This presentation gives a brief review of past and present challenges in the multibody modeling and the dynamic analysis of wheeled vehicles. The emphasis of the presentation is on the weakest link of a vehicle model--the tires. The evolution of tire models, like any other component in a multibody model, has experienced major advances during the past three decades. Early tire models were comprised of simple analytical expressions or they were purely empirically based curve fitting procedures. Recent models are more complex and have moved towards representing the structure of a tire in more detail. In this presentation we investigate the possibility of employing existing high-resolution finite-element tire models in multibody dynamics.

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Virtual Prototyping technology is very important in new product development, and it's a main trend for manufacturing industry. It's necessary to open this kind of course for cultivating talents of multi-body dynamics. From teaching and test links the students' product development ability based on multi-body dynamics platform can be increased. Very year there are about one thousand and two hundred students should partake this course learning. This course is divided in two parts of theoretical study and test link, and the curriculum setup is based on Recurdyn software. In this paper, some study methods, design examples, design idea and software are presented and an effective education procedure is discussed. In this paper some samples can be provided such as chain, V-Bbelt Tutorial and MTT2D Tutorial with IGES Import virtual prototype. Some design procedures and methods can be offered based on Recurdyn software. as follows: create new models, set working condition, create design points, create all parts models, imposing forces and constraints, test model, refining model, iterating model, optimize model and customize interface. From the above design procedures, the virtual prototype can be gotten and has been optimized design analysis. From the design results of virtual prototype, physical model machine can be made. The above design procedures and methods can be applied for all kinds of virtual prototype design. From the above training, the students can have a kind of design concept, and this is very important for students to resolve some actual problems. The students can engage in researching and technology development work. When they go to operating post, they can bring these design ideas to their work and can increase working efficiency. The student is user of any new technology because of its special education background. So education methods and study condition are very crucial. So the course of multi-body dynamics is very important for the students' development and innovation of manufacturing industry.

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Signing for tracked vehicles that are operated on unpaved roads or soft ground, it is important to analyze the interaction between a machine and soil. In vehicles with a crawler such as a bulldozer and loading shovel, interaction analysis is done for the decrease of examination frequency and the performance increase. However, this is difficult to analyze because the interaction and the soil behavior such as compression, shear, friction and soil adhesion, are complex. Recently, with improvements of computers, the method of simulation concerning powder behavior has progressed and the simulation of complex particle behavior has become possible in the field of powder technology. As such, the Distinct Element Method (DEM) is received attention in the field of terramechanics. DEM uses various simulations analyzing the interaction between a machine and the ground. However, conventional DEM has the problem of a sphere approximation of each particle. This means that particle roughness of the soil is not considered. Soil behavior, especially 3-D behavior, is influenced by particle roughness because the soil condition is changed by compaction. In this research, the soil model considering particle roughness is built to express the varying shape of soil particles. Particle roughness is expressed by using "particle clusters," which contain some sphere particles as an agglomeration. Vehicles running on soft ground get traction force by shear resistance from the ground. It is reported that the shear resistance is maximized under the front-idler of the vehicle. In this research, attention is focused on the interaction under the front-idler, that is, traction of the soil by a grouser in the driving system. To validate the interaction simulation between grouser and soil by using this soil model, 3-D traction simulations and experiments were carried out. Comparing the results of the simulations and experiments in soil behavior, it was shown that simulation models conformed closely to experimental soil behavior in shear face and soil flow. Also, it could be found that traction resistance on the simulations was qualitatively similar to that on the experiments. Therefore, this soil model considering particle roughness was validated.

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Since 1960 in Japan, accidental injury has been the leading cause of the death of children. The number of injuries that require hospitalization is estimated to be 20-175 times more than the number of deaths. In addition, the number of injuries that need visits to the doctor is estimated to be 1900-15,800 times more than the number of deaths. Thus, accidental injury to children is a health concern. Effective countermeasures against such accidents are required for accident prevention and mitigation. Currently, much accident data about children have been collected by Advanced Industrial Science and Technology. Using these data, such accident data statistics as type, location, and the region of the body injured in the accident have been studied. However such information is often fragmented. For instance, although injured body regions and locations where the accidents occurred are available from the data, how the accidents and injuries actually occurred often remains unclear. Therefore, suggesting effective countermeasures and evaluating their effectiveness is occasionally difficult. In this study, we simulated accident reconstruction to understand accident situations and to propose and evaluate effective countermeasures. A multibody child human model was constructed and used for this simulation. Its geometry was based on the geometry of an adult polygon model. The joint characteristics and contact stiffness of this child human model were calculated by scaling the adult characteristics from the literature. Such physical characteristics as the mass, the position of the center of gravity, and the moment of inertia were calculated by volume on the assumption that humans have uniform density. This child h u m a n model's biofidelity was evaluated by a series of impact test simulations that represented the evaluation with a Q3 dummy. Using this validated child human model, we reconstructed accidents based on accident data. Such accident situations as child's posture were identified and reconstructed by an optimization technique. As a result, a multi-body child hum an model was reconstructed based on the height and weight data of injured children taken from the accident data. The mass ratio of each body segment and the child human model's geometry were evaluated. The results clearly show that each body segment of the child human model has reasonable geometry and mass ratio. In addition, most impact simulations showed reasonable biofidelity of the child human model, although the result of the thoracic impact simulation indicated that the child human model has a stiff thorax. The child human model's posture and location where the accidents occurred were identified by an optimization technique. The injured region and the injury index estimated by accident simulation agreed well with the accident data.

