Showing papers on "Inertia published in 2003"
02 Nov 2003
TL;DR: From the experiments, it is clear that a PSO with increasing inertia weight outperforms the one with decreasing inertia weight, both in convergent speed and solution precision, with no additional computing load.
Abstract: A PSO with increasing inertia weight, distinct from a widely used PSO with decreasing inertia weight, is proposed in this paper. Far from drawing conclusions from sole empirical study or rule of thumb, this algorithm is derived from particle trajectory study and convergence analysis. Four standard test functions are used to confirm its validity finally. From the experiments, it is clear that a PSO with increasing inertia weight outperforms the one with decreasing inertia weight, both in convergent speed and solution precision, with no additional computing load.
263 citations
TL;DR: An adaptive backstepping control with friction compensation scheme is presented and system robustness and asymptotic position tracking performance are shown through simulation and experimental results.
Abstract: An adaptive backstepping control with friction compensation scheme is presented. A third-order linear dynamic model is used for the AC motor control system design while the LuGre dynamic friction model with nonuniform friction force variations characterizes the friction force. Nonlinear adaptive control laws are designed to compensate the unknown system parameters and disturbances. System robustness and asymptotic position tracking performance are shown through simulation and experimental results.
202 citations
TL;DR: In this paper, a comprehensive theoretical model for capillary-driven flow of a perfectly wetting liquid into circular cylindrical tubes is presented, which considers the meniscus reorientation, the dynamic contact angle as well as inertia, convective and viscous losses inside the tube and the reservoir.
Abstract: Capillary-driven flow of a perfectly wetting liquid into circular cylindrical tubes is studied. Based on an analysis of previous approaches, a comprehensive theoretical model is presented which is not limited to certain special cases. This model considers the meniscus reorientation, the dynamic contact angle as well as inertia, convective, and viscous losses inside the tube and the reservoir. The capillary-driven flow is divided into three successive phases where first inertia then convective losses and finally viscous forces counteract the driving capillary force. This leads to an initial meniscus height increase proportional to the square of time followed by a linear dependence and finally the Lucas–Washburn behavior where the meniscus height is proportional to the square root of time. The three phases are separated by two characteristic transition times which are determined by the Ohnesorge number and the inertia of the liquid. Experiments were carried out under microgravity condition in a carefully chosen range of Ohnesorge numbers and initial liquid heights to cover the complete process from the initial meniscus development to the final Lucas–Washburn behavior. Good agreement of experimental and theoretical data is found throughout the complete range of experiment parameters. The existence of all three flow regimes predicted by the theory is verified by the experiments.
198 citations
12 Oct 2003
TL;DR: It has been found that the proposed design has yielded successful simulation and experimental results, and the maximum load inertia corresponding to the rotor-bar depth has been determined from the simulation results.
Abstract: This paper presents a successful design of a high-efficiency small but novel interior permanent-magnet motor using NdBFe magnets. It is designed to operate both at line and variable frequencies. Line start with high inertia load was a special consideration. Time-stepping finite-element analysis has been used to successfully predict the dynamic and transient performances of the prototype motors. It has been found that the proposed design has yielded successful simulation and experimental results. The maximum load inertia corresponding to the rotor-bar depth has been determined from the simulation results.
189 citations
TL;DR: Three regimes of granular avalanches in fluids are put in light depending on the Stokes number St which prescribes the relative importance of grain inertia and fluid viscous effects and on the grain/fluid density ratio r.
Abstract: Three regimes of granular avalanches in fluids are put in light depending on the Stokes number St which prescribes the relative importance of grain inertia and fluid viscous effects and on the grain/fluid density ratio $r$. In gas ($r\ensuremath{\gg}1$ and $\mathrm{S}\mathrm{t}g1$, e.g., the dry case), the amplitude and time duration of avalanches do not depend on any fluid effect. In liquids ($r\ensuremath{\sim}1$), for decreasing St, the amplitude decreases and the time duration increases, exploring an inertial regime and a viscous regime. These three regimes are described by the analysis of the elementary motion of one grain.
