The Design and Control of a Rigid-flexible Coupling Positioning Stage for Enhanced Settling Performance

2021 ◽  
Author(s):  
Hao Peng ◽  
Zhijun Yang ◽  
Wenchao Xue ◽  
Ruirui Huang ◽  
Yi Huang
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Mechanical Design ◽  
Dead Zone ◽  
Low Frequency ◽  
Poor Performance ◽  
Experimental Tests ◽  
Control Performance ◽  
Flexible Coupling ◽  
Positioning Stage

Abstract Traditional high-speed precision motion stage (HSPMS) design pursues high-stiffness structure to achieve fast response. However, such structure leads to high-frequency disturbance near dead zone of friction, which causes poor performance in controlling HSPMS. To this end, this paper proposes the active disturbance rejection control (ADRC) based mechanical design to reduce the bandwidth of friction disturbance and improve the control performance of HSPMS. It is proved that the low-frequency disturbance can be more effectively tackled by the extended state observer (ESO) in the frame of ADRC. In particular, rigid-flexible coupling (RFC) positioning stage is presented for converting the high-frequency friction disturbance into the low-frequency elastic deformation disturbance by flexure hinges. The experimental tests are carried out for both traditional stage and RFC stage. It is clearly shown that compared with traditional design, the control performance of RFC stage is remarkably promoted.

scholarly journals Active Q Flux Concept for Sensorless Control of Synchronous Reluctance Machines

2021 ◽  
Author(s):  
zhendong zhang ◽  
Jacob M. Lamb
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Sensorless Control ◽  
Control Performance ◽  
Unstable Region ◽  
Low Speed ◽  
Salient Pole ◽  
Seamless Transition ◽  
Active Flux

<p>This paper proposes a new scheme to use active flux on q-axis for sensorless control of synchronous reluctance machines (SynRM). Conventionally, “Active Flux” on d-axis is adopted to convert a salient pole machine into a fictitious non-salient pole machine. However, the injected d-axis flux can deteriorate high frequency injection (HFI) sensorless control performance or even run the system into unstable region at low speed. This paper demonstrates active flux on q-axis can support back-EMF sensorless control at high speed and improve low speed HFI performance substantially. A seamless transition from HFI sensorless method to back-EMF voltage method is attained after adopting the proposed active q flux. Experiment results are used to validate the proposed method.</p>

scholarly journals Seismic Qualification of Electrical Cabinet Using High-Fidelity Simulation under High Frequency Earthquakes

2020 ◽  
Vol 12 (19) ◽  
pp. 8048
Author(s):  
Hoyoung Son ◽  
Seonggwan Park ◽  
Bub-Gyu Jeon ◽  
Woo-Young Jung ◽  
Jongwoong Choi ◽  
...  
Keyword(s):  
Seismic Response ◽  
High Frequency ◽  
Power Plants ◽  
Low Frequency ◽  
Experimental Tests ◽  
Design Guidelines ◽  
High Fidelity ◽  
High Fidelity Simulation ◽  
Nonstructural Components ◽  
Fundamental Frequencies

Most nuclear and nonnuclear power plants have been designed in the frequency range of 2 to 10 Hz, but now, the design guidelines for structural and nonstructural components such as electrical cabinets must be improved by including high frequency greater than 10 Hz for sustainable energy. The electrical cabinet is the essential piece of equipment for safety functions and the uncertainty of seismic capability in power plants. Consequently, the attention of this study focused on evaluating the seismic demands of the electrical cabinet under high frequency earthquakes and also, seismic qualification of the electrical cabinet using the identification of experimental tests and numerical models. An experimental test based on ICC-ES AC 156 and IEEE std.344 was conducted for seismic qualification of the cabinet and then, a high-fidelity finite element model to capture the significant deformation was developed in this study. It is observed that the fundamental frequencies were 16 and 24 Hz from the experimental tests, respectively. In order to verify the proposed high-fidelity simulation model, the target fundamental frequencies of the cabinet were evaluated in the ABAQUS platform. It was interesting to note that the reconciliation of experimental and analytical results was extremely identical. Furthermore, in order to evaluate seismic response characteristics of the cabinet subjected to high and low frequency earthquakes, time history analysis was conducted in this study, using the ABAQUS platform. As a result, the observation showed that the seismic response of the cabinet system under a high frequency earthquake was relatively higher than that of low frequency. It can be very important to note that the cabinet system was sensitive to high frequency vibration.