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This paper discusses stability and performance of a full-train system employing inerters. First, a twenty-eight degree-of-freedom (DOF) train model was built on AutoSim^<TM> and linearized for analysis in Matlab^<TM>. We then optimized the critical speed of the system and showed that the critical speed can be significantly improved by employing inerters. Third, we discussed the system's transient responses and illustrated that the settling time can be greatly shortened by using inerters. Lastly, a novel mechatronic inerter was considered for further improvement of the train system.

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This study deals with the modeling and analysis method for the elastohydrodynamic lubrication system such as journal bearing coupled with flexible multibody dynamics (or Multi-Flexible-Body Dynamics, MFBD) in order to analyze dynamic bearing lubrication characteristics such as pressure distribution and oil film thickness. In order to solve coupled fluid-structure interaction system, this study uses two main parts. The one is the MFBD solver and the other is elastohydrodynamic module. The elastohydrodynamic lubrication module developed in this study transmits the force and torque data to the MFBD solver which can solve general dynamic systems that include lots of rigid and flexible bodies, joints, forces, and contact elements. And then, the MFBD solver analyses the position, velocity, and accelerations of the flexible multibody system with the pressure distribution results of the elastohydrodynamic module. And the MFBD solver transmits the position and velocity information to the elastohydrodynamic solver continuously. Moreover, other functions such as mesh grid control and oil hole and groove effects are implemented. Finally, numerical examples for bearing lubrication systems are demonstrated.

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Knee joint kinematics analysis using an optimal sensor set and a reliable algorithm would be useful in the gait posture analysis. An original approach for ambulatory estimation of knee joint kinematics in anatomical coordinate system was presented, which was composed of physical-sensor difference based algorithm and virtualsensor difference based algorithm. To test the approach, a wearable monitoring system composed of accelerometers and magnetometers was developed and evaluated on lower limb. The flexion/extension (f/e), abduction/adduction (a/a) and inversion/extension (i/e) rotation angles of the knee joint in the anatomical joint coordinate system were estimated. In this method, since there was no integration of angular acceleration or angular velocity, the result was not distorted by offset and drift. And the three knee joint angles within the anatomical coordinate system were independent of the orders which must be considered when Euler angles were used. Besides, since there were no physical sensors implanted in the knee joint based on the virtual-sensor difference based algorithm, it was feasible to analyze knee joint kinematics with less numbers and kinds of sensors than ever before. Compared with result from the reference system, the developed wearable sensor system was available to do gait analysis with fewer sensors and high degree of accuracy.

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The modeling for the total system of the hybrid excavator is presented by introducing the flexible multibody system with the electric-hydraulic drive system, which consists of the engine, the battery system, the generator, and actuators driven by the electric-hydraulic power train system. The attachment and the hydraulic system of the hybrid excavator are formulated by introducing the nonlinear finite element analysis. The power electronic system, which includes the battery system, the generator, the convertor, the motor, and the controller, is modeled by employing the analogy of the hydraulic circuits. Firstly, the dynamic simulations are performed by using this model in the boom system for the operability design. It is demonstrated that the vibration control is effective to reduce the residual vibration of the boom. Secondly, the dynamic simulations are carried out for the energy saving performances of the hybrid excavator, which are conducted on the actual operation such as the excavating, and so on. It is verified that the simulation results for both the power and the energy saving performance fairly agree with the experimental ones. The energy saving effects of the hybrid excavator can be expected to be more than 40% for the actual operation comparing with the conventional one.

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Recently, HILS(Hardware in the Loop Simulation) has been investigated in the field of the multibody dynamics, which combined the MBD simulation with the actual mechanical system. The fast calculation is necessary for the HILS system in order to require the real time simulation. This paper presents a fast simulation technique using the improved domain decomposition method with the iteration in the flexible multibody system in which the flexible linkage system and the hydraulic drive system are coupled with each other.

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A combined multibody and finite element approach is given to solve the dynamic interaction of a Shinkansen train (high-speed train in Japan) and the railway structure including post-derailment during an earthquake. The motion of the train is expressed in multibody dynamics. Efficient mechanical models to express interactions between wheel and track structure including post-derailment are given. The motion of a railway structure is modeled with various finite elements and also with rail and track elements expressed by multibody dynamics and FEM. Based on the present method the computer program has been developed for the dynamic interaction of a Shinkansen train and railway structure including post derailment during an earthquake. Numerical examples are demonstrated.

