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

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The motion and vibration of a moving body running on a complicated 3 dimensional (3D) trajectory considering an air resistance are investigated in this paper. A roller coaster is treated with here as a concrete example of moving body. The equations of motion of a roller coaster in which a trajectory and a vehicle are coupled are derived by using differential algebraic equation. In the previous paper, a roller coaster has been modeled as a one-wheel vehicle. In this paper, it is modeled as a two-wheel vehicle. The Baumgarte method is adopted for numerical stabilization. In this analysis, the influence of air resistance and rolling resistance, and the interaction between a vehicle and passengers as for a riding comfort of roller coaster are investigated. And also, the transmissibility of vibration through suspensions of roller coaster is studied in order to keep the safe security in the strength of rotating wheels and shafts. Besides, a part of simulations are compared with the experiments reported by previous paper.

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This paper presents a simplified approach for the forward dynamics of the 6-PUS parallel manipulator. In the proposed method, the parallel manipulator is divided into the limb parts and the platform part at the passive spherical joints. For both parts, the equivalent dynamic equations related to the passive joints are obtained based on the transformation principles of dynamics between different spaces. Then, in acceleration level, the dynamic model for both parts can be rewritten in the form of linear equations on the generalized constraint forces and the linear accelerations of the passive joints on the condition that the state (position and velocity) of the manipulator is specified. According to the force coupling and geometry constraint of passive joints, the closed form solution for the generalized constraint forces can be derived readily from the linear equations combined by the separated parts. In the level of position and velocity, task variables of the manipulator, namely the position and orientation of the moving platform, are chosen as the system's generalized coordinates, which results in the utilization of the inverse kinematics for the state transformation between the workspace and the passive joints space. Consequently, by virtue of the obtained constraint forces, the dynamics of the manipulator can be replaced by a single free rigid body (the platform) with specified external forces provided by the environment through the end-effector and the limbs through the passive spherical joints, respectively. At last, some numerical results are provided and compared to validate the correctness and effectiveness of the proposed approach.

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End-effector trajectory tracking of flexible multibody systems is a challenging task. In this paper feed-forward control designs based on quasi-static deformation compensation and exact model inversion for end-effector trajectory tracking are presented. They are combined with a simple feedback strategy and tested by simulation of a very flexible two arm manipulator. With both approaches good results for end-effector trajectory tracking are obtained. It is shown that a significant improvement of the inverse model approach is achieved by including the elastic rotation of the first arm in the system output description. This yields the far best accuracy of the tested approaches.

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The purpose of this research paper is to construct a low-order model of a geometrical constrained gossamer structure, especially for a solar sail. Currently, JAXA is working on a spin type solar power sail spacecraft. Computational analysis of the sail membrane's large mathematical model is difficult and time consuming. Therefore, this issue has a negative impact on design aspects. As a result, the model reduction technique is required. In other words, with a feasible, shortened, computational analysis period, a trade-off would be possible when designing and determining operation procedures. However, there is no model reduction methodology about solar sail dynamics. In this research paper, firstly, the full-order model of the spin type solar sail craft is modeled by the geometrically nonlinear FEM based on the energy momentum method (EMM). As a result, the numerical time integration is unconditionally stable. Secondly, the low-order model is constructed by the empirical model reduction method. And finally and complementarily to the former and latter sentence, the geometrical constraint is modeled by the penalty method based on the EMM. In this research paper, we will show that the low-order model can approximate the full-order model with sufficient accuracy.

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It is the objective of this investigation to discuss effects of using table-update and table-interpolation algorithms on the accuracy of the analysis of vehicle/turnout interactions. To this end, contact geometry analysis procedure is generalized for turnout simulations such that tongue rail profiles available from measurement and/or drawing can be automatically interpolated and used for producing multiple look-up contact tables. Having obtained multiple look-up contact tables, the wheelset trajectory coordinate is used to locate the nearest look-up contact tables to be interpolated for determining the location of contact point at every time-step in the dynamic analysis. The effects of the number of multiple contact tables on the accuracy of predicting the location of contact points are investigated. This leads to an important insight into the choice of intervals between the contact tables being generated. It is demonstrated that undesirable discontinuous changes in contact points inevitable for the table-update algorithm can be reduced using the table-interpolation algorithm.