scholarly journals Self-Motion and the Shaping of Sensory Signals

2010 ◽  
Vol 103 (4) ◽  
pp. 2195-2207 ◽  
Author(s):  
Robert A. Jenks ◽  
Ashkan Vaziri ◽  
Ali-Reza Boloori ◽  
Garrett B. Stanley
Keyword(s):  
High Frequency ◽  
High Speed ◽  
External Environment ◽  
Low Frequency ◽  
Head Rotation ◽  
Object Localization ◽  
Behavioral Variability ◽  
Sensory Signals ◽  
Behavioral Variables ◽  
Self Motion

Sensory systems must form stable representations of the external environment in the presence of self-induced variations in sensory signals. It is also possible that the variations themselves may provide useful information about self-motion relative to the external environment. Rats have been shown to be capable of fine texture discrimination and object localization based on palpation by facial vibrissae, or whiskers, alone. During behavior, the facial vibrissae brush against objects and undergo deflection patterns that are influenced both by the surface features of the objects and by the animal's own motion. The extent to which behavioral variability shapes the sensory inputs to this pathway is unknown. Using high-resolution, high-speed videography of unconstrained rats running on a linear track, we measured several behavioral variables including running speed, distance to the track wall, and head angle, as well as the proximal vibrissa deflections while the distal portions of the vibrissae were in contact with periodic gratings. The measured deflections, which serve as the sensory input to this pathway, were strongly modulated both by the properties of the gratings and the trial-to-trial variations in head-motion and locomotion. Using presumed internal knowledge of locomotion and head-rotation, gratings were classified using short-duration trials (<150 ms) from high-frequency vibrissa motion, and the continuous trajectory of the animal's own motion through the track was decoded from the low frequency content. Together, these results suggest that rats have simultaneous access to low- and high-frequency information about their environment, which has been shown to be parsed into different processing streams that are likely important for accurate object localization and texture coding.

scholarly journals Small-Scale Drilling Test Rig For Investigation of Axial Excitation On The Drilling Process

2018 ◽  
Vol 148 ◽  
pp. 16001
Author(s):  
A. Austefjord ◽  
S. Blaylock ◽  
I. Forster ◽  
M. Sheehan ◽  
C. Wright
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Low Frequency ◽  
Advanced Technology ◽  
Small Scale ◽  
Drilling Process ◽  
Generation Process ◽  
Rock System ◽  
Drilling Rig ◽  
Axial Excitation

This paper describes the design, construction and operation of a small-scale drilling rig for the purpose of investigation of the effect of axial excitation on the drilling process. The rig is bench top in size and has been designed to drill small rock samples, whilst at the same allowing axial excitation to be induced into the drilling process. The rig has been designed to drill the rock without any drilling fluids – so allowing improved observation of the chip generation process. Additionally, the drilling weight on bit is applied via masses, so allowing greater representation of the dynamic behavior of the drilling process – i.e. capturing more natural frequencies. The results from the rig have been obtained over two frequency ranges – low frequency (0-50 Hz) and high frequency (50-250 Hz). Results show that improved rate of penetration is obtained with axial excitation – with low and high frequency optima occurring. These optima can be related to the behavior of the string in the two frequency ranges – in the low frequency range, the entire string acts in unison; whereas at high frequency, only the bit/rock system is active. As a result, it is concluded that for low frequency operation, only information about the drill string is required to optimize performance; whereas for high frequency operation, information about the bit/rock system is required to optimize performance. Observation of the chip generation process via high speed video has shown that during axial excitation, regular shaped bricks are ejected when compared with the typical wedge- shaped chips that are normally ejected during the drilling process. It is concluded that, during the axial excitation process, the chips are being ejected via a levering action, so allowing a more efficient and quicker process. MIT [1] provided background classes, project guidance and project review as part of an NOV/MIT advanced technology program. Larger scale lab tests and/or field tests are required to verify/validate these conclusions.

