Air Gap Unbalance

Motorized spindles widely used for high-speed precision machine tools are very sensitive to the mass unbalance of rotors; thus, their balancing problem is always a research hotspot. Although many significant studies were done regarding the theory and application of various rotor balancing technologies for motorized spindles, the particularity of motorized spindles is not carefully considered in the existing balancing approaches. When the rotor unbalance of a motorized spindle occurs in operation, it is subject to both the mass unbalance-induced inertia force and air gap unbalance-induced electromagnetic force, which is an important feature that distinguishes the motorized spindle from a mechanical spindle. This paper describes an investigation into the corrected adaptive balancing approach of a motorized spindle by newly introducing a coefficient representing the removing effect of the air gap unbalance of the motor on the balancing capacity into the balancing formula. The determination of the newly defined coefficient refers to the calculation of electromagnetic force caused by the dynamic air gap eccentricity of motor; thus, much attention is paid to the analytical derivation of the unbalanced magnetic pull (UMP). Finally, a motorized spindle with an electromagnetic ring balancer was developed; then, the balancing tests and vibration signal analysis were done to validate the effectiveness of the newly proposed balancing approach in residual vibration reduction. It can be seen from the test results under different cases that the proposed balancing approach is effective.

A New Simulation Model for Vertical Spiral Ground Heat Exchangers Combining Cylindrical Source Model and Capacity Resistance Model

Considering the heat capacity inside vertical spiral ground heat exchanger (VSGHEX) in the simulation is one of the most noteworthy challenge to design the ground source heat pump (GSHP) system with VSGHEXs. In this paper, a new simulation model for VSGHEXs is developed by combining the ICS model with the CaRM. The developed simulation model can consider the heat capacity inside VSGHEX and provide dynamic calculation with high speed and appropriate precision. In order to apply the CaRM, the equivalent length was introduced. Then, the equivalent length was approximated by comparing the results of the CaRM and the numerical calculation. In addition, the calculation model of the VSGHEX was integrated into the design and simulation tool for the GSHP system. The accuracy of the tool was verified by comparing with the measurements. The error between supply temperatures of the measurements and calculation is approximately 2 °C at the maximum. Finally, assuming GSHP systems with VSGHEXs, whose spiral diameter was 500 mm and depth was 4 m, were installed in residential houses in Japan, the required numbers of VSGHEXs were estimated. The results showed a strong correlation between the total heating or cooling load and the required number. Therefore, the required number can be estimated by using the simplified approximate equation.

Analog modulation by the flexoelectric effect in liquid crystals.

We have solved the long-standing problems of stability and hysteresis, and we are able to obtain the homogeneous uniform lying helix structure in polymer-free cholesteric liquid crystals. This is instrumental for the present work to demonstrate the analog modulation at high speed and high precision. The device is configured for the transverse field switching wherein the substrate surface is flat. In addition to the response time of 10 ms at room temperature, we have obtained the R-squared and the adjusted R-squared as a measure of true sine wave for the sinusoidal responding transmissions from 1 Hz to 100 kHz that are all greater than 0.9993. In a Michelson interferometer, the phase shift at wavelength 633 nm after two passes has been measured to be equal to about $\pi /{9}$π/9 at 4.6 V/µm for the chiral-doped nematic mixtures E7.

Effect of interlayer design on the mechanical properties of AlTiCrN and multilayered AlTiCrN/TiSiN hard coatings

The adhesion strength and mechanical properties of hard coatings on substrates can be improved by adding an interlayer, which is also known as an adhesion, buffer, or seed layer. Cathodic-arc deposition (CAD) of hard coating often results in residual stresses, and the optimized design of the hard coating interlayer helps to reduce residual stress and improve mechanical properties, which is expected to extend the useful life of high speed precision stamping die applications. AlTiCrN transition metal nitride has been used as a protective hard coating because of its high hardness (~36 GPa) and resistance to high temperature oxidation up to 1100 °C. In this study, multicomponent hard coatings of AlTiCrN and AlTiCrN/TiSiN, which in the form of AlTiCrN/TiSiN multilayers, were deposited by cathodic-arc deposition. During the coating process, gradient TiN and CrN were deposited, respectively, as interlayers with different structures to control the residual stress and adhesion strength between the coatings and substrates. AlTiCr and TiSi alloy targets were used to deposit hard AlTiCrN/TiSiN coatings. The multicomponent AlTiCrN/Ti and AlTiCrN/Cr with Ti and Cr interlayers showed high residual stresses of −8 GPa and −8.4 GPa, respectively. The multilayered AlTiCrN/TiSiN coating with intermediate CrN and transition AlTiN/CrN multilayers under the top AlTiCrN/TiSiN multilayers possessed the lowest residual stress (−3 GPa). The residual stress changed by modifying interlayer configuration before the top AlTiCrN/TiSiN multilayers. The design of AlTiCrN/TiSiN multilayered coatings with interlayers of CrN and AlTiCrN/CrN can decrease residual stress and possessed good impact fatigue performance, which can be effective to reduce damage and cracking of hard coatings during cyclic impact loading.

