bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adaptive Motion and Force Control of Robots Performing a Complete Task
Authors: Pagilla Prabhakar R. , Yu Biao 
Published: February 2021

Abstract
In this work, we consider adaptive motion and force control of a robot performing a complete task. By a complete task we mean that the robot desired task contains both free motion and constrained motion. Further, we also consider transition from free motion to constrained motion. We divide the motion of the robot into three phases: (i) inactive phase, where the robot is in free motion, (ii) transition phase, where the transition from free motion to constrained motion takes place, and (iii) active phase, where the robot is in constrained motion with simultaneous force and position control. Uncertainty of the constraint results in the impact of robot with the constraint surface when transition from free motion to constrained motion. We design stable control laws for the three phases that results in an efficient algorithm for robots performing a complete task. Extensive experiments are conducted to show the validity of the proposed control designs.
Synchronization of Two Common-Base-Coupled Nonlinear Rotating-Eccentric-Driven Shakers
Authors: Senator Martin 
Published: February 2021

Abstract
The synchronization, or lock-in, of two coupled, similarly sized rotating-eccentric-driven shakers is studied. The shakers are coupled only by being mounted on a common base, which is suspended on springs and dampers and constrained to translate along a line. This setup models a simplified conceptual version of a no-synchronizing-gearing counter-rotating-eccentric-driven telephone-cable-burying vibrating plow. An approximate quantitative theory of the synchronization of the rotors of these coupled nonlinear autonomous systems is developed in a form that is simple to understand and numerically evaluate. This analysis allows predicting, with good accuracy, whether or not the rotors will synchronize, and if so, to also predict transient and steady state properties of the locked-in motion.
An Experimental Evaluation of Smart Damping Materials for Reducing Structural Noise and Vibrations
Authors: Ahmadian Mehdi , Jeric Kristina M. , Inman Daniel J. 
Published: February 2021

Abstract
An experimental evaluation of the benefits of smart damping materials in reducing structural noise and vibration is presented. The construction of a special test rig for measuring both vibrations and structure-borne noise is discussed. Next, the application of smart damping materials, specifically piezoceramics with electrical shunts, in reducing the vibrations of a test plate is discussed. It is shown that the smart damping materials are able to effectively reduce the vibration peaks at multiple frequencies, with minimal amount of added weight to the structure, as compared to passive viscoelastic damping materials. Further, the test results show that the structure-borne noise at the vibration peaks is substantially reduced with the smart damping materials. The results indicate the viability of smart damping materials for many industrial applications where reducing noise and vibrations is desired with minimal amounts of added weight, or at frequencies below the effective range of passive damping materials.
Relaxation Methods for Nonlinear Dynamics and Hysteresis Operators
Authors: Kurdila A. , Li J. 
Published: February 2021

Abstract
Previous research has demonstrated that rigorous modeling and identification theory can be derived for structural dynamical models that incorporate control influence operators that are static Krasnoselskii-Pokrovskii integral hysteresis operators. Experimental evidence likewise has shown that some dynamic hysteresis models provide more accurate representations of a class of structural systems actuated by some active materials including shape memory alloys and piezoceramics. In this paper, we show that the representation of control influence operators via static hysteresis operators can be interpreted in terms of a homogeneous Young’s measure. Within this framework, we subsequently derive dynamic hysteresis operators represented in terms of Young’s measures that are parameterized in time. We show that the resulting integrodifferential equations are similar to the class of relaxed controls discussed by Warga [10], Garnkrelidze [24], and Roubicek [25].
The formulation presented here differs from that studied in [10], [24] and [25] in that the kernel of the hysteresis operator is a history dependent functional, as opposed to Caratheodory integral satisfying a growth condition. The theory presented provides representations of dynamic hysteresis operators that have provided good agreement with experimental behavior in some active materials.
Influences of Coupler Consisting of Rotational Stiffness and Mass on Wave Propagation and Mode Localization in Simply Supported Multispan Beams
Authors: Kim Dong-Ok , Kim Jong-In , Lee In-Won 
Published: February 2021

Abstract
The influences of coupler on wave propagation and mode localization in simply supported multispan beams with couplers consisting of lumped rotational stiffness and mass on supports are studied. A transfer matrix equation governing the vibrational wave propagation in the simply supported multispan beams with couplers is newly derived and simplified. The eigenvalue of the simplified transfer matrix show that the larger stiffness or the larger mass of coupler makes the internal coupling between spans weaker and so it makes the system more sensitive to mode localization. As the wave frequency or the eigenvalues of the system increases, the mass effect is increased while the stiffness effect is decreased. In a case considering the large stiffness and mass at the same time, there is a region with relatively wider passbands and narrower stopbands having small attenuation rates and the normal modes in it become delocalized ones. As an example structure, simply supported two span beam with a coupler at the mid-span is considered.
An Advanced Damper Model for the Dynamics of Dry Friction Damped Systems
Authors: Guillen Jérôme , Pierre Christophe , Lagrange Thomas 
Published: February 2021