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Generally speaking, the mechanical systems can be classified into two main groups: open-loop and closed-loop systems. In this investigation, a recursive method is developed for the dynamic analysis of open-loop flexible systems. The nonlinear generalized Newton-Euler equations are developed for flexible bodies that undergo large translational and rotational displacements. These equations are formulated in terms of a set of time invariant scalars, vectors and matrices that depend on the spatial coordinates as well as the assumed displacement fields, and these time invariant quantities represent the dynamic coupling between the rigid body motion and elastic deformation. The method to solve equations of motion for open-loop systems consisting of interconnected rigid and flexible bodies is presented in this paper. This method applies recursive method with the Newton-Euler method for flexible bodies to obtain a large, loosely coupled system equation of motion. In this paper, the computer implementation of dynamic analysis method in flexible multibody dynamics is described. The computational procedures which are used to automatically construct and numerically solve the system of loosely coupled dynamic equations expressed in terms of the absolute and joint coordinates are discussed. This computer 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 nonlinear Coriolis and centrifugal forces associated with the absolute, joint and elastic coordinates. The force module is used to numerically evaluate the generalized external and elastic forces associated with the absolute, joint and elastic coordinates. Computational efficiency is achieved by taking advantage of the structure of the resulting system of loosely coupled equations. The absolute, joint and elastic accelerations are integrated forward in time using direct numerical integration methods. The absolute positions and velocities can then be determined using the kinematic relationships. The solution techniques used to solve for the system equations of motion can be more efficiently implemented in the vector or digital computer systems. The algorithms presented in this investigation are illustrated by using cylindrical joints that can be easily extended to revolute, slider and rigid joints. The nonlinear recursive formulations developed in this paper are demonstrated by a numerical example.

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According to the problem of a truck steering heaviness, the paper built the truck virtual model and steering efforts test environment by multibody dynamics software ADAMS, and improved the steering system. Using the virtual model and virtual test environment, the steering efforts virtual tests had been finished. At the same time, to verify the simulation results, the steering effort road tests of the improvement truck had been processed. The result shows that simulation and road test had good consistency, the improvement of the steering system improved the truck steering efforts.

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For a typical mechatronic system, the mechanical system and control system is designed in serial, which makes it difficult to design the mechatronic system efficiently and perfectly. In order to foresee the final control performance of the two-axis Fast Steering Mirror system (FSMs), Mechanical-Control Co-simulation Method is presented in this paper. The Mechanical-Control Co-simulation Method is taken by the Adams and Matlab software together. Firstly, the dynamic model of FSMs mechanical system is built in Adams exactly. Secondly, Mechanical-control Co-analyzing Model is set up in Matlab/simulink environment with Adams/control interface toolbox. Thirdly, parameters of the mechanical system are identified and the controller is designed, and then, the open-loop and close-loop control performance is studied in detail. FSMs is machined and assembled, and the open-loop and close-loop performance is tested to validate the accuracy of the Mechanical-Control Co-simulation Method. Experimental results show that the difference of resonance frequency between the simulation model and experiment model is less than 5%, and the difference of bandwidth between the designed and the tested is less than 15%. These omissions in no way impacted the general validity of the work or concept presented in this thesis.

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This research presents modeling techniques of a stabilized remote controlled weapon system on the naval ship using multi-physics simulation. Multibody model, aero-hydro force interaction, and control interface are incorporated with each other. In order to verify the stabilization of orientation of remote controlled weapon system, the results from the dynamic model incorporated with MATLAB/Simulink are compared with the results from actual 6-DOF motion simulator. A shock absorber of the gun is essential of reducing the fire shock and dynamic model of shock absorber is characterized by the stiffness and damping constants. In order to obtain the actual damping and stiffness constants, a vibration experiment for the shock absorber of the gun is performed. In order to make the dynamic model of a naval ship enable to float on the sea, aero-hydro force elements are used. Also a wave force modeling technique is proposed in order to simulate wave motions in the sea.

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A robust design optimization of the convertible roof module mechanism is presented under consideration of the production uncertainty that has influence on the kinematic behavior of the convertible roof module mechanism. Random design variables are the positions of joints of the mechanism with uncertainty. In general, as the design goals for those mechanism behaviors are represented as the deviations over the roof module movements, it is very difficult to evaluate the analytical design sensitivity because the deviation is defined by using the max-value and the min-value over the parameter interval. Thus, this study introduces a meta-model technique to avoid the difficulty. Also, the sample variances for the design goals are approximated from those meta-models. In addition, a sequential approximation optimization technique is used to solve a robust design problem for the convertible roof module mechanism. The robust design problem has 8 random design variables with uncertainty. The proposed approach requires only 87 evaluations until converged.

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In a time history analysis of multibody system, time step size in numerical integration has to be appropriately decided to keep accuracy and stability. As they are controlled by the product of step size and the absolute maximum eigenvalue of the system, it is important to investigate the eigenvalues. In this paper an eigenvalue equation is derived and solved for typical models of nonlinear multibody system with Baumgarte's constraints, then the effect of its eigenvalues to the stability is confirmed by a time history analysis. As a conclusion it is found that (1) Eigenvalues are obtained by a linearized equation , and they can be used to evaluate the stiffness of a system. (2) Baumgarte's constraints expressed as Φ+2αΦ+β^2Φ=0 have the eigenvalues which equal the roots of the characteristic equation s^2+2αs+β^2=0. When α=β, its mode has the critical damping, which means the constraint errors reduce fast, so it is recommended that α=β. (3) As the eigenvalues come from Baumgarte's constraints affect the numerical stability as well as the physical one. The values α(=β) are desirable to be large, but less than the maximum physical eigenvalue.

