Kinematic analysis of mechanisms is a precursor to their dynamic analysis and hence is a very important component in the courses related to Machine Design and Theory of Machines. There are various methods like analytical, numerical, and graphical for kinematic analysis of mechanisms. While teaching to undergraduate students graphical methods are emphasized in the curriculum as the students find them relatively easy to understand. Graphical method includes drawing of position of links followed by the velocity and acceleration diagrams in vector-loop form yielding velocity and acceleration polygons. Drawing these polygons is time consuming and becomes tedious for different orientations of links. A computer based approach can certainly be a useful tool in this matter. There are various software packages available which seem to be helpful in forward kinematic analysis. However, in the best knowledge of the authors, none of them draw velocity and acceleration polygons. In this paper, a module to draw Velocity and Acceleration Diagrams or VAD module is presented. It was developed as a part of MechAnalyzer software, a 3D model based mechanism learning software. The VAD module is helpful in forward kinematic analysis of various planar mechanisms preloaded in it, and draws position, velocity, and acceleration polygons. It has an interesting feature of animating the drawing of polygons in the way they are drawn by a teacher on the board of a classroom.

The efficient contact modeling and algorithms for the precise mechanical systems are the most important issue and still challenging area in computational multi-body dynamics (MBD). Because many mechanical engineers demand to analyze the realistic contact behavior for the colliding or sliding contact problems, an efficient and accurate contact modeling and analysis algorithms are very important when analyzing the contact force distributions and the contact force variations for their precise mechanical systems. However, the existing contact methods and algorithms [1-3] were not enough to perform for the realistic contact behanior as much as expected becasue the existing contact algorithms have been developed based on the facetted triangle planes to represent the contact surfaces. When the contact surfaces are generated by the facetted triangles for contact analysis, the represented triangle contact surfaces have a geometrical error inherently. As a result, the contact force results are not enough accurate and smooth. In order to resolve this contact problem, Choi [4] suggested a new contact algorithm using a cubic spline surface representation method and related contact algorithms. Choi's contact algorithms used a compliant contact force model based on the Hertzian contact theory [1-5]. Then, to evaluate the accurate and smooth contact forces, the contact normal directions and the penetration depth between contact pair are calculated by using the cubic spline (Hermite) surface interpolation. But, this smooth algorithm was not still enough for the highly precise mechanism analysis such as a ball screw mechanical problem because there are many ball geometries and the shpae of balls should be represented very accurately. As a result, in this paper, the ball screw mechanical system are modelled and simulated with the new developed contact algorithms based on the analytical sphere geometry for the balls. Because, the screw geometry cannot be easily represented by the simple analytic equations, so it is applied the cubic spline surface interpolation method to the screw contact geometry based on the Choi's contact algorithms [4]. The new propesed contact algorithms are implemented and tested in RecurDyn [6] as a ‘Geo Sphere Contact' which can be applied to the contact problems between a sphere geometry and a complex general surface. Thereforce, the many balls to surface contact problems can be calculated more efficiently and faster by using the new contact algorithms. This new contact algorithm and its contact results will be introduced in this paper.

In the MFBD (Multi-Flexible-Body Dynamics) [1], the contact analysis is very important. To develop the general purpose contact algorithm for rigid and flexible bodies, the Generalized Geometry Contact algorithm, which is called, ‘Geo Contact', has been developed by Choi's [2-4] for the contact problems between the rigid and flexible bodies with the general shaped geometries. But, in the previous researches, the nodal approach for flexible body was considered. The flexible body is actually classified as two types. The one is a nodal flexible body based on the Finite Element Method and the orther is a modal reduction flexible body. The modal reduction flexible body is widely used in the MFBD system for the efficient analysis for small deformation problems. In order to get a flexible body of modal reduction, the CMS(Component Mode Synthesis) analysis of Craig-Bampton's[5] is widely used. Therfore, in this study, we will expand the existing contact algorithm to the modal reduction flexible body. The schematic diagram in Figure 1 show what kind of improvement is needed to support the contact for the modal reduction flexible body in the previous Generalized Geometry Contact (Geo Contact) algorithm. We will show how to adapt and show the contact results of various contact cases with three types of body. The whole contact cases are six cases such as (1) rigid-rigid body, (2) rigid-nodal flexible body, (3) rigidmodal reduction flexible body, (4) nodal flexible-modal reduction flexible body, (5) nodal flexible-nodal flexible body, and (6) modal reduction flexible-modal reduction flexible body.

Recently more and more small-sized vehicles like a personal vehicle for small-group have been studied. As the mass of small-sized vehicle is similar to that of occupant, coupling behavior between them is important compared with conventional vehicle. Therefore, it is necessary to developing small-sized vehicle with a consideration to the dynamics of the human body riding on a vehicle. In this research, numerical simulation of human body dynamics on a vehicle was conducted. Generally, a human model is often simulated whole body in numerical simulation. However, whole body model has multiple degrees of freedom and property. Moreover, the influence of parameters of human is uncertainty and it is difficult to set accurate parameters. In this paper, the dynamics of only trunk of the human body which has little degrees of freedom on a vehicle was studied. Thus, these parameters of human motion control are identified from result of experiment and the simulation model. Furthermore, human motion is considered from characteristics of parameters which gained.

