Spring-damper Model Research Articles

Hand Modeling and Motion Reconstruction for Individuals

In this paper, we propose a new method of reconstructing hand models for individuals including link structure models, homologous skin surface models and homologous tetrahedral mesh models in a reference posture. The skin surface model is defined as a threedimensional triangularmesh, obtained by deforming a template mesh so as to fit the landmark vertices to the corresponding marker positions obtained by a motion capture system. In this process, anatomical dimensions for the subject, manually measured by a caliper, are also used as the deformation constraints. As for the link structure model, the local coordinate system related to each link consists of the joint rotation center and the axes of joint rotation, which can be estimated based on the deformation of the skin surface of the template model relative to the one of the individual. By using obtained individual hand model, hand postures in a motion sequence are also reconstructed based on the landmark points and the corresponding marker positions obtained from the motion capture system. Virtual spring-damper models located between the landmarks and the markers are used in physically-based simulation for the posture reconstruction.

Dynamic Model of Spindle-Holder Taper Joint of BT40 Holder

The dynamic characteristics of spindle-holder taper joint greatly influencethe performance of machine tools. This paper proposed a 24-DOFs spring-damper model to deal with the dynamic model of spindle-holder taper joint. To identify the stiffness of springs and damping coefficient of damper, a parameter identification method was developed based on the inverse relationship of dynamic matrix and frequency response function matrix. Using modal test and the proposed dynamic model, the taper joint of BT40 holder was studied. At the end of this paper, a case was presented to validate the dynamic model. Because the radial, tangential and axial effects of the taper joint were all taken into considerations, the proposed model provided a higher accurate model of spindle-holder taper joint.

1A1-A08 二関節バネダンパ機構が外乱下の棒高跳びに与える効果(ワイヤ駆動系の機構と制御)

Pole vault is an interesting task because of its high performance using a large elastic element. Although previously we showed that active bending motion is effective to improve pole vault height, it was sensitive to disturbance. In order to stabilize pole vaulting performance, physical feedback is important because of its quick response. Therefore, we focused on musculoskeletal system, especially its bi-articular spring-damper system, and investigated its contribution to stabilization of pole vaulting. We compared pole vaulting performance of a non spring-damper model, a mono-articular spring-damper model and a bi-articular spring-damper model in simulation on the disturbed condition. As a result, we found that the mono-articular spring-damper model and the bi-articular spring-damper model tended to be reduce negative effect of large disturbance at early timing of pole bending motion. In addition, bi-articular spring-damper model had intermediate response characteristics to disturbance between other two models. These results implicate that musculoskeletal system contributes to stabilize pole vault.

Ellipse Contact-Impact with Non-Fixed Position

The purpose of this paper is to study the contact-impact between ellipse and ground. The contact-impact position is non-fixed when the ellipse is rotated. Ellipse equations are built by generalized coordinates. The contact point is estimated by the elliptical geometric characteristics and equations. Do dynamics analysis by the method of continuous processing which uses spring damper mode in this point. This spring damper mode is based on the nonlinear spring damper model of Hunt-Crossley. Friction is ignored in this paper. Finally the numerical solution is given by Matlab.

On the Dynamics of Lubricated Cylindrical Roller Bearings, Part II: Linear and Nonlinear Vibration Analysis

This article is the second part of two companion papers. In the first article, curve-fitted relations of stiffness and damping coefficients of a single roller-to-race contact of lubricated roller bearings were developed. In the present work, these relations are applied to a rotor–bearing system. Two cases are studied to investigate the influence of lubricated cylindrical roller bearings on the vibration characteristics of the rotor system. In the first case, lubricated contacts are simulated as a linear spring–damper model. The overall stiffness and damping matrices are calculated by using the dynamic coefficients of individual load sharing rollers. These matrices are used in the finite element analysis of flexible rotor. In the second case, the nonlinear structural vibration of a lubricated cylindrical roller bearing is studied. Equations of motion of bearing elements are derived using the Lagrange equation. A nonlinear load–deflection contact model developed through the derived curve-fitted relations of dynamic coefficients is used in the equations of motion. Equations of motion are solved by a fourth-order Runge-Kutta integration method. The response of bearing elements under free vibration and due to rotating unbalance is studied for damped and undamped cases. Furthermore, results obtained using elastohydrodynamic finite and infinite contact theories are compared.