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Structural optimization based on durability values is an important tool for the design of light weight structures. One essential part of the optimization loop is the Elastic Multibody System (EMBS) simulation. An important issue for the simulation of the EMBS is the automated reduction of the flexible body's degrees of freedom. Therefore, totally automated Krylov-subspace based reduction processes for mechanical systems are introduced. Besides, an H_2-optimal SOIRKA algorithm is compared with a Second Order Adaptive Global Arnoldi (SOAGA) algorithm. For the automated reduction process error estimation is necessary. Three different error estimators are introduced and compared. In addition, automated error controlled reduction with snapshot-based approximation of frequency-weighted Gramian matrices is a suitable reduction scheme. Advanced basis construction schemes from Reduced Basis methods, e.g. the Greedy and the adaptive Greedy algorithm, improve and accelerate the reduction process. A numerical example demonstrates the approximation capability in the frequency domain.

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Shake tables are used for studying the effects of vibration or evaluating the physical properties of materials or structures. In this paper, cross-talk phenomenon in a two-axis electro-dynamic shake table utilizing hydrostatic oil bearings is examined by both experimental and multi-body dynamics (MBD) approaches. Once cross-talk begins, the performance of the shake table significantly degrades. In this investigation of cross-talk phenomena, first, experiments were conducted and then simulation analyses were carried out. The authors improvised and approximated an oil bearing element to use with a general purpose MBD software. This paper describes the modeling of the oil bearing, the mechanical system and the electrical system. The results of experimental studies using an actual shake table and computer simulations were compared. Acceleration responses are in fairly good agreement under specific conditions. Mechanisms of the cross-talk were partly elucidated in terms of natural frequencies and mode shapes with respect to the change of the vertical location of the horizontally directed actuating force or the change of the oil film thickness. These studies also proved the usefulness of using MBD for analyzing the coupled mechanical and electrical systems. Due to the lack of a hydrostatic oil bearing element in RecurDyn at the time of this study, the authors employed nonlinear springs to simulate the hydrostatic behavior of the oil bearings.

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The accurate knowledge of High-speed motorized spindle dynamic behavior during machining is important in order to ensure the reliability of machine tools in service and the quality of machined parts. More specifically, the prediction of stable cutting regions, which is a critical requirement for high-speed milling operations, requires accurate estimation of tool/holder/spindle set dynamic modal parameters. These estimations are generally obtained through the Frequency Response Function (FRF) measurements of the non-rotating spindle. However, significant changes in modal parameters are expected to change during operation due to spindle high-speed rotation. The spindle modal variations are highlighted through an integrated dynamic high-speed spindle-bearing system finite element model taking into account rotor dynamics effects. The dependency of dynamic behavior on speed range is then investigated and determined with accuracy. The objective of the proposed paper is to validate these numerical results through an experimental-based approach. Hence, an experimental set up is elaborated to measure the rotating tool vibration during machining operation in order to measure the spindle modal frequencies variation with respect to spindle speed in an industrial environment. The identification of spindle natural frequencies under rotating condition is challenging due to the low number of sensors and the presence of many harmonics in the measured signals. In order to overcome the mentioned issues and to extract characteristics of the system, the spindle modes are determined through a 3 step procedure. First, spindle modes are highlighted using the Frequency Domain Decomposition (FDD) technique with a new formulation at the considered rotating speed. These identified modes are then analyzed through the value of their respective damping ratio in order to separate harmonics component from structural spindle natural frequencies. Finally, the stochastic properties of the modes are also investigated by considering the probability density of the retained modes. Results show a good correlation between numerical and experimental-based identified frequencies. The spindle-tool identified modal properties during machining allow considering the numeric model to be well representative of real dynamic effects during machining. Using this model, a new stability lobe diagram is proposed. By integrating the predicted model in the chatter vibration stability law, which indicates whether the design would lead to a chatter vibration-free cutting operation, accurate spindle cutting conditions can be predicted.

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In order to tackle with the problems surrounding the environment, the aged society and the individual mobility right, the new type of vehicle which is compact and convenient is expected to be developed. The authors have been investigated such a vehicle called Personal Mobility Vehicle (PMV), which is friendly for human and the environment. In this paper, we proposed the two-wheeled inverted pendulum vehicle moved by human pedaling. The basic mechanism of this new vehicle consists of the system of the stabilization control for inverted pendulum and the pedaling torque by a human. This system has following benefits. It realizes the longer usage of battery than the conventional one thanks to the human power. It is a healthy vehicle due to the pedaling and the seating style makes the driver longer travel than standing. From the academic point of view, it is very important to investigate the interaction with the control of the two-wheeled inverted pendulum vehicle and the human motion. We analyzed the two types of the drive system. One is the mechanical drive system and the other is the electric drive system. The mechanical drive system has the chains between the gear at the pedal and the gears at the wheels. The in-wheel motors are used for the stabilization. As for the electric drive system, the electric generator generates electricity by pedaling and the produced energy is stored by the battery. The in-wheel motors are rotated by the electricity comes from the battery. In the numerical simulation, the vehicle is stabilized by an optimal controller. The influence of the constant pedaling torque and variable one on the stabilization control were compared. It was shown that the variable pedaling torque became the disturbance to the inverted pendulum vehicle and the torque for the stabilization would be necessary according to the disturbance. Therefore, it is found that the electric drive system which drives the in-wheel motors by the less varying torque command from the battery is more effective than the mechanical drive system that directly convey the human power to the wheels. Finally, we confirmed the basic motion of the proposed vehicle by using the prototype vehicle. The vehicle was successfully stabilized by the controller and moved by the human pedaling