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A coupling calculation method using dynamics and lubrication for a rotor and floating bush bearing system has been developed to predict self-excited oscillations and unbalance oscillations using a flexible multibody dynamics technique with hydrodynamic lubrication theory. Based on experimental results using a floating bush bearing, an accurate and numerically efficient lubrication model is proposed to calculate the hydrodynamic force, the bush rotating speed and the temperature of the oil film. In the multibody dynamics analysis, the rotor was modeled using the finite element method to include bending elasticity and the gyroscopic effect. The bearing bush was modeled by a rigid body. The coupling analysis between the rotordynamics and the oil film force of the bearing was performed by an in-house flexible multibody dynamics solver. Subsequently, the detailed mechanism of the rotor oscillation and the influence of some design parameters were investigated by numerical simulations and experiments.

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In this study, we examined the problem of minimizing the energy consumption of multibody systems using passive elastic elements for energy storage. In a previous paper⁽¹⁾, we only considered the motion in the horizontal plane. In this paper, we allowed spatial motion under gravity. Firstly, based on the linearized equations of motion, we analyzed the relationship between the consumed energy and the operating time using optimal control theory. Then, we derived a condition for the operating time to be optimal, and proposed an optimal design method for springs. Finally, we demonstrated the effectiveness of our design method by applying it to robot manipulator arms.

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The purpose of the present study is to develop a three-dimensional efficient interactive model and a numerical procedure to simulate a tire on soft ground, which can be applied to multibody dynamics for off-road vehicles. For motion analysis of the tire on soft ground, it is necessary to describe the elastic deformable behavior of the tire and the behavior with large displacement and local disruption of soft ground. A three-dimensional analysis must be conducted in order to express the complex behavior of the tire on soft ground due to the deformation of the tire and the landform of soft ground, such as ground heaving in the vicinity of the tire side edge. As the tire model, we adopt a distributed lumped mass-spring model, in which a rigid wheel is connected to a number of tire-masses by Voigt elements. This tire model allows us to describe the local deformation of the tire and the distributed contact pressure between the tire and soft ground. In addition, as the soft ground model, we adopt a discrete element (DE) model, in which soft ground consists of a number of rigid soil particles. This ground model allows us to express the discrete behavior of soft ground. Furthermore, the contact between the tire and the soft ground is defined as the contact between the tire patches constructed of tire-masses and the soil particles of soft ground. Numerical simulations of the tire behavior on soft ground have been carried out under several conditions using the proposed model. The numerical results revealed that three-dimensional motion analysis of the tire behavior on soft ground is possible, and that the proposed model and the numerical procedure could be validated through comparison with previous experimental results on the tractive and cornering performance of the tire on soft ground.

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A robust optimization process for a design of convertible roof module, where production uncertainty exists at all times influencing the kinematic behavior of the moving mechanism, is presented in this paper. The production uncertainty is considered as random design variables affecting the positions of joints of the moving mechanism with a certain level of uncertainty. In general, the design goals for the behavior of those mechanisms are quantitatively represented with the deviations over the total roof module movements and therefore, it is very difficult to evaluate the analytical design sensitivity as the deviations are defined by using the maximum and minimum value over the parameter intervals. Thus, this study introduces a meta-model technique to overcome the difficulties involved with the evaluation of design sensitivity. Also, the exemplary variances for the design targets are approximated from those meta-models. In addition, a sequential approximation optimization technique is used to solve a robust design problem for the convertible roof module mechanism. The robust design problem has 8 random design variables with uncertainties involved. The proposed approach requires only 87 evaluations until convergence was achieved.

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