Comparing the probing systems of coordinate measurement machine: Scanning probe versus touch-trigger probe

An increasing level of research is focalising around the Coordinate Measurement Machine (CMM) as an important dimensional inspection instrumentation, that is utilised in a wide range of industrial metrology applications with its high precision measurement capabilities, flexibility and high measurement speed. The key functional section of the CMM is the probing system, that enables capturing of spatial coordinate data along measurement surfaces. This research compared the measurement performance parameters (measurement uncertainty and measuring time) of the scanning probing system against the touch-trigger probing system, conducting experiments for rectangular and spherical geometries on a CMM. As a result, it was concluded that there are no statistically significant differences between the scanning method uncertainty of scanning probing system and the touch-trigger measuring method uncertainty of touch-trigger probing system for investigated geometries. The scanning method was concluded as quicker with the disadvantage of relatively higher calibration time. Contributions are offered through extending current knowledge on CMM probing systems and guiding industrial CMM measurement strategies.

Dynamic Performances of Foil Bearing Supporting a Jeffcot Flexible Rotor System Using FEM

Aerodynamic bearings have received considerable attention in recent decades and are increasingly being used in applications where high speed, low loads and high precision are required. Aerodynamic applications mainly concern auxiliary power units (APU) and air-conditioning machines (ACM). From the industrial point of view, the static and dynamic characteristics of these bearings rotating at very high speed must be determined. According to the literature, studies carried out on this type of bearing consider the elastic deformations of the foils due to the pressure generated in the air film. The linear approach is from time to time adopted for the prediction of the dynamic behavior of these bearings, which is not always justified. This paper aims to present a step towards a better mastery of the non-linear dynamic behavior of a flexible rotor-air bearing system. We will focus on finite element modeling (FEM) of the non-linear isothermal elasto-aerodynamic lubrication problem in the case of a radial bearing operating in a dynamic regime. We will present the effects of rotational speed, unbalance eccentricity, and rotor mass on the non-linear response of rigid and compliant bearings. We use a partitioned approach which treats fluid and structure as two computation domains solved separately; reducing the development time needed for a monolithic code which is difficult to manage when the geometries or the physical properties of the problem to be treated become complex.

High‐performance control method for the MSTMP motor

Permanent magnet synchronous motor (PMSM) is the ideal drive for the magnetically suspended turbo-molecular pump (MSTMP) for its high power density, reliable operation and high energy efficiency. Rotor position information is necessary to drive the PMSM. However, because of the installation space limitation and reliability requirement, position sensorless control technology without mechanical position sensors is more attractive. In this study, a sliding mode observer is adopted to estimate the back electromotive force (EMF) that contains the position information. Since the high-order harmonics in the back EMF would lead to harmonic position errors, a fixed frequency extraction filter is proposed to filter out the harmonics. A high precision speed control is of importance to ensure the performance of the MSTMP and also contributes to achieving a better position estimation accuracy, especially under strong disturbances. Therefore, a composite speed controller combining a sliding mode speed controller and a sliding mode disturbance observer is proposed to improve the speed control performance of the MSTMP. The effectiveness of the proposed high-performance control method for the MSTMP motor is evaluated with experiments.

Research on ultra-low speed driving method of traveling wave ultrasonic motor for CMG

The single-gimbal of control moment gyro (SGCMG) servo system needs high stability, high precision and low speed operation. Therefore, a novel driving approach of ultrasonic motor, called the superposition pulse driving method, is proposed in the present study by prolonging the turn-off time of the conventional micro-stepping driving method. Then, three types of contact models are proposed with the variable of pre-pressure between stator and rotor. Moreover, a theoretical analysis is carried out according to the classical friction binomial law. Results of the performed experiment show that, applying the superposition drive method may lead to the significant reduction of periodic vibration’s adverse effect caused by mechanical system’s inertia on the motor speed. Furthermore, it is found that the proposed method not only eliminates the alternating oscillation of the motor speed with large amplitude period, but also it significantly reduces the velocity volatility. It is found that compared with the micro-stepping method, the velocity volatility reduces four groups of different average velocity by about 200% thereby effectively improving the stability of the system. This implies the feasibility of the proposed scheme and ensures a precise adjustment of the satellite attitude by the SGCMG.

Two Optimized General Methods for Inverse Kinematics of 6R Robots Based on Machine Learning

For the 6R robot, there is no analytical solution for some configurations, so it is necessary to analyse inverse kinematics (IK) by the general solution method, which cannot achieve high precision and high speed as the analytical solution. With the expansion of application fields and the complexity of application scenarios, some robots with special configuration have become the research hotspot, and more high-speed and high-precision general algorithms are still being explored and studied. The present paper optimized two general solutions. Elimination is a numerical solution, which has high accuracy, but the solution process is complex and time-consuming. The present paper optimized the elimination method, derived the final matrix expression directly through complex coefficient extraction and simplifying operation, and realized one-step solution. The solving speed was reduced to 15% of the original, and the integrity of the method was supplemented. This paper proposed a new optimization method for the Gaussian damped least-squares method, in which the variable step-size coefficient is introduced and the machine learning method is used for the research. It was proved that, on the basis of guaranteeing the stability of motion, the average number of iterations can be effectively reduced and was only 4-5 times, effectively improving the solving speed.

