Asymmetric indirect-driven self-sensing actuation and its application to piezoelectric systems

2020 ◽  
pp. 014233122093820
Author(s):  
Bin Hu ◽  
Chee Khiang Pang ◽  
Jie Wan ◽  
Shuyu Cao ◽  
Jern Khang Tan ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Hard Disk Drives ◽  
Piezoelectric Element ◽  
Error Variance ◽  
Phase Lag ◽  
Positioning Systems ◽  
Mechanical Responses ◽  
Control Command ◽  
Component Matching ◽  
First Time

Self-sensing actuators use a single piezoelectric element as actuators and sensors simultaneously. This paper proposes the asymmetric indirect-driven self-sensing actuation (AIDSSA) circuit to realize the concept of self-sensing in piezoelectric-actuated systems. Unlike traditional circuits relying on differential amplifiers, the AIDSSA circuit is constructed with only op-amps and uses negative feedback to reject the common-mode interferences from the control command. The new circuit requires simpler conditions of component matching and is able to sense the mechanical responses with a uniform gain and without a phase lag. The actuator is able to achieve full-stroke actuation while sensing is performed, because AIDSSA introduces no undesirable dynamics into the control loop. For the first time, the sensing and actuation transfer functions in self-sensing actuators have become fully decoupled at all frequencies. The investigation takes the form of an industrial application of hard disk drives, and demonstrates the usefulness the circuit in complex positioning systems. Experimental results show that the position error variance, a measure of disturbance rejection capability, has been improved by about 15% in the track-following mode relative to the same servo before modifications.

scholarly journals Strain Sensing With Piezoelectric Zinc Oxide Thin Films for Vibration Suppression in Hard Disk Drives

2008 ◽  
Author(s):  
Sarah Felix ◽  
Stanley Kon ◽  
Jianbin Nie ◽  
Roberto Horowitz
Keyword(s):  
Vibration Suppression ◽  
Transfer Functions ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Strain Sensing ◽  
Linear Quadratic ◽  
H2 Control ◽  
Hard Drives ◽  
Optimization Methodology

This paper describes the integration of thin film ZnO strain sensors onto hard disk drive suspensions for improved vibration suppression for tracking control. Sensor location was designed using an efficient optimization methodology based on linear quadratic gaussian (LQG) control. Sensors were fabricated directly onto steel wafers that were subsequently made into instrumented suspensions. Prototype instrumented suspensions were installed into commercial hard drives and tested. For the first time, a sensing signal was successfully obtained while the suspension was flying on a disk as in normal drive operation. Preliminary models were identified from experimental transfer functions. Nominal H2 control simulations demonstrated improved vibration suppression as a result of both the better resolution and higher sensing rate provided by the sensors.

Application of Mixed H2/H∞ Data Driven Control Design to Dual Stage Hard Disk Drives

2018 ◽  
Author(s):  
Omid Bagherieh ◽  
Prateek Shah ◽  
Roberto Horowitz
Keyword(s):  
Closed Loop ◽  
Transfer Functions ◽  
Hard Disk Drives ◽  
Control Design ◽  
Hard Disk ◽  
Data Driven ◽  
Disk Drives ◽  
Design Strategies ◽  
Data Driven Approach ◽  
Dual Stage

A data driven control design approach in the frequency domain is used to design track following feedback controllers for dual-stage hard disk drives using multiple data measurements. The advantage of the data driven approach over model based approach is that, in the former approach the controllers are directly designed from frequency responses of the plant, hence avoiding any model mismatch. The feedback controller is considered to have a Sensitivity Decoupling Structure. The data driven approach utilizes H∞ and H2 norms as the control objectives. The H∞ norm is used to shape the closed loop transfer functions and ensure closed loop stability. The H2 norm is used to constrain and/or minimize the variance of the relevant signals in time domain. The control objectives are posed as a locally convex optimization problem. Two design strategies for the dual-stage hard disk drive are presented.

