The present paper proposes two kind of mine detection robots which mean the six-legged walking robot with two manipulators based on the added stability, mobility, and functionality. One robot is COMET-II which is driven by electric power and not so big robot. The another robot is a full autonomous robot COMET-III which is driven by hydraulic power. COMET-III has a crawler and six legs and its weight is 900Kg. The improved this kind of robot will be engaged for mine detection job in Afghanistan soon.

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In this paper, a research background and current activities of multibody researchers in Korea are briefly reviewed. Most of Korean researchers in multibody dynamics field had obtained their doctoral degrees from universities in the United States of America, i.e., University of lowa, University of Arizona, University of Illinois, University of Michigan, etc. Multibody codes currently used in Korea, i.e., ADAMS, DADS, RecurDyn, and Autodyn7,are also reviewed.

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The researches of multibody dynamics have long been done in Japan. In this paper, the recent developments are surveyed from the conference proceedings and the transactions of the engineering societies of Japan. The D & D Conference proceedings and the transactions of the JSME are mainly focused and the activities of the workshops and the technical committees in the JSME are reported. Some reviews of the researches in the world are also given. The software developments of multibody dynamics in Japan are briefly reviewed.

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In this paper we discuss about a motion of a system consisting of a string and rigid bodies at its end. A tethered subsatellite in space is known as an example of this system. The string in planar motion is described by using Absolute Nodal Coordinate method. In this method, it is easy to describe the motion of the string with large deformation, rotation and translation displacement. The string motion is influences on the motion of the rigid bodies. In other words, the connection point is constrained by the end of the string. Therefore the motion of the system is calculated using differential algebraic equations. First, the motion of the string with large deformation, rotation and translation displacement is simulated for a simple case. The numerical results agreed with the experimental results qualitatively. Second, simulations for three cases : a string and rigid bodies, a string with no transverse deflection and rigid bodies, a string and a simple mass are performed. In these cases, the end of the string moves horizontally. As a result, the mechanism of the interaction between the string deflection and the rigid bodies rotation is made clear numerically.

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Accurate seismic analysis of large deformable moving structures is still unsolved problems in the field of earthquake engineering. In order to analyze the problems, the dynamics of flexible beam undergoing large deformation has been studied by the authors. Generally this type problem is tackled by the finite element method. There are three basic finite element formulations which are used in the dynamics of flexible beams. There are the floating frame of reference approach [1,2,3], the finite segment method [4,5], and the large rotation vector approach [6] Recently, the absolute nodal coordinata (ANC) formulation for beam elements was proposed by A. A. Shabana [7,8]. In this procedure, there is no need to transform the element matrices into the global ones because the equations of motion are already defined in terms of the absolute nodal coordinates defined in the global reference frame. Consequently, the mass matrix becomes constant with time, whereas the stiffness matrix becomes nonlinear function of time, even in case of linear elastic deformation. One possible method to avoid such cumbersome of the absolute nodal coordinate formulation in calculating elastic forces is to assume the infinitesimal deformation theory for beams undergoing large rotation. A new time independent formulation for bending motion in calculating elastic forces of the beam, and consequently the constant stiffness matrix were derived by the authors [9]. In this formulation, the elastic force for axial deformation is still time dependent. When we calculate the dynamic problems of a flexible moving structure such as a crane during earthquakes, application of large deformation theory for the structures composing of the beam elements is unavoidable to obtain accurate results. Respose calculation, in this case, requires the damping property as well as mass and stiffness properties of the structures. This paper firstly summarizes the former researches done by the authors and then considers the introduction of damping property into the flexible system described by the absolute nodal coodinates. In the practical linear theory of structural dynamics, Rayleigh damping is often used to describe the system damping because of its simplicity and practicality. It may be attractive in the response calculation if we introduce Rayleigh type damping into nonlinear equations of motion described by ANC formulation. We have tried to develop a procedure of introduction of Rayleigh type and other type damping matrices into ANC formulation. Reasonable assumptions lead to practical damping matrices for calculating structual seismic responses. Our former formulation for ANC plays an important role for our present study.