Nonlinear dynamic analysis of a rotor-bearing-seal system under two loading conditions

The operating speed of the rotating machinery often exceeds the second or even higher order critical speeds to pursue higher efficiency. Thus, how to restrain the higher order mode instability caused by the nonlinear oil-film force and seal force at high speed as far as possible has become more and more important. In this study, a lumped mass model of a rotor-bearing-seal system considering the gyroscopic effect is established. The graphite self-lubricating bearing and the sliding bearing are simulated by a spring-damping model and a nonlinear oil-film force model based on the assumption of short bearings, respectively. The seal is simulated by Muszynska nonlinear seal force model. Effects of the seal force and oil-film force on the first and second mode instabilities are investigated under two loading conditions which are determined by API Standard 617 (Axial and Centrifugal Compressors and Expander-compressors for Petroleum, Chemical and Gas Industry Services, Seventh Edition). The research focuses on the effects of exciting force forms and their magnitudes on the first and second mode whips in a rotor-bearing-seal system by using the spectrum cascades, vibration waveforms, orbits and Poincaré maps. The first and second mode instability laws are compared by including and excluding the seal effect in a rotor system with single-diameter shaft and two same discs. Meanwhile, the instability laws are also verified in a rotor system with multi-diameter shaft and two different discs. The results show that the second loading condition (out-of-phase unbalances of two discs) and the nonlinear seal force can mainly restrain the first mode instability and have slight effects on the second mode instability. This study may contribute to a further understanding about the higher order mode instability of such a rotor system with fluid-induced forces from the oil-film bearings and seals.

Effects of eccentric phase difference between two discs on oil-film instability in a rotor–bearing system

The operating speed of the rotating machinery often exceeds the second order or even higher order critical speeds to pursue higher efficiency. Thus, the second mode whirl/whip can appear when the operating speeds approach or exceed twice the second order critical speed according to the reference A. Muszynska (2005) [1]. In this study, we investigate how the eccentric phase difference between two discs influence the oil-film instability (the first/second mode whirl/whip) in a rotor–bearing system. Firstly, a lumped mass model with 20 degrees of freedom (DOFs) of a rotor system with two discs considering the gyroscopic effect is developed. The graphite bearing and sliding bearing are simulated by a spring-damping model and a nonlinear oil-film force model based on the assumption of short bearings, respectively. The research focuses on the effect of eccentric phase differences of two discs on the onset of instability and nonlinear responses of the rotor–bearing system by using the bifurcation diagrams, spectrum cascades, vibration waveforms, orbits and Poincaré maps. The results show that the instability speed increases when the eccentric phase difference becomes larger and it increases almost linearly when the eccentric phase difference is greater than 20°. Moreover, complicated combination frequency components related to the first and second mode whirl/whip frequencies are also excited and the transfer of the self-excited vibration energy between the first and second mode whips can be observed under a larger eccentric phase difference. The study may contribute to a further understanding of the oil-film instability of such a rotor–bearing system.

Toward Photorealism in Endoscopic Sinus Surgery Simulation

Endoscopic sinus surgery (ESS) is the surgical standard treatment for chronic rhinitis/rhinosinusitis and nasal polyposis. There is a reported complication rate of 5-10% associated with this type of surgery. Simulation has been advocated as a means to improve surgical training and minimize the rates of complication and medical error. This study aimed to show how a virtual reality ESS simulator was developed, with particular emphasis on achieving satisfactory photorealism and surgical verisimilitude. Sinus computed tomography scans were processed to create a triangle-based three-dimensional mesh model; this was incorporated into a spring-damper model of thousands of interconnected nodes, which is allowed to deform in response to user interactions. Dual haptic handpiece devices were programmed to simulate an endoscope and various surgical instruments. Textures and lighting effects were added to the mesh model to provide an accurate representation of the surgical field. Effects such as vasoconstriction in response to "virtual" decongestant were added. The final simulated endoscopic view of the sinuses accurately simulates the moist and glossy appearance of the sinuses. The interactive tissue simulation system enables the user to interactively cut and remove tissue while receiving accurate haptic feedback. A working prototype of the simulator has been developed that leverages recent advances in computer hardware to deliver a realistic user experience, both visually and haptically. This new computer-based training tool for practicing ESS provides a risk-free environment for surgical trainees to practice and develop core skills. The novel use of customized precision force feedback (haptic) devices enables trainees to use movements during training that closely mimic those used during the actual procedure, which we anticipate will improve learning, retention, and recall.

A Tool for Modeling and Analysis of BTF Toolholder-Spindle System

This paper introduces the development of a tool for modeling and analysis of BTF toolholder-spindle system, based on ANSYS software. The tool is developed in parametric design method. Most parameters are defined automatically except a few parameters requiring users to input, which improves the modeling efficiency greatly. The interface joint of the BTF toolholder-spindle is established by adopting spring-damping model and defined by custom element unit Matrix27. The proposed model reflects the characters of the joint on the properties of BTF toolholder-spindle effectively. A case study is given to verify the efficiency and accuracy of the developed tool.