Abstract
In this work, a new, flexible friction damper model is introduced, for application to turbomachinery bladed-disk assemblies. The damper is modeled as a massless structure characterized by a stiffness matrix. It is connected to two (possibly more) structural systems at an arbitrary number of friction points where slip can occur. A new procedure is presented to calculate the force transmitted by the damper at each frictional interface. The multi-harmonic, hybrid, frequency/time method introduced previously by the authors, along with the Broyden resolution algorithm, are modified to handle this advanced damper model and to predict the steady-state periodic response of the system. The method is successfully applied to a four-degree of freedom friction damper connecting two beams at four frictional points. Several interesting features of the non-linear response are revealed, such as: situations where the damper slips at some frictional points and sticks at the other points; and complexity of the frequency response of the system, due to the existence of several modes of vibration that correspond to combinations of stick/slip motions at the various frictional interfaces.
An Experimental Investigation of Vortex-Induced Vibration of Drag-Cable
Authors: Fang Kai-xiang , Jiang Gue-he 
Published: February 2021

Abstract
In order to explore the vibration law of a cylindrical cable excited by wake vortices when a cable of a sonar is dragged underwater, an experimental research on the law of cable model vibration has been done. This paper introduces the model design, test conditions and measurement & analysis system in broad outline. The law of the model vibration and the mutual influence of some factors affecting vortices, such as Strouhal number, Reynold number, drag speed, dip angle and diversion patterns etc. have been discussed. These test data and research result afford us technological basis to further study this subject and design the sonar cable.
Using Genetic Algorithms for the Optimal Design of Fluid Journal Bearing
Authors: Lin Yun-Jeng , Noah Sherif T. 
Published: February 2021

Abstract
The current methods of designing journal bearings are achieved by trial and error and mathematical programming. A new method is used here to design the journal bearings, i.e., Genetic Algorithms (GA). GA is a very efficient method, providing relatively an easy way to find the optimum solution. For that purpose we need to construct the proper objective function for the design of the journal bearing. Then the rest exhaustive and repeated task could be left to the computer. GA can solve the linear or nonlinear, single parameter or multiparameter system.
Genetic Algorithms are very different from the traditional optimization techniques. It is a new generation of artificial intelligence and its principles mimic the behavior of the biologic genes in the natural world. It will search the best set of parameters of the objective function, reproduce them, eliminate unsuitable sets of parameters, cross-couple the survival sets of parameters, execute mutations and then return to plug the values of the new variables into objective function to repeat these procedures. Its execution is simple and could reach the solution in a very short time. According to these characteristics, it is a very powerful method for finding the minimum dissipation of energy in the journal bearing. This approach opens new paradigm for optimization. The GA’s procedure is robust and works even if the functions involve are not continuous and have no derivatives. The resulting set of optimal parameters was compared with the results of a recent paper addressing the same problem.
Transverse Vibrations of a Centrally Clamped Rotating Circular Disk
Authors: Nayfeh Ali H. , Jilani Adel , Manzione Piergiuseppe 
Published: February 2021

Abstract
The transverse vibrations of a circular disk of uniform thickness rotating about its axis with constant angular velocity are analyzed. The results specialized to the linear case of disks clamped at the center and free at the periphery are in good agreement with those reported in the literature. The natural frequencies of spinning hard and floppy disks are obtained for various nodal diameters and nodal circles. Primary resonance is shown to occur at the critical rotational speed at which, in the linear analysis, the spinning disk is unable to support arbitrary spatially fixed transverse loads. Using the method of multiple scales, we determine a set of four nonlinear ordinary-differential equations governing the modulation of the amplitudes and phases of two interacting modes. The symmetry of the system and the loading conditions are reflected in the symmetry of the modulation equations. They are reduced to an equivalent set of two first-order equations whose equilibrium solutions are determined analytically. The stability characteristics of these solutions is studied; the qualitative behavior of the response is independent of the mode being considered.
Dynamics of a Continuous System With Clearance and Motion Limiting Stops
Authors: Metallidis P. , Natsiavas S. 
Published: February 2021

Abstract
The present study generalises previous research work on the dynamics of discrete oscillators with piecewise linear characteristics and investigates the response of a continuous model system with clearance and motion-limiting constraints. More specifically, in the first part of this work, an analysis is presented for determining exact periodic response of a periodically excited deformable rod, whose motion is constrained by a flexible obstacle. This methodology is based on the exact solution form obtained within response intervals where the system parameters remain constant and its behavior is governed by a linear equation of motion. The unknowns of the problem are subsequently determined by imposing an appropriate set of periodicity and matching conditions. The analytical part is complemented by a suitable method for determining the stability properties of the located periodic motions. In the second part of the study, the analysis is applied to several cases in order to investigate the effect of the system parameters on its dynamics. Special emphasis is placed on comparing these results with results obtained for similar but rigid rods. Finally, direct integration of the equation of motion in selected areas reveals the existence of motions, which are more complicated than the periodic motions determined analytically.
A New Order-N Order-N3 Hybrid Parallelizable Algorithm for a Multi-Rigid-Body Mechanical System
Authors: Anderson Kurt S. , Duan Shanzhong 
Published: February 2021