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Dynamic behaviours of nonlinear oscillator originated from the viscoelastic arch described by fractional-order differential are presented in this paper. The background of the research is based upon two engineering practices. One is that the viscoelastic features of some polymeric materials can be accurately modelled by fractional calculus constitutive law. The other, both geometrical and material nonlinearity of some arches can not be neglected in many cases such as the vibration with large displacement or large strain and the vibration control by means of polymeric dampers . The simplified Duffing-like model of the arch with nonlinear damping described by fractional derivative constitutive law was carefully studied here. The results show that because of both geometrical nonlinearity and nonlinear damping the chaotic vibration of the arch appears evidently in forced vibration. And the stronger damping from nonlinear fractional derivative obviously affects the dynamic behaviour of nonlinear fractional differential arch.

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Composite material is made by two or more different materials with different properties by physical or chemical method. Composite material possesses special features which the materials compose it don't have. Stiffness, strength and thermal properties of composite material are promoted obviously compared with isotropic material. Due to the non-symmetric fiber layer-ups, additional bending deformations may occur in case that the composite beam is applied with centrifugal force or uniform thermal force, which has significant effect on dynamic performance of the multi-body system. In this paper, the influence of the additional bending deformation caused by centrifugal force and temperature variation on the dynamic performance of composite flexible multi-body system was investigated. Based on constitutive and nonlinear strain-displacement relation, variational dynamic equation for each composite planar beam was established by using virtual work principle and finite element method, and then dynamic equations for composite flexible multi-body system were derived. Simulation of the crank-slider system shows that for non-symmetric composite beams, difference i n the elastic modulus and thermal expansion coefficient may lead to additional bending deformation, which would significantly influence dynamic performance of the system.

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The recently presented formulation in the field of railroad multibody dynamics, called moving shape functions method, allows to model the track flexibility in a very efficient manner. In this method the rail deformations are described using shape functions defined in a trajectory frame of reference. Results of the transient and steady curving and its stability for an unsuspended wheelset travelling on flexible curved tracks are shown.

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In this paper, we compared several kinds of matrix libraries on a real-time analysis environment. The computational speed of multibody dynamic analysis depends on the number of bodies and constraints and the eigenfrequency of the system to be analyzed, and it is necessary to enhance the computational efficiency to realize real-time analysis of a large size system or of high frequency phenomena. Our real-time simulation environment of this study was with xPC Target, which is one of the MATLAB products. First, we evaluated the performance of matrix libraries by solving large-size linear equation consisting of random numbers. Next, the matrix libraries were embedded to real-time multibody dynamics code developed by authors and the computational time was evaluated. The simulation model was multiple pendulums model and we investigated relationship between calculation performance and the number of bodies. Finally we analyzed vehicle dynamics as an example of actual multibody system, and the performance of using matrix libraries is discussed.

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Feed-forward control designs based on quasi-static deformation compensation and exact model inversion for end-effector trajectory tracking are presented. They are tested by simulation of a very flexible two arm manipulator. With both approaches good results for end-effector trajectory tracking are obtained. A significant improvement of the inverse model approach is achieved by inclusion of the elastic rotation of the first arm in the system output description. This yields the far best accuracy of the tested approaches.

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The conventional friction force model is used in many kinds of contact algorithms. The friction coefficient of the conventional friction force model is only a function of relative velocity. When you simulate a simple contact model, in which a body is on a sloped surface, if the friction coefficient between the body and sloped surface is less than the static friction coefficient, the body should be stuck. But in the case of conventional friction force model, the body will be sliding because the relative velocity must have a non-zero value in order to generate the friction force. In order to solve this kind of problem, the stick-slip friction force models have been developed by many researchers. In the case of stick-slip friction force model, the body can be stuck on the sloped surface because the friction force will be a non-zero value, even though the relative velocity approaches zero. In this paper, the stick-slip friction model is applied in the contact algorithm of multi-body dynamics (MBD) systems and two friction models are compared. From the applied stick-slip friction model, we can get more realistic results and improved solving speed.

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Recently, the computer simulation becomes more important to reduce the development cost and the lead time. In many fields, the virtual prototype using computer simulation has already replaced the real prototype. However, in the mechatronics field, there are still difficulties in using the virtual prototypes because the mechatronics is the inter-disciplinary system which includes the several different fields such as mechanical field, electrical field. The main reason is that it is difficult to connect the different disciplinary environments each other and visualization of them is also difficult. So, it is needed to develop an easy environment which can resolve this difficulty. This study proposes the inter-disciplinary simulation environment which includes the firmware and the mechanical system. Since it is very difficult to test and debug the firmware and the hardware together, a virtual environment using CAE and CASE technologies is desirable. In this study, an example of a robot using LEGO Mindstorms^[○!R] will be used. The virtual environment to develop, test and debug firmware will be proposed using RecurDyn(CAE), ZIPC(CASE) and Mindstorms