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Dynamics of multi-link manipulators are highly nonlinear and depend on the time varying configuration. This paper presents a method of gain scheduling which consists in designing a linear time invariant (LTI) controller for each operating point and in switching controller when the operating conditions change. Each LTI controller is designed based on LMI approach in which an optimization problem is defined as a mixed H_2/H_∞ control problem with pole placement. The performance of the force and the position controls is defined by the H_2 norm, and the robust stability according to gain scheduling is evaluated with the H_∞ norm and the pole placement of the closed-loop system. The effectiveness and the practicability of the proposed method are verified by both simulations and experiments with 2-link manipulator system.

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This study is concerned with the motion and vibration control strategy for a flexible-link mechanism composed of smart structures in order to achieve the high performance and stability. Reducing vibration and making positioning time faster are simultaneously required in this system. Technology of smart structures is introduced in the flexible-link system to achieve the vibration reduction. The smart flexible-link is composed of the flexible-link and the piezoelectric film which has the sensor/actuator functions for itself, and so its mechanism is extremely suitable for controlling the vibration. Modeling and control strategy are presented to enhance the motion and vibration control performance.

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For vision-based controlled flexible arm, the accuracy of the finite dimensional dynamic models and stability become very important for controller design. This paper designs suitable controller for a flexible arm with vision-based control. Input of the controller is the measured position error of the beam tip, which can be directly obtained by camera. In spite of the observed differences of results between actual system and simulated system, the results are good enough to validate the arm model. Simulation and experimental results show that the PID controller is acceptable. It is also stressed that two limiting factors, which are the camera sampling rate and a dead band in the velocity command, will influence the properties of the control system for vision-based controlled flexible arm.

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In mechanical designs much attention is to be paid to human beings from the standpoint of comfort and safety. In order to predict and to evaluate the effect of vibration to human body, dynamic characteristic models were built. In this study, a dynamic model of upper human body having vibration input from the sitting surface mainly in vertical direction is built. The model has a structure of spinal column with the head and the neck on neck, where the spinal column is the main transfer path of vibration from the sheet. The model is constructed by using the Multi-Body Dynamics approach. The whole spinal column is curved like a S character, and is a complicated structure. Anatomically the spinal column is made by piling up 32-34 vertebrae having intervertebral discs inbetween. The intervertebral disc is relatively soft compared with the vertebra and is deformable to the load of the spinal column. Therefore it is considered that the intervertebral disc can be expressed by using a rotational spring and a rotational damper, and that the vertebrae are connected by revolute joints. In this paper a simplified model of sitting human having ten degrees of freedom is constructed, where all the parameters are determined based on the fitness of two transmissibilities, that is, experimental one and analytically predicted one. The model was linearized in order to reduce the computational load, and to simplify the behavior. Further application of the model such as the load evaluation inside the spinal column is also examined.

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Simulators have been used to evaluate drivers' reactions to various transportation products. Most researches, however, have been concentrated on their technical performance, thus this paper considers driver's motion perception on a vehicle simulator through the analysis of human sensibility ergonomics. A sensibility ergonomic method is proposed in order to improve the faithfulness of vehicle simulators. A simulator of a passenger vehicle consists of such three modules as vehicle dynamics, virtual environment, and motion representation modules. To evaluate drivers' feedback, human perceptions are categorized into a set verbal expressions collected and investigated to find the most appropriate ones for translation and angular accelerations of the simulator. The cut-off frequency of the washout filter in the representation module is selected as one of the most influencing sensibility factors. Sensibility experiments were carried out to find possible correlation between the verbal expressions and the cut-off frequency of the filter. This study suggests a methodology to obtain an ergonomic database that can be applied to the sensibility evaluation of dynamic simulators.

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It is attempted to produce theoretically various skier's posture in the "parallel turn". The skier is modeled by a multibody system and its posture is drawn by using a 3D-CAD system referring to the pictures videotaped on a snow slope. One can understand the skier's ski control reproducing continuously the skier's postures. The position of the skier's center of gravity is estimated considering the mass of each human part. The force acting on the ski from the skier is estimated from the gravity force and inertia force of the skier. The edging angle between ski and snow slope is estimated. Furthermore, a new skier's ski control model is proposed by using the motion of the skier's center of gravity, the force acting to the ski from the skier, and the edging angle.

