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Proceedings of the 1999 smart structures and materials - mathematics and control in smart structures

作者： Koko, Tamunoiyala S. Smith, Malcolm J. Orisamolu, Irewole R. Martec Ltd Halifax NS Canada

In this paper, the integrated finite element methodology developed in our earlier work for designing active vibration control strategies in smart structures, is extended to compute the stresses and strains in the structure, due to combined thermal, mechanical and electrical excitations. A layered composite brick elements with linear strain-displacement and linear thermopiezoelectric constitutive relations is used to model the structure. The method, which has been encoded into a software called smartCOM provides a design and analysis capability that simultaneously accounts for the coupled thermopiezoelectric and control capabilities of the smart structural systems. Numerical examples are provided for structures with surface bonded piezoelectric sensors and actuators, under various types of mechanical, thermal and electrical load. Comparisons are made to other available solutions to verify the accuracy of the smartCOM simulations. The method provides accurate results and is seen as a valuable tool for the design and analysis of these smart structures.

关键词： Intelligent structures

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Wavelets transform for boundary control of smart thin - Walled beam cantilever

Wavelets transform for boundary control of smart thin - Wall...

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smart structures and materials 1999 Conference

作者： Poterasu, VF Tech Univ Iasi RO-6600 Iasi Romania

ISBN: (纸本)0819431419

Wavelets provide a new tool in vibration, identification and control. By their properties wavelets transform are stronger than FEM and FFT. We dispose to several wavelets family as Haar, Daubechies, Morlet, Mallat, etc. and use the filter banks for vibration analysis. This paper deals with the problem of controlling the bending oscillations of a thin walled cantilever beam with arbitrary cross section. The control is achieved via the action of a bending moment applied at a tip of structure. A-possibility to generate the control bending moment at the wing tip is via the implementation into the structure of piezoactuators. The velocity feedback control allows the possibility to generate damping through the feedback gain coefficient. Feedback law where the bending moment at a tip is proportional to the velocity is included into matrix wavelet implementation. Numerical examples for PDE are computed and compared with other examples for particular cases included in earlier paper of Librescu, Na. The paper uses the Haar wavelet transform to algebrize PDE leading to a powerful and general method to study the nonlinear problems with more flexibility and localization of peak resonance in comparison with other procedures.

关键词： smart thin walled beam wavelet transform boundary control

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Roll maneuvering of flexible aircraft with distributed-parameter actuation via modal synthesis

Roll maneuvering of flexible aircraft with distributed-param...

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smart structures and materials 1999 Conference

作者： Öz, H Khot, NS Ohio State Univ Columbus OH 43210 USA

ISBN: (纸本)0819431419

The focus is on obtaining and identifying optimal distributed-parameter-control equivalent actuation profiles for desired roll maneuvers by a modal synthesis approach. The solution for distributed-parameter-control of an aeroelastic system is developed by synthesis of modal-state-space controllers designed via the globally power optimal Independent Modal-Space control (IMSC) technique. The desired maneuver(set-point) control performance is achieved by a modal-performance-output synthesis (MPOS) approach. The MPOS approach requires that each independent modal controller be allocated a desired portion of the total desired output performance. In view of this, a modal performance-output allocation optimization problem is also defined, which minimizes a hybrid measure of control power and elastic strain energy of the structure during aeroelastic control. Insight to distributed-parameter-control equivalent actuation solutions are sought by considering the aeroservoelastic interactions among vehicle motion, aerodynamics, structural flexibility and control actuators from the perspective of work-energy, control power, and control loading requirements. The modal synthesis approach is illustrated fora Eight vehicle wing design to achieve a 90 deg/sec roll-rate in a Mach 2 flight condition at altitude (20000 ft) via distributed-parameter equivalent actuation. The preliminary results indicate that such a roll-rate maneuver can be accomplished via distributed-parameter actuation with feasible levels of control power, work-energy, and control loadings through eliciting favorable aeroservoelastic interactions.

关键词： aeroelasticity aeroservoelasticity IMSC modal control distributed-parameter-control control power wing shaping distributed-parameter actuation non-self-adjoint system control

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Non linear motion and force control of shape memory alloys actuators

Non linear motion and force control of shape memory alloys a...

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smart structures and materials 1999 Conference

作者： Benzaoui, H Chaillet, N Lexcellent, C Bourjault, A Lab Automat Besancon LAB UMR CNRS 6596 F-25000 Besancon France

ISBN: (纸本)0819431419

Among the numerous studies published in the field of shape memory alloys (SMA), an important part is devoted to the thermomechanical properties of these materials. Few studies have been done in order to develop control laws of SMA actuators for temperature, position and force control with guaranteed stability and performances. The reason is that these materials have an highly non linear dynamic behavior (including hysteresis) because of the physical principle of motions which is a solid-solid phase transition (between an austenitic and a martensitic phase). It is then difficult to guaranty stable control and to predict the dynamic behavior in closed-loop (trajectory and effort). For this purpose, this paper is focused on control of such actuators. To obtain a control law for the closed-loop motion or force control, we use a non linear dynamic model performed in a previous work. With this dynamic model, we use non linear control techniques based on the Lie algebra to obtain the control laws for the position or the force closed-loop. Experimentation show that the proposed method is very useful for the control of SMA actuators.