An efficient formulation based on component mode synthesis method and penalty method is presented to investigate the contact-impact of flexible multi-body system. Generally, the Hertzian contact law is the most commonly used method in engineering applications. However, the Hertzian contact theory is restricted to smooth and continuous surfaces. In addition to Hertzian contact law, Lagrange method and penalty method are commonly used for contact-impact analysis. However, by using nonlinear finite element method, a tremendous number of degrees of freedom in the contact-impact problems will increase the time cost significantly. With the consideration of these two problems, a formulation combining the component mode synthesis method and the penalty method is presented to investigate the contact-impact problems of flexible multi-body system numerically. Based on the component mode synthesis technique, a flexible body is divided into two parts: the contact zone and the non-contact zone. For the non-contact zone, by using the fixed-interface substructure method for reference, a few low-order modal coordinates are used to replace the nodal coordinates of the nodes, and meanwhile, the nodal coordinates of the local impact region are kept.

When the power transmission systems are designed or improved, the understanding of gear dynamics is essential and very important. Especially, the gear system is hard to investigate because the gear noises should be carefully controlled. As a result, when designing and developing gear transmission systems, it is very important to grasp the noise and to reduce the noise. In previous study, to reduce the calculation time and to represent a flexibility, a rotational joint and force element with a bending stiffness are applied between teeth and trunk [5]. We called it Quasi-flexible-body (QFB) gear model and this model was implemented in RecurDyn [11]. It is good to obtain the dynamic transmission error (DTE) which are utilized to evaluate the noise, but it takes an extra time to decide the bending stiffness coefficient than one body gear model because all teeth body are separated from the trunk. Therefore, this paper proposes the variable stiffness contact force method and one body gear model to reduce the process to decide the bending stiffness. The variable stiffness contact force method is a modified compliant contact force model based on the Hertzian contact theory [6, 9]. The one body gear model has a whole rigid body with a joint in the body center. In the geometry of the gear teeth, the biarc method [4] is used to approximate the involute tooth profile to two arcs. It can resolve the contact geometry complexity. Also numerical results have been compared with the previous Quasi-flexible-body (QFB) gear model and the experimental data [2, 3].

To reduce the collision shock and injury risk to an infant in an in-car crib (or in a child safety bed) during a car crash, it is necessary to keep the force acting on the crib constant and below a certain allowable value. To this end, we propose a semi-active in-car crib with joint application of regular and inverted pendulum mechanisms. The crib is supported like a pendulum by arms, and the pendulum system is supported like an inverted pendulum by arms. This system not only reduces the impulsive force but also transfers the force to the infant's back using a spin control system, i.e., the force acts perpendicularly on the crib. The spin control system was developed previously. The present study focuses on the development of a crib movement system. In this paper, the semi-active acceleration control law is derived for controlling the acceleration of the crib directly. The semi-active control system is build using the dynamic equation for the jerk of the crib. The effectiveness is confirmed by using software for multibody dynamics simulation; Adams (MSC Software Co.), and some results are reported.

This research proposes a novel control technique for a new panel quasi-static deployment and retraction using electromagnetic force. This panel system is modeled using multibody dynamics for numerical simulations. Although electromagnetic deployment has many beneficial points, it still has a major technical issue. This issue is that vibrations on panels persists for a long time, and hence its motion does not converge quickly. To eliminate or dampen these vibrations, we propose both feed-forward and feed-back control methods. These methods can reduce convergence time of deployment motion by at most 60 percent. Additionally, in order to realize feed-back control, it is needed to estimate the state variables of panels, that is, the angle of the panels. For that purpose, we introduce a new approach to determine the angles which utilizes the electromagnetic field generated by the deployment system. This new method accomplishes the determination of the angles to an accuracy of at worst 4 degrees and on average 1 degree.

This study proposes a novel attitude control method for a space membrane using electromagnetic torque in a space mission. Currently, an increasing number of satellites are presently utilizing extensible large area structures after launch in orbit. Previously, attitude control of a large deployed membrane has been achieved by thrusters. Although, the attitude can be controlled rapidly, the thrusters make the space system more complicated and lower reliable system. Moreover, the thrusters make the limitation of fuel, thus the attitude control operations should be carefully scheduled including contingency plans. As another attitude control system, attitude control using solar radiation pressure was also proposed. Although the system does not need fuel, the membrane needs longer period for attitude maneuvers with small solar radiation torque, since the membrane has a large angular momentum with spin angular velocity to keep the deployed membrane shape with central fugal force. In this study, electromagnetic wires placed on a membrane are utilized for attitude control by the interaction with an outer magnetic field. With the proposed system, the satellite can control its attitude without fuel, which makes space systems more simple and reliable. Furthermore, in this system, electrical wires placed on the edge of the membrane generate the hoop magnetic force to keep membrane shape without central fugal force by spin angular velocity. Thus, the membrane does not need to have spin angular velocity, which results in smaller angular momentum in the membrane. Therefore, with the proposed method, the membrane can achieve more rapid attitude control maneuver. Finally, numerical simulations are conducted to assess the usefulness of the proposed method using Particle-Based Model.