Measurement of High Frequency Viscoelastic Properties of Deformed Rubber

2016 ◽  
Vol 715 ◽  
pp. 139-146 ◽  
Author(s):  
Tadayoshi Shoyama ◽  
Koji Fujimoto
Keyword(s):  
Resonance Frequency ◽  
High Frequency ◽  
High Speed ◽  
Dynamic Properties ◽  
Loss Modulus ◽  
Low Frequency ◽  
Soft Materials ◽  
Load Cell ◽  
Universal Prediction ◽  
Response Method

Bearings of small turbo machines support high speed rotors rotating with the frequency over 1 [kHz]. Such bearings are often supported with O-rings made of soft materials like rubber to attenuate high frequency oscillations. Dynamic properties of rubber supporters have been measured experimentally for individual dimensions, but the universal prediction of dynamic properties for various frequencies is difficult not only because rubbers exhibit nonlinearity against its strain, but because O-ring supporters deform heterogeneously. For the precise prediction, it is necessary to investigate the viscoelasticity of rubber under various deformations and frequencies. Such properties can be measured by the standard shear vibration non-response method of ISO 6721-6 (JIS K 7244-6). However this is applicable only to low frequency range under 100 [Hz] because of the limitation of resonance frequency of the load cell. In this research, based on BERM (Base Excitation Resonant Mass) method, a new method was developed to measure the complex shear modulus at high frequencies up to 1 [kHz] of rubber sheets under homogeneous shear deformations. In the presented method, the force is calculated from the acceleration of the mass instead of the direct measurement by a load cell. Hence accurate measurement became possible even in the range beyond the resonance frequency of a load cell. The measured shear storage modulus G’ and shear loss modulus G” of deformed rubber were presented.

scholarly journals Wall pressure beneath a transitional hypersonic boundary layer over an inclined straight circular cone

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Siwei Dong ◽  
Jianqiang Chen ◽  
Xianxu Yuan ◽  
Xi Chen ◽  
Guoliang Xu
Keyword(s):  
Boundary Layer ◽  
High Frequency ◽  
High Speed ◽  
Low Frequency ◽  
Axial Direction ◽  
Wall Pressure ◽  
Hypersonic Boundary Layer ◽  
High Frequency Signal ◽  
Local Boundary ◽  
Half Angle

AbstractProperties of wall pressure beneath a transitional hypersonic boundary layer over a 7∘ half-angle blunt cone at angle of attack 6∘ are studied by Direct Numerical Simulation. The wall pressure has two distinct frequency peaks. The low-frequency peak with f≈10−50 kHz is very likely the unsteady crossflow mode based on its convection direction, i.e. along the axial direction and towards the windward symmetry ray. High-frequency peaks are roughly proportional to the local boundary layer thickness. Along the trajectories of stationary crossflow vortices, the location of intense high-frequency wall pressure moves from the bottom of trough where the boundary layer is thin to the bottom of shoulder where the boundary layer is thick. By comparing the pressure field with that inside a high-speed transitional swept-wing boundary layer dominated by the z-type secondary crossflow mode, we found that the high-frequency signal originates from the Mack mode and evolves into the secondary crossflow instability.

scholarly journals Active Q Flux Concept for Sensorless Control of Synchronous Reluctance Machines

2021 ◽  
Author(s):  
zhendong zhang ◽  
Jacob M. Lamb
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Sensorless Control ◽  
Control Performance ◽  
Unstable Region ◽  
Low Speed ◽  
Salient Pole ◽  
Seamless Transition ◽  
Active Flux

