A remote control and media-sharing system using smart devices

The remote control and media sharing of electronic devices are key services in smart homes. The incorporation of mobile smart devices in these services has become a popular trend. Existing services require that these devices are located in the same local network. This paper presents the design and implementation of an integrated service architecture that supports the remote control of home appliances and the sharing of digital media between indoor and outdoor devices. The proposed design follows standards related to digital homes, and this study presents the details of its hardware and software components.     

Active vibration control of smart piezoelectric beams: Comparison of classical and optimal feedback control strategies

This paper presents a numerical study concerning the active vibration control of smart piezoelectric beams. A comparison between the classical control strategies, constant gain and amplitude velocity feedback, and optimal control strategies, linear quadratic regulator (LQR) and linear quadratic Gaussian (LQG) controller, is performed in order to investigate their effectiveness to suppress vibrations in beams with piezoelectric patches acting as sensors or actuators. A one-dimensional finite element of a three-layered smart beam with two piezoelectric surface layers and metallic core is utilized. A partial layerwise theory, with three discrete layers, and a fully coupled electro-mechanical theory is considered. The finite element model equations of motion and electric charge equilibrium are presented and recast into a state variable representation in terms of the physical modes of the beam. The analyzed case studies concern the vibration reduction of a cantilever aluminum beam with a collocated asymmetric piezoelectric sensor/actuator pair bonded on the surface. The transverse displacement time history, for an initial displacement field and white noise force disturbance, and point receptance at the free end are evaluated with the open- and closed-loop classical and optimal control systems. The case studies allow the comparison of their performances demonstrating some of their advantages and disadvantages.     

On the optimal design of elastic beams

In this paper we investigate the optimal dynamics of simply supported nonlinearly elastic beams with rectangular cross-sections. We consider the elastic beam under the assumption of time-dependent intensive transverse loading. The state of the beam is described by a system of partial differential equations of the fourth order. We deal with the problem of choosing the optimal shape for the beam. The optimal shape is determined in such a way that the deflection of the nonlinearly elastic beam for any given time is minimal. The problem of choosing the optimal shape is formulated as an optimal control problem. To solve the obtained problem effectively, we use the optimality principle of Bellman (Bellman and Dreyfus 1962; Bryson and Ho 1975) and the penalty function method (Polyak 1987). We present a constructive algorithm for the optimal design of nonlinearly elastic beams. Some simple examples of the implementation of the proposed numerical algorithm are given.     

Numerical simulations of cantilever beam response with saturation control and full modal coupling

Numerical simulations of the response of a uniform, cantilever beam subjected to a base excitation are performed. A saturation absorber is implemented to control the beam response. In previous investigations of similar configurations, the inertial and structural properties of the piezoelectric actuators have been neglected, resulting in an analytical model of a uniform beam. This investigation includes the nonuniformities in the beam properties that are introduced when piezoelectric actuators are bonded to the uniform beam. The resulting coupling between uniform, cantilever beam modes is fully included in the analytical model. It is shown that this modal coupling has a significant effect on the beam response, which is not present when modal coupling is neglected.     

An optimal control approach to robust tracking of linear systems

In our early work, we show that one way to solve a robust control problem of an uncertain system is to translate the robust control problem into an optimal control problem. If the system is linear, then the optimal control problem becomes a linear quadratic regulator (LQR) problem, which can be solved by solving an algebraic Riccati equation. In this article, we extend the optimal control approach to robust tracking of linear systems. We assume that the control objective is not simply to drive the state to zero but rather to track a non-zero reference signal. We assume that the reference signal to be tracked is a polynomial function of time. We first investigated the tracking problem under the conditions that all state variables are available for feedback and show that the robust tracking problem can be solved by solving an algebraic Riccati equation. Because the state feedback is not always available in practice, we also investigated the output feedback. We show that if we place the poles of the observer sufficiently left of the imaginary axis, the robust tracking problem can be solved. As in the case of the state feedback, the observer and feedback can be obtained by solving two algebraic Riccati equations.     