A multibody dynamics model for an omni wheel keeping its vertical orientation permanently in time is under development and verification. Such vertical positioning of the wheel plane is guaranteed if for instance the wheel belongs to the larger multibody system, wheeled vehicle, rolling on the horizontal floor. Base classes developed earlier for the multibody applications with contacts involving friction are used. A generalization has been performed for the former model of contact tracking algorithm between roller and horizontal floor. This generalization includes non-zero angle between the roller axis of rotation and plane of the omni wheel. Contact tracking algorithm is implemented in two cases: (a) implicit and (b) explicit. Computer models for these cases (a) and (b) are currently “embedded” into the omni wheel model earlier verified. Thus for simplicity we analyze a multibody system comprising the wheel plus set of rollers being mounted along its circumference. A remainder of the vehicle is replaced by the wrench properly arranged in a way such that the wheel keeps its vertical orientation permanently in time. The experimental computations performed have shown that two algorithms of the contact tracking generate completely identical dynamics of the whole multibody system.

This paper presents a simulation technique of the coupling system with electromagnetic system, hydraulic system and rigid body system for dynamic simulation of rigid body system driven by the electric motor. From the fuel consumption improvement point of view, the electric drive system is applied to the construction machinery using the electric motor which can regenerate the slowdown energy effectively. Permanent magnet synchronous motors (PMSM) that have the features of small size and high efficiency characteristics are put into general use to the electric drive system. Therefore, it is important to consider the magnetic characteristics of the PMSM for the evaluation of the electric drive system. This simulation technique has an outstanding feature for numerical stability by considering strong-coupling analysis with electromagnetic system, hydraulic system and rigid body system by formulating the PMSM characteristics using mathematical models considered magnetic saturation and cross-coupling effects. It is verified that the simulation technique is valid for the actual system by comparing the test results using the HILS system for the electric motor with the dynamic simulation ones.

This paper presents the development of a HILS system for evaluating the dynamic characteristics of the electric motor in the actual digging operation of the hydraulic excavator. This system can act the actual load on the motor by calculating the coupling system equations of motion with the rigid body system and the hydraulic system in real-time. The real-time simulation is conducted by newly developed simulation model that the rigid bodies are actuated by the linear hydraulic actuator. A test rig is developed following this concept, in which the load computed by real-time simulation of the actual digging operation on the hydraulic excavator is acted to the electric motor. The test results with developed testing system are compared with the simulation results using the simulation model with the electric motor.

The motion accuracy and dynamic performance of the flexible beams used in space structures are heavily affected by their large deformations during the motion, which leads to an unpredictability of the trajectory of the ends. Structural instability may occur in some extreme cases. The shape of the cross-sections and the material properties are important factors that influence the deformation of the flexible beams. In this paper, the boundary features of the variable cross-section beams are taken into consideration and the stiffness matrix is derived based on the nonlinear continuum mechanics approach. The dynamic model of the beam is established based on the absolute nodal coordinate formulation. The state-space equation of the moving beam is developed based on the Lyapunov theory. A criterion method of the kinematic stability of the flexible beams is proposed, by which the effect of material properties and variable cross-sections is investigated. The results indicate that with a small Young's modulus, the variable cross-section beam shows a better stability than the constant cross-section beam. As the Young's modulus increases, the stability time of the constant cross-section increases much more than the variable cross-section beam. When the Young's modulus reaches a certain value, the kinematic stability of the constant cross-section beam does not change any more.

The purpose of this study is to propose the analytical model of tires and to examine the mechanism of polygonal wear from the numerical results. Polygonal wear is one of the abnormal phenomena caused in a time delay system. A number of studies on polygonal wear of tires have been conducted. However, the investigation of the growing process of polygonal wear is not sufficient because the surface shape of the tire changes constantly by wear. Therefore, a numerical simulation model which can examine the transient behavior is necessary. In this paper, the tire model composed of mass points is proposed. The wheel is simulated as a rigid body, and the tire tread is simulated as a number of masses positioned around the circumference. The tire masses are connected to points around the circumference of the wheel by rotational and translational Voigt elements. The tire masses are connected by translational Voigt elements. Elastic contact is defined between the tire and the road surface. A slider is set in the tangential direction to express the Coulomb friction when a slip occurs. Numerical simulations have been carried out under several conditions using the proposed model. The distribution of the contact forces and the slip ratio were examined. The basic characteristics of the model are confirmed. After confirming the validity of the model, the wear shapes of tires were examined by the proposed model. It was shown that the polygonal wear occurred under certain conditions.