Detection of tissue properties using a piezoelectric vibration-based syringe

For safety improvement purposes, detection of tissue properties at the tip of the needle in real-time is helpful in controlling the movement of the needle in the operation of invasive surgical tools. According to the energy-based force model, the mechanical impedance of tissue can be represented approximately by a spring-damping model. In this study, a vibration-based syringe which adopts piezoelectric elements to vibrate the needle is proposed to identify tissue properties. In principle, by measuring the input electrical impedance of the vibration-based syringe, the mechanical impedance of tissue can be detected indirectly while the syringe exerts a vibration on the tissue. The model of the piezoelectric driven syringe and the procedure for evaluating the electromechanical interaction are given, and the mechanical impedance of tissue is evaluated by simulation. The proposed detection method has potential for applications of identifying tissue properties in epidural punctures and estimation of the degree of ablation in thermal surgery systems.

DYNAMIC SIMULATION OF BIPED WALKING ON LOOSE SOIL

Most of the studies on biped walking on even or uneven terrain have assumed stiff ground. This paper proposes a dynamic contact model between foot and loose soil. The proposed contact model provides sinkage of the foot, slip of the sole and reactive force acting on the foot on loose soil. Sinkage of the foot and slip of the sole are calculated utilizing terramechanics model, which are important characteristics for biped robot to walk on loose soil. Reactive force acting on the foot on loose soil is calculated using spring-damper model between the foot and the deformed ground. By applying the proposed contact model to a usual dynamics simulator, dynamic sinkage and slip phenomenon during biped walking on loose soil are simulated. Additionally, in order to verify the simulation result, experiments were carried out using a humanoid robot.

A hybrid haptic guidance model for tank gunners in high precision and high speed motor skill training

Haptic-based paradigms for human motor skill training which include virtual fixture, record-play method, shared control scheme and haptic disturbance have been proposed and widely used for applications like surgery, assembly, rehabilitation, motor skill and so on. However, no haptic-based training scheme applies to all types of human motor skills that new ideas and new approaches should be explored for some special training tasks. For example, tank gunners have to be rigorously trained to be able to complete the most accurate manipulation in the shortest possible time. Accuracy and operating speed are both critical for them to grasp the skill; therefore, tank gunnery is defined as a type of high precision and high speed human motor skill. In this paper, a hybrid spring-damper model which fuses haptic fixture and record-play is presented to simultaneously train accuracy and operating speed. The training approach is suitable for novices at all levels since force feedback is decomposed into two components: one for training accuracy, the other for training speed. The virtual envelope depicting is chosen as the training task for novices to validate the effectiveness of the proposed haptic-based scheme in high precision and high speed skill training. Experimental results indicate that force feedback generated based on the hybrid model can benefit novices in fast improving performances on tank gunnery.

Spring-Damping Model of Moving Boundary in SPH

Traditional boundary force method of SPH applies Lennard-Jones equation to compute the virtual repulsive force by calculation of molecular force. But this method is strongly non-linear and easily leads to not convergence in calculation. In this paper, spring-damping boundary force model is utilized to solve the problem of moving boundary. Using spring-damping boundary force model, rotary moving boundary of screw channel-driven has been simulated and the result is well consistent with the simulation of Fluent. Comparing with traditional boundary force equation, this model is long-term stable and its effectiveness has been validated by case study.

A Class of Contracting Stream Operators

In (Tucker, J. V. and Zucker, J. I. (2007) Computability of analog networks. Theoret. Comput. Sci., 371, 115–146; Tucker, J. V. and Zucker, J. I. (2011) Continuity of operators on continuous and discrete time streams. Theoret. Comput. Sci., 412, 3378–3403), Tucker and Zucker present a model for the semantics of analog networks operating on streams from topological algebras. Central to their model is a parametrized stream operator representing the network along with a theory that concerns the existence, uniqueness, continuity and computability of a fixed point of that stream operator. We narrow the scope of this paper from general topological algebras to algebras of streams that assume values only from a Banach space. This restriction facilitates the definition of a fairly broad class of stream operators to which the theory described in the above two papers applies. As a demonstration in their original work, the authors provide two case studies: analog networks that model the behavior of simple mass-spring-damper systems. The case studies showcase the theory well, but they seem to require the imposition of somewhat peculiar conditions on the parameters (the masses, the spring constants and the damping coefficients). The extra conditions—while not catastrophic to the case studies—make them somewhat unsatisfying. We show here that while their original mass–spring–damper models do not fall within our new class, they can be trivially reconfigured into equivalent models that do. This modification obviates the extra conditions on the parameters.