Structural protection using MR dampers with clipped robust reliability-based control

Magnetorheological (MR) damper is one of the most promising semi-active control devices for mitigating seismic response, and so, it has received significant attention in recent years. Because of the inherent nonlinear nature of MR damper devices, one challenge to effectively utilize this technology is the development of an appropriate control algorithm. A semi-active control methodology is presented to control structural systems using MR dampers that addresses structural modeling uncertainties. Based on the same idea as the clipped-optimal linear controller, the proposed semi-active control law uses a robust reliability-based active linear control methodology to calculate the reference control forces that the MR dampers attempt to produce approximately. These reference control forces can be calculated using incomplete response measurements at the current and/or previous time steps without any state estimation. The main purpose of the proposed approach is to achieve a more robust performance for uncertain structural systems subjected to uncertain strong-motion excitation. The performance of the proposed approach is demonstrated through a simulated example of a ten-story building with MR dampers installed. Y. Shi formerly from the Department of Civil and Environmental Engineering, University of Macau, Macau SAR, China.     

压电智能夹层及其特性分析

压电智能夹层可以有效地解决压电自诊断系统中直接使用压电片引起的弊端.通过适当改进当前的柔性印刷线路工艺制作出的压电智能夹层,不仅具有柔性印刷线路的特点,而且,应用在结构健康监测系统中还有其他一些独特的优越性能.并利用压电智能夹层进行了初步的拉伸载荷识别,同压电片相比,识别效果更明显.     

Design of noise and period-time robust high-order repetitive control, with application to optical storage

Repetitive control is useful if periodic disturbances or setpoints act on a control system. Perfect (asymptotic) disturbance rejection is achieved if the period time is exactly known. The improved disturbance rejection at the periodic frequency and its harmonics is achieved at the expense of a degraded system sensitivity at intermediate frequencies. A convex optimization problem is defined for the design of high-order repetitive controllers, where a trade-off can be made between robustness for changes in the period time and for reduction of the error spectrum in-between the harmonic frequencies. The high-order repetitive control algorithms are successfully applied in experiments with the tracking control of a CD-player system.     

国产新型智能阀门定位器的设计

智能型阀门定位器已经成为现代过程控制系统的关键设备之一。为了进一步提高定位器的控制性能,研制了一款新型全电子式智能阀门定位器,介绍了该款定位器的主要组成部分和关键核心技术。此定位器采用比例式压电阀作为气动放大与驱动部件,利用自适应等多种智能控制技术,提高了智能阀门定位器的定位精度和抗干扰性能。该定位器具有功耗低、集成度高和运行可靠性好等优点,推动了国产电子式智能阀门定位器产业的发展。     

Exact solutions for dynamic analysis of composite plates with distributed piezoelectric layers

Exact solutions are presented for analyzing dynamics of composite plates with piezoelectric layers bonded at the top and the bottom surfaces. The expressions for mechanical displacements, stresses, electric displacements and potential are derived from constitutive relations and field equations for the piezoelectric medium under applied surface traction and electric potential. The procedure is illustrated with a simply supported symmetric cross-ply (0°/90°/0°) graphite–epoxy composite plate covered with piezoelectric material polyvinylidene fluoride (PVDF). Results are in good agreement with those obtained from finite element model.     

Modelling of uncertain systems with application to robust process control

A method for black-box identification of uncertain systems is presented. The method identifies a nominal model and an uncertainty model set, consisting of unfalsified uncertainty models. Minimisation of a Chebyshev criterion leads to computationally favourable linear programming problems and allows the possibility to include a priori information in the form of linear constraints without making the computations more complex. Using data compression via correlation computations solves the computation problem associated with identifying unfalsified uncertainty models. The application of set-valued uncertainty models to robust process control is illustrated in a simulation study of robust model predictive control of a distillation column.     

Constrained optimal control: an application to semiactive suspension systems

This article applies three different control techniques to the design of a quarter-car semiactive suspension system. The three techniques, originally developed to solve a constrained optimal control problem, are optimal gain switching, discontinuous variable structure control and explicit model predictive control. All of them divide the state space into convex regions and assign a linear or affine state feedback controller to each region. The partition of the state space is computed off-line. During the on-line phase, the controller switches between the subcontrollers according to the current state. All the above techniques gave satisfactory results when applied to the design of semiactive suspension systems. A detailed comparison in terms of computational complexity, performance and simplicity of the design is proposed in the article.     