In this paper the steady state deformation and natural frequency of the infinitesimal free vibration measured from the position of the corresponding steady state deformation are investigated for rotating Euler beam with arbitrary setting angle at constant angular velocity. A corotational finite element formulation combined with the floating frame method is employed here. The equations of motion of the rotating beam are defined in the inertia coordinates, which is coincident with a global moving coordinates rigidly tied to the hub of the rotating beam. The element deformation nodal forces, inertia nodal forces, stiffness matrix, centripetal stiffness matrix, mass matrix and gyroscopic matrix are systematically derived by consistent linearization of the fully geometrically non-linear beam theory using the d'Alembert principle and the virtual work principle in the current inertia element coordinates, which is coincident with the current rotating element coordinates. The steady state equilibrium equations may be obtained by dropping the terms of the time derivatives in the equation of motion. The governing equations for linear vibration are obtained by the first order Taylor series expansion of the equation of motion at the position of steady state deformation. Numerical examples are studied to investigate the steady state deformations and the natural frequencies of rotating Euler beams with different setting angles and angular velocities.

In this research, the folding and unfolding properties of the bi-convex boom whose edges are combined using slide fasteners are evaluated experimentally. The bi-convex boom is the extension boom which have superior features such as lightweight, highly rigid and storable. We propose the method of forming closed cross section by combining convex booms using slide fasteners. Folding and unfolding tests under hanging gravity compensation are conducted using trail product of this boom. And the folding and unfolding properties of the boom are evaluated. Consequently, the boom bended in folding because of the low restoring force from pressed cross section to circular cross section. So we added the guide rollers to the unfolding and unfolding mechanisms in order to raise the restoring force of the boom. And we indicate that it is possible to unfold normally using this unfolding and unfolding mechanisms added guide rollers.

A topology optimization methodology is proposed for the flexible multibody system undergoing both large overall motion and large deformation. The system of concern is modeled via the absolute nodal coordinate formulation (ANCF). The equivalent static load (ESL) method is employed to transform the topology optimization of nonlinear dynamic response into a static one, and evaluated to adapt to the ANCF by splitting the elastic deformations of the flexible components from the overall motions of those components. During the static topology optimization, the material interface is implicitly described as the zero level set of a higher-dimensional scalar function. Then, the semi-implicit level set method (LSM) with the additive operator splitting (AOS) algorithm is employed to solve the corresponding Hamilton-Jacobi partial differential equation (PDE). In addition, the expert evaluation method of weights based on the Grey theory is utilized to define the objective function. Finally, two numerical examples are provided to validate the proposed methodology.

In aprvious study on representing shaft movement during a golf swing, we made a simulation model expressing golf club movement during a golf swing and demonstrated 3D club movement via an FEM model with shaft flexibility and the golfer's grip. We then computed the inertia force as input data. As a result, we concluded that this simulation model is able to represent behavior during the golf swing. However, there was a difference of deflection value near impact timing. Therefore, we are concerned that there is another cause for the shaft's deflection. Thus, we represented the deflection torque generated by the cross product of the shaft deflection and the inertia force. As for computing these input data, the shaft movement during the swing was measured with a 3D motion capture system (VICON Blade). The sampling frequency was 500 Hz and markers were attached to the shaft. Examinees were two average golfer's. Using these measured data, we simulated the shaft movement under four grip conditions with different grip stiffnesses. For the results of this simulation, the simulated deflection behavior was close to the measured deflection behavior with the deflection torque. Moreover, considering the fit grip condition, the deflection behaviors were improved. As a result of this research, we reached the following conclusion that the shaft movement is generated by a combination of the grip condition, vibration component of inertia force and the torque generated by the cross product.

Accurate modeling of a flexible body requires motion with large deformation, rotation, and time-varying length to be considered. A numerical analysis method for such motion has been formulated using a variable-domain finite element model and the absolute nodal coordinate formulation. However, the calculation cost of this method is very high due to the use of non-linear finite elements with time-varying length. Thus, in the present paper, we apply the multiple timescale method to the equation of motion in order to reduce the calculation cost and maintain the calculation accuracy. In addition, we compare two sets of timescales and evaluate the analysis range of this method for each of the sets.

Self-deployable space structures such as de-orbit device using membranes and solar sails have been actively studied and developed in recent years. These structures have convex tapes as extension booms in many cases because those tapes have lightweight, high efficiency for storage, and high self-extending force. Among those booms, a braid coated bi-convex(BCON) boom has been proposed by Watanabe, et al. The BCON boom consists of two convex tapes and braid mesh. The BCON boom has higher specific rigidity than a single convex tape, so that it is expected to apply it for various large space structures. The author conducted microgravity experiments in order to perform the demonstration of deployment and to verify the validity of numerical analysis. In tis paper, deployment analysis and microgravity experimental result are reported.

The nonlinear finite element solution procedures for the inclined cable due to both the static and timevarying support movements are formulated. The finite element results for the cable due to static support movements are validated by the exact catenary profile of the cable. The in-plane nonlinear vibrations of inclined cable excited by sinusoidal time-varying support motions are then analyzed with the finite element method. Some numerical results are presented and discussed.