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Muscular moment arm length as a dynamic muscular parameter is the foundation of biomechanical analysis of human musculoskeletal system. The purpose of this study is to estimate individual dynamic muscular moment arm length of lower limb in the sagittal plane during gait. In the paper, a series of regression equations obtained by inputting skeletal morphological parameters of lower limb was structured to calculate muscular origin-insertion coordinates in musculoskeletal coordinates system. The anthropometric method of measuring skeletal morphological parameters of lower limb was designed to represent individual skeletal features, which method can be conveniently operated on subject body in vivo. By integrating the kinematical data and the origin-insertion coordinates, an algorithm was developed to calculate dynamic muscular moment arm length. This algorithm can be applied on estimation of the dynamic parameters of single articular muscles and biarticular muscles. By our experimental studies of 10 subjects, data of the dynamic muscular parameters were collected in the sagittal plane during normal walking. Data collected were typical dynamic muscular moment arm lengths of lower limb, including muscles of Soleus (SO), Tibilis Anterior (TA), Biceps Femoris Caput Breve (BS), Glusteus (GU), Vastus (VS), Iliopsoas (IL), Gastrocnemius (GA), Rectus Femoris (RF) and Hamstring (HA). The results suggest that the method is feasible for estimating personalized dynamic muscular moment arm length to build biomechanical model.

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In this study, we consider the problem of minimizing the energy consumption of multibody systems using passive elastic elements for energy storage. In a previous paper (Schiehlen and Iwamura, 2009), we only considered the motion in the horizontal plane. In this paper, we allow spatial motion under gravity. Firstly, based on the linearized equations of motion, we analyze the relationship between the consumed energy and the operating time using optimal control theory. Then, we derive a condition for the operating time to be optimal, and propose an optimal design method for springs. Finally, we show the effectiveness of the design method by applying it to robot manipulator arms.

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This study is an extension of a newly introduced approach to account transverse shear deformation in absolute nodal coordinate formulation. In the formulation, shear deformation is usually defined by employing slope vectors in the element transverse direction. This leads to the description of deformation modes that, in practical problems, may be associated with high frequencies. These high frequencies, in turn, could complicate the time integration procedure, burdening numerical performance of shear deformable elements. In a recent study of this paper's authors, the description of transverse shear deformation is accounted for in a two-dimensional beam element, based on the absolute nodal coordinate formulation without the use of transverse slope vectors. In the introduced shear deformable beam element, slope vectors are replaced by vectors that describe the rotation of the beam cross-section. This procedure represents a simple enhancement that does not decrease the accuracy or numerical performance of elements based on the absolute nodal coordinate formulation. In this study, the approach to account for shear deformation without using transverse slopes is implemented for a thin rectangular plate element. In fact, two new plate elements are introduced: one within conventional finite element and another using the absolute nodal coordinates. Numerical results are presented in order to demonstrate the accuracy of the introduced plate element. The numerical results obtained using the introduced element agree with the results obtained using previously proposed shear deformable plate elements.

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Lightweight deployable structures are required in many space missions. The numerical analysis of deployable space structures is becoming more and more necessary and a software tool supporting this activity, from the preliminary design to the final verification, has thus a clear interest in space industry. The goal of the DESCAS (DEployment Simulation of Complex Antenna Structures) ESA project was to get accurate solutions for those mathematically stiff problems. The main results of this project are presented in this paper, highlighting the capability of the implicit non-linear finite element approach to model efficiently and simulate the dynamic behavior of flexible deployable systems. Two industrial benchmarks are presented. The first one is a Large Deployable Reflector Antenna developed by Thales Alenia Space and the Russian-Georgian subcontractor NPO-EGS. The second one is a deployable antenna based on a Tape-Spring hinge concept, proposed by EADS Astrium Satellites

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The kinematic optimization of planar linkages is the stage following a synthesis process and belongs to the detailed design stage. In kinematic synthesis problems, the guidance of several points and bodies with prescribed motion subject to space constraints is a difficult task to be achieved by an unknown mechanism. An available software prototype able to solve this kind of problems is firstly used for enumerating solutions satisfying some precision positions and the space constraint. Then, the BOSS-QUATTRO software is used to refine the kinematic errors for fine time steps. Some preliminary results for optimizing a flap-tab mechanism are presented.

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The usual way of shock absorber description in the framework of multibody system dynamics is the usage of force-velocity characteristics that allow to describe the damper force with respect to the relative velocity of damper compression and extension. The disadvantage of this approach to the damper description consists in the lack of force dependency on changing velocity conditions because the characteristic is usually measured for the given harmonic kinematic excitation. The method presented in this paper is characterized by extended measurement based on a hydraulic actuator, which can be used for a wider set of excitation signals. Moreover the relative motion acceleration is evaluated as the second independent variable and thus the obtained damper force can be viewed as a function of two variables (velocity and acceleration) -- it is so called global damper characteristic. Particular damper characteristic measurements are described in the paper together with data processing and possible model identification. Then the characteristics are used in a quarter car model in order to develop the methodology of the global characteristics modelling implementation and force calculation. The quarter car model is created using the real data and parameters of the SKODA 21 Tr trolleybus. The introduced shock absorber modelling methodology brings a more accurate damper description mainly for the simulations with changing loading conditions in the form of varying excitation or changing vehicle speed.