ELECTROSTATIC DISCHARGE EFFECT ON TMR RECORDING HEAD: A FLEX ON SUSPENSION CAPACITANCE APPROACH

2009 ◽  
Vol 23 (17) ◽  
pp. 3586-3590 ◽  
Author(s):  
NUTTACHAI JUTONG ◽  
APIRAT SIRITARATIWAT ◽  
DUANGPORN SOMPONGSE ◽  
PORNCHAI RAKPONGSIRI
Keyword(s):  
Human Body ◽  
Electrostatic Discharge ◽  
Hard Disk Drives ◽  
Electrical Characteristics ◽  
Disk Drives ◽  
Human Body Model ◽  
Recording Head ◽  
Body Model ◽  
Recording Heads ◽  
First Time

Electrostatic discharge (ESD) effects on GMR recording heads have been reported as the major cause of head failure. Since the information density in hard-disk drives has dramatically increased, the GMR head will be no longer in use. The tunneling magnetoresistive (TMR) read heads are initially introduced for a 100 Gbit/in2 density or more. Though the failure mechanism of ESD in GMR recording heads has not been explicitly understood in detail, a study to protect from this effect has to be done. As the TMR head has been commercially started, the ESD effect must be considered. This is the first time that the TMR equivalent circuit has been reported in order to evaluate the ESD effect. A standard human body model (HBM) is discharged across R+ and R- where the capacitances of flex on suspension (FOS) are varied. It is intriguingly found that the electrical characteristics of the TMR head during the discharge period depend on the discharge position. This may be explained in terms of the asymmetry impedance of TMR by using adapted Thevenin's theory. The effect of FOS components on TMR recording heads is also discussed.

scholarly journals Predicting the consumption speed of a premixed flame subjected to unsteady stretch rates

2021 ◽  
Author(s):  
Meysam Sahafzadeh ◽  
Seth B. Dworkin ◽  
Larry W. Kostiuk
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Time Scale ◽  
Transfer Functions ◽  
Laminar Flame ◽  
Premixed Flames ◽  
Turbulent Flames ◽  
Response Analysis ◽  
Phase Lag

The stretched laminar flame model provides a convenient approach to embed realistic chemical kinetics when simulating turbulent premixed flames. When positive-only periodic strain rates are applied to a laminar flame there is a notable phase lag and diminished amplitude in heat release rate. Similar results have being observed with respect to the other component of stretch rate, namely the unsteady motion of a curved flame when the stretch rates are periodic about zero. Both cases showed that the heat release rate or consumption speed of these laminar-premixed flames vary significantly from the quasi-steady flamelet model. Deviation from quasi-steady behaviour increases as the unsteady flow time scale approaches the chemical time scale that is set by the stoichiometry. A challenge remains in how to use such results predictively for local and instantaneous consumption speed for small segments of turbulent flames where their unsteady stretch history is not periodic. This paper uses a frequency response analysis as a characterization tool to simplify the complex non-linear behaviour of premixed methane air flames for equivalence ratios from 1.0 down to 0.7, and frequencies from quasi-steady up to 2000 Hz using flame transfer functions. Various linear and nonlinear models were used to identify appropriate flame transfer functions for low and higher frequency regimes, as well as extend the predictive capabilities of these models. Linear models were only able to accurately predict the flame behaviour below a threshold of when the fluid and chemistry time scales are the same order of magnitude. Other proposed transfer functions were tested against arbitrary multi-frequency stretch inputs and were shown to be effective over the full range of frequencies.

scholarly journals Testing and Development of Transfer Functions for Weighing Precipitation Gauges in WMO-SPICE

2017 ◽  
Author(s):  
John Kochendorfer ◽  
Rodica Nitu ◽  
Mareile Wolff ◽  
Eva Mekis ◽  
Roy Rasmussen ◽  
...  
Keyword(s):  
Transfer Functions ◽  
Precipitation Amount ◽  
Wind Speeds ◽  
Small Manufacturer ◽  
Lower Porosity ◽  
Precipitation Gauge ◽  
Reference Amount ◽  
First Time ◽  
High Winds ◽  
Better Than