Abstract
In this paper, a new hybrid parallelizable algorithm involving formulations of different computational orders is presented for chain systems. The parallel system model is constructed through the separation of certain system interbody joints so that largely independent multibody subchain systems are formed. These sub-chains in turn interact with one another through associated unknown constrain forces fc¯ at those separated joints. Within each of the floating subchains, equations of motion for the system of bodies are produced using a recursive state space O(n) formulation, while the equations associated specifically with the floating “composite” base body are formed using a more tradition O(n3) approach. Parallel strategies are used to form and solve constraint equations between subchains concurrently. 41% computational savings can be achieved for the floating base body motion description by using O(n3) approach relative to using sequential O(n) procedure.
A Vector Oriented Implementation Method for Efficient Dynamic Simulation of Multibody Vehicle Models
Authors: Bae D. S. , Kim H. W. , Yae H. 
Published: February 2021

Abstract
The most time taking processes in a dynamic analysis of multibody vehicle models are generation and LU-decomposition of various matrices. This research proposes a vector oriented implementation algorithm for explicit numerical integration methods so that relatively low cost computers can be used for the realtime simulation of the multibody vehicle dynamics models consisting of many bodies and joints, a powertrain model, antiroll bars, and tires. Newton chord method is employed to solve the equations of motion and constraints. The equations of motion and constraints are formulated such that the Jacobian matrix for Newton chord method is needed to be generated and LU-decomposed only once for a dynamic analysis. As a result, only computations which need to be carried out in runtime are residual vectors of the governing equations. Convergence analysis of Newton chord method with the proposed Jacobian generation method is carried out. The proposed algorithm yielded close solutions to exact solutions for a prototype vehicle multibody model in realtime on a 400 Mhz PC compatible.
Efficient Human Motion Planning Using Recursive Dynamics and Optimal Control Techniques
Authors: Lo Janzen , Metaxas Dimitris 
Published: February 2021

Abstract
We present an efficient optimal control based approach to simulate dynamically correct human movements. We model virtual humans as a kinematic chain consisting of serial, closed-loop, and tree-structures. To overcome the complexity limitations of the classical Lagrangian formulation and to include knowledge from biomechanical studies, we have developed a minimum-torque motion planning method. This new method is based on the use of optimal control theory within a recursive dynamics framework. Our dynamic motion planning methodology achieves high efficiency regardless of the figure topology. As opposed to a Lagrangian formulation, it obviates the need for the reformulation of the dynamic equations for different structured articulated figures.
We use a quasi-Newton method based nonlinear programming technique to solve our minimum torque-based human motion planning problem. This method achieves superlinear convergence. We use the screw theoretical method to compute analytically the necessary gradient of the motion and force. This provides a better conditioned optimization computation and allows the robust and efficient implementation of our method. Cubic spline functions have been used to make the search space for an optimal solution finite.
We demonstrate the efficacy of our proposed method based on a variety of human motion tasks involving open and closed loop kinematic chains. Our models are built using parameters chosen from an anthropomorphic database. The results demonstrate that our approach generates natural looking and physically correct human motions.
A New Design Methodology for Planar Vibration Absorbers
Authors: Blanchet Pat , Lipkin Harvey 
Published: February 2021

Abstract
A new methodology is presented for the design of planar vibration absorbers. For the most part, previous methods have dealt with systems constrained to a single degree-of-freedom and require the absorber to be along the line of the exciting force. The presented methodology is more versatile and allows the placement of the absorber as a design freedom. Three specific design techniques for force and couple excitations are detailed along with numerical examples illustrating the results.
On Some Intrinsic Features of the Dynamics of Mechanisms
Authors: Lerbet Jan 
Published: February 2021

Abstract
Using Lie group theory, we propose to analyse the dynamics of closed mechanisms without introducing frames or bases. After a brief presentation of the mathmatical tools, the kinematics of closed mechanisms is devolopped and the manifold of configurations described. It is then possible to obtain the dynamic equations by using the principle of virtual power. An intrinsic Lagrange’s multiplier A is introduced to take the closure equation into account. Explicit linear combinations for the elimination of A are given too. Last, some kinematic relations are given which are usefull for linearisation or for numerical integration.
Sliding Bearing Nonlinear Vibration Prediction
Authors: Jáuregui Juan Carlos , González Oscar M. 
Published: February 2021