<p>This paper proposes a new scheme to use active flux on q-axis for sensorless control of synchronous reluctance machines (SynRM). Conventionally, “Active Flux” on d-axis is adopted to convert a salient pole machine into a fictitious non-salient pole machine. However, the injected d-axis flux can deteriorate high frequency injection (HFI) sensorless control performance or even run the system into unstable region at low speed. This paper demonstrates active flux on q-axis can support back-EMF sensorless control at high speed and improve low speed HFI performance substantially. A seamless transition from HFI sensorless method to back-EMF voltage method is attained after adopting the proposed active q flux. Experiment results are used to validate the proposed method.</p>

scholarly journals High Frequency Performance of Piezoelectric Diaphragms for Impedance-Based SHM Applications

2020 ◽  
Vol 2 (1) ◽  
pp. 16
Author(s):  
Guilherme Rezende ◽  
Fabricio Baptista
Keyword(s):  
High Frequency ◽  
Structural Damage ◽  
Low Cost ◽  
Low Frequency ◽  
Experimental Tests ◽  
Piezoelectric Transducers ◽  
Low Frequencies ◽  
High Frequencies ◽  
Electromechanical Impedance ◽  
Damage Indices

Piezoelectric transducers are used in a wide variety of applications, including damage detection in structural health monitoring (SHM) applications. Among the various methods for detecting structural damage, the electromechanical impedance (EMI) method is one of the most investigated in recent years. In this method, the transducer is typically excited with low frequency signals up to 500 kHz. However, recent studies have indicated the use of higher frequencies, usually above 1 MHz, for the detection of some types of damage and the monitoring of some structures’ characteristics that are not possible at low frequencies. Therefore, this study investigates the performance of low-cost piezoelectric diaphragms excited with high frequency signals for SHM applications based on the EMI method. Piezoelectric diaphragms have recently been reported in the literature as alternative transducers for the EMI method and, therefore, investigating the performance of these transducers at high frequencies is a relevant subject. Experimental tests were carried out with piezoelectric diaphragms attached to two aluminum bars, obtaining the impedance signatures from diaphragms excited with low and high frequency signals. The analysis was performed using the real part of the impedance signatures and two basic damage indices, one based on the Euclidean norm and the other on the correlation coefficient. The experimental results indicate that piezoelectric diaphragms are usable for the detection of structural damage at high frequencies, although the sensitivity decreases.

A comprehensive optimal design method for magnetorheological dampers utilized in DMU power package

2021 ◽  
pp. 146442072110496
Author(s):  
Fanghui Xu ◽  
Dawei Dong ◽  
Yan Huang ◽  
Rui Zhang ◽  
Shizhe Song ◽  
...  
Keyword(s):  
Optimal Design ◽  
High Frequency ◽  
High Speed ◽  
Low Frequency ◽  
Mr Damper ◽  
Magnetic Flux Density ◽  
Objective Functions ◽  
Damping Force ◽  
Optimal Method ◽  
Mr Dampers

The diesel multiple unit (DMU) has been widely used in high-speed railway service due to its flexibility and economy. Considering the broadband and complex vibration generated by DMU power package, the advanced semi-active suspension with magnetorheological (MR) dampers is introduced to promote anti-vibration performance. In this work, a comprehensive optimal design approach for MR damper used in DMU power package is proposed. Quasi-static modeling process is conducted to obtain MR damper's low-frequency outputs, while its high-frequency damping forces are calculated by physical modeling considering the fluid compressibility and piston assembly inertia. Then the objective functions and optimization variables are determined. Based on response surface and linear correlation analysis, the influence of the optimal variables on the objective functions is discussed. Using reference-point based nondominated sorting approach (NSGA-III), the evolutionary many-objective optimization is conducted. In addition, magnetic design is incorporated into the optimal process to ensure the magnetic flux density in the effective working area. Finally, an optimized MR damper prototype is manufactured and tested. By comparing the experimental damping force with calculated results in both low-frequency and high-frequency ranges, the effectiveness of the presented optimal method for MR dampers is validated.

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