Although more than 55 years have been passed, we have not known posicast shaped function (PSF) is a unique input command for one rapid rest-to-rest motion in one natural period and if there are more generalized expressions or not. Recently, we have deduced a feedforward formula, termed vibration manipulation function (VMF), to manipulate a 1DOF linear undamped floating oscillator from the dynamics of three-vibro-impact oscillators under Grover algorithm. Since VMF is a linear combination of half-integer trigonometric functions, it can express general input command to transfer the oscillator from arbitral initial position and velocity to arbitral aimed ones. As a special case of VMF, we can define an input command for rest-to-rest motion in one natural period, termed roVMF. In this study we have proved any PSF for the undamped 1DOF oscillator (uPSF) can be expressed by roVMF. Moreover, since uPSF has more strict symmetrical property than roVMF, we conclude the set of uPSF, U_up, is contained in the set of roVMF, U_roV. Hence roVMF is more general expression of uPSF.

An effective reduction technique is proposed for flexible multibody systems and the systems are meshed by spatial gradient-deficient beam elements of absolute nodal coordinate formulation (ANCF). The proposed reduction method can deal with both small and large deflection via enhanced Craig-Bampton method based on ANCF (ECB-ANCF). The enhanced Craig-Bampton (CB) method considers the effect of residual modes to construct the transformation matrix, such method obtains the natural frequencies and modes of the system more accurately in structural dynamics. To avoid using small deflection assumption, the proposed approach uses the initial bending stiffness matrices of the whole system to get the approximate modes of the flexible multibody system. Moreover, the nonlinear elastic force in reduced model is simplified by keeping some low-order nonlinear terms for a lower computational cost. Thus above two points result in a truncation error. Finally, one example which compare the reduced with full models in large deflection are presented to demonstrate the efficiency and accuracy of the proposed method ECB-ANCF.

In recent years, there are lots of research for membrane structure with lightweight and high storability. However the ground experiments of membrane structure have problems. It is difficult to simulate the micro gravity environment and highly vacuum environment simultaneously on the ground. So, there are often done deployment experiment of a small scale model on the ground.[3] However, there is a problem that small scale models and large scale models don't always performe the same deployment bahavior as each other. Therefore, if similarity rule between large scale models and small scale models at deployment will be established, we can predict deployment of the large scale model on the ground. This paper propose the similarity rule of between large scale models and small scale models at deployment.

Space robots are already playing an important role in planetary exploration and on-orbit missions due to their capability to work in hazardous and too risky space environment. For a free-floating space robot, neither position nor attitude of the vehicle are actively controlled. The free-floating space manipulators exhibit holonomic behavior due to its linear momentum conservation and non-holonomic due to the angular momentum conservation. In the dynamic modeling of multibody systems, the selection of coordinates to describe its motions are important. The equations of motion can be formulated easily in large number of natural coordinates, however the drawback is the large number of mixed differential-algebraic equations. The numerical solution of these equations is computationally inefficient for forward dynamics but efficient for inverse dynamics. On the other hand, the dynamic formulation using the relative coordinates is cumbersome, while they are computationally efficient. Further, the extra effort is required for the computation of the absolute positions, velocities, and accelerations of the multibody systems if one is interested to know its configuration for animation and other applications. Here, the equations of motion were written first in natural coordinates, then velocity transformation matrix was used to derive the minimal set of equations of motion in relative coordinates.

The paper is focused on the control assembly of the VVER 1000 nuclear reactor. The multibody model of the control assembly of the VVER 1000 nuclear reactor was created in the alaska simulation tool. The multibody model is suitable for the investigation of its dynamic response in the course of a drop of the rod control cluster assembly. The influences of the pressurized water have to be introduced in the multibody model because the rods control cluster assemblies are falling in a limited space and water resistance is not negligible. Possible contacts of the falling rod control cluster assembly with adjacent structural parts inside the reactor are supposed. In case of emergency state the lifting system mechanism is set off and the rods control cluster assemblies can drop down through the protective tubes to the reactor core with fuel assemblies and stop the nuclear reaction. When the absorber rods reach the lower part of the core, they pass through the guide channel narrowing, which has the function of hydraulic shock absorbers for stopping the rods control cluster assemblies drop. Using the multibody model there were investigated limit curves of two parametrically set deformations of fuel assembly guide tubes, at which the absorber rods still reach lower part of the core. On the basis of results of the rod control cluster assembly drop simulations it is possible to state that the maximal deformations (they are in order of several millimetres) of fuel assembly guide tubes at given deformation curves fulfil the prescribed limits given for the nuclear power plants safety estimation.

The drive axle of one front-engine rear-drive (FR) car vibrates strongly at Tip-in with high level noise in the cabin, while the vibration and noise consist of mainly second and forth order of engine rotation speed. Multi-body dynamics model is built to study how the vibration is excited and comes into being. The coupling vibration theory of drive axle pitch motion and powertrain torsional motion is analyzed by the model and vehicle test, the results show that powertrain torsional vibration will act on the drive axle through tire and excite its pitch vibration. Two ways to improve vibration performance of rear axle are given and simulation verification is done.