Abstract
This study presents a method for analyzing and predicting the jump phenomena of a sliding bearing. The nonlinear behavior is caused by a discontinuity on the stiffness. These conditions are due to the number of rolling elements in contact and the backlash along the perpendicular direction of the motion.
It is shown here that the nonlinear stiffness of the sliding bearing presents jump phenomena. A detailed analysis of the nonlinear stiffness parameters and its effects on the jump conditions are included. In this paper only large displacements are considered.
Numerical results are compared to time domain measurements where the nonlinear behavior is clearly identified. This comparison shows under which condition the system behaves almost as a linear system, whereas under which conditions it behaves highly nonlinear.
Vibration of Moving Flexible Bodies (Formulation of Dynamics by Using Normal Modes and a Local Observer Frame)
Authors: Kawamoto Atsushi , Inagaki Mizuho , Aoyama Takayuki , Mori Nobuyuki , Yasuda Kimihiko 
Published: February 2021

Abstract
This paper deals with the formulation that can analyze vibration noise problems practically in the flexible multibody systems. Many kinds of formulations have been proposed on the flexible multibody systems so far. They are categorized into several groups according to their purposes and coordinate systems. The floating frame of reference formulation is at present the most popular method for general purpose simulations among them. The formulation uses Cartesian coordinates for the position of a body, Euler angles or Euler parameters for the orientations, and modal coordinates for the elastic degrees of freedom. The equations of motion with these different kinds of coordinates are complicated because of coupling between rigid body motion and elastic vibration. On the other hand, the linear theory of elasto-dynamics appears to be simple and could be practical for some limited uses. But it neglects the effect of the elastic deformation on the rigid body motion. In many cases, the effect is significant and essential. In this paper, we propose a new formulation with rigid body modes and a local observer frame (LOF) for large amplitude rigid body motion, and with elastic modes for small amplitude elastic vibration. The LOF is updated properly to compensate the gap between rigid body motion and the LOF motion. The new formulation makes the coupling terms as simple as possible without any loss of the effect of the elastic deformation on the rigid body motion and gives the uniform description in each modal coordinate.
Treatment of Lubrication in Long Bearings for Joint Clearances in Multibody Mechanical Systems
Authors: Ravn P. , Shivaswamy S. , Lankarani H. M. 
Published: February 2021

Abstract
Proper modeling of joint clearance is of great importance in the analysis of multibody mechanical systems. The clearance may be due to wear or imperfection in manufacturing. When there is no lubricant in the clearance, solid-to-solid contact occurs. The impulse due to contact between the links is transmitted throughout the system. The presence of a lubricant avoids such contact, as the hydrodynamic forces developed by the lubricant film supports the loads acting on the bodies and prevents the bodies from coming into contact. In this paper, an analysis of revolute joint clearances in multibody mechanical systems with and without lubricant is presented. Hydrodynamic theory of long bearing is utilized in this study. Unlike the traditional machine design approach, the instantaneous lubricant forces are the unknown and evaluated in terms of the known geometrical position and velocity of the journal and bearing. In the case of analysis of a joint clearance with no lubricant, a modified Hertzian relation is used to model the impact or contact between the journal and bearing, which includes a hysteresis damping term to account for the energy dissipation during impact. The methodology is applied for the analysis of a slider-crank mechanism having a clearance in the piston pin. The simulations are carried out with and without lubricant and the results are compared. It is shown that the lubricant results in a steady motion with fewer peaks in the required cranking moment for the system.
Analytical Reformulation of the Multibody Dynamics of a Satellite
Authors: Sanchez Nestor 
Published: February 2021

Abstract
The topic of dynamics has been somehow reshaped by computational power. The areas of computer algebra and symbolics now allow us to deal with a more involved analytical manipulation of equations. At the same time, the everyday increasing power of numerics put into our hands new tools to solve old problems. In this case, we reformulate the problem of the dynamics of a three body multibody system by using symbolic manipulation of the Newtonian equations, to produce a set of differential equations that can be solve with standard codes. This treatment should produce not only the same results as the numerical approach, but it allows us to use the analytical equations to expand the analysis into design, control and stability. The paper shows the process to build the symbolic code using Maple language, or any algebraic manipulator. The proper equations will be derived to solve for the unknowns angles {ψ,ϕ,θ}, in terms of the prescribed quantities {α(t),β(t),γ(t)t}, and initial conditions. This procedure gives a good idea about the nonlinear response of the satellite to the control parameters. The size of the equations obtained is large. However, considering the type of analysis that could be done with a set like this and the capacity of large computers, it will pay off the extra effort. The codes that could be used for further analysis would find folds, branch points, period doubling bifurcations, Hopf bifurcations, torus bifurcations, by changing the parameters of the governing equation. A large number of important applications will develop in this area in the near future.