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Passengers traveling in vehicles running on uneven roads and tracks are subject to whole-body vibrations. Ride comfort is based on the subjective human perception of mechanical vertical vibrations due to randomly uneven guideways. Thus, for the ride comfort evaluation the global system consisting of the guideway, the vehicle suspension, the vehicle body and the passenger has to be modelled and dynamically analyzed. The state equations of the vehicle-guideway system and the human perception dynamics via ISO standards are presented as well as the covariance analysis of the resulting randomly excited global system. The ride comfort analysis is discussed for two vehicle models: a half-car and a full car. The results show a remarkable change in the ride comfort evaluation due to the revised standard ISO 2631.

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This paper uses the multi-body dynamics simulation software ADAMS, establishes the dynamics modeling of the new Hy-Vo silent chain meshing with involute sprockets, based on the analysis of the meshing mechanism of the new Hy-Vo silent chain and sprocket, the reasonable structural parameters of the new Hy-Vo silent chain are defined, and the meshing simulation of the new of Hy-Vo silent chain drive is conducted. Simulation results show that the meshing mechanism of th new Hy-Vo silent chain and involute sprockets is a new kind of meshing mechanism, due to the dual function of the variable pitch feature and meshing with involute sprockets alternately using outer and inner flanks of the link plates, which can significantly reduce the polygon effect, the meshing simulation of the new Hy-Vo silent chain and sprockets will provide an effective means of dynamic design for the Hy-Vo silent chain drive with different pitch, different number of teeth.

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In recent years, high speed railway vehicle technologies have been studied and investigated in order to develop its performances with the objectives of improving riding comfort, noise reduction and high efficiency from environmental aspect. One of the essential performances is current collection stability. Operating at high speed condition, the current collection system which consists of contact wire and pantograph suffers from contact force variation. In order to reduce such variation, pantograph design should comprise of active control thus realizing stability. Numerical analysis can be applied to model the current collection and in particular simulate the contact force variation itself. In this study, Finite Element Method and Absolute Nodal Coordinate Formulation are used to model the wire. A free vibration experiment that focuses on tension of wire is performed to validate the numerical models. The validated result from the experiment demonstrates the accuracy of the numerical analysis in modeling the wire. The techniques are then applied to model the contact wire for the contact force investigation. The result indicated the availability of pantograph design via simulation to achieve steady contact force.

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This paper presents a new semi-recursive method for solving the dynamic equations of rigid body multibody systems with implicit integrators, closely related with the methods presented by Bae et al. (2001) and Rodriguez et al. (2004). This method considers the open chain relative coordinates as position variables, but only the independent relative velocities and accelerations, making the system smaller and more efficient to solve. Almost all the terms of the resulting formulation can be evaluated recursively, and some of them can be simplified for certain cases.

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Several years ago, the authors proposed a method for the efficient simulation of the dynamics of multibody systems: an index-3 augmented Lagrangian formulation with projections in velocities and accelerations to the constraint manifold, which relied on Newmark-type algorithms for the numerical integration in time. The formalism showed to be robust and efficient when facing a number of large and complex problems, as the detailed models of cars and excavators. On the other hand, hydraulic actuators are present in many industrial applications of multibody dynamics techniques, like in the case of the heavy machinery field. When simulating the dynamics of this kind of problems, two different approaches are common: to resort to kinematically guide the variable length of the actuator, thus avoiding the need to consider the dynamics of the hydraulic system; or to perform a multi-rate integration of both phenomena if a more detailed description of the problem is required, for example, when the objective of the study is to optimize the pump control. This work addresses the inclusion of hydraulic actuators dynamics in the method for the simulation of multibody system dynamics mentioned above. The resulting formalism is developed, and the raised numerical issues are discussed. An academic example serves to compare the complexity and efficiency of the simplified (kinematic guidance), multi-rate and unified approaches, leading to conclude that the robustness of the method is preserved and that the efficiency of the method is moderately penalized.

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The paper considers the optimization of the flexible components of mechanical systems modeled as multibody systems. This approach aims at considering as precisely as possible the dynamic loading of the structural components under service conditions in their mechanical systems. While most of the structural optimization developments have been conducted under static or quasi static conditions, the approach is clearly a challenge. Naive applications of this approach generally lead to fragile and unstable results. To elaborate a robust and reliable approach, we investigate and compare several formulations of the optimization problem. Different optimization algorithms are also tested. To explain the efficiency of the various solution approaches, the complex nature of the design space is investigated. The developments are illustrated using the test-case of the structural design of the links of a two-arm robot subject to a trajectory tracking constraint.

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The bicycle is an intriguing machine as it is laterally unstable at low speed and stable, or easy to stabilize, at high speed. During the last decade a revival in the research on dynamics and control of bicycles has taken place. Most studies use the so-called Whipple model of a bicycle. In this model a rigid rider is rigidly connected to the rear frame. However, from experience it is known that some form of control is required to stabilize the bicycle and/or carry out tracking operations. This control is either carried out by steering or by performing some sort of upper body motions. Note that in both cases the system is underactuated. The precise control used by the rider is still under study. This paper addresses the question whether the underactuated bicycle is controllable by only steering or upper body motion in the forward speed range of 0 to 36 km/h. Whipple-like models are studied with either steering or upper body control. It is shown that at certain specific forward speeds some modes are uncontrollable. However, either the forward speed is extremely low or the uncontrollable modes are all stable modes and are therefore of no concern to the rider.