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Along with the steadily rising elderly population in Japan, the number of aged persons with difficulties in walking is increasing. These patients undergo rehabilitation in hospitals which impose a constant and heavy burden upon the health care personnel who must assist them. Additionally, there is growing shortage for caregivers in the hospital care. For patients to rehabilitate by themselves, an ambulation support machine is needed that can prevent them from falling. In this paper deals with a sensor-controlled ambulation support machine that can prevent them from a falling. The control methods of the machine are examined for a fall from the viewpoint of the biomechanics. First, a typical pattern of falling are described while using an ordinary walker during rehabilitation. Second, the sensor-controlled ambulation support machine developed in this paper is explained. Third, the mathematical musculo-skeletal model is described to analyze the muscular tensions of a human leg during the fall. Fourth, using the musculo-skeletal model, the muscular tensions of a human leg are analyzed in preventing from the fall by using the sensor-controlled machine. Finally, the results reveal that the musculo-skeletal analysis is useful to evaluate the control methods of the machine and to develop an ambulation support machine that can prevent the fall.

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The modeling methodology for the dynamics stability analysis of a flexible plate, which is axially forced to be moved from a constraint area into an unconstraint area filled with fluid with high speed driving velocity, is developed. As a result, we found that the fluid force destabilize the system, and the divergence type instability phenomena occur in the system due to the fluid force in the case of the high speed of the plate and high density of the fluid.

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Recently, dynamic analysis of the vibration problems of flexible material moving along the axial direction, such as wire or plate in the mill, has been required. For this purpose, the dynamic analysis of planar beams moving along the axial direction is developed in this study. In the former studies, for example, a model in which part of the beam is composed of small rigid bodies and springs is proposed. However, it is necessary to use many elements for obtaining an accurate vibration mode in this model. On the other hand, the beams are discretized using the FEM in this paper. Also, the effects of the motion along the axial direction, large displacements and geometricla nonlinearity are taken into account in this model. Therefore it is possible to obtain accurate results using this model with a small number of elements. Moreover, this method is adapted into the two boundary conditions in this study. At first, in the case of fixed-fixed boundary condition, the phenomena whereby the rigidity of the beams becomes very low near the critical speed, is presented using this model. The accuracy of this model is proved by showing that the critical speed obtained from this model is very close to the one obtained from the strict solution result. Secondly, in the case of fixed-free boundary condition, the dynamic response of the moving beam is calculated. This analysis shows the phenomena whereby the beam vibrates violently with the axial direction movement. This phenomena is called the spaghetti problem. Moreover, the calculated result is compared with the model in the former study. When the number of elements becomes less than 20,the calculation result using the model of former study may not be accurate because it treats the effect of axial direction movement in a discontinuous way. On the other hand, the calculation result using this model is accurate when the number of elements is only 3. This is the reason why this model treats the effect of axial direction movement in a continuous way. Finally, it is approved that the model proposed in this study is accurate and effective to treat the dynamics of flexible beam moving along the axial direction.

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The paper presents a multiport model of flexible multibody systems by analogy with connection multiports in electrical circuits. We employ the finite element method to describe deformations of flexible bodies associated with large overall motions, which we incorporate into the multiport model in order to set up various kinematical and dynamical relations appeared in the flexible multibody systems. It is shown that a concept of a fundamental pair, that is, a pair of a mechanical joint and its adjacent body is introduced so that we can recognize the flexible multibody system as an interconnected system of such fundamental pairs. Then we demonstrate how kinematical and dynamical relations such as geometric nonlinear effects associated with the flexible deformations and kinematical relations due to the mechanical joint can be modeled as the nonenergic multiports, and we also illustrate that dual connection matrices effectively represent their mathematical expressions. Finally it is shown that the interconnection of the nonenergic multiports with physical elements provides a multiport model of the flexible multibody system and also that the required mathematical models can be systematically formulated by the present approach.

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In this paper, an efficient method for constraint force analysis of specified joints has been developed in a serially connected open chain multibody systems. The system equations of motion are derived using the recursive formulation. However, constraint forces are computed non-recursively for specified joints. The efficiency of the proposed formulation has been validated by the operational count and the CPU time measure, comparing with recursive Newton-Euler formulation. Simulations of the 7-DOF RRC robot arm have been carried out to validata solutions of constraint reaction forces by comparing with those from the commercial dynamic analysis program DADS.