关键词： SMA actuators thermomechanical modeling motion control force control

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Shaping of distributed piezoelectric sensors for flexural vibrations of smart beams

Shaping of distributed piezoelectric sensors for flexural vi...

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smart structures and materials 1999 Conference

作者： Irschik, H Krommer, M Pichler, U Johannes Kepler Univ Inst Mech & Mech Engn Div Tech Mech A-4040 Linz Austria

ISBN: (纸本)0819431419

This paper is concerned with flexural vibrations of smart beams. Layers made of piezoelectric material are used to perform a distributed sensing of strains. In the present contribution, special emphasis is given to the sensor shaping problem, which can be stated as follows: Seek a shape function of the distributed sensor such that a mechanical interpretation of the sensor output is possible, e.g. to interpret the output as deflection, or as a slope. The scope of the present contribution is to find a class of easy to obtain analytic solutions of this inverse problem, and to present an experimental verification. Within the context of the Bernoulli-Euler beam theory, sensor equations are derived taking into account the coupling of mechanical and electrical fields. The principle of virtual work is then applied to derive integral equations for the structural deformations e.g. deflection, slope, curvature. Comparing these integral equations, the above sensor shaping problem is solved. Beams with different boundary conditions are considered. Furthermore, shape functions responsible for non-uniqueness of the shaping problem are derived. These nilpotent solutions may be added to the above derived solution of the sensor shaping problem without influencing the measured sensor signal. The analytical results of the sensor shaping problem are realized in a series of experiments for a cantilever beam, without and including a redundant support. Deflections measured by the new type of distributed piezoelectric sensor are compared to laser based distance measurements. Excellent coincidence between these measurements is found.

关键词： flexural vibrations smart beams piezoelectric sensors sensor shaping problem nilpotent solutions

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Development of active 6-DOF microvibration control system using giant magnetostrictive actuator

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Proceedings of SPIE - The International Society for Optical Engineering 1999年 3671卷 229-240页

作者： Nakamura, Yoshiya Nakayama, Masanao Masuda, Keiji Tanaka, Kiyoshi Yasuda, Masashi Fujita, Takafumi Fujita Corp Yokohama Japan

An active 6-DOF microvibration control system using giant magnetostrictive actuators is developed in order to realize microvibration-free space for precision instruments which hate vibration. A giant magnetostrictive actuator is suitable as a displacement actuator for active microvibration control, because it is both compact and durable and also its response against input is fast and reliable. The developed device consists of a table, six air springs, eight magnetostrictive actuators and six accelerometers on the table. Four actuators are set in the horizontal directions, and another four in the vertical direction. Since air springs and actuators as a unit of vertical support system are arranged in parallel, readjustment of the system is quite easy, even when operating load on the table is changed. The dimension of table is 2000 mm in length and 1400 mm in width and 230 mm in height and the weight of about 2 tons. Operating load on the table is 2 tons. A giant magnetostrictive rod is 6 mm in diameter and 50 mm in length. The actuators operate within the stroke range of ±25 μm. Feedback control strategy using only six components of table acceleration on the table is adopted and the controller is designed by a model matching method. The obtained control performance of the system through two vibration control tests can be summarized as follows: (1) Root-mean-square values of the table accelerations under micro-tremor are reduced to 1/3 to 1/10 of the floor accelerations, and kept less than 0.008 cm/s2. (2) Induced vibrations by impacts acting on the table disappear in less than 0.05 sec.

关键词： Vibration control

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Peak to peak control of an adaptive tensegrity space telescope

Peak to peak control of an adaptive tensegrity space telesco...

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smart structures and materials 1999 Conference

作者： Sultan, C Corless, M Skelton, RE Purdue Univ Sch Aeronaut & Astronaut W Lafayette IN 47907 USA

ISBN: (纸本)0819431419

This paper proposes a new space telescope design in which the classical truss structure of the telescope is replaced by a tensegrity structure. A tensegrity structure is a prestressed structure whose structural shape is guaranteed by the interaction between elastic members in tension (tendons) and a set of rigid members (bars). A nonlinear dynamical model of a two stage tensegrity telescope is derived. Static analysis is performed for tensegrity telescopes composed of two stages. The performance specifications for the control system are formulated in terms of the peak lvalue (L-infinity norm) of the pointing and alignment errors. The control system is designed to minimize a certain upper bound on this peak value subject to a peak value constraint on the external disturbances. Evaluations of the design are performed through numerical simulations of the closed loop system.