Abstract. Adjustments for the undercatch of solid precipitation caused by wind were developed for different weighing gauge/wind shield combinations tested in WMO-SPICE. These include several different manufacturer-provided unshielded and single-Alter shielded weighing gauges, a MRW500 precipitation gauge within a small, manufacturer-provided shield, and host-provided precipitation gauges within double-Alter, Belfort double-Alter, and small Double-Fence Intercomparison Reference (SDFIR) shields. Previously-derived adjustments were also tested on measurements from each weighing gauge/wind shield combination. The transfer functions developed specifically for each of the different types of unshielded and single-Alter shielded weighing gauges did not perform significantly better than the more generic and universal transfer functions developed previously using measurements from eight different WMO-SPICE sites. This indicates that wind shield type (or lack thereof) is more important in determining the magnitude of wind-induced undercatch than the type of weighing precipitation gauge. It also demonstrates the potential for widespread use of the previously-developed, multi-site single-Alter shielded and unshielded transfer functions. In addition, corrections for the lower-porosity Belfort double-Alter shield and a standard double-Alter shield were developed and tested using measurements from two separate sites for the first time. Among all of the manufacturer-provided shields tested, with an average undercatch of about 5 %, the Belfort double Alter shield required the least amount of correction, and caught ~ 80 % of the reference amount of precipitation even in snowy conditions with wind speeds greater than 5 m  s−1. The SDFIR-shielded gauge accumulated 98 % of the Double-Fence Automated Reference (DFAR) precipitation amount on average, accumulated 90 % of the DFAR accumulation in high winds, and was almost indistinguishable from the full-sized DFAR used as a reference. In general, the more effective wind shields, that were associated with smaller unadjusted errors, also produced more accurate measurements after adjustment.

Using impressed current cathodic protection systems of pipelines for electromagnetic exploration

Geophysics ◽  
2018 ◽  
Vol 83 (4) ◽  
pp. B155-B165 ◽  
Author(s):  
Tobias Lindau ◽  
Michael Becken
Keyword(s):  
Cathodic Protection ◽  
Transfer Functions ◽  
Spatial Behavior ◽  
Local Source ◽  
Phase Lag ◽  
Injection Point ◽  
Frequency Dependency ◽  
Pipeline Segment ◽  
Impressed Current ◽  
Impressed Current Cathodic Protection

Low-frequency electromagnetic (EM) signals generated by networks of technical infrastructure such as power-lines, pipelines, or railways may provide a cheap and efficient means to perform EM depth sounding of the upper few kilometers of the earth. We attempt to use the signals emitted by an impressed current cathodic protection (ICCP) system of a 35 km long gas pipeline segment in northwestern Germany. The installed ICCP system uses a periodical 12 s on/3 s off current switching scheme, which resembles current waveforms used in controlled-source electromagnetics (CSEM). In contrast to CSEM, where a grounded electrical dipole is used as the source, the current flow in pipelines is not constant along its legs. Our efforts are therefore concentrated toward the determination of the temporal and spatial behavior of the electrical current within the investigated pipeline segment. Although the time dependency of the current can be measured directly at the injection point, the spatial distribution is only accessible through indirect observations. We use fluxgate magnetic field measurements at multiple locations directly above the pipeline to infer the local source current and its frequency-dependency and phase lag. We observe that the current decays roughly exponentially away from the injection point, exhibits a position-dependent frequency dependency, and experiences a phase shift that accumulates to more than 30° at the ends of the segment. These effects can be consistently explained with a transmission line model. Having determined the current distribution, we can represent the pipeline as an EM source superposed of point dipoles. The estimated source model allows us to predict the electric (and magnetic) fields at remote locations. To verify our approach, we deploy an array of telluric recorders in the vicinity of the pipeline, estimate the frequency-domain transfer functions, and invert the data into a 3D electrical conductivity model using smoothness-constrained inversion techniques.

scholarly journals Improving the Performance of Dynamic Ship Positioning Systems: A Review of Filtering and Estimation Techniques

2020 ◽  
Vol 8 (4) ◽  
pp. 234 ◽  
Author(s):  
Denis Selimović ◽  
Jonatan Lerga ◽  
Jasna Prpić-Oršić ◽  
Sasa Kenji
Keyword(s):  
State Of The Art ◽  
Estimation Procedure ◽  
Error Variance ◽  
Positioning Systems ◽  
Estimation Algorithms ◽  
Control Signals ◽  
Complex Control System ◽  
Positioning Technique ◽  
Directional Wave ◽  
Estimation And Filtering

Various operations at sea, such as maintaining a constant ship position and direction, require a complex control system. Under such conditions, the ship needs an efficient positioning technique. Dynamic positioning (DP) systems provide such an application with a combination of the actuators mechanism, analyses of crucial ship variables, and environmental conditions. The natural forces of induced nonlinear waves acting on a ship’s hull interfere with the systems. To generate control signals for actuators accurately, sensor measurements should be filtered and processed. Furthermore, for safe and green routing, the forces and moments acting on the ship’s hull should be taken into account in terms of their prediction. Thus, the design of such systems takes into account the problem of obtaining data about the directional wave spectra (DWS). Sensor systems individually cannot provide high accuracy and reliability, so their measurements need to be combined and complemented. Techniques based on the recursive Kalman filter (KF) are used for this purpose. When some measurements are unavailable, the estimation procedure should predict them and, based on the comparison of theoretical and measured states, reduce the error variance of the analyzed signals. Different approaches for improving estimation algorithms have evolved over the years with the indication of improvement. This paper gives an overview of the state-of-the-art estimation and filtering techniques for providing optimum estimation states in DP systems.