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In this paper, a model for a steering system equipped with an electric motor is constructed. Both the steering wheel angle and steering wheel torque are applied as the input, and difference between the two cases are clarified simulation involving frequency responses, eigenvalues, and transient responses.

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This paper presents a design method for the parallel torsion bars and dual wishbones suspension. The suspension's topological structure is represented by a graph. Base on the theory of multibody dynamics the suspension mathematical model has been built. The calculation method for the suspension stiffness is formulated and the matching relation between the stiffness of the upper and lower torsion bars is analyzed. The relation between the suspension and whole vehicle performance is discussed in this paper, such as the influence of guide mechanism size parameter on suspension stiffness, and kinematics characteristic. The vehicle maneuverability is also considered in this paper. At last we propose an optimization model of the suspension guide mechanism size and angle parameters. An application suspension model is formed and analysis of the suspension is performed. The analysis results are confirmed by the example.

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In this paper, the nonlinear dynamic modeling methods for the virtual design of tracked vehicle are investigated by using multibody dynamic simulation techniques. The results include high oscillatory signals resulting from the impulsive contact forces and the use of stiff compliant elements to represent the joints between the track links. Each track link is modeled as a body which has six degrees of freedom, and two compliant bushing elements is used to connect track links. The efficient contact search kinematics and algorithms in the context of the compliance contact model are developed to detect the interactions between track links, rollers, sprockets, and ground for the sake of speedy and robust solutions. In order to validate the developed nonlinear multibody dynamic model against the experimental measurements, several empirical techniques are suggested and applied to the physical proving ground tests of the high mobility tracked vehicle. In this empirical validations, positions, velocities, accelerations and forces of the chassis and the track sub-systems are correlated accordingly.

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The Hanshin-Awaji earthquake disaster occurred in Kobe area of Japan in 1995. Japanese government has decided to construct a three-dimensional Full Scale Earthquake Testing Facility from the lessons of this earthquake disaster. The facility is under construction of the supervision of the National Research Institute for Earth Science and Disaster Prevention (NIED). The purpose of constructing this shaking table is to conduct fracturing and collapsing tests of full scale structures. In the tests, the traditional operation and control procedure such as the trial excitation method for the shaking table cannot be effective, because dynamic property of the test structures varies with the progress of fracturing and collapsing. The need for developing new operation and control methods for the shaking table is high and urgent. In this paper, dynamic interaction behaviors of the shaking table with a bi-linear test model is firstly studied and reducing the interaction effect from the motion of the shaking table by employing the Minimal Control Synthesis (MCS) algorithm is tried, and the efficacy of the MCS algorithm through the simulations and experiments by using the two dimensional small scale shaking table with a bi-linear test model structure is shown.

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In this paper, a precise nonlinear dynamic analysis of an automatic pipe-cutting machine and design process for the speed controller using the nonlinear model are presented. This machine uses magnet to attach itself to the pipe against gravity. The machine has well aligned four wheels that are driven by DC motor and its speed is measured with hall sensors in the motor. During pipe cutting process, the tangential force due to the gravity acting on the pipe-cutting machine widely varies. That is, without any control, the cutting machine gets fast when moving from the top to the bottom of the pipe and slow when moving from the bottom to the top. Actually the system is kind of a nonlinear system where the tangential component of the gravity is function of climbing angle of the cutting machine along the pipe. The cutting quality is deteriorated with irregular cutting speed. Especially jerking motion is critical. It is necessary to maintain constant cutting speed to obtain good cutting quality. To design a precise controller for this system, it is necessary to obtain a dynamic model of the system as exact as possible. The machine is modeled as a nonlinear multibody dynamic system and the multibody model is verified with experimentally measured results. For the design of control system, the interactive off-line computer simulation with developed dynamic model is performed with experimentally obtained parameters. Co-simulation processing method is proposed to estimate angular position along the pipe from the feedback signal of motor. and compensate gravity effect to obtain constant driving speed.