关键词： Mirrors Space telescopes Telescopes control systems control systems design Optical instrument design Space mirrors Adaptive control Device simulation Mathematical modeling

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Thermoelectric control of Shape Memory Alloy microactuators: a thermal model

Thermoelectric control of Shape Memory Alloy microactuators:...

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smart structures and materials 1999 Conference

作者： Abadie, J Chaillet, N Lexcellent, C Bourjault, A Lab Automat Besancon LAB UMR 6596 F-25000 Besancon France

ISBN: (纸本)0819431419

Microtechnologies and microsystems engineering use new active materials. These materials are interesting to realize microactuators and microsensors. In this category of materials, Shape Memory Alloys (SMA) are good candidates for microactuation. SMA wires, or thin plates, can be used as active material in microfingers. These microstructures are able to provide very important forces, but have low dynamic response, especially for cooling, in confined environment. The control of the SMA phase transformations, and then the mechanical power generation, is made by the temperature. The Joule effect is an easy and efficiency way to heat the SMA wires, but cooling is not so easy. The dynamic response of the actuator depends on cooling capabilities. The thermal convection and conduction are the traditional ways to cool the SMA, but have limitations for microsystems. We are looking for a reversible way of heating and cooling SMA microactuators, based on the thermoelectric effects. Using Peltier effect, a positive or a negative electrical courant is able to pump or produce heat, in the SMA actuator. A physical model based on thermal exchanges between a Nickel/Titanium (NiTi) SMA, and Bismuth/Telluride (Te3Bi2) thermoelectric material has been developed. For simulation, we use a numerical resolution of our model,with finite elements, which takes into account the Peltier effect, the Joule effect, the convection, the conduction and the phase transformation of the SMA. We have also developed the corresponding experimental system, with two thermoelectric junctions, where the SMA actuator is one of the element of each junction. in this paper, the physical model and its numerical resolution are given, the experimental system used to validate the model is described, and experimental results are shown.

关键词： thermoelectricity Peltier effect SMA microactuators

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Numerical model for the optimal design of composite laminated structures with piezoelectric laminae

Numerical model for the optimal design of composite laminate...

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Proceedings of the 1999 smart structures and materials - mathematics and control in smart structures

作者： Correia, Victor M.Franco Soares, Cristovao M.Mota Soares, Carlos A.Mota Escola Nautica Infante D. Henrique Paco de Arcos Portugal

In this work, refined finite element models based on higher order displacement fields have been developed to study the mechanical and electrical behavior of laminated composite plate structures with embedded and/or surface bonded piezoelectric actuators and sensors. Sensitivity analysis and optimization techniques are also applied in order to maximize the piezoelectric actuator efficiency, improve the structural performance and/or minimize the weight of the structure. To show the performance of the proposed models several illustrative and simple examples are presented.

关键词： Plates (structural components)

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Development of active 6-DOF microvibration control system using giant magnetostrictive actuator

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Conference on smart Systems for Bridges, structures, and Highways at smart structures and materials 1999

作者： Nakamura, Y Nakayama, M Masuda, K Tanaka, K Yasuda, M Fujita, T Fujita Corp Tech Res Inst Tsuzuki Ku Yokohama Kanagawa Japan

ISBN: (纸本)0819431451

An active 6-DOF microvibration control system using giant magnetostrictive actuators is developed in order to realize microvibration-free space for precision instruments which hate vibration. A giant magnetostrictive actuator is suitable as a displacement actuator for active microvibration control, because it is both compact and durable and also its response against input is fast and reliable. The developed device consists of a table, six air springs, eight magnetostrictive actuators and six accelerometers on the table. Four actuators are set in the horizontal directions, and another four in the vertical direction. Since air springs and actuators as a unit of vertical support system are arranged in parallel, readjustment of the system is quite easy, even when operating load on the table is changed. The dimension of table is 2000mm in length and 1400mm in width and 230mm in height and the weight of about 2tons. Operating load on the table is 2tons. A giant magnetostrictive rod is 6mm in diameter and 50mm in length. The actuators operate within the stroke range of +/-25 mu m. Feedback control strategy using only six components of table acceleration on the table is adopted and the controller is designed by a model matching method. The obtained control performance of the system through two vibration control tests can be summarized as follows: (1) Root-mean-square values of the table accelerations under micro-tremor are reduced to 1/3 to 1/10 of the floor accelerations, and kept less than 0.008cm/s(2). (2) Induced vibrations by impacts acting on the table disappear in less than 0.05sec.

关键词： active microvibration control giant magnetostrictive actuator 6-DOF system

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