Recently a number of nursing care equipments to aid lift and transfer for aged person have been developed. Especially, rotational boom type care lifts are widely used due to its simplicity and usefulness. However, this type of lifts sometimes provide a feeling of uneasiness since while lift-up human body center moves backward than the position of the heel. Hence, in this paper, we propose a telescopic boom type care lift in order to approximate lift-up motion to a natural human standing-up trajectory. By using a multibody dynamics approach, we show that the proposed mechanism can achieve nearly natural standing-up motion and is able to reduce required force to lift-up than conventional type lift. Then, we develop a prototype telescopic boom type care lift and verify its effectiveness through experiments. Finally, we also consider the optimal design problem of the proposed care lift structure.

General model of optimal control for the deployment process of scissor-type deployable mast is established to select the optimal forces in order to make the deployment process smoothly. Genetic algorithm is used to avoid the massive sensitivity calculation of gradient-based optimization method during the optimization process, which can find the optimization value in global area. The adaptive crossover probability and mutation probability functions are improved to avoid the premature problem and the slow convergence of genetic algorithm. Efficiency and accuracy of the numerical results are validated through the numerical example.

This paper describes optimum values of an electrical circuit used in energy harvesting using a piezoelectric element or a DC motor. Energy harvesting technique recovers energy from environment. We target the energy harvesting methods that extract energy from mechanical vibration systems in this research. The vibration energy is usually extracted through an electrical circuit using a piezoelectric element or a DC motor as an electromechanical transducer. In order to extract energy effectively, the circuit and additional vibration system must be tuned optimally. The optimum values of the electrical circuit and additional vibration system can be derived based on impedance matching when the vibration source includes only a single excitation frequency; however, in certain cases, the vibration of the vibration sources is modeled by random excitation. The optimum values derived based on the impedance matching are not optimum if the vibration source includes several excitation frequencies. Therefore, the optimum values for the case of random excitation were also derived in this study. The optimum values for the case of random excitation are also effective for the cases of energy harvesting using free vibration. The effectiveness of the derived optimum values of the electrical circuit and additional vibration system was verified through numerical simulations.

In urban railway systems, which have numerous sharp curves, countermeasures for wear development are necessary in order to control wheel and rail wear. Thus, it is important to predict the development of wheel wear. However, the observation of wear development in practical systems requires a great deal of time and is not efficient. In order to predict the wheel wear profile, a numerical analysis conducted using multi-body dynamics software is proposed. We herein propose a model for the prediction of wheel wear development by incorporating the proposed model of wear development into SIMPACK. First, based on the motion analysis of the vehicle using SIMPACK, the contact pressure, slip ratio, and other necessary parameters are obtained. In order to create a worn wheel profile using the proposed model, the wear depth is derived. The current wheel profile is updated using the wear profile, and is adopted as the new wheel profile in SIMPACK. The wear depth is calculated based on the wear theory of Archard and Ward. Typical commuter rail vehicles in Japan, which adopt a modified arc wheel profile, are used as the model vehicle in the numerical analysis. A total of 400 nodes placed on the wheel surface at intervals of 0.4 mm are updated by spline interpolation. Wear development in the wheel/rail contact area is calculated, and the nodes are replaced by the calculated wear depth. The validity of the wear coefficient used in the simulation is discussed. The results of the numerical analysis are also compared with the experimental results to discuss the amount of wear from the viewpoint of mechanical and tribological contact problems.

The maintenance work on rail defects, especially rail corrugation, is very important for railway operation. Therefore, the study on the mechanism of the generation of rail corrugation is very helpful to make a maintenance plan. First of all, to investigate the generation situation of the rail corrugation, we measured the rail surface roughness in some curve sections. Secondly, in order to investigate the cause of the generation of rail corrugation, we conducted on-board measurement using commercial train with accelerometers installed on its axle-box. Finally, we executed vehicle dynamic simulation by means of multibody dynamics for verifying the influence of the track supporting stiffness involved the generation of the rail corrugation. As a simulation result, in the case of sleepers supported hard, the significant peak was seen in the frequency band that corresponded to the wavelength of the rail corrugation on high rail in the power spectrum of axle-box acceleration. On the other hand, in the case of sleeper supported soft, any peaks were not seen in the power spectrum. Therefore, we conclude that the track stiffness relates to the generation of the rail corrugation.

Recent railway vehicle carbodies have been light weighted and structurally simplified. These carbodies tend to have flexural vibration modes with complicated three-dimensional deformation according to vibration measurement test results by the authors. The box-type model was proposed as a numerical analysis model to analyze these bending vibrations. This model can treat the three-dimensional vibration of the carbody with a small degree of freedom (DOF) compared with the finite element (FE) model. In the simulation of the railway vehicle, commercial multi-body simulation software SIMPACK is widely used. Therefore, it is considered that the various simulations in consideration of the flexural vibration of the carbody can be performed easily by importing the box-type model into SIMPACK. In this paper, we proposed a method to import the box-type model into SIMPACK. In this method, the box-type model was imported into SIMPACK through simple FE model having the same structure with the conventional boxtype model. Next, the running simulations to calculate the vertical vibration of the railway vehicle were carried out by using the analysis model. As a result, good agreements were obtained between the simulation results and the running test results in acceleration power spectral densities (PSDs) of each measurement point of the vehicle. From these results, the validity of the model was confirmed.