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The present paper proposes a six-legged walking robot having two manipulators which offers added stability, mobility, and functionality. In this research, neuro-based position and force hybrid motion control for walking on irregular terrain is studied. Comparison with conventional position and force hybrid control demonstrates the high efficiency oth the proposed neuro-based position and force hybrid control system. The neuro-based position and force hybrid control system includes six-axis force sensors in each leg, which provide not only control in the vertical direction; i. e., in the direction of gravity, but also control in the walking direction. This platform has proven to be very useful on irregular terrain including obstacles of random height and random position. Consequently, autonomous stable walking in an unknown environment has been realized through the experiments.

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In this paper, the well-conditioned observer is designed so that the observer is less sensitive to the ill-conditioning factors in transient and steady-state observer performance. An L_2-norm based condition number of the observer eigenvector matrix has been proposed as a main index in the observer performance. For the well-conditioned observer design, the non-normality measure and the observability condition of the observer matrix are considered. These two constraints are specified into the desirable observer gain region that satisfies a small condition number and a stable observer. The observer gain selected in this region guarantees well-conditioned estimates in the observer performance. In this study, well-conditioning properties are investigated regarding the Luenberger observer and the Kalman filter for 2^<nd> order systems. In designing Kalman filters, the covariance ratio between the process noise and the measurement noise is shown to be a design variable and its effect on the condition number is characterized.

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Engineering systems have very large degrees of freedom in their finite element models. And it is not possible to measure the correct responses at all degrees of freedom because of economic and physical restrictions. This measurement sparseness caused by the characteristics of the measuring instrument and/or by the inexperience of the experimenter is an inevitable factor in the damage detection and assessment. Thus, the sparseness and the noise in the measurements should be considered properly in the force identification. In this study, the regularization method is adopted to alleviate the ill-posedness of the inverse problems. This technique identifies constitutive parameters in the analytical model such that is gives the best possible correlation with the measured test data. The dynamic response due to external force of vehicle structure is described in terms of strain form experimental and analytical response. This procedure can be used to get the transferred force to use an input data of fatigue analysis for a sub-structure of which the experimental response is difficult to get directly. To examine the proposed method, the external force applying on city bus is identified. Using finite element analysis and experiment, fatigue life of a window pillar is analyzed under the identified force by the procedure of above mentioned.

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The method of modeling for the identification of horizontal bodywork system is described, ARMAX model which describes the characteristic of bodywork is founded according to vibration equations. The vibration parameter is identified by compute.

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Time finite element method was used for analysis of multibody dynamics. Hamilton's law played an important role in the present formulation. Constraint equations were introduced in the functional through Lagrange's multiplier. A simple example showed that the existing method did not yield the stable numerical solutions once the constraint equations existed. The way for satisfying the constraint equations were modified in this paper so that the stable numerical solutions were obtained. Numerical results presented herein showed the effectiveness of this modification.

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The purpose of this study is to develop a procedure for performing a dynamic analysis of a multibody system moving along nonlinear trajectories at variable velocity. The finiteelement equations of motion were derived in the case that the multibody ststem undergoes large translational and rotational displacements in three dimensions. Then a computational code for time history responses of multibody systems was developed using the derived equations. Numerical solutions calculated by the developed computational code were compared with experimental results on cantilever beams. As an application of the new method, the time history response of a flexible link system for movement along a nonlinear trajectory at variable velocity was calculated using the developed computational code.

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This paper presents an efficient method for flexible multibody dynamic analysis. The proposed method is the one using reduced deformation modes, which are obtained from the finite element model with reduced nodal degrees of freedom. In case of a large-scaled flexible body in multibody systems, i. e. a vehicle body structure, the finite element model of the body has such many nodal degrees of freedom that computational costs should be increased. They result in decreasing efficiency of flexible multibody dynamic analyses. Using reduction methods such as the Guyan one, the generalized dynamic one and the component mode synthesis one, etc, Total nodal degrees of freedom of a finite element model are divided into master and slave ones. And then the reduced model corresponding to the master nodal degrees of freedom is gained and reduced deformation modes are computed from the reduced model. Flexibility information corresponding to the reduced deformation modes is economically obtained in terms of nodal coordinates, mode shapes, modal stiffness matrix, modal mass matrix and lumped mass matrix. Using the virtual work principle, the equation of motion of the flexible body is derived with a few assumptions according to reduction of nodal degrees of freedom. The effectiveness of the proposed method is verified in numerical examples of a high-speed rotating beam and a bump-passing mini-bus.

