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Mechanical Systems (mechanical + system)
Selected AbstractsA subspace approach to balanced truncation for model reduction of nonlinear control systemsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 6 2002Sanjay Lall Abstract In this paper, we introduce a new method of model reduction for nonlinear control systems. Our approach is to construct an approximately balanced realization. The method requires only standard matrix computations, and we show that when it is applied to linear systems it results in the usual balanced truncation. For nonlinear systems, the method makes use of data from either simulation or experiment to identify the dynamics relevant to the input,output map of the system. An important feature of this approach is that the resulting reduced-order model is nonlinear, and has inputs and outputs suitable for control. We perform an example reduction for a nonlinear mechanical system. Copyright © 2002 John Wiley & Sons, Ltd. [source] 16×16 Mirror type optical switch with integrated fiber alignment and steady switching stateMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2008Qinghua H. Chen Abstract This paper reports a micro electro mechanical system (MEMS) 16×16 free space optical switch based on high-reflectivity mirrors. The mirror monolithically integrated with the fiber grooves can enlarge its rotation angles up to 90°, and keep this as a steady state to steer the optical signal. The reflectivity of the mirror is measured to be 93.1 , 96.3%. The smallest fiber-mirror-fiber insertion loss is 2.1 dB by utilizing optiFocusTM collimating lensed fibers. Moreover, only about ±0.01 dB oscillating amplitude of insertion loss is provoked after the device is tested for 15 min for 5 , 90 Hz in the vertical vibration amplitude of 3 mm. In addition, excellent antifatigue performance of the mirror, which can endure more than 109 cycles of actuation, has been proven. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3012,3016, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23879 [source] Frequency characteristics of flexibly vibration discrete-continuous mechatronic systemPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008A. BuchaczArticle first published online: 26 FEB 200 The purpose of this paper is formulating of problem of flexibly vibrating mechatronic system. The main approach of the subject was to formulate the problem in the form of set of differential equation of motion and state equation of considered mechatronic model of object. The considered flexibly vibrating mechanical system is a continuous beam, clamped at one of its end. Integral part of mechatronic system is a transducer, extorted by harmonic voltage. In the paper the linear mechanical subsystem and linear electric subsystem of mechatronic system has been considered. The methods of analysis and obtained results can be base on design and investigation for this type of mechatronic systems. The mechatronic system formed from mechanical and electric subsystems with electromechanical bondage has been considered. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Torsional Vibration Damping Through Frictional Torsion Damper with Structural Friction and Slide Taken into ConsiderationPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Zbigniew Skup Ph. DSC The paper is concerned with a non-linear discrete stationary mechanical system containing a frictional torsion damper. Proper effect of vibration damping in a two-degree-of freedom system can be reached by the right selection of geometrical parameters for given loads, as pre-determined by a mathematical model. Structural friction was considered, as well as small relative sliding of damper's discs cooperating with a plunger. The system vibrates under harmonic excitation. The problem was considered on the assumption of uniform unit pressure distribution between the contacting surfaces of friction discs and the plunger. When the discs are sliding, the friction coefficient varies, depending on relative angular velocity. Friction characteristics were assumed on the basis of the author's own research and experimental testing by other authors. Properties of the material were assumed to be in accordance with classical theory of elasticity. The author analysed the influence of parameters of the dynamic system upon amplitude and frequency characteristics as well as on phase and frequency characteristics. The equation of motion was solved by means of the slowly-varying-parameters method and, in order to compare the results, by means of numerical simulation. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fuzzy approach to dependability performance evaluationQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 7 2008Dejan Ivezi Abstract This paper presents a model for dependability performance evaluation by fuzzy sets utilization. Basic dependability indicators (reliability, maintainability and maintenance support) are used for the analysis of technical systems' conditions from the aspects of design, construction, maintenance and logistics. These indicators as well as associated dependability expressions itself are described by linguistic variables, which are characterized by a membership function to the defined classes. The proposed model is primarily appropriate for introduction, analysis and synthesis of information related to quality of systems in operation. Such data are often available only as experts' judgment and estimations. A practical engineering example (mechanical system at bucket wheel excavator) has been presented to demonstrate the proposed dependability analysis and synthesis model. Copyright © 2008 John Wiley & Sons, Ltd. [source] The mathematical