This paper aims at removing noise/jitters with the help of Kalman filter technique. The application being considered is that of an industrial robot KUKA KR-5 to be remotely controlled by an exoskeleton. The exoskeleton is a wearable device, which senses the motion of the human limb, through the various sensors and potentiometers embedded in the design. Signals from the human subject’s elbow is reflected using a one DOF exoskeleton and its control has been discussed [3]. The external forces acting on the remote/virtual arm is replicated on the arm exoskeleton system developed in our laboratory [4]. This motion is then mapped to the KUKA. The motion of the human limb being sensed by the exoskeleton, is observed to be noisy. There is a significant amount of jittering observed even when the exoskeleton is maintained static and motion is not provided. This causes the KUKA to respond to the exoskeleton’s ‘no motion’ state through a visible vibration. A minute vibration in the exoskeleton (caused due to a slight activity in the human arm) causes noise propagation during exoskeleton tele-operation. It could be felt at the remote station manipulator by a noticeable displacement of 2mm in the KUKA KR5 robot. This causes disruption in the motion mapping between the two. This removal of this noise/jitter is being aimed at in order to precisely control the motion of the robot. There are standard filters that were implemented to take care of the noise propagation. Butterworth, Chebyshev and median filter were implemented which can be used for noise removal/reduction. This implies suppressing or removing certain frequencies causing interference. The standard filters generally introduce an initial delay in the system which varies as the order of the filter varies. Hence the system response is improved but lags behind the actual response by a few seconds (variable). Kalman filter is robust against uncertainty in process and noise covariance [2]. The Kalman filter works on a predict-update mechanism. It uses the previous state and the current measurement to predict the current state. Thus, the delay can be avoided by providing a good approximation of the previous (a-priori) state estimate. Hence, the Kalman filter can be considered to be a delayless system. Moreover, Kalman filter is computationally efficient and also minimizes mean square error [1] The Kalman filter algorithm works in two-step procedure: Predict and Update. An important requirement for implementing a Kalman filter is that the dynamics of the system under consideration should be known well in order to define a model that defines the dynamics of the system accurately. It mainly estimates the state of unknown variables using a series of consecutive measurements over a defined period of time and with a known sample time. These series of measurements give a precise estimate of the next state of the system as compared to that obtained using a single measurement. The estimate thus obtained as a result is more stable and thus the filter is also known to smooth out the output, removing variations due to the noise present. Kalman filter designed for real-time estimation of the orientation of human limb segments

This paper proposes a novel foot structure for a small biped robot using toes like a human foot to enhance its walking behaviour. This is to aim to make the robot gait more natural and more stable in the walking process. Besides, in this study, we also mention a new approach for generating the gait pattern of the biped robot by the approximated optimization method which applied the Differential Evolution algorithm (DE) to objective function approximated by Artificial Neural Networks (ANNs). To evaluate this method achievement, the biped robot was simulated by multi-body dynamics simulation software, ADAMS (MSC software, USA). The robot posture is comparable to the human in one cycle of the walking process. As a result, we confirmed the biped robot with the proposed foot structure can walk naturally. The approximated optimization method by DE algorithm and ANNs is an effective approach to generate a gait pattern for the humanoid robot. Moreover, this method is simpler than the conventional methods using Zero Moment Point (ZMP) criterion.

A lot of applications require controlling the orientation of an object and this can be achieved using mechanical input devices or mechanisms with electronic sensors. It is desired that these mechanisms are balanced, such that they retain their orientation even after the user has stopped using it. This can be achieved using active or passive balancing techniques. A passively balanced mechanical input device utilizes springs or/ placement of optimum masses at appropriate distances such that the overall forces and moments acting on the mechanism are balanced. As the configuration of the links change according to the user's input, the mechanism should be designed such that the overall centre of mass remains constant. In this paper, a novel 3-R Orientation Sensing Mechanism (3-ROSM) is presented, which consists of three moving links and one fixed link. The characteristic feature of this mechanism is that the three axes of the links are intersecting as found in various gimbal linkage systems. The balancing is carried out using counterweights placed on linkages on the moving links. The end result is a mechanism that can be used as a hand operated balanced mechanism (HOBM) in applications such as tele-surgery; control of a CCTV camera mounted on a gimbal mechanism, etc., which utilize master-slave robotics as a principle. The proposed mechanism has been modelled and simulated for dynamic analyses in a CAD software and found to be suitable for passive balancing.

This paper shows a prosthetic wrist joint that has 3 rotary axes controlled in an antagonistic actuation similar to a human musculo-skeletal system. Some dexterous actions of human arm toward external entities are much attributed to adjustability of its joint stiffness. The joint stiffness of human articulations or of those of any other vertebrate animals is adjustable due to an antagonistic structure of their musculoskeletal system and non-linear elasticity of individual muscle. In our previous studies we have developed a mechanical system that mimics the human musculoskeletal system, in which muscle-like actuators: ANLES (actuator with non-elasticity system) was developed and deployed in antagonistic manner to control rotation angles and rotary stiffness of a multi-DOF robotic joint. This paper shows a subsequent development of the 3 DOF wrist joint. Main points of refinement are as follows. First is a downsizing to serve it as a forearm prosthesis having an active wrist joint, second is an extension of stiffness adjustable range especially that of inner/outer rotation.