scholarly journals Feasibility Test and Analysis for Heavy Haul Freight Using WDPS Based on MIMO-OFDM

2020 ◽  
Vol 10 (12) ◽  
pp. 4074
Author(s):  
Kangmi Lee ◽  
Taewon Park
Keyword(s):  
Control Function ◽  
Propagation Distance ◽  
Centralized Control ◽  
Control Command ◽  
Heavy Haul ◽  
Mimo Ofdm ◽  
Braking Control ◽  
Feasibility Test ◽  
5 Ghz ◽  
First Time

The technical feasibility of a heavy haul freight using WDPS (Wireless Distributed Power System) was verified for the first time in Korea. That consisted of a master locomotive, 50 freights and a slave locomotive. The master and slave locomotives were equipped with WDPS to distribute traction and braking control command data. MIMO-OFDM, which is strong in multi-path, was applied to the WDPS, and a repeater was installed on the 25th freight to secure coverage even with signal attenuation according to the terrain (curve, gradient) of the driving section. The test was carried out at an average speed of 100 km/h in the approximately 21 km from Jillye station to Busansinhang station in Korea. As a result of the test, it was confirmed that the traction function, braking function, pantograph control function, MCB function, and safety circuit function of the heavy haul freight using WDPS were perfectly controlled. Additionally, the air braking time was reduced by about 50% compared to the centralized control as the braking was controlled by two locomotives at the same time. For the first time, the operational feasibility of heavy haul freight using WDPS based on MIMO-OFDM in the 2.4 GHz/5 GHz band with a relatively short propagation distance was verified.

A NEW METHODOLOGY FOR THE CONSTRUCTION OF OPTIMIZED RUNGE–KUTTA–NYSTRÖM METHODS

2011 ◽  
Vol 22 (06) ◽  
pp. 623-634 ◽  
Author(s):  
D. F. PAPADOPOULOS ◽  
T. E. SIMOS
Keyword(s):  
Schrödinger Equation ◽  
Schrodinger Equation ◽  
First Integrals ◽  
New Method ◽  
Phase Lag ◽  
Nyström Methods ◽  
Algebraic Order ◽  
Runge Kutta ◽  
First Time ◽  
Zero Phase

In this paper, a new Runge–Kutta–Nyström method of fourth algebraic order is developed. The new method has zero phase-lag, zero amplification error and zero first integrals of the previous properties. Numerical results indicate that the new method is very efficient for solving numerically the Schrödinger equation. We note that for the first time in the literature we use the requirement of vanishing the first integrals of phase-lag and amplification error in the construction of efficient methods for the numerical solution of the Schrödinger equation.

Dynamics and control performance of hard disk drives with passive dampers

2004 ◽  
Vol 218 (12) ◽  
pp. 1555-1568 ◽  
Author(s):  
L M Xu ◽  
N Guo ◽  
S Zeng ◽  
R M Lin ◽  
H Du
Keyword(s):  
Dynamic Characteristics ◽  
Transfer Functions ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Data Access ◽  
Open Loop ◽  
Structure Design ◽  
Disk Drives ◽  
Phase Loss ◽  
Dynamics And Control

The residual vibration is one of the primary mechanical problems that affect the dynamic characteristics of the head actuator assembly in hard disk drives, and the data access speed and positioning resolution. A discrete damping device has been developed to suppress the quasi-rigid-body mode and a reduction of 10 dB in amplitude is shown possible. The servo performance of the head actuator assembly with and without the damping device is presented in this paper, together with the measurement and prediction of the dynamic characteristics. Both closed- and open-loop transfer functions of the plant are measured in the actual operating environment on a servo test stand and compared with the simulation. It is found that the use of passive damping in the structure design allows for a greater margin of error at the crossover frequency since less phase loss results when notch filters are used, thus improving the stability robustness in feedback control.

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