Sensorless speed control of 6/4-pole switched reluctance motor with ANFIS and fuzzy-PID-based hybrid observer

This paper presents the sensorless speed control of 6/4 pole SRM drive based on hybrid observer (HO). It consists of two modes, i.e., current sliding mode observer is for high speed and flux linkage sliding mode observer is for low speed control. A nonlinear model of SRM is simulated in MATLAB/Simulink. HO is simulated from low to high speed level, and also estimated position and speed errors are optimized with ANFIS and fuzzy-PID methods. Experimental validation is taken for three set speeds, and measured results are compared with the simulated results. Overall speed and position estimated error, electromagnetic torque ripple output results are compared, and its values are tabulated at the end. This observer has the advantages of high-precision speed control without any additional hardware, and also performance has improved.

Fast Unmixing of Noisy Hyperspectral Images Based on Vertex Component Analysis and Singular Spectrum Analysis Algorithms

Efficient denoising is of great significance to unmixing hyperspectral images. In the present study, a fast unmixing method for noisy hyperspectral images based on the combination of vertex component analysis and singular spectrum analysis is proposed. First, the noisy endmember spectra are extracted by using the vertex component analysis algorithm. Then the singular spectrum analysis is used to denoise the endmember spectrum. When compared with the hyperspectral data as a whole, the amounts of endmember spectral data are known to be small. If only denoising endmember spectral data were to be performed, then the denoising time will be greatly improved, and image information can be effectively preserved. The method has high precision and fast speed for unmixing the noisy hyperspectral image. The advantages of this method will be more apparent when dealing with large amounts of hyperspectral data. In this article, different noise images are experimented with using this method, and strong experimental results are obtained.

Adaptive Sliding Mode Control With Feedforward Compensator for Energy-Efficient and High-Speed Precision Motion of Feed Drive Systems

Industrial feed drive systems, particularly ball-screw and lead-screw feed drives are among the dominating components in production and manufacturing industries. They operate around the clock and at high speeds for coping with the growing production demands. Adversely, high-speed motions cause mechanical vibration, high-energy consumption, and poor tracking performance. Thus, over the years, the research community has invested in precision control and energy saving for these systems. Although there are many control strategies in the literature, such as sliding mode and model predictive controls, further research is necessary for performance enhancement. This study focuses on both high-speed precision control and energy-saving control for feed drive systems. An adaptive nonlinear sliding mode controller with a feedforward compensator for plant uncertainties is designed and its stability is confirmed through the Lyapunov stability theories. For performance evaluation, simulations and experiments are conducted and results are compared with those of an adaptive nonlinear sliding model controller. Results revealed that, based on the proposed controller, the tracking errors of feed drive systems can be reduced by about 33% on average and the maximum tracking error by about 64% on average. In addition, the energy consumption can be reduced by about 2% under similar tracking performance.

Design and Test of a Double-Curved Guiding Groove for a High-Speed Precision Seed-Metering Device

HighlightsThe instability of the seed release point in a seed-metering device is proved theoretically.A double-curved guiding groove at the seed-release point improves the seed-metering uniformity.A discrete element model was used to examine effects of the design parameters on the metering performance.The critical parameters for the double-curved guiding groove design were determined.Abstract. The instability of the seed release point in a seed-metering device is one of the main causes of the non-uniformity of seed spacing. To improve the seed spacing uniformity, a double-curved guiding groove (DGG) was designed based on the prerelease adaptive principle. The DGG was used at the seed release point of an existing high-speed precision soybean seed-metering device with a double-setting plate. The results showed that the prerelease curved surface of the DGG was capable of guiding seeds to be released at the same seed release point at all times, and the adaptive curved surface of the DGG prevented any changes in seed velocity caused by friction or collisions between seeds and the meter, thereby improving the seed spacing uniformity significantly. A discrete element model was developed and validated with laboratory tests. Through simulations using the model, the primary and secondary factors of the DGG impacting the qualified rate of seed metering (QRM) and the coefficient of variation of the seed spacing uniformity (CVU) were identified and were, in descending order, the spacing of prerelease (SPR), the starting position of prerelease (SPP), the inclination angle of the seed outlet (ASO), and the inclination angle of the receiving cup (ABR). Regression equations of the QRM and CVU with the two main impacting factors were then established. For a planter travel speed of 10 km h-1, the optimal SPR was 10 mm, and the optimal SPP was 40°, where the QRM was 100% and the CVU was 16.61%. When compared to seed metering without the DGG, the CVU was reduced by 2.55%, showing that the DGG significantly improved the uniformity of seed spacing. Keywords: Double-curved guiding groove, Discrete element method, Seed-metering device, Travel speed, Uniformity.