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Energy-Momentum Conservation Algorithm is proposed to stabilize the time integral of equation of motion. This method has established already for no constraint motion. But application of this method to the constraint motion is still under discussion in literatures. In this paper, the authors propose a general energy-momentum conservation algorithm for the motion of flexible bodies under some typical geometrical constraints. We derive the incremental constraint matrix that guarantees the conservation of the energy, linear momentum, and angular momentum, and discuss the rule and importance of the B matrix

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In-vehicle tests for benchmarking advanced vehicle control devices with real test drivers are time-consuming, expensive, and not reproducible. But, using Hardware-In-the-Loop Simulation (HILS), real system can be easily tested in closed loop with a simulated vehicle. Because of this advantage, commercial product for HILS has been popular. Lately, The Math Works, Inc releases the product for performing real-time rapid prototyping in PC hardware, such as xPC target, Real-Time Workshop, Virtual Reality and so on. Using theses, HILS for testing Anti-lock Brake System (ABS) was developed. This paper describes a PC based HILS that includes a simple vehicle dynamics and tire models adapted to run in real time. Reliable vehicle models for HILS require detailed modeling of suspension and tire behavior, and those models were made using dynamic model with kinematic & compliant suspension characteristics obtained by rig test and semi-empirical tire model in this paper.

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In this paper, the authors propose a real-time multibody analysis method for automobile. This analysis method realizes real-time analysis with 91 degrees of freedom automobile model. The purpose of this proposal is to develop driving simulator with multibody vehicle model, and this proposed analysis method is successfully applied to our driving simulator with 6-axes motion system. The performance and accuracy of proposed real-time analysis method are investigated in this paper.

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In this paper, a real-time multibody vehicle dynamics and control model has been developed for an intelligent vehicle simulator. The simulator consists of a scenario module for preceding vehicle motion, a control module including ACC (Adaptive Cruise Control) logic and a throttle/brake switching logic, and a real-time multibody vehicle dynamics module. The real-time multibody vehicle model has been developed based on the subsystem synthesis method. To see the effectiveness of the developed model, various ACC simulations such as preceding vehicle following, cut-out, stop-and-go have been carried out. The CPU times taken for the simulations have been also measured to see whether the developed model meets the real-time requirements.

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This paper introduces an economical and effective full-scale driving simulator for study of human sensibility and development of new vehicle parts. The developed PNUVDS (Pusan National University Vehicle Driving Simulator) consists of several subsystems : a motion platform, a motion controller, a visual and audio system, a PC-based vehicle dynamic analysis system, and a vehicle operating system. The control problem of the motion platform is very important to accurately reappear a various vehicle motion when maneuvering a vehicle driving simulator. However, real-time robust control may be a difficult task because the motion platform is the nonlinear complex system. Therefore, this study proposes the sliding mode controller with perturbation compensator using observer-based fuzzy adaptive network (FAN). This control algorithm is designed to solve the chattering problem of a sliding mode control and to select the adequate fuzzy parameters of the perturbation compensator. For evaluating the trajectory control performance of the proposed approach, a tracking control of the motion platform is experimentally carried out. And then, the driving performance of the simulator is evaluated by using human perception and sensibility of some drivers in various driving condition.

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Obstacle avoidance for discrete-link spatial hyper-redundant manipulators in known environments is considered. The manipulator is divided into two sections, a proximal section that has not entered the space among obstacles and a distal section among the obstacles. The application of harmonic potential functions is extended to obstacle avoidance for the distal section in three-dimensional space, in order to avoid local minima in cluttered environments. A modified panel method is used to generate the potential of any arbitrary shaped obstacle in three-dimensional space. An alternative backbone curve concept and an efficient fitting method are introduced to control the trajectory of proximal links. The fitting method is recursive and avoids the complications involved with solving large systems of nonlinear algebraic equations. Combination of the three-dimensional safe path derived from the harmonic potential field and the backbone curve concept leads to an elegant kinematic control strategy that guarantees obstacle avoidance for spatial hyper-redundant robotic manipulators.