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Based on the analysis of the meshing theory and tooth profiles of the existing silent chain, this paper puts forward the meshing mechanism of the new high-speed rounded-pin silent chain meshing with involute sprockets using alternately outer and inner flanks of the link plates. The new silent chain is compatible with the inner and outer flanks of the link plates, the new silent chain is used especially for high-speed operation conditions, the polygon effect, shock and vibration can be reduced, the noise and wear can be decreased. The new silent chain drive can fundamentally improve the high-speed transmission performance of the silent chain. The paper analyzes the meshing and roll-cutting theory of the silent chain, sprocket and hob-cut, and the harmonic relationships of the main parameters of the three components are established, the correct meshing conditions of the silent chain, sprocket and tool rack are put forward, and the corresponding analytical expression are derived that can be used to guide the design and calculation of the new silent chain, sprocket and tool rack. Under the premise without taking into account the clearance between the link plate hole and pin, using mechanical dynamics analysis software ADAMS, the paper establishes the parameterized dynamic simulation model of the new type silent chain and sprocket, and analyzes the change rule that the radius r of the integrated curvature of the inner flank of the link plate changes with the chain pitch p, the number of teeth Z and the sprocket tooth profiles.

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In this paper, focus on the new products development of 88 meter aerial platform fire engine, a virtual prototype model of aerial platform fire engine is established based on the multi-body dynamic software RecurDyn. The luffing mechanism, telescope mechanism, rotation mechanism and working platform leveling mechanism of the aerial platform fire engine system are simulated and analyzed using multi-body dynamic method. The operating radius and the trajectories of the key points of the aerial platform fire engine is analyzed. Load-bearing characteristics of each mechanism hinges are checked, and the mechanism-control coupling dynamics simulation model of the working platform leveler with the PID control is established, which provides important design foundation for the design of each mechanism' s drive device--hydraulic cylinder. The research results provide important design basis and scientific evaluation index for the design of new aerial platform fire engine.

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In recent years, there is a trend of small pitch, high-speed, multiple species and high-Performance in the study of silent chain, and the silent chain drive has been used more widely in the timing drive system of auto engine. The silent chain drive has been used in the car engine timing drive system and oil pump drive system in many famous international auto companies, such as GM,Ford,Chrysler,Benz,BMW,Audi,V W and so on . The silent chain has the characters of compact size ,high reliability and high wear resistance,which the gear drive and belt drive don't have. So there are broad prospects in the silent chain drive. This paper analyzes the stress distribution of the pin and the chain plate through building the flexible multi-body contact model of rounded-jointed silent chain and sprocket by using the multi-body dynamics software Recurdyn V7R1, which is an important Mechanics basis for the structure design and the optimization of the silent chain plate.

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In this paper, based on the multi-body dynamics software RecurDyn, flexible multi-body contact mechanical model of Hy-Vo silent chain and sprocket is established, the dynamic contact stress is studied when the Hy-Vo silent chain is meshing with sprockets, the stress variation of heterogeneous pins contacting is analyzed when the angle of two adjacent links varied. A new method is proposed to measure the pitch of the link in the realistic condition. This paper's conclusion provides an important design basis for the structure design and weight save design of the Hy-Vo silent chain.

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With the improvement of the speed and load of the automotive engine, and silent chain technology, as silent chain has a compact structure, high transmitting efficiency, high reliability and high wear resistance, its vibration and noise is low, and the silent chain have the advantage of lifelong maintenance-free, it significant overcomes the gear drive and belt drive performance, therefore, the silent chain is increasingly widely used in automotive engine timing system. Based on the analysis of the new silent chain with inner-outer compound meshing mechanism, and based on the combination of multi-body dynamics theory and modern contact dynamics theory, using the multi-body dynamics software RecurDyn, the paper establishes the timing silent chain system simulation model. Under the condition of variable speed and variable load at high speed, the multi-body dynamics model of engine timing silent chain system has been simulated. By analyzing the working path of the silent chain under the different speed and load operating conditions, the paper studied the dynamic response of the timing silent chain system and obtains the tensioning force curve of plate, pin, sprocket, damping plate, board and tensioner throughout the operating cycle of the timing silent chain system. After analysis and comparison of the calculated results, the multi-body dynamics model of the engine timing silent chain system is verified to be reasonable. The research result has important practical significance for reducing the development and production cycle of physical prototypes.

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The virtual prototype of axial piston pump is discussed in detailed through the application in investigation of piston/cylinder pair. Three sub-models are introduced firstly. The data is transferred between three sub-models through software interface. The liquid-solid coupling and rigid-flexible coupling of piston/cylinder pair model is achieved through the co-simulation model which is called virtual prototype. Then several related test rigs are mentioned. And the comparisons of simulation results and experimental results demonstrate that the virtual prototype of axial piston pump has a great potential in axial piston pump design. At last, the influence of load pressure, inclined angle of swash plate and clearance between piston and bushing on properties of piston/cylinder pair is analyzed. The simulation results indicate that the design of piston/cylinder pair is the key factor in determining the limit pressure and maximum swash plate angle, and reduction of clearance between piston and cylinder contributes to reduction of leakage and friction force of piston/cylinder pair, and improvement of the carrying ability of the oil film.

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