Design and control of a real-time variable stiffness vibration isolator

2009 ◽  
Author(s):  
S. Opie ◽  
W. Yim
Keyword(s):  
Real Time ◽  
Variable Stiffness ◽  
Time Variable ◽  
Vibration Isolator ◽  
And Control

Static Force Model-Based Stiffness Model for Pneumatic Muscle Actuators

2015 ◽  
Vol 18 ◽  
pp. 207-214 ◽  
Author(s):  
József Sárosi ◽  
Ján Piteľ ◽  
Jaroslav Šeminský
Keyword(s):  
Variable Stiffness ◽  
Relative Displacement ◽  
Time Variable ◽  
Force Model ◽  
Power Weight ◽  
Static Force ◽  
Pneumatic Muscle ◽  
Stiffness Model ◽  
Muscle Actuators ◽  
And Control

Pneumatic muscle actuators (PMAs) differ from general pneumatic systems as they have no inner moved parts and there is no sliding on the surfaces. During action they reach high velocities, while the power/weight and power/volume rations reach high levels. The main drawbacks of PMAs are limited contraction (relative displacement), nonlinear and time variable behaviour, existence of hysteresis and step-jump pressure (to start radial diaphragm deformation) and also antagonistic connection of PMAs to generate two-direction motion. These make PMAs difficult to modelling and control. In this paper a new stiffness model and the variable-stiffness spring-like characteristics are described and tested using two Fluidic Muscles made by Festo Company. The muscles have the same diameter, but different length.

Design and Control of a Real-Time Variable Modulus Vibration Isolator

2011 ◽  
Vol 22 (2) ◽  
pp. 113-125 ◽  
Author(s):  
S. Opie ◽  
W. Yim
Keyword(s):  
Real Time ◽  
Vibration Absorbers ◽  
Vibration Isolator ◽  
Primary Isolation ◽  
Power Failure ◽  
Variable Modulus ◽  
Isolation Systems ◽  
Fail Safe ◽  
And Control ◽  
Damping Systems

A magnetorheological elastomer (MRE-based semi-active (SA) vibration isolator is developed and tested in real-time with a SA controller, illustrating the feasibility of MRE-based isolators. While several researchers have applied MREs to tunable vibration absorbers (TVAs), little work has been done using MREs in primary isolation systems. Further, in cases where TVAs were developed, few SA controllers were implemented in proof of concept experiments. This article presents a magnetically biased MRE-based vibration isolator, which enables the device to have a fail-safe operation in the event of a power failure. To test the effectiveness of the MRE isolator, a SA controller is developed to minimize the payload velocity. A comparison by simulation of variable modulus and damping systems is also presented. Finally, experimental results are given, showing that the MRE isolator and SA controller system reduce resonances and payload velocities by 16-30% when compared to passive systems.

Microstructural investigation of surface roughness in MBE-grown AlAs

1995 ◽  
Vol 53 ◽  
pp. 454-455
Author(s):  
R. Rajesh ◽  
R. Droopad ◽  
C. H. Kuo ◽  
R. W. Carpenter ◽  
G. N. Maracas
Keyword(s):  
Thin Film ◽  
Real Time ◽  
Growth Control ◽  
Native Oxide ◽  
Effusion Cell ◽  
Surface Oxide Layer ◽  
Microstructural Investigation ◽  
Mbe Growth ◽  
Film Substrate ◽  
And Control

Knowledge of material pseudodielectric functions at MBE growth temperatures is essential for achieving in-situ, real time growth control. This allows us to accurately monitor and control thicknesses of the layers during growth. Undesired effusion cell temperature fluctuations during growth can thus be compensated for in real-time by spectroscopic ellipsometry. The accuracy in determining pseudodielectric functions is increased if one does not require applying a structure model to correct for the presence of an unknown surface layer such as a native oxide. Performing these measurements in an MBE reactor on as-grown material gives us this advantage. Thus, a simple three phase model (vacuum/thin film/substrate) can be used to obtain thin film data without uncertainties arising from a surface oxide layer of unknown composition and temperature dependence.In this study, we obtain the pseudodielectric functions of MBE-grown AlAs from growth temperature (650°C) to room temperature (30°C). The profile of the wavelength-dependent function from the ellipsometry data indicated a rough surface after growth of 0.5 μm of AlAs at a substrate temperature of 600°C, which is typical for MBE-growth of GaAs.

Adaptive Signal Analysis and Interpretation for Real-time Intelligent Patient Monitoring

1994 ◽  
Vol 33 (01) ◽  
pp. 60-63 ◽  
Author(s):  
E. J. Manders ◽  
D. P. Lindstrom ◽  
B. M. Dawant
Keyword(s):  
Computer Architecture ◽  
Real Time ◽  
Data Abstraction ◽  
Monitoring Strategy ◽  
Intelligent Monitoring ◽  
Patient Status ◽  
On Line ◽  
Main Components ◽  
And Control ◽  
Adaptive Signal

Abstract:On-line intelligent monitoring, diagnosis, and control of dynamic systems such as patients in intensive care units necessitates the context-dependent acquisition, processing, analysis, and interpretation of large amounts of possibly noisy and incomplete data. The dynamic nature of the process also requires a continuous evaluation and adaptation of the monitoring strategy to respond to changes both in the monitored patient and in the monitoring equipment. Moreover, real-time constraints may imply data losses, the importance of which has to be minimized. This paper presents a computer architecture designed to accomplish these tasks. Its main components are a model and a data abstraction module. The model provides the system with a monitoring context related to the patient status. The data abstraction module relies on that information to adapt the monitoring strategy and provide the model with the necessary information. This paper focuses on the data abstraction module and its interaction with the model.

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