A Dynamic Model of Electrostrictive Unimorph Actuators for Haptic Devices

2016 ◽  
Author(s):  
Tahzib Safwat ◽  
Ryan Tosto ◽  
Michael D. Grissom ◽  
Christopher D. Rahn
Keyword(s):  
Frequency Response ◽  
Dynamic Model ◽  
Time Domain ◽  
Haptic Feedback ◽  
High Strain ◽  
Piezoelectric Materials ◽  
Domain Model ◽  
Electroactive Polymer ◽  
Step Response ◽  
Compliant Actuators

Piezoelectric materials are commonly found in many devices, but their usage is limited by the low strain and high stiffness of the material. This prevents their use in “soft” applications, such as compliant actuators for haptic feedback devices and wearable technology. The actuation dynamics of a ferro-electric relaxor terpolymer, a type of soft and high strain electroactive polymer (EAP), are examined. This paper studies the unimorph actuator via a linearized time-domain model and experiments to validate the model include step response and frequency response of tip displacement.

Swing Reduction of Ropeway Carriers by Means of Two-Ball Rolling Type Damping Equipment: 2nd Report — Way to Implement Desired Damping for Two-Ball System

2007 ◽  
Author(s):  
H. Sato ◽  
M. Chishima
Keyword(s):  
Friction Coefficient ◽  
Frequency Response ◽  
Dynamic Model ◽  
Time Domain ◽  
Damping Coefficient ◽  
Ball Rolling ◽  
Safety And Reliability ◽  
Transport Safety ◽  
Time Domain Response ◽  
Rolling Balls

To enhance transport safety and reliability of ropeway systems, it is essential to reduce the swing of the carriers that results from wind, etc. In the previous report [1], we provided a practical damping equipment using two rolling balls (hereinafter described as “two-ball rolling type damping equipment”) to reduce the swing of ropeway carriers. A linearized dynamic model is proposed. Then, on the basis of relevant parameters, the frequency response and time domain response of the system is studied and discussed. In this report, we will study relationship between theoretical best damping coefficient ratio and friction coefficient of two-ball system. Then we will provide the way to implement the desired damping for the two-ball system. We will then provide the detail on how to estimate the inherent damping within the two-ball system. In addition, we will show and discuss two balls behavior when this equipment works experimentally.

Computation of the time‐domain response of a polarizable ground

Geophysics ◽  
1982 ◽  
Vol 47 (11) ◽  
pp. 1574-1576 ◽  
Author(s):  
D. Guptasarma
Keyword(s):  
Time Domain ◽  
Complex Impedance ◽  
Fractional Power ◽  
Domain Model ◽  
Frequency Function ◽  
Step Response ◽  
Linear Filter ◽  
Complex Frequency ◽  
Time Domain Response ◽  
Impedance Functions

Computation of the theoretical time‐domain response of a polarizable ground on the basis of a frequency‐domain model of relaxation, e.g., a Cole‐Cole or any other model that involves a fractional power of the complex frequency variable, runs into difficulties either because the Laplace transform can only be written as a very slowly converging summation or because it cannot be written in closed computable form. A clear way around this is to use a digital linear filter. A filter is presented in this paper that has been designed specifically to work well with complex impedance functions that tend asymptotically to real values at both extremes of the frequency variable, the magnitude descending monotonically from the low‐frequency asymptote to the high frequency asymptote. This filter produces the step response from the real part of the impedance‐versus‐frequency function with reasonable accuracy for all impedance functions that one may like to represent by models of electrical relaxation for a polarizable ground, but it does not work for functions containing sharp resonances or discontinuities.

A High Order, Lumped Parameter, Jet Dynamic Model for the Frequency Response of Laminar Proportional Amplifiers

1981 ◽  
Vol 103 (4) ◽  
pp. 317-323
Author(s):  
T. M. Drzewiecki
Keyword(s):  
Frequency Response ◽  
Dynamic Model ◽  
Low Frequency ◽  
Electrical Circuit ◽  
High Order ◽  
Step Response ◽  
Average Particle ◽  
Laplace Domain ◽  
Lumped Parameter ◽  
Good Agreement

