The influence of the strain rate sensitivity of the yield stress on multiple impact of three identical spheres were examined by FEM analysis in this study. Firstly the influence on colliding behavior were investigated. Then, the influence on macro-characteristics such as maximum contact force, maximum deformation, coefficient of restitution were investigated in detail. The main results obtained from this study were listed below. (1)The post impact speed of ball 2 (central ball) receives almost none of influence of the strain rate sensitivity of the yield stress. However, the post impact speed of ball 1 (collision ball) is overestimated and those of ball 3 (ball of another side) is underestimated if the strain rate sensitivity of the yield stress is ignored. In addition, a time delay was seen in the speed change during collision in the case without strain rate sensitivity. (2)The maximum deformation and impact duration are overestimated, and maximum contact force and contact pressure are underestimated, if the strain rate sensitivity of the yield stress is ignored. Further, the influences increase with increase in impact speed. (3)The contact stiffness and coefficient of restitution are underestimated in the case without strain rate sensitivity of the yield stress, and the influence become greater with impact speed in e₁₁ than e₁₂. In addition, e₁₁ showed a negative value (re-collision) in the case with strain rate sensitivity when impact speed increased, while e₁₂ was positive in the case without strain rate sensitivity. The influence of the strain rate sensitivity on the contact stiffness and the re-collision in detail in future.

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In this paper, we analyze the behavior of the chain for mooring offshore structures (M. A. Rahmen et al.2006，M. H. Kim et al.2005) by the analytical method of the multibody dynamics. For this system, there are two problems in the conventional method. One is the description of rotation for the rigid body. It leads to high nonlinearity and singularity caused by rotation. The other is the calculation efficiency due to the degree of freedom increases. In this research, in order to solve these problems, we introduces ”Rotation update equation”, which uses an incremental rotation for describing rotation matrix. This method doesn’t use the rotation angle in the equation, therefore the problems are mentioned improved. It can also reduce the calculation time, too. Moreover, this study introduces the normalization of the equation of rotation with the time step. It enables us to reduce the times of iteration procedure. This research compares the calculation results by the proroposed method and the results by the conventional method.

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This paper proposes a concept for the design and control of an energy saving manipulator utilizing passive elastic elements for energy storage. Firstly, we review our previously proposed method and the practical design of an energy saving manipulator briefly. This method reduces the energy consumption by using natural frequencies and eigen modes of the system. Therefore, when the weights of the system are changed by transferring some objects or when the boundary conditions are changed, we should adjust stiffnesses of the system. Hence, in this paper, we propose a very simple variable stiffness mechanism that can change rotational stiffnesses around the manipulator joint axes. This mechanism makes it possible to adjust the natural frequencies and eigen modes of the manipulator. A prototype 2DOF manipulator with the variable stiffness mechanism is developed by using the linear springs and the reaction wheels to verify the proposed method. Experimental results show the effectiveness of the proposed energy saving manipulator concept.

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Reconstruction of dynamics is executed for making multi-physical domain modeling and simulation necessary for 1DCAE in model based design and development of mechanical products possible. The aims of this reconstruction are the following two headings. 1. The basis of dynamics is changed from the relation between force and motion to the energy which is only one common physical value ruling all areas of dynamics, including statics, kinetics, fluid dynamics, thermodynamics, electromagnetics and chemistry. 2. Symmetry and causality of the natural world are introduced in dynamics. Some new laws and a new expression of potential energy of the elastic body are proposed in dynamics by the author for realizing these two headings

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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. Hence, various motion generation methods are proposed for such robots. The methods using configuration space have been utilized for a long time. However, these methods require enormous computation since the methods use iterative calculation. Meanwhile, the methods using the pseudo-inverse and null-space of the Jacobian matrix is widely used. Then the dedicated evaluation indexes are needed to solve the redundancy. These processes generally require the advanced expertise. Recently, “virtual spring-damper hypothesis” was proposed as the motion generation method without using the expertise and iterative calculation for high redundant systems. In this method, the end-effector of the robot arm and reference point is connected by the virtual spring and damper in simulation space. The dynamic motion simulation is performed, then, from the simulation result, reference motion of the real robot arm is obtained. In a previous study, a method that extends the virtual spring-damper hypothesis was proposed. In the proposed method, the virtual external force and torque are used to satisfy multiple constraints. The effectiveness of the method was confirmed through several numerical simulations, but dynamic posture stabilization was not considered in a previous study. In this paper, the method that consider the posture stabilization using the zero-moment-point(ZMP) is proposed, and verify the effectiveness of the method.