Stabilization and shape control of a 1D piezoelectric Timoshenko beam

In this paper we show how to perform stabilization and shape control for a finite dimensional model that recasts the dynamics of an inflatable space reflector in port-Hamiltonian (pH) form. We show how to derive a decentralized passivity-based controller which can be used to stabilize a 1D piezoelectric Timoshenko beam around a desired shape. Furthermore, we present simulation results obtained for the proposed decentralized control approach.     

Open-loop and closed-loop robust optimal control of batch processes using distributional and worst-case analysis

The recognition that optimal control trajectories for batch processes can be highly sensitive to model uncertainties has motivated the development of methods for explicitly addressing robustness during batch processes. This study explores the incorporation of robust performance analysis into open-loop and closed-loop optimal control design. Several types of robust performance objectives are investigated that incorporate worst-case or distributional robustness metrics for improving the robustness of batch control laws, where the distributional approach computes the distribution of the performance index caused by parameter uncertainty. The techniques are demonstrated on a batch crystallization process. A comprehensive comparison of the robust performance of the open-loop and closed-loop system is provided.     

Distributed machining control and monitoring using smart sensors/actuators

The study of smart sensors and actuators led, during the past few years, to the development of facilities which improve traditional sensors and actuators in a necessary way to automate production systems. In another context, many studies have been carried out aimed at defining a decisional structure for production activity control and the increasing need of reactivity leads to the autonomization of decisional levels close to the operational system. We study in this paper the natural convergence between these two approaches and we propose an integration architecture, dealing with machine tool and machining control, that enables the exploitation of distributed smart sensors and actuators in the decisional system.     

Optimal placement of active bars in active vibration control for piezoelectric intelligent truss structures with random parameters

Considering the randomness of physical parameters of structural material, geometric dimensions of active bars and passive bars, applied loads and control forces simultaneously, the optimization of active bar’s placement and feedback gains for the vibration control of intelligent truss structures are studied in this paper. Firstly, the performance function is developed based on the maximization of dissipation energy due to control action. Then, the optimal mathematical model with the reliability constraints on dynamic stress and displacement response is built. The numerical feature of dynamic response based on probability of intelligent structure is developed. Finally, a planar intelligent truss structure is used as an example to demonstrate the rationality and validity of the presented model and approach in structural active vibration control.     

Determination of optimal actuator forces and positions in smart structures using adjoint method

The problem of optimal design of structures with active support is analyzed in the paper. The sensitivity expressions with respect to the generalized force and the position of actuator are derived by the adjoint structure approach. Next, the optimality conditions are formulated by means of an introduced Lagrangian function. The problem of introduction of a new actuator is also considered and the condition of modification is expressed by means of the topological derivative. The obtained sensitivity formula, optimality conditions and modification conditions are applied in the optimization algorithm with respect to the number, positions and generalized forces of the actuators. Numerical examples of optimal control of beams illustrate the procedure proposed in the paper.     

Active control of beam with magnetostrictive layer

The paper analyses the damping characteristics obtained using a distributed magnetostrictive layer bonded to an aluminum beam for different boundary conditions and coil configurations. The magnetostrictive layer produces the actuating force required to control the vibration in the beam, based on a negative velocity feedback control law. The control input is the current to the solenoid surrounding the beam. Prior formulations in the literature have assumed that the current through the coil is a function of axial distance. Even though this assumption is mathematically valid, a physical consideration of the problem limits such an assumption. In the present study, perhaps for the first time, a finite element formulation, physically consistent with the problem has been developed. Vibration reduction in the beam, by positioning the magnetostrictive layer and its current carrying actuating coil pair along the beam is investigated. Issues associated with control for different boundary condition are highlighted.     

基于Smart Client的电气操作票系统的设计与实现

随着信息产业的快速发展,传统的C/S或B/S模型的电气操作票系统不能满足实际应用的需求,利用新技术对原系统进行改进成为亟需解决的问题.讨论了目前比较先进的Smart Client技术,并利用该技术对原有的电气操作票系统进行设计与改进,介绍了系统的结构、关键技术和功能的实现.该系统已经成功的应用于全国很多电厂,并取得了很好的效果.