175 citations
TL;DR: In this article, a non-incremental solution procedure for the finite rotation and large deformation analysis of plates is presented, which is based on the absolute nodal coordinate formulation, leads to plate elements capable of representing exact rigid body motion.
Abstract: In this investigation, a non-incremental solution procedure for the finite rotationand large deformation analysis of plates is presented. The method, whichis based on the absolute nodal coordinate formulation, leads to plateelements capable of representing exact rigid body motion. In thismethod, continuity conditions on all the displacement gradients areimposed. Therefore, non-smoothness of the plate mid-surface at the nodalpoints is avoided. Unlike other existing finite element formulationsthat lead to a highly nonlinear inertial forces for three-dimensionalelements, the proposed formulation leads to a constant mass matrix, andas a result, the centrifugal and Coriolis inertia forces are identicallyequal to zero. Furthermore, the method relaxes some of the assumptionsused in the classical and Mindlin plate models and automatically satisfiesthe objectivity requirements. By using a generalcontinuum mechanics approach, a relatively simple expression for theelastic forces is obtained. Generalization of the formulation to thecase of shell elements is discussed. As examples of the implementationof the proposed method, two different plate elements are presented; oneplate element does not guarantee the continuity of the displacementgradients between the nodal points, while the other plate elementguarantees this continuity. Numerical results are presented in order todemonstrate the use of the proposed method in the large rotation anddeformation analysis of plates and shells. The numerical results, whichare compared with the results obtained using existing incrementalprocedures, show that the solution obtained using the proposed methodsatisfies the principle of work and energy. These results are obtainedusing explicit numerical integration method. Potential applications ofthe proposed method include high-speed metal forming, vehiclecrashworthiness, rotor blades, and tires.
163 citations
08 Dec 2003
TL;DR: From the experiments, it is clear that aPSO with increasing inertia weight outperforms the one with decreasing inertia weight, both in convergent speed and solution precision, with no additional computing load compared with the PSO with a decrease inertia weight.
Abstract: A PSO with increasing inertia weight, distinct from a widely used PSO with decreasing inertia weight, is proposed in this paper. Four standard test functions with asymmetric initial range settings are used to confirm its validity. From the experiments, it is clear that a PSO with increasing inertia weight outperforms the one with decreasing inertia weight, both in convergent speed and solution precision, with no additional computing load compared with the PSO with a decreasing inertia weight.
156 citations
TL;DR: This work clarifies how the performance and robustness of the perturbation observer are changed according to the variation of the Q-filter parameters and model parameter (i.e., inertia) perturbations in discrete control systems.
Abstract: A discrete perturbation observer (DPO) is suggested in state-space form for motion control applications. In existing disturbance observer design methods, the low-pass filter (so-called Q-filter) is central. However, the effect of the Q-filter on performance and robustness has not been clarified, specifically in the discrete-time domain. Considering the discrete Q-filter, with general order and inertia perturbations as a structured model uncertainty, we clarify how the performance and robustness of the perturbation observer are changed according to the variation of the Q-filter parameters and model parameter (i.e., inertia) perturbations in discrete control systems. Experimental results show the validity of the analysis and the effectiveness of the DPO.
148 citations
TL;DR: In this article, the authors consider the averaged flow properties of a suspension in which the Reynolds number based on the particle diameter is finite so that the inertia of the fluid phase is important.