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Recently, several types of nursing care equipment to aid the lifting and transfer of aged persons have been developed. Especially, rotational boom-type care lifts are used widely because of their simplicity and usefulness. However, such lifts sometimes provide a feeling of uneasiness because during lift-up, the center of the human body moves backward relative to the position of the heel. Hence, in our previous study, we proposed a telescopic boom-type care lift to approximate the trajectory of the lift-up motion of a human standing up naturally. By using a multibody dynamics approach, we showed that the proposed mechanism can achieve nearly natural standing-up motion and requires a smaller force for lift-up than that required by the conventional-type lift. In this paper, we consider the optimal design of the proposed care lift structure. We propose an algorithm to seek optimal design parameters that minimize the error between the tip trajectory of the lift and the human chest trajectory measured using a motion capture system. We develop a prototype telescopic boom-type care lift with the optimal design parameters and confirm that it can reduce the burden on cared-for persons compared with that imposed by the previous design.

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This paper presents an approach to deal with the identification of continuous-time Hammerstein systems, characterized by a series connection of a static nonlinear element and a linear dynamic element. The static nonlinear element is a sum of known basis functions and the linear dynamic element is a parametric rational transfer function. The proposed method is based on the projection of input-output data onto the finite dimensional parameter space whose basis is determined by the structure of an overparameterized representation of the Hammerstein model. Simulation results show the effectiveness of the proposed continuoustime identification method.

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In this paper, two methods of folding a thick circular panel are studied based on origami engineering. A thick circular panel is rigid and folded around the central hub. One method is based on trimming the volume by bisecting panels of dihedral angles between adjacent facets and the other is applying thin films with specified widths at fold-lines. The former method is effective for some specific models but it cannot be able to apply to this model. The latter method using thin films compensate for the disadvantage of the former method and found that it can be applied to the thick panel foldings.

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Origami structure has two major characteristics; light and rigid, foldable and deployable. And so, it is used effectively in industry. If we can fold empty cans and plastic bottles after drinking, it is possible to consider new industrialization, but it has not been put to practical use yet. Recently, Tachi-Miura 's Polyhedron is drawing attention as a three - dimensional version of Miura - Ori. On the other hand, Nojima regarded Tachi-Miura's Polyhedron as a type of paring origami, also developed a more compact, paring origami structure. It is called Nojima's Polyhedron. These can be folded in the vertical direction of the cylindrical shell as well as in the radial direction. The applicability of these two paring origami structures is examined in this paper. We studied the crushing and spring back characteristics of both structures, and explore their possibility. First, we studied about geometrical features of each Polyhedron and shows that the analysis models are made from 5 key nodes. After that we prepared some analysis models and made some analysis with LS-DYNA, software by finite element method. Then, we tried optimization analysis to minimize the crushing force of each Polyhedron structure and spring back analysis to examine the possibility of application to aluminum cans.

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Implantable artificial lung has not been developed yet, because the alveolar structure in the human lung is too fine and too complicated to be artificially made and manipulated. I proposed an Origami model of the human alveolar structure which mimics the respiratory motion by changing the folding angles. I recently have simulated the gas-exchange in the human lung using an extended 4D alveolar model with the capillary space in the alveolar wall, and revealed that the huge surface area corresponding to a tennis court is unnecessary for human beings and that the fine alveolar structure is required not for gas-exchange but for the lung elastic recoil. Therefore, it is possible to make an implantable artificial lung by combing Origami Engineering and computational simulation study for the respiratory physiology.

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The earthquake is natural disaster which is irresistible and hard to forecast. In the earthquake, the helmets play an important role in protecting the head of people. The traditional helmets have some disadvantages of storability. Though very few foldable helmets have been designed, the price of those are expensive. In order to overcome these disadvantages, and from the prospect of application to origami-engineering, we challenged to invent a foldable helmet based on origami structures. We designed the helmet using the origami structures of accordion cover origami structure/honeycomb origami structure and the low-priced energy absorption material of corrugated cardboard. Because the designed origami helmet is necessary to satisfy the safety performance, the impact FEM analyses are done to investigate the mechanical characteristics of the designed origami helmets. And the experiments are also done to confirm the safety performance of the designed helmets. Finally, the numerical analysis results are compared with the experimental results.

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As part of house design and selling procedures, the option to create and observe the final result using a scale model is essential to analyze and make important decisions about the shape of the house, or structural modifications. In this work, we developed a methodology able to create a three-dimensional (3D) house-model using its elevation views (north, south, east, and west). After the 3D model is created, a top-view projection of the house’s ceiling is used to similar shape matching with a previously known ceiling from the satellite image. Here, we proposed a polygon matching methodology using genetic algorithms (GA) in combination with image processing procedures. After the best matching polygon is found, the scale given by the satellite image is used to rectify the 3D house-model proportions and to make a scale model. The rectified dimensions are used to create an origami crease pattern from all the parts of the house, and create a scale house-model using paper materials.

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