Smart Technologies

Worden, Keith; Bullough, W. A.; Haywood, Jonathan

doi:10.1142/4832

Cited by 69 publications

(47 citation statements)

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“…Nowadays many researchers focus their work on applying NiTi to actuator applications, but a e-mail: Czechowicz@lps.rub.de fundamental problems for their commercial use still remain. This includes control paradigms and functional fatigue effects [1]. Hence the present work deals with concepts, resolving these problems by integration of an appropriate calculation into a numerical simulation of the activation behavior of SMA wire actuators.…”

Section: Shape Memory Actuators and Their Importance For Mechatronicamentioning

confidence: 99%

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Control loops with detection of inner electrical resistance and fatigue-behaviour by activation of NiTi -Shape Memory Alloys

Meier

Czechowicz

Haberland

2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract. Shape memory alloys are smart materials. Due to their ability to change into a previously imprinted actual shape through the means of thermal activation, they are suitable as actuators for microsystems and, within certain limitations, macroscopic systems. To apply these smart materials to a wide range of industrial applications, a simple method of controlling the actuator effect is required. The detection of inner electrical resistance allows to gauge the actuator movement. By usage of a microcontroller a smart system without any hardware sensors can be realized. Changing outer boundary conditions can be compensated by software. Furthermore an analysis and a description of the functional fatigue, affecting the control loop, is of particular importance. A fatigue calculator dependent upon duty cycle is subjoined to the existing actuator simulation implemented in MATLAB/ SIMULINK. The focus of the simulation-model is on the activation behaviour of the SMA actuator, which defines its rate of heating and cooling. These parameters describe the dynamical characteristics of the actuator and the complete SMA powered system. Different load conditions, various actuator geometries and shapes, e.g. wire or spring actuator are simulated by the calculation of the energetic balance of the whole system. The numerical model can be used to simulate time variant heating currents in order to achieve an optimal system performance for a defined time response of the actuator. Shape memory actuators and their importance for mechatronical systemsShape memory alloys (SMAs) exhibit the remarkable property to recover a previously imprinted shape after a deformation. That effect can occur either at constant temperatures (mechanical memory, pseudoelasticity), or changing temperatures (thermal memory). Both effects rely on the martensitic phase transformation [1]. (martensite) into B2 (austenite) initiates by exceeding the austenite start temperature. This is linked to a shape change. During subsequent cooling the reconversion of the material is provoked by the . This work focuses on the one way effect in combination with restoring force devices, the so called extrinsic two way effect [2]. Most commonly used shape memory materials are binary nickel titanium alloys (NiTi), consisting nearly of a 50 % ratio of both elements. The ratio is the crucial factor for setting up transformation temperatures. Shape memory alloys have certain characteristics which are unique in comparison to other actuating principles.competitiveness of micro-and mechatronical systems is determined by precision, cost, quality and simplifications. Systems driven by shape memory elements can be used for smart actuators, which include aspects of flexibility and mass decimation in addition to the above-qouted. The aspect of simplification is related to memory actuator generally consists of fewer parts than conventional ones. The reduction of parts often enhances the reliability of actuating components. Besides the mass of shape memory systems, as compared to other a...

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Section: Shape Memory Actuators and Their Importance For Mechatronicamentioning

confidence: 99%

“…That effect can occur either at constant temperatures (mechanical memory, pseudoelasticity), or changing temperatures (thermal memory). Both effects rely on the martensitic phase transformation [1]. (martensite) into B2 (austenite) initiates by exceeding the austenite start temperature.…”

mentioning

confidence: 99%

Control loops with detection of inner electrical resistance and fatigue-behaviour by activation of NiTi -Shape Memory Alloys

Meier

Czechowicz

Haberland

2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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“…Usually in aerospace, robotics and automotive structures, this vibration is not wanted and can lead to catastrophic failure [1]. Space robots are usually made of lightweight materials to help them launch.…”

Section: Introductionmentioning

confidence: 99%

“…They usually have very low damping ratios, high dimensional order and parameter uncertainties in dynamics, thus, the unwanted vibrations of the flexible links will be unavoidable [2]. Thus, it is necessary to control lightweight flexible structures, which implies that structural flexibility can no longer be ignored [1,2]. The issue of active vibration control is an important concern.…”

Section: Introductionmentioning

confidence: 99%

“…There are numerous control techniques, both classical and modern, which can cope with the vibration suppression of flexible structures with piezoelectric ceramics (PZT) patches as distributed sensors and actuators [1][2][3][4][5][6][7][8][9][10][11][12]. These techniques are involved in the application of smart materials, featuring piezoelectric actuators and sensors, to the flexible structure to suppress unwanted vibration.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Comparison Research on Active Vibration Control for Flexible Piezoelectric Manipulator Using Fuzzy Controller

Wei

Qiu

Han

et al. 2009

J Intell Robot Syst

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Space manipulators are flexible structures. Vibration problem will be unavoidable due to motion or external disturbance excitation. Model based control methods will not maintain the required accuracy because of the existence of nonlinear factors and parameter uncertainties. To solve these problems, fuzzy logic control laws with different membership function groups are adopted to suppress vibrations of a flexible smart manipulator using collocated piezoelectric sensor/actuator pair. Also, dual-mode controllers combining fuzzy logic and proportional integral control are designed, for suppressing the lower amplitude vibration near the equilibrium point significantly. Experimental comparison research is conducted, using fuzzy control algorithms and the dual-mode controllers with different membership functions. The experimental results show that the adopted fuzzy control algorithms can substantially suppress the larger amplitude vibration; and the dual-mode controllers can also damp out the lower amplitude vibration significantly. The experimental results demonstrate that the proposed fuzzy controllers and dual-mode controllers can suppress vibration effectively, and the optimal placement is feasible.

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Shape‐Memory Alloys

2007

Van Nostrand's Scientific Encyclopedia

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Smart Technologies

Cited by 69 publications

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Control loops with detection of inner electrical resistance and fatigue-behaviour by activation of NiTi -Shape Memory Alloys

Control loops with detection of inner electrical resistance and fatigue-behaviour by activation of NiTi -Shape Memory Alloys

Experimental Comparison Research on Active Vibration Control for Flexible Piezoelectric Manipulator Using Fuzzy Controller

Shape‐Memory Alloys

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