pendulum from Gauß via Jacobi to RiemannANNALEN DER PHYSIK, Issue 6 2009W. Dittrich Abstract The goal of this article is to introduce double-periodic elliptic functions on the basis of a "simple" mechanical system, that of the mathematical pendulum. Thereby it is not geometry that is in the foreground, as in Gauß's analysis of the lemniscatian curve, but rather the calculation of the specific attributes of elliptic functions with the aid of a periodic integrable system. Not the spatial degree of freedom, but the time variable is continued into the complex plane. This will make it possible for us to not only identify the known real period of the pendulum oscillation, but also to detect a second imaginary period. Only then does the solution of the equation of motion become a Jacobi-type elliptic function. Using the Cauchy integral theorem, which Gauß was already familiar with, as well as the simplest Riemannian surface of the function , we want to calculate the analytic and topological characteristics of the oscillatory motion of a pendulum. Our intent is to show that elliptic functions could have appeared much earlier than 1796 in the literature. Admittedly, for this the field of complex numbers was necessary, as represented in the Gaußian plane of complex numbers. However, Gauß was unwilling to publish his findings because of his "fear of the cry of the Boeotians". [source] Strategies for the numerical integration of DAE systems in multibody dynamicsCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 2 2004E. Pennestrì Abstract The number of multibody dynamics courses offered in the university is increasing. Often the instructor has the necessity to go through the steps of an algorithm by working out a simple example. This gives the student a better understand of the basic theory. This paper provides a tutorial on the numerical integration of differential-algebraic equations (DAE) arising from the dynamic modeling of multibody mechanical systems. In particular, some algorithms based on the orthogonalization of the Jacobian matrix are herein discussed. All the computational steps involved are explained in detail and by working out a simple example. It is also reported a brief description and an application of the multibody code NumDyn3D which uses the Singular Value Decomposition (SVD) approach. © 2004 Wiley Periodicals, Inc. Comput Appl Eng Educ 12: 106,116, 2004; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20005 [source] Wavelet Transforms for System Identification in Civil EngineeringCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2003T. Kijewski Although challenges did not surface in prior applications concerned with mechanical systems, which are characterized by higher frequency and broader-band signals, the transition to the time-frequency domain for the analysis of civil engineering structures highlighted the need to understand more fully various processing concerns, particularly for the popular Morlet wavelet. In particular, as these systems may possess longer period motions and thus require finer frequency resolutions, the particular impacts of end effects become increasingly apparent. This study discusses these considerations in the context of the wavelet's multi-resolution character and includes guidelines for selection of wavelet central frequencies, highlights their role in complete modal separation, and quantifies their contributions to end-effect errors, which may be minimized through a simple padding scheme. [source] Reliability Aspects of Microsystems for Automotive Applications,ADVANCED ENGINEERING MATERIALS, Issue 4 2009Roland Müller-Fiedler Abstract The implementation of microsystems in automotive applications is certainly one of the driving forces for the success of MEMS as an industrial technology on mass production level. In many cases, automotive systems based on microsensors are critical to safety. Consequently, microsystems have to assure an accurate, reliable, and failsafe operation during the entire lifetime of the vehicle. Since, the car represents a harsh environment for electronic or mechanical systems and components, reliability issues of MEMS have moved more and more into the focus of research and development. In particular, reliability aspects related to packaging and assembly have become a key issue in lifetime investigations. The packaging of microsystems comprises a variety of materials and material combinations, that directly affect the stability of MEMS components. Therefore, sophisticated characterization methods are needed to extract the reliability-relevant material parameters. This paper gives an introduction into investigations of the stability assessment of glass frit bonding as well as new bonding technologies based on metallic sealing of MEMS devices. [source] Kinematic and dynamic analysis of open-loop mechanical systems using non-linear recursive formulationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 12 2006Yunn-Lin Hwang Abstract In this paper, a non-linear recursive formulation is developed for kinematic and dynamic analysis of open-loop mechanical systems. The non-linear equations of motion are developed for deformable links that undergo large translational and rotational displacements. These equations are formulated in terms of a set of time invariant scalars and matrices that depend on the spatial co-ordinates as well as the assumed displacement field, and these time invariant quantities represent the dynamic coupling between the rigid-body modes and elastic deformations. A new recursive formulation is presented for solving equations of motion for open-loop chains consisting of interconnected rigid and deformable open-loop mechanical systems. This formulation is expressed by the