The AETOURNOS Project: Using a Flock of UAVs as a Cyber Physical System and Platform for Application-driven Research

This position paper presents the Airborne Embedded auTonomOUs Robust Network of Objects and Sensors (AE-TOURNOS) platform. We have two main goals: firstly conducting research in swarming/flocking of UAVs, mixing robotics, wireless sensor and actuator networks, and secondly using this as an application domain and a challenge/demo platform for other researches. After giving an overview of the project context, questions and contributions, we give details about our first attempt to implement an autonomous flocking behavior based on a spring-damper model in sim–ulation, combining our first physical experiments and developments with the potential hardware. The lessons learned help us build a research and action plan for the year to come.

Modeling and Simulation of Clamp Band Dynamic Envelope in a LV/SC Separation System

The clamp band system is a typical locked and separated device of the launch vehicle (LV) / the spacecraft (SC), and its release-separation process is one of the important factors that affect the LV/SC separation movement. A nonlinear spring-damper model was employed to describe the contact-impact behavior between the V-segment of the clamp band and the LV/SC interface, and lumped mass method was used to depict the clamp band. By using ADAMS, a dynamic model of the clamp band system was established. The simulation results show that the impulse of the explosive bolts and the stiffness of lateral-restraining springs have significant effects on the clamp band dynamic envelope. The shock of the satellite-vehicle separation is very vulnerable to the clamp band pretension and the friction coefficient between the V-segment and the LV/SC interface.

Verification of equivalent mass–spring–damper models for crowd–structure vibration response prediction

This paper describes the modal testing and in situ vibration monitoring of a high profile UK stadium during 2004 and 2005, including multiple concerts and sports events. The paper explains how current design guides pertaining to crowd dynamic loading of grandstands can be practically implemented using experimental modal data or finite element (FE) models. Three major pieces of guidance are considered: Canadian, ISO, and UK. Particular attention is given to new UK Recommendations as they are a major diversion from other methods and have yet to be robustly verified against real events on full-scale structures. This paper is therefore a unique verification exercise for all three guidelines because it makes use of rare combined in situ video and structural vibration response data pertinent to crowd dynamic loading of grandstands. Canadian guidance is found to predict the order of magnitude of responses well but lacks reliable precision, whilst the UK Recommendations are found to be very good at recreating res...

Study on Flux-Pinned Interaction between High-Temperature Superconductor and Permanent Magnet and Flux-Pinning’s Self-Stability

Flux pinned effect (FPE) takes place in high-temperature superconductors (HTSC) when being cooled below critical temperature in magnetic field and appears the self-stable with resisting the disturbing and recovering the initial equilibrium position , even in the failure of control, which is ideal for the activities of spacecraft. In order to investigate the special phenomenon, the image-dipole model (IDM) for interaction and spring-damper model (SDM) for system are adopted in this paper. IDM are based on two assumed images and SDM linked with flux-pinned interface is based on virtual spring and damper. Two models effectively deal with the flux-pinning and give some clear expressions. When moving along single orient, this paper demonstrates the pairs’ self-stability based on two models.

Application of viscoelastic hybrid models to vehicle crash simulation

This paper presents an application of physical models composed of springs, dampers and masses in various arrangements to simulate a real car collision with a rigid pole. Equations of motion of these systems are being established and subsequently solutions to obtain differential equations are formulated. We begin with a general model consisting of two masses, two springs and two dampers and illustrate its application to modelling fore-frame and aft-frame of a vehicle. Hybrid models, as being particular cases of two-mass–spring–damper model, are elaborated afterwards and their application to predict results of real collision is shown. Models’ parameters are obtained by fitting their response equations to the real vehicle's crush coming from the data measurement analysis. For the full-scale experiment and created models we perform comparative analysis of both kinematic and energy responses.

Research on Dynamic Wear of Revolution Joint with Clearance for Mechanical System

In order to study the dynamic wear of revolution joint with clearance in mechanical system, the dynamic model of mechanical system with joint clearance is presented. The clearance model is established based on clearance vector model. The contact dynamic model in joint clearance is established using the nonlinear equivalent spring-damp model and the friction effect is considered by using correction Coulomb friction model. And then the models are incorporated into dynamics simulation software ADAMS, the dynamics model of mechanical system with joint clearance is established based on ADAMS and the simulation is made. Furthermore, the contact dynamics parameters are drawn and calculate the wear volume of joint clearance based on Archard’s wear model. Finally, a crank follower mechanical system is used to perform the simulation and the dynamic wear characteristics are analyzed.