Abstract: We consider the averaged flow properties of a suspension in which the Reynolds number based on the particle diameter is finite so that the inertia of the fluid phase is important. When the inertia of the particles is sufficiently large, their trajectories, between successive particle collisions, are only weakly affected by the interstitial fluid. If the particle collisions are nearly elastic the particle velocity distribution is close to an isotropic Maxwellian. The rheological properties of the suspension can then be determined using kinetic theory, provided that one knows the granular temperature (energy contained in the particle velocity fluctuations). This energy results from a balance of the shear work with the loss due to the viscous dissipation in the interstitial fluid and the dissipation due to inelastic collisions. We use lattice-Boltzmann simulations to calculate the viscous dissipation as a function of particle volume fraction and Reynolds number (based on the particle diameter and granular temperature). The Reynolds stress induced in the interstitial fluid by the random motion of the particles is also determined. We also consider the case where the interstitial fluid is moving relative to the particles, as would occur if the particles experienced an external body force. Owing to the nonlinearity of the equations of motion for the interstitial fluid, there is a coupling between the viscous dissipation caused by the fluctuating motion of the particles and the drag associated with a mean relative motion of the two phases, and this coupling is explored by computing the dissipation and mean drag for a range of values of the Reynolds numbers based on the mean relative velocity and the granular temperature.
145 citations
TL;DR: In this article, the analysis of the incompressible laminar shear driven flow in a channel of which one of the walls carries a macro roughness pattern while the opposite one has a parallel velocity is discussed from the standpoint of lubrication theory and it is shown that the usual simplified models as the Reynolds or the Stokes equations are not applicable.
Abstract: The present work deals with the analysis of the incompressible laminar shear driven flow in a channel of which one of the walls carries a macro roughness pattern while the opposite one has a parallel velocity. The problem is discussed from the standpoint of lubrication theory and it is shown that the usual simplified models as the Reynolds or the Stokes equations are not applicable. Numerical results are presented for three types of two dimensional macro-roughness and two versions of a three dimensional one. It is shown that a pressure generation effect occurs with increasing the relative importance of convective inertia. Previous analyses found in the literature discussed only the increase of the shear stress due to the presence of the macro roughness but the lift effect due to the pressure generation has never been enlightened up to now. It is further discussed that, extrapolated to a very large number of macro roughness characterizing a textured surface, this new effect could be added to the other lift generating mechanisms of the lubrication theory. It could thus bring a different light on inertia effects stemming from the use of textured surfaces.
144 citations
TL;DR: In this article, the authors have developed a new formulation for the sliding joint between two very flexible bodies, where a surface parameter is introduced as an additional new variable in order to facilitate the formulation of this sliding joint.
Abstract: A wide variety of mechanical and structural multibody systems consist ofvery flexible components subject to kinematic constraints. The widelyused floating frame of reference formulation that employs linear modelsto describe the local deformation leads to a highly nonlinear expressionfor the inertia forces and can be applied to only small deformationproblems. This paper is concerned with the formulation and computerimplementation of spatial joint constraints and forces using the largedeformation absolute nodal coordinate formulation. Unlike the floatingframe of reference formulation that employs a mixed set of absolutereference and local elastic coordinates, in the absolute nodalcoordinate formulation, global displacement and slope coordinates areused. The nonlinear kinematic constraint equations and generalized forceexpressions are expressed in terms of the absolute global displacementsand slopes. In particular, a new formulation for the sliding jointbetween two very flexible bodies is developed. A surface parameter isintroduced as an additional new variable in order to facilitate theformulation of this sliding joint. The constraint and force expressionsdeveloped in this paper are also expressed in terms of generalizedCholesky coordinates that lead to an identity inertia matrix. Severalexamples are presented in order to demonstrate the use of theformulations developed in the paper.
TL;DR: In this paper, the performance of the force-coupling method (FCM) for particulate flow at microscales is investigated, where the authors restrict attention to flows where they may neglect fluid inertia (Stokes flows), particle inertia and Brownian motion.
TL;DR: Friction induced limit cycles are predicted for a simple motion system consisting of a motor-driven inertia subjected to friction and a PID-controlled regulator task and the disappearance of the hunting behavior for controller gains larger than the gain corresponding to the cyclic fold bifurcation point is indicated.
TL;DR: A fully coupled finite-element method is used to investigate the steady flow of a viscous fluid through a thin-walled elastic tube mounted between two rigid tubes, which induces an additional local pressure drop when the tube buckles and its cross-sectional area is reduced.