recursive relationships and the generalized non-linear equations for deformable mechanical systems to obtain a large system of loosely coupled equations of motion. The main processor program consists of three main modules: constraint module, mass module and force module. The constraint module is used to numerically evaluate the relationship between the absolute and joint accelerations. The mass module is used to numerically evaluate the system mass matrix as well as the non-linear Coriolis and centrifugal forces associated with the absolute, joint and elastic co-ordinates. Simultaneously, the force module is used to numerically evaluate the generalized external and elastic forces associated with the absolute, joint and elastic co-ordinates. Computational efficiency is achieved by taking advantage of the structure of the resulting system of loosely coupled equations. The solution techniques used in this investigation yield a much smaller operations count and can more efficiently implement in any computer. The algorithms and solutions presented in this paper are illustrated by using an industrial robotic manipulator system. The numerical results using this formulation are also presented and discussed in this paper. Copyright © 2006 John Wiley & Sons, Ltd. [source] A generalized dimension-reduction method for multidimensional integration in stochastic mechanicsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2004H. Xu Abstract A new, generalized, multivariate dimension-reduction method is presented for calculating statistical moments of the response of mechanical systems subject to uncertainties in loads, material properties, and geometry. The method involves an additive decomposition of an N -dimensional response function into at most S -dimensional functions, where S,N; an approximation of response moments by moments of input random variables; and a moment-based quadrature rule for numerical integration. A new theorem is presented, which provides a convenient means to represent the Taylor series up to a specific dimension without involving any partial derivatives. A complete proof of the theorem is given using two lemmas, also proved in this paper. The proposed method requires neither the calculation of partial derivatives of response, as in commonly used Taylor expansion/perturbation methods, nor the inversion of random matrices, as in the Neumann expansion method. Eight numerical examples involving elementary mathematical functions and solid-mechanics problems illustrate the proposed method. Results indicate that the multivariate dimension-reduction method generates convergent solutions and provides more accurate estimates of statistical moments or multidimensional integration than existing methods, such as first- and second-order Taylor expansion methods, statistically equivalent solutions, quasi-Monte Carlo simulation, and the fully symmetric interpolatory rule. While the accuracy of the dimension-reduction method is comparable to that of the fourth-order Neumann expansion method, a comparison of CPU time suggests that the former is computationally far more efficient than the latter. Copyright © 2004 John Wiley & Sons, Ltd. [source] Adaptive motion/force tracking control of holonomic constrained mechanical systems: a unified viewpointINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 5 2007Chian-Song Chiu Abstract This paper proposes a robust adaptive motion/force tracking controller for holonomic constrained mechanical systems with parametric uncertainties and disturbances. First, two types of well-known holonomic systems are reformulated as a unified control model. Based on the unified control model, an adaptive scheme is then developed in the presence of pure parametric uncertainty. The proposed controller guarantees asymptotic motion and force tracking without the need of extra conditions. Next, when considering external disturbances, control gains are designed by solving a linear matrix inequality (LMI) problem to achieve prescribed robust performance criterion. Indeed, arbitrary disturbance/parametric error attenuation with respect to both motion and force errors along with control input penalty are ensured in the L2 -gain sense. Finally, applications are carried out on a two-link constrained robot and two planar robots transporting a common object. Numerical simulation results show the expected performances. Copyright © 2006 John Wiley & Sons, Ltd. [source] Application of Filippov method for the analysis of subharmonic instability in dc,dc convertersINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 8 2009Damian Giaouris Abstract We propose a method of estimating the fast-scale stability margin of dc,dc converters based on Filippov's theory,originally developed for mechanical systems with impacts and stick-slip motion. In this method one calculates the state transition matrix over a complete clock cycle, and the eigenvalues of this matrix indicate the stability margin. Important components of this matrix are the state transition matrices across the switching events, called saltation matrices. We applied this method to estimate the stability margins of a few commonly used converter and control schemes. Finally, we show that the form of the saltation matrix suggests new control strategies to increase the stability margin, which we experimentally demonstrate using a voltage-mode-controlled buck converter. Copyright © 2008 John Wiley & Sons, Ltd. [source] Necessary conditions for the N -representability of pair distribution functionsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 7 2006Paul W. Ayers Abstract A necessary condition for the N -representability of the electron pair density proposed by one of the authors (E. R. D.) is