This study deals with the robot hand based on the original finger mechanism consisting of a planetary gear system and serially connected four bar linkages. It also has a mechanism for adjusting stiffness of fingers (VSM: Variable Stiffness Mechanism), which allows to give passive gripping force to a gripping object according to the object’s elasticity. The mechanism is merely driven by mechanical elements without sensory feedback from tactile or force sensors attached to fingertip or sole. The total number of motor for driving the robot hand is six, all of which are equipped in the palm. Rotation angle of motor is detected by optical encoder equipped to each motor. The robot hand achieves soft and adaptive gripping action due to VSM that changes the joint stiffness of the fingers by adjusting tension of the spring attached to the planetary gear system equipped in every finger except the thumb. Driving tests show that it achieves typical gripping and pinching motions of a human hand in daily life without any sensory feedback and also show that the VSM works effectively.

The purpose of this study is to develop an artificial finger that has versatile application fields such as humanoid robotics, prosthesis for disabled persons or industries. So far we have developed artificial fingers that has an underactuated mechanism based on our original mechanism called “double planetary gear system” (DPGS). The DPGS provides not only flexion-extension of the three joints of a finger, but also adduction-abduction controlled by two motors. It also has a stiffness adjuster to control joint stiffness with no sensory feedback. This paper presents some improvements of the finger parts followed by analytical and experimental considerations.

Research in the area of autonomous climbing robots for inclined and vertical surfaces of different materials has gathered interest in the recent past. Climbing robots have potential applications such as cleaning, inspection, and maintenance at hard-to-reach locations of civil structures. The proposed climbing robot is composed of two-mobile modules connected by a three degrees of freedom (DOF) manipulator for obstacle avoidance and wall transition purpose. Dynamics and control of the climbing robot has been presented in this paper. The forward and inverse kinematic model has been derived and the Lagrangian dynamic model has been employed to derive the governing equations for computing the joint response and driving torques. A PID-computed torque controller has been employed to solve the derived governing equations and simulation results have been evaluated numerically from the kinematic and dynamic model. Further, two stage motion simulation of climbing robot for avoiding an obstacle on vertical wall is performed using MATLAB programing. The simulation results show the actual joint trajectories are closely approaching to the desired joint trajectories for a given initial and final robot positions on vertical wall. The corresponding driving torque required at each joint has also been evaluated.

In our previous study we have developed the seven axes multi joint gripper (MJG) having a variable stiffness mechanism and have showed it achieves some dexterous grasping. In this paper, we discuss a hand having a number of mluti-joint fingers that was subsequently designed on the basis of the former MJG. The mechanism mainly consists of a serially connected differential gear systems controlled by only two actuators: one for driving all of the joints simultaneously and the other for adjusting stiffness of every joints all together. The hand succeeded envelope grasping of various shape objects with no sensory feedback. The experiments also revealed that the hand with three multi-joint finger successfully achieves transition from pinching to envelope grasping. It also discuss how joint stiffness should be set according to handling modes of the hand.

Recently, robots with high degree-of-freedom (DOF) have been used widely in various fields. These robots are able to conduct multiple purposes such as obstacle avoidance, postural control, trajectory tracking, etc. simultaneously using their redundancy. However, the robots with high degree of freedom cannot specify their inverse kinematics uniquely. Also, iterative calculations are required to generate motions which satisfy multiple demands in conventional methods. Since, the computational complexity increases explosively when the DOF of the robot increases, these methods are not appropriate for motion generation of the high DOF robots. In this paper, a new method is proposed, which generates robot motion through feedback control simulation using the dynamic model of multi-body robots with several virtual external forces which represent multiple demands. Then, the effectiveness of the method is confirmed through numerical simulation.

The article is devoted to mathematical modeling of control of multi-axle vehicle drive wheels, equipped with hydrostatic transmission with intelligent drive systems of wheeled running gear. We consider the equations of motion, the surface movement models and control models.

The paper describes the research conducted at the NNSTU named after R.E. Alekseev to design and create the multistage manual transmissions with automatic control and pneumatic actuator. It represents a general scheme of the transmission control, general equations that allow choosing the necessary pneumatic actuator parameters. It presents the process of gearshifting and determines the dependencies: -of the pressure rise in the power cylinder from the electro-valve jet diameter; -of the pneumatic cylinder rod displacement from the pressure for different diameters of the jet; -of the pneumatic cylinder rod displacement from time; -of the free power for different values of the maximum pressure in the receiver and the jet diameter; -of rotational speed during gearshifting in the synchronization process -of the total torque of unlocking during gearshifting; -when the synchronizer unlocking and the gear clutch shifting; -of the power cylinder rod displacemen for the total time of gearshifting. It presents the results of experimental studies and the results of comparison of theoretical and experimental data for the gearshifting time.