Abstract: A fully coupled finite-element method is used to investigate the steady flow of a viscous fluid through a thin-walled elastic tube mounted between two rigid tubes. The steady three-dimensional Navier–Stokes equations are solved simultaneously with the equations of geometrically nonlinear Kirchhoff–Love shell theory. If the transmural (internal minus external) pressure acting on the tube is sufficiently negative then the tube buckles non-axisymmetrically and the subsequent large deformations lead to a strong interaction between the fluid and solid mechanics. The main effect of fluid inertia on the macroscopic behaviour of the system is due to the Bernoulli effect, which induces an additional local pressure drop when the tube buckles and its cross-sectional area is reduced. Thus, the tube collapses more strongly than it would in the absence of fluid inertia. Typical tube shapes and flow fields are presented. In strongly collapsed tubes, at finite values of the Reynolds number, two ’jets‘ develop downstream of the region of strongest collapse and persist for considerable axial distances. For sufficiently high values of the Reynolds number, these jets impact upon the sidewalls and spread azimuthally. The consequent azimuthal transport of momentum dramatically changes the axial velocity profiles, which become approximately $\uTheta$-shaped when the flow enters the rigid downstream pipe. Further convection of momentum causes the development of a ring-shaped velocity profile before the ultimate return to a parabolic profile far downstream.
TL;DR: In this paper, a set of differential equations governing the fluid flow and fluid-membrane coupling are obtained for a valveless micropump working at high frequencies, and an approximate analytical solution is derived under the action of an external sinusoidal excitation force.
Abstract: Through flow field simplification, a set of differential equations governing the fluid flow and fluid–membrane coupling are obtained for a valveless micropump. The dimensional analysis on the equations reveals that the ratio of the inertial force of the fluid to the viscous loss is dependent on the size ratios among internal elements of the pump. For a micropump working at high frequencies, these two forces possess the same order of magnitude, and this phenomenon is independent of the excitation frequency and fluid type. For the liquid medium, the inertial force of the fluid is around O(102)–O(103) times as that of the plate membrane, and is also larger than the elastically deformed force of the plate when the excitation frequency is close to the plate fundamental frequency. For the case where there is no pressure difference between the inlet and the outlet, an approximate analytical solution is derived for the micropump under the action of an external sinusoidal excitation force. It shows that a phase shift lagging the excitation force exists in the vibration response. For certain combinations of micropump size and fluid–solid density ratios, the phase shift can come to 90° at a specific excitation frequency ω* due to the action of fluid inertia. Away from ω*, the phase shift becomes smaller. The amplitude response of coupling vibration changes nonlinearly with the excitation frequency and reaches maximum at another frequency ω** ≠ ω*. Due to the nonlinearity of viscous loss, resonance does not seem to occur at any frequency. To obtain a larger average flux, the two loss coefficients of the nozzle should be minimized while their difference should be maximized. Under the action of the fluid inertia, there exists an optimal working frequency (equal to ω*) at which the average flux is maximum. This optimal frequency is dependent on the size of the micropump, the material properties of the plate, the fluid properties and has no relation with the excitation force. For the case where a pressure difference between the inlet and the outlet exists, a constraint condition between the excitation force and the pressure difference is obtained.
TL;DR: Simulation and experimental works have been performed and they show that the proposed observer-based tension feedback controller performs as well as a classical tension feedback Controller using a tension transducer.
Abstract: Low cost and high productivity are two primary goals in design of a web transport system. One approach to achieve low cost is through the implementation of observer techniques in place of tension transducers. To achieve high productivity, it is normally required to increase the process speed. However, as the process speed or variation of the speed is high, system friction and inertia of rotation of rolls could cause problems in implementation of observer techniques for tension estimation and control. Few of the previous studies have considered the problems of friction and inertia in a single article. This paper proposes an observer with friction and inertia compensation. The proposed observer has a feedback configuration and it is able to estimate web tension precisely regardless of the effects of friction and inertia. Linearization and decentralization techniques are implemented. Design of the proposed observer-based tension feedback controller is performed in the frequency domain. Eccentricity of unwind roll is considered as sinusoidal disturbances to the system. A procedure for design of the proposed controller and eccentricity of rolls are discussed. Simulation and experimental works have been performed and they show that the proposed observer-based tension feedback controller performs as well as a classical tension feedback controller using a tension transducer.