This paper presents a high-order, lumped parameter, jet-dynamic model for laminar proportional amplifiers (LPA’s). The governing equations for the lumped-parameter representation of the flow regimes found in the input of an LPA are derived in the Laplace domain, and an equivalent electrical circuit is obtained. The input governs the overall response of the LPA and may be modeled in its simplest form by five reactive components. The transmission of the signal from input to output is delayed by a transport time (determined by observation of flow visualization of a step response) equal to twice the average particle transit time. A pressure difference is then developed at the splitter that is proportional to the loading and the vent conditions. This signal is acoustically fed back to the control region of the jet, augmenting jet deflection when in phase. The vent inductance is found to have a significant influence on the low-frequency gain. Resonant regions determined by this model correspond closely to edgetone eigenfrequencies reported in the literature. Experimental data have shown good agreement with theory for the amplitude frequency response of LPA’s and excellent agreement for the phase shift. An engineering guide developed for the bandpass characteristics of LPA’s indicates that operating bandwidths of up to 14 kHz can be expected for amplifiers with a nozzle width of 0.25 mm, and ultrasonic operation appears feasible with devices having nozzle widths as large as 0.1 mm.

A Simple Yet Theoretically Based Time Domain Model for Fluid Transmission Line Systems

1973 ◽  
Vol 95 (4) ◽  
pp. 498-504 ◽  
Author(s):  
J. T. Karam ◽  
R. G. Leonard
Keyword(s):  
Transmission Line ◽  
Time Domain ◽  
Experimental Tests ◽  
Domain Model ◽  
Step Response ◽  
Amplitude Dependence ◽  
Proposed Model ◽  
Finite Line ◽  
Infinite Line ◽  
Good Agreement

A simple, theoretically based time domain model for the propagation of small, arbitrary signals in a finite, circular, fluid transmission line is developed. A recent simple theoretical solution for the step response at a downstream point in a semi-infinite fluid line is combined with a two-port representation of a finite line. The major feature of this finite line model is two “filters” which represent a convolution of their arbitrary inputs with the unit impulse response at the equivalent location in a semi-infinite line. Experimental tests are reported which further verify the simple semi-infinite line solution and verify the response of several example systems containing finite lines. The models developed herein show good agreement with experiment. The major anomaly noted was an amplitude dependence in the experimental response for signals larger than one percent of the bulk modulus of the fluid. Since the theory represents a linearized, small perturbation model, such disagreement might have been anticipated and is viewed as a limitation, rather than invalidation, of the model. Finally, quantitative comparisons are made between the proposed model and those in current use.

scholarly journals Simulation and time-frequency analysis of the longitudinal train dynamics coupled with a nonlinear friction draft gear

2020 ◽  
Vol 9 (1) ◽  
pp. 124-144
Author(s):  
Caglar Uyulan ◽  
Ersen Arslan
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Controller Design ◽  
Response Characteristic ◽  
Domain Model ◽  
Step Response ◽  
Time Frequency ◽  
Draft Gear ◽  
Train Dynamics ◽  
The Time Domain

AbstractTrain safety and operational efficiency can be improved by investigating the dynamics of the train under varying conditions. Longitudinal train dynamics (LTD) simulations performed for such purposes, usually by utilising a nonlinear time-domain model. This paper covers two modes of LTD results corresponding to the time domain and frequency domain analysis. Time-domain solutions are essential to evaluate the full response used for parameter optimisation and controller design studies while frequency domain solutions can provide significant but straightforward clues regarding system dynamics. An advanced draft gear model, which works under a four-stage process is constructed considering all structural components, geometric relationships, friction modelling and dynamic characteristics such as hysteresis, stiffening, state transition, locked unloading, softening. Then, this model is parametrically reduced and implemented into an LTD simulation. The simulation in the time domain is conducted assuming a locomotive connected with a nine wagon via “ode3” fixed-step solver. The transfer function among the first wagon acceleration (output) and the locomotive force (input) estimated through system identification methodology. Then, the identification results interpreted by investigating step-response characteristic and best response giving parameter set is selected. Next, the modal and spectral analysis performed to reveal the behaviour of the in-train forces and the effects of vibration. This paper discusses a reliable methodology for the longitudinal dynamic analysis of the multi-bodied train in time and frequency domain and clarifies in-train vibration behaviour under the existence of sophisticated draft gear.

scholarly journals Prediction of deepwater riser VIV with an improved time domain model including non-linear structural behavior

2021 ◽  
Vol 236 ◽  
pp. 109508
Author(s):  
Sang Woo Kim ◽  
Svein Sævik ◽  
Jie Wu ◽  
Bernt Johan Leira
Keyword(s):  
Time Domain ◽  
Domain Model ◽  
Structural Behavior ◽  
Non Linear ◽  
Deepwater Riser
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