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This paper presents a prototype of a new in-pipe inspection robot which can move for a long distance. The In-pipe inspection robot system consists of a driving mechanism, a CCD camera and light emitting diodes. The driving mechanism is structured by a rubber bellows, many friction rings and an electromagnetic valve. It is driven by pneumatic pressure and vacuum pressure. These two pressures are switched by the electromagnetic valve. The pneumatic pressure (0.3 MPa [gage]) is used to stretch and the vacuum pressure (-0.08 MPa [gage]) is used to shrink the rubber bellows. The rubber bellows is 33 mm in outer diameter, 23 mm in inner diameter and 150 mm long. The friction rings convert the stretching and shrinking motion of the bellows into the moving force. The CCD camera and the light emitting diodes are able to find for a crack in the pipe. Consequently, The in-pipe inspection robot moves freely in the pipe, and can find the crack. It was possible to move the distance of 20 m with the speed of 24 mm/s.

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As a method to realize a high effciency and high-speed biped robot, we studied the self-excited walking of a fourlink biped mechanism with feet on level ground. The biped mechanism possesses a single motor at the hip joint and active lock mechanisms at both passive knee joints. We showed that the self-excitation control enables the three-degree-of-freedom planar biped model with feet to walk on level grond by mumerical simulation. From the parameter study of the biped model of 0.64m leg height, we found that stable walking locomotion is possible over a wide range of feedback gain, foot radius of no more than 0.3m and other link parameter values. Then we manufactured a biped robot 2 that was similar to the analytical model. After parameter modification, we demonstrated that the biped robot can perform natural dynamic walking on a level plane. It was also shown that the simulated results agree with the experimental walking locomotion.

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This study deals with the optimum trajectory planning for one-link flexible arm. By using the optimum trajectories, the flexible arm can rotate from its initial position to a desired location in given movement execution time without large troublesome vibrations, and additional feedback control devices besides the controller of a existing actuator are not necessary. The method generating the optimum trajectories is based on only the natural frequencies of the flexible arm. Hence, if only the natural frequencies are known, the desired trajectories can be simply obtained in real time. Considering only the first natural frequency, the information needed for creating the desired trajectories is the first natural period, the given movement execution time, and an angle of rotation. The effect of the desired trajectories on reducing the vibrations of the flexible arm was confirmed experimentally. It is clear that the vibrations of the flexible arm were reduced enough by using the desired trajectories, even if the given movement execution time was shorter than the first natural period.

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Contact processes may be represented by local discretization, by a rigid body approach or by a mixed method using both ideas. For the dynamics of mechanical systems a rigid body approach is described achieving good results also for multiple contact problems. This paper considers mainly contacts in multi-body systems where the corresponding contact constraints vary with time thus generating structure-variant systems. The equations of motion for dynamical systems with such an unilateral behavior are discussed, solution methods and applications are presented.

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Barrel polishing used in surface finishing is a very efficient processing method. However, the workpiece may have separated from the abrasive depending on the processing conditions. Though the machining condition has been determined based on experiment and experience in the expert, it is expected that the numerical simulation of the behavior of workpiece and abrasive examine it. In the barrel, compressive forces, shearing force and frictional force, etc. affect workpieces, abrasive and wall. Therefore, it is important to know the motion states of abrasive and workpieces, etc. in order to examine machining condition and cause of the segregation. In this study, the behavior of two kinds of particles in which material or diameter differ in the rotary barrel was examined both experimentally and numerically by discrete element method (DEM). To begin with, the behavior of particles in the rotary barrel that rotates about its horizontal axis in a two-dimensional system was fundamentally examined in order to specify the generation factor of the segregation. Secondary, the behavior of particles in a three-dimensional planetary barrel was examined. Then, the figure for the condition of the segregation of filled particles is shown, examining distribution rate of particles. As a result, it was demonstrated that the segregation is the combination of diameter and mass of the filled particles in both motion forms.