TL;DR: An analysis of the National Highway Traffic Safety Administration Inertia Database is presented and regression equations that approximate moments of inertia and center of gravity height given basic vehicle properties including weight, width, length and height are given.
Abstract: Vehicle handling and stability are significantly affected by inertia properties including moment of inertia and center of gravity location. This paper presents an analysis of the National Highway Traffic Safety Administration (NHTSA) Inertia Database and gives regression equations that approximate moments of inertia and center of gravity height given basic vehicle properties including weight, width, length and height. The handling and stability consequences of the relationships of inertial properties with vehicle size will be analyzed in terms of other vehicle dynamics models and the use of a nonlinear maneuvering simulation.
10 Nov 2003
TL;DR: This paper extends the current state-of-the-art in soft tissue simulation by introducing a six-degree of freedom macroscopic elastic sphere described by mass, inertia and volumetric properties and presents an efficient method to approximate collision detection between multiple bodies in real-time.
Abstract: Mass-spring systems have widely and effectively been used for modeling in real-time deformable objects. Easier to implement and faster than finite elements, these systems, on the other side, suffer from several drawbacks when coming to render physically believable behaviors. Neither isotropic or anisotropic materials can be controlled easily and the large number of springs and mass points composing the model makes it fastidious to define parameters to control elongation, flexion and torsion at a macroscopic level. Another weakness is that most of the materials found in nature maintain a constant or quasi-constant volume during deformations; unfortunately, mass-spring models do not have this property. In this paper, we extend the current state-of-the-art in soft tissue simulation by introducing a six-degree of freedom macroscopic elastic sphere described by mass, inertia and volumetric properties. Spheres are placed along the medial axis transform of the object whose centers are connected by a skeleton composed of a set of three-dimensional elastic links. Spheres represent internal mass, volume and control the global deformation of the object. The surface is modeled by setting point masses on the mesh nodes and damped springs on the mesh edges. These nodes are connected to the skeleton by individual elastic links, which control volume conservation and transfer forces between the surface and volumetric model. Using this framework we also present an efficient method to approximate collision detection between multiple bodies in real-time.
TL;DR: In this paper, a three-dimensional simulational model of a human walking is presented, which consists of eight rigid body parts, including thigh, shank, and foot, connected by a revolute joint.
Abstract: A three-dimensional simulational model of a human walking is presented. The biped is anthropomorphic, i.e., its inertial and kinematical properties are similar to human ones. The biped consists of eight rigid bodies. Each leg consists of three parts: thigh, shank, and foot. The trunk is modeled as two rigid bodies connected by a revolute joint. The inertia properties of head and arms are included in trunk properties. Each leg has 7 degrees of freedom. The whole modelled biped has 21 degrees of freedom. The impact and friction effects are considered in the ground reaction force modeling. The ground is represented by a flat, rigid surface. The normal to the ground component of reaction force depends on penetration of the foot into the ground and on the velocity of this penetration. The tangential reaction is represented in terms of a pseudo-Coulomb friction model (in this model of friction there is no stiction phase, i.e., the bodies are moving relative to each other at a negligibly small velocity)...
TL;DR: In this article, a procedure for the identification of parameters describing a single-mode response of a structure possessing cubic geometric and inertia nonlinearities and linear (viscous) and quadratic response is presented.
Abstract: We present a procedure for the identification of parameters describing a single-mode response of a structure possessing cubic geometric and inertia nonlinearities and linear (viscous) and quadratic...
TL;DR: In this paper, the vibrational behavior of a cracked cantilever beam carrying end mass and rotary inertia is investigated through the crack model and the values of the ratio between the cracked and uncracked beam natural frequencies, the frequency ratio, are examined and are shown to follow well-defined trends with respect to the crack parameters and end mass.