generalized. This shows a link between this necessary condition and other, more widely known, N -representability conditions for the second-order density matrix. The extension to spin-resolved electron pair densities is considered, as is the extension to higher-order distribution functions. Although quantum mechanical systems are our primary focus, the results are also applicable to classical systems, where they reduce to an inequality originally derived by Garrod and Percus. As a simple application, bounds to the average angle between an electron pair are derived. It is shown that computational methods based on variational minimization of the energy with respect to the electron pair density can give extremely poor results unless robust N -representability constraints are considered. For reference, constraints for the N -representability of the pair density are summarized. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Time-varying linear controllers for exponential tracking of non-holonomic systems in chained formINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 7 2007Yu-Ping Tian Abstract In this paper, the authors address the tracking problem for non-holonomic systems in chained form with target signals that may exponentially decay to zero. By introducing a time-varying co-ordinate transformation and using the cascade-design approach, smooth time-varying controllers are constructed, which render the tracking-error dynamics globally ,,-exponentially stable. The result shows that the popular condition of persistent excitation or not converging to zero for the reference signals is not necessary even for the globally ,,-exponential tracking of the chained-form system. The effectiveness of the proposed controller is validated by simulation of two benchmark mechanical systems under non-holonomic constraints. Copyright © 2006 John Wiley & Sons, Ltd. [source] Further constructive results on interconnection and damping assignment control of mechanical systems: the Acrobot exampleINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 14 2006Arun D. Mahindrakar Abstract Interconnection and damping assignment passivity-based control is a controller design methodology that achieves (asymptotic) stabilization of mechanical systems endowing the closed-loop system with a Hamiltonian structure with a desired energy function,that qualifies as Lyapunov function for the desired equilibrium. The assignable energy functions are characterized by a set of partial differential equations that must be solved to determine the control law. A class of underactuation degree one systems for which the partial differential equations can be explicitly solved,making the procedure truly constructive,was recently reported by the authors. In this brief note, largely motivated by the interesting Acrobot example, we pursue this investigation for two degrees-of-freedom systems where a constant inertia matrix can be assigned. We concentrate then our attention on potential energy shaping and give conditions under which an explicit solution of the associated partial differential equation can be obtained. Using these results we show that it is possible to swing-up the Acrobot from some configuration positions in the lower half plane, provided some conditions on the robot parameters are satisfied. Copyright © 2006 John Wiley & Sons, Ltd. [source] Geometric control of mechanical systems: modelling, analysis, and design for simple mechanical control systems, Francesco Bullo and Andrew D. Lewis, Springer, New York, NY, 2005INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 11 2006Stefano Stramigioli No abstract is available for this article. [source] Intelligent control of DC motor driven mechanical systems: a robust learning control approachINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2003Tae-Yong Kuc Abstract A robust learning controller is presented for DC motor driven mechanical systems with friction. The proposed controller takes advantage of both robust and learning control approaches to learn and compensate periodic and non-periodic uncertain dynamics. In the learning controller, a set of learning rules is implemented in which three types of learnings occur: one is direct learning of desired inverse dynamics input and the other two learning of unknown linear parameters and nonlinear bounding functions in the models of system dynamics and friction. The global asymptotic stability of learning control system is shown by using the Lyapunov stability theory. Experimental data demonstrate the effectiveness of developed learning approach to tracking of DC motor driven mechanical systems. Copyright © 2002 John Wiley & Sons, Ltd. [source] Chattering-free sliding mode control for a class of nonlinear mechanical systemsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 12 2001Vicente Parra-Vega Abstract Second-order sliding mode control (2-smc) and dynamic sliding mode control (dsmc) eliminate the disturbing characteristic of chattering in static sliding mode control under the assumption that the derivative of the sliding surface is available or complex inequalities at the acceleration level can be constructed. In this paper, passivity-based adaptive and non-adaptive chattering-free sliding mode controllers are proposed assuming that the upper bound of the norm of the derivative of the sliding surface is available, a weaker and easy to implement assumption in comparison to those of 2-smc and dsmc. The closed-loop system accounts explicitly for the invariance condition without reaching phase, and therefore for a desired transient response with global exponential convergence of tracking errors. Preliminary experiments are presented. Copyright © 2001 John Wiley & Sons, Ltd. [source] Controlled