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This paper has investigated the physical properties of a racket and has derived the contact forces, contact time, coefficient of restitution, and deformations during impact between a ball and racket. Furthermore, it has predicted the power or post- impact ball velocity with a forehand groundstroke. It is based on the experimental identification of the dynamics of racket-arm system and the approximate nonlinear impact analysis with a simple forehand stroke swing model. The predicted results could explain the mechanism of impact between a ball and a racket with different physical properties. It enables us to predict the various factors associated with impact and performance of the various racket.

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This paper investigated the feel or comfort of the arm or hand in an impact. It derived the shock vibrations of the wrist joint caused by the impact when a player hits flat forehand drive. Furthermore, it predicted the sweet spots of a racket in terms of feel. It was based on the identification of the racket-arm system and the predicted coefficient of restitution between a racket and a ball. The predicted waveform of the shock vibrations at the wrist joint agreed fairly well with the measured ones during actual forehand stroke by a player, showing that the shock vibrations of the wrist joint are transmitted from an impulse at the impact location and the several vibrations mode components of the racket. The predicted results could also explain the difference in sweet spots of a racket in terms of feel or comfort of rackets with different weight and weight balance. This study enables us to predict the various factors associated with impact and performance of the various racket.

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A new Methodology for dynamical analyses applicable to a very large class of rigid and flexible multibody systems is presented. It is based on a variable-gain error correction method with scaling, and has the following distinctive features : (i) All kinds of holonomic and nonholonomic equality constraints can be treated in a plain and unified manner; (ii) Stability of the constraints is always attained; (iii) The formulation has an order N computational cost in terms of both the constrained and unconstrained degrees of freedom, regardless of the system topology; (iv) Unlike the traditional recursive order N algorithms, it is quite amenable to parallel computation; and (v) Since no matrix operations are involved, it can be implemented to very simple general-purpose simulation programs. Versatility, dynamical validity and efficiency of the approach are checked through numerical studies of several particular systems.

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In this study, we compared the efficiencies of two famous methods which use relative coordinates for forward dynamics : the original fully recursive algorithm and modified recursive algorithm. The fully recursive algorithm is modified a little bit for improvement by using the same form of velocity transformation as the modified recursive algorithm. To compare the efficiencies, we expressed the number of multiplications and divisions as a function of system parameters. By varying the parameters, we check the effect of parameters on the efficiencies and it turned out that the fully recursive algorithm is more efficient for the system with long chains, while the modified recursive algorithm is more efficient for the parallel system with many constraints. In the results, two algorithms showed equal efficiency for the number of bodies in chain, n=9&acd;13 with variation by the number of constraints and parallelism.

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In this study, a general procedure and kernel of the AutoDyn7 (AUTOmobile DYNamics in G7) are explained. In the AutoDyn7 program, an efficient and systematic formulation for dynamic analysis of multibody systems with flexible bodies is derived using the velocity transformation technique. In order to reduce the number of elastic coordinates, elastic deformations are represented by the vibration normal modes obtained from finite element analysis. The Rapid-App for GUI (Graphic User Interface) builder and the Open Inventor for 3D graphic library have been employed to develop these programs in Silicon Graphics workstation. Several special purpose modules of the AutoDyn7 program are introduced to analyze vehicle dynamic characteristics, with efficiency and precision. To show the applications of the AutoDyn7 program, a vehicle modeling and stability analysis are performed with various running conditions.

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This paper presents a new method, Pseudo-Interference Stiffness Estimation (PISE), for evaluating the equivalent mesh stiffness and the mesh load in gear system. The PISE method is based on evaluation of the geometric overlap of two assumedly rigid bodies and estimation of the contact force based on this artificial overlap area(or volume) and the singular stiffness(at the point of contact) of the bodies. Computationally, this procedure is orders of magnitude about 2000 times in our numerical simulation) faster than finite element analysis of contacting bodies. This significant gain in computational efficiency leads itself to practical dynamic simulation of complex gear systems. In this paper, examples of two cylinders contact problem were solved by PISE method and finite element contact model. The results from both methods show reasonable agreement. PISE is then applied to gear teeth contact problem to estimate the equivalent mesh stiffness. The estimated results were compared with the finite element contact results. The comparison from PISE and finite element contact analysis also shows good agreement.

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