TL;DR: A model based on energy considerations is presented to explain experimental data, drawing the important conclusion that it is the inertia of the particle, assisted by Reynolds dilatancy, the driven force behind its ascension mechanism.
Abstract: The rise dynamics of a large particle, in a granular bed under vertical vibrations, is experimentally studied with an inductive device designed to track the particle while it climbs through the granulate under different conditions. A model based on energy considerations is presented to explain our experimental data, drawing the important conclusion that it is the inertia of the particle, assisted by Reynolds dilatancy, the driven force behind its ascension mechanism. The ascension reveals a friction profile within the column which remains unchanged for different accelerations.
TL;DR: In this paper, the authors manipulated moment of inertia and drag by varying the length and composition of the rods and by wielding them in air or in water, and the perceived length of rods was a function of inertia in both media conditions.
Abstract: Following a procedure employed by Pagano and Donahue (1999), participants reported the lengths of occluded rods wielded in air or water. In this experiment we manipulated moment of inertia-the resistance to angular rotation due to the rod's mass distribution-by varying the length and composition of the rods. We manipulated drag-the resistance to object movement due to the displacement of a fluid medium -by varying the length of the rods and by wielding them in air or in water. The rods were constructed such that moment of inertia and drag were decorrelated. Although the torques required to wield in water are substantially greater than those required to wield in air, the perceived lengths of rods wielded in the 2 media were equivalent. Perceived length was a function of inertia in both media conditions; there was no significant contribution of drag. The experiment demonstrated that perceivers can extract the physical invariant of inertia by attending to the time-varying patterns from the complex arrays of ...
TL;DR: In this article, a multibody biomechanical model of the trampolinist and the recurrently interacting trampoline bed is developed, including both the motion equations and the determination of joint reactions.
Abstract: This paper presents an extensive study on the trampoline-performed planar somersaults. First, a multibody biomechanical model of the trampolinist and the recurrently interacting trampoline bed are developed, including both the motion equations and the determination of joint reactions. The mathematical model is then identified –the mass and inertia characteristics of the human body are estimated, and the stiffness and damping characteristics of the trampoline bed are measured. By recording the actual somersault performances the motion characteristics of the stunts, i.e. the time variations of positions, velocities and accelerations of the body parts are also obtained. Finally, an inverse dynamics formulation for the system designated as an under-controlled system, is developed. The followed inverse dynamics simulation results in the torques of muscle forces in the joints that assure the realization of the actual motion. The reaction forces in the joints during the analyzed evolutions are also determined. Using the kinematic and dynamics characteristics, the nature of the stunts, the way the human body is maneuvered and controlled, can be studied.
TL;DR: Theoretical stability derivatives for a slender missile through use of the concept of inertia coefficients of its cross section were derived in this article. But they were derived for the cross section of a configuration consisting of a slender body of revolution with low aspect ratio wings and unequal vertical tails, and the inertia coefficients were determined by the velocity potentials for two-dimensional motion of the crosssection in two mutually perpendicular directions and for rotation about an axis perpendicular to the cross-section.
Abstract: Theoretical stability derivatives are determined for a slender missile through use of the concept of inertia coefficients of its cross section. The inertia coefficients are determined by the velocity potentials for two-dimensional motion of the cross section in two mutually perpendicular directions and for rotation about an axis perpendicular to the cross section. The inertia coefficients are derived for the cross section of a configuration consisting of a slender body of revolution with low aspect ratio wings and unequal vertical tails.
TL;DR: In this article, the necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference, and the analysis eliminates a restriction inherent in the work of Szabo (Rheol Acta 36:277-284 (1997)).
Abstract: The necessary inertia compensation used in the force balance for the filament stretching rheometer is derived for an arbitrary frame of reference. This enables the force balance to be used to extract correctly the extensional viscosity from measurements of the tensile force at either end of the elongating fluid column in any of the different experimental configurations that have been introduced to date. The present analysis eliminates a restriction inherent in the work of Szabo (Rheol Acta 36:277–284 (1997)).