Lagrangians and the stabilization of Euler,Poincaré mechanical systemsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 3 2001Anthony M. Bloch Abstract In this paper we develop a constructive approach to the determination of stabilizing control laws for a class of Lagrangian mechanical systems with symmetry , systems whose underlying dynamics are governed by the Euler,Poincaré equations. This work extends our previous work on the stabilization of mechanical control systems using the method of controlled Lagrangians. The guiding principle behind our methodology is to develop a class of stabilizing feedback control laws which yield closed-loop dynamics that remain in Lagrangian form. Using the methodology for Euler,Poincaré systems, we analyse stabilization of a satellite and an underwater vehicle controlled with momentum wheels. Copyright © 2001 John Wiley & Sons, Ltd. [source] Carbothermal Synthesis of ,-SiC Micro-RibbonsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2008Gleb N. Yushin We report the synthesis of microscopic ,-SiC ribbons (belts) on the surface of a graphite rod at 1800°,1900°C by a carbothermal process. The width of the ribbons produced ranged from 500 nm to 5 ,m and the aspect ratio was up to 400. The ribbon thickness ranged from 50 to 800 nm. Their growth mechanism was explained by accelerated growth along the twin boundary. SiC whiskers grew on the rod along with the ribbons. Frequently, ribbons were growing from the tip of a whisker or whiskers were growing from the edge of a ribbon. SiC ribbons may find applications in high-temperature sensors, photo-electronic devices, or robust cantilevers in micro (or nano) electro mechanical systems. Alternatively, they can be used as reinforcements in composite materials, conferring anisotropic mechanical properties, such as unidirectional flexibility, to the composite. [source] Mechanical properties of tribologically modified nanolayersLUBRICATION SCIENCE, Issue 4 2005D. Shakhvorostov Abstract Wear in modern mechanical systems is characterised by ultra-low wear rates in the range of a few nanometres per hour. The surfaces of the materials involved, as well as their volumes, experience modifications as regards morphology, crystalline arrangement, and chemical bonds. The depth of the tribological interactions under given conditions extends to a micrometre or less. To probe these thin modified zones, synchrotron-based X-ray diffraction and nano-indentation were applied. The specimens were taken from tribometer experiments employing the radionuclide technique to measure ultra-low wear rates. To obtain different degrees of tribological interaction, various loads and sliding velocities were applied. The specimens were subdivided according to the total power dissipated during the tribometer experiment. [source] Non-standard finite difference schemes for multi-dimensional second-order systems in non-smooth mechanicsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 7 2007Yves Dumont Abstract This work is an extension of the paper (Proc. R. Soc. London 2005; 461A:1927,1950) to impact oscillators with more than one degree of freedom. Given the complex and even chaotic behaviour of these non-smooth mechanical systems, it is essential to incorporate their qualitative physical properties, such as the impact law and the frequencies of the systems, into the envisaged numerical methods if the latter is to be reliable. Based on this strategy, we design several non-standard finite difference schemes. Apart from their excellent error bounds and unconditional stability, the schemes are analysed for their efficiency to preserve some important physical properties of the systems including, among others, the conservation of energy between consecutive impact times, the periodicity of the motion and the boundedness of the solutions. Numerical simulations that support the theory are provided. Copyright © 2006 John Wiley & Sons, Ltd. [source] Ventriculo-arterial coupling and mechanical efficiency with remifentanil in patients with coronary artery diseaseACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2004D. Pittarello Background:, Optimum transfer of energy from the left ventricle to the arterial circulation requires appropriate matching of these mechanical systems. Left ventricular-arterial coupling describes this relationship between the ventricular elastance (Ees) and arterial elastance (Ea). The ratio of these elastances defines the efficiency of myocardium and provides in our study a useful technique for assessment of the actions of remifentanil. The purpose of this study was to evaluate the effects of remifentanil on ventriculo-arterial coupling in cardiac surgery in patients with coronary artery disease. Methods:, Fourteen patients with coronary artery disease, submitted intraoperatively to cardiac anesthesia for myocardial revascularization, were examined prospectively. With the use of transesophageal echocardiography (TEE) and different dicrotic arterial pressures, we determined the ventricle elastance (Ees), the arterial elastance (Ea) and myocardial efficiency before and after administration of a slow-bolus of remifentanil (1 µ kg,1). Results:, Remifentanil decreases significantly the ventricular elastance (from 6.09 mmHg ml,1 m,2 to 4.88) (P < 0.05), with a less, but however, significant decrease of arterial elastance (from 3.68 mmHg ml,1 m,2 to 3.13) (P < 0.05). Despite causing simultaneous declines, maintains a good myocardial efficiency (0.64,0.68) with no significant difference. Conclusion:, Although remifentanil depresses ventricular and arterial elastance, preserves a good left ventricular-arterial coupling and mechanical efficiency, despite a little increase of coupling. However, these effects are maintained only during a slow intravenous infusion and are dose-dependent with impairment of coupling, that may contribute to decline in overall cardiovascular performance, at higher anesthetic dose and rapid infusion in patients with a severe myocardial dysfunction. [source] Dynamics and control of underactuated mechanical systems: analysis and simple experimental verificationPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009Wojciech Blajer Underactuated mechanical systems are systems with fewer control inputs than the degrees of freedom, m < n, the relevant technical examples being e.g. cranes, aircrafts and flexible manipulators. The determination of an input control strategy that forces an underactuated system to complete a set of m specified motion tasks (servo-constraints) is a demanding problem. The solution is conditioned to differential flatness of the problem, denoted that all 2n state variables and m control inputs can algebraically be expressed, at least theoretically, in terms of the desired m outputs and their time derivatives up to a certain order. A more practical formulation, motivated hereafter, is to pose the problem as a set of differential-algebraic equations, and then obtain the solution numerically. The theoretical considerations are illustrated by a simple two-degree-of-freedom underactuated system composed of two rotating discs connected by a flexible rod (torsional spring), in which the pre-specified motion of the first disc is actuated by the torque applied to the second disc, n = 2 and m = 1. The determined control strategy is then verified experimentally on a laboratory stand representing the two-disc system. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Numerical integration of differential-algebraic equations with mixed holonomic and control constraintsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008Mahmud Quasem The present work aims at the incorporation of control (or servo) constraints into finite,dimensional mechanical systems subject to holonomic constraints. In particular, we focus on underactuated systems, defined as systems in which the number of degrees of freedom exceeds the number of inputs. The corresponding equations of motion can be written in the form of differential,algebraic equations (DAEs) with a mixed set of holonomic and control constraints. Apart from closed,loop multibody systems, the present formulation accommodates the so,called rotationless formulation of multibody dynamics. To this end, we apply a specific projection method to the DAEs in terms of redundant coordinates. A similar projection approach has been previously developed in the framework of generalized coordinates by Blajer & Ko,odziejczyk [1]. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Mechanical Stability for the Hand-Arm SystemPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008Aurora Felicia Pop The present paper contains a study regarding importance stability in the mechanical systems, mechanical systems are emerging under mechanical vibrations action, it referring especially to the human hand,arm system. Mechanical systems stability is directly influenced of the dumper and the elasticity factors. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] "New" branched structures of mechanical systems as result of synthesis of selected class of dynamical characteristicsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2006Andrzej Buchacz In this paper the problem of synthesis has been formulated and its basics has been formalized, according to the discrete mechanical systems with branched structure represented by graphs. In this case the essential field of basic conceptions according to the concerned class of structures and used graphs has been described. The way of receiving "new" structures as a result of synthesis of characteristics into partial fraction has been presented farther on. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] On the variational formulation of systems with non-holonomic constraintsANNALEN DER PHYSIK, Issue 9 2009D.H. Delphenich Abstract In a previous article by the author, it was shown that one could effectively give a variational formulation to non-conservative mechanical systems by starting with the first variation functional instead of an action functional. In this article, it is shown that this same approach will also allow one to give a variational formulation to systems with non-holonomic constraints. The key is to use an adapted anholonomic local frame field in the formulation, which then implies the replacement of ordinary derivatives with covariant ones. The method is then applied to the case of a vertical disc rolling without slipping or friction on a plane. [source] Integrability and the variational formulation of non-conservative mechanical systemsANNALEN DER PHYSIK, Issue 1 2009D.H. Delphenich Abstract It is shown that one can obtain canonically-defined dynamical equations for non-conservative mechanical systems by starting with a first variation functional, instead of an action functional, and finding their zeroes. The kernel of the first variation functional, as an integral functional, is a 1-form on the manifold of kinematical states, which then represents the dynamical state of the system. If the 1-form is exact then the first variation functional is associated with the first variation of an action functional in the usual manner. The dynamical equations then follow from the vanishing of the dual of the Spencer operator that acts on the dynamical state. This operator, in turn, relates to the integrability of the kinematical states. The method is applied to the modeling of damped oscillators. [source] | ||||||||||||||||||||||||||||