TL;DR: In this paper, a closed-formulae for the determination of the principal axes and principal moments of inertia of the Earth's tensor of inertia was developed based on the exact solution of the eigenvalue-eigenvector problem.
Abstract: The dynamic figure of the Earth, characterized by the principal axes and principal moments of inertia, is estimated from satellite-derived gravitational harmonic coefficients of second degree in recent global Earth gravity models and from the dynamic ellipticity resulting from the precession constant observed through very-long-baseline interferometry (VLBI). Closed, exact formulae for the determination of these parameters of the Earth's tensor of inertia are developed based on the exact solution of the eigenvalue–eigenvector problem, including a rigorous error propagation. These formulae are applied to determine (a) static components and accuracy of the Earth's tensor of inertia at epoch and (b) the variation with time of the Earth's tensor of inertia and its accuracy. The best-fitting principal moments of inertia and second-degree harmonic coefficients in the principal-axes system are found from an adjustment involving four global gravity field models and six different values for the dynamic ellipticity. The evolution with time of the dynamic figure of the Earth is determined from the mean pole path and the observed secular rate of change in the second-degree zonal coefficient. It is found that differences in the principal moments of inertia change significantly over the time interval from 1962 to 2000, whereas changes in the absolute values cannot be reliably resolved due to the uncertainty in the dynamic ellipticity.
TL;DR: In this paper, the authors proposed a simple and cheap system, able to produce a macroscopic (centimetric) travel with a very high (nano-metric) resolution.
Abstract: The aim of the research presented in this paper was to propose a simple and cheap system, able to produce a macroscopic (centimetric) travel with a very high (nano-metric) resolution. The solution principle described yields a theoretically infinite travel range based on the accumulation of successive steps. The travel range of the prototype realised is equal to 2 cm , the size of the steps being about 20 nm . The actuation is based on the stick–slip effect: during the first stage of a step, the legs of the actuator slowly translate the carried structure; in the second stage the legs are moved back in their initial position very quickly, so that, thanks to their inertia, the structure stays at the same place. Each leg of the system, glued on a main frame, consists in a piezoelectric device working in shear mode, ended by a ruby hemisphere. The structure itself is in steel to get a sufficiently high inertia. An originality of the proposed translator is that the guiding elements of the structure (guiding grooves) are also used to transmit the motion. The friction force between the legs and the grooves can be tuned thanks to a magnet placed in the main frame, allowing to adjust the normal load on the legs. The paper presents the different functional elements of the translator and its electronic command system, and explains its functioning. The influence of several parameters (supported load, friction, resistive axial load) on the step size and thus on both the resolution, hence the speed of the system is then studied. Finally, the power losses are identified and estimated.
Patent•
06 Aug 2003TL;DR: A combustion state estimating apparatus for estimating the state of combustion in an internal combustion engine includes an angular acceleration calculator that calculates a crank angle acceleration, and a combustion state estimator that estimates the combustion state of a combustion engine based on the crank angle accelerometer as discussed by the authors, in which an average value of inertia torque caused by a reciprocating inertia mass is substantially zero.
Abstract: A combustion state estimating apparatus for estimating the state of combustion in an internal combustion engine includes an angular acceleration calculator that calculates a crank angle acceleration, and a combustion state estimator that estimates the state of combustion in the internal combustion engine based on the crank angle acceleration in a crank angle interval in which an average value of inertia torque caused by a reciprocating inertia mass of the internal combustion engine is substantially zero. Thus, the combustion state estimating apparatus excludes the effect that the inertia torque caused by the reciprocating inertia mass has on the angular acceleration, and therefore is able to precisely estimate the state of combustion based on the angular acceleration.
TL;DR: In this article, an efficient method is proposed for choosing suitable components when the inertial loads are dominant, and the effects of the system parameters are discussed, where the correct choice of the motion law is followed by a suitable